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<?xml version="1.0"?>

<!DOCTYPE TEI.2 SYSTEM "base.dtd">





<publicationStmt><distributor>BASE and Oxford Text Archive</distributor>


<availability><p>The British Academic Spoken English (BASE) corpus was developed at the

Universities of Warwick and Reading, under the directorship of Hilary Nesi

(Centre for English Language Teacher Education, Warwick) and Paul Thompson

(Department of Applied Linguistics, Reading), with funding from BALEAP,

EURALEX, the British Academy and the Arts and Humanities Research Board. The

original recordings are held at the Universities of Warwick and Reading, and

at the Oxford Text Archive and may be consulted by bona fide researchers

upon written application to any of the holding bodies.

The BASE corpus is freely available to researchers who agree to the

following conditions:</p>

<p>1. The recordings and transcriptions should not be modified in any


<p>2. The recordings and transcriptions should be used for research purposes

only; they should not be reproduced in teaching materials</p>

<p>3. The recordings and transcriptions should not be reproduced in full for

a wider audience/readership, although researchers are free to quote short

passages of text (up to 200 running words from any given speech event)</p>

<p>4. The corpus developers should be informed of all presentations or

publications arising from analysis of the corpus</p><p>

Researchers should acknowledge their use of the corpus using the following

form of words:

The recordings and transcriptions used in this study come from the British

Academic Spoken English (BASE) corpus, which was developed at the

Universities of Warwick and Reading under the directorship of Hilary Nesi

(Warwick) and Paul Thompson (Reading). Corpus development was assisted by

funding from the Universities of Warwick and Reading, BALEAP, EURALEX, the

British Academy and the Arts and Humanities Research Board. </p></availability>




<recording dur="01:03:53" n="10253">


<respStmt><name>BASE team</name>



<langUsage><language id="en">English</language>



<person id="nm0217" role="main speaker" n="n" sex="m"><p>nm0217, main speaker, non-student, male</p></person>

<person id="om0218" role="observer" n="o" sex="m"><p>om0218, observer, observer, male</p></person>

<person id="sf0219" role="participant" n="s" sex="f"><p>sf0219, participant, student, female</p></person>

<person id="sf0220" role="participant" n="s" sex="f"><p>sf0220, participant, student, female</p></person>

<person id="sm0221" role="participant" n="s" sex="m"><p>sm0221, participant, student, male</p></person>

<person id="sm0222" role="participant" n="s" sex="m"><p>sm0222, participant, student, male</p></person>

<person id="sf0223" role="participant" n="s" sex="f"><p>sf0223, participant, student, female</p></person>

<person id="sf0224" role="participant" n="s" sex="f"><p>sf0224, participant, student, female</p></person>

<person id="sm0225" role="participant" n="s" sex="m"><p>sm0225, participant, student, male</p></person>

<person id="sf0226" role="participant" n="s" sex="f"><p>sf0226, participant, student, female</p></person>

<person id="sm0227" role="participant" n="s" sex="m"><p>sm0227, participant, student, male</p></person>

<personGrp id="ss" role="audience" size="s"><p>ss, audience, small group </p></personGrp>

<personGrp id="sl" role="all" size="s"><p>sl, all, small group</p></personGrp>

<personGrp role="speakers" size="13"><p>number of speakers: 13</p></personGrp>





<item n="speechevent">Lecture</item>

<item n="acaddept">Zoology </item>

<item n="acaddiv">ls</item>

<item n="partlevel">PG</item>

<item n="module">Man's impact on the environment</item>




<u who="nm0217"> okay think we've probably got a quorum <pause dur="0.3"/> # <pause dur="1.8"/> we <pause dur="0.3"/> # we're going to be recorded for posterity today </u><pause dur="0.2"/> <u who="ss" trans="pause"> oh </u><u who="nm0217" trans="overlap"> do you want to say do you want to say something about what you're doing <pause dur="0.7"/> do you mind </u><u who="om0218" trans="overlap"> yeah <pause dur="0.2"/> # well <pause dur="0.8"/> i'm working at CALS which is next door Centre for Applied Studies and and we <pause dur="0.6"/> work with international students who <pause dur="0.2"/> entering the university <pause dur="0.4"/> trying to help them to prepare for <pause dur="0.5"/> listening to lectures and writing <pause dur="0.7"/> # assignments and so on <pause dur="0.6"/> and i'm going round the university collecting recordings of lectures <pause dur="0.3"/> in different departments so that i can have a look at the kinds of <pause dur="0.5"/> language that's used <pause dur="0.3"/> in lectures <pause dur="0.7"/> so then we hope we can improve our teaching <vocal desc="laughter" n="sl" iterated="y" dur="2"/> </u><pause dur="0.9"/> <u who="nm0217" trans="pause"> yeah so we're going to be recorded for posterity on a C-D i think is it </u><pause dur="0.5"/> <u who="om0218" trans="pause"> a minidisc <pause dur="0.2"/> yes </u><u who="nm0217" trans="overlap"> wow </u><pause dur="0.2"/> <u who="sf0219" trans="pause"> ooh </u><u who="nm0217" trans="latching"> technology <pause dur="0.4"/> so if any of you want to shout out Judas in the middle of the lecture <vocal desc="laughter" n="sl" iterated="y" dur="2"/> Bob Dylan fans would only understand that one <pause dur="0.3"/> <vocal desc="laughter" iterated="y" dur="1"/><pause dur="1.2"/> # it's quite ironic 'cause i got <pause dur="0.6"/> # <pause dur="0.2"/> at the end

of the <trunc>firs</trunc> the student response for the first year module <pause dur="1.0"/> i did last term i got four-point-<pause dur="0.2"/>seven out of five for audibility of voice when i told my wife this she said she thought i was making it up 'cause she said i mumble all the time <pause dur="1.2"/><vocal n="ss" desc="laughter" iterated="y" dur="1"/> it's usually when i she says things like oh isn't it about time you painted that window sill with all the little teeth marks in i say yeah all right <gap reason="inaudible" extent="1 sec"/> <vocal desc="laughter" n="sl" iterated="y" dur="2"/> <pause dur="1.0"/> so <shift feature="voice" new="laugh"/> # anyway <shift feature="voice" new="normal"/> <pause dur="0.5"/> i'll try and be fairly # <pause dur="0.9"/> audible today <pause dur="1.4"/> # <pause dur="0.6"/> this also means that if there's anything we don't want to appear on the tape i can write it on the board and # <vocal desc="laughter" n="sl" iterated="y" dur="2"/> <pause dur="1.2"/> and see <pause dur="0.3"/> # now there's a slight change to the programme like the video i was going to show you today i lent to a student who of course hasn't returned it on time despite several reminders <pause dur="0.4"/> so # i'll have to show it to you # what i'll probably do is to you in week nine <pause dur="0.6"/> # when we've got <trunc>tho</trunc> <pause dur="0.3"/> in week nine <pause dur="0.3"/> on the timetable we've got debate preparation <pause dur="0.8"/> on that day i've got to give two lectures to the first years

which i won't finish till eleven <pause dur="0.8"/> so what i'll probably do is have a have a meeting <pause dur="0.4"/> say for half an hour at eleven o'clock to discuss the debate <pause dur="0.2"/> the following week <pause dur="0.8"/> and then # i'll show you the video which is about forty-five minutes <pause dur="0.5"/> so we'll do that in week nine so what i've done instead today is i've picked out some more <pause dur="0.6"/> # slides so at the end of the two lectures today we're going to have <pause dur="0.7"/> # a couple of dozen slides to back up some of the things i'm going to talk about <pause dur="1.3"/> now we're going to do # <trunc>th</trunc> <trunc>th</trunc> in fact we're going to do three topics today <pause dur="1.6"/> # <pause dur="0.5"/> before the coffee break i'm going to talk about pesticides <pause dur="0.5"/> and then after the coffee break <pause dur="0.9"/> i'm going to <pause dur="0.9"/> cover <pause dur="0.2"/> # introduce you to the concepts of risk assessment as they're used in environmental management <pause dur="1.0"/> and also in human <pause dur="0.6"/> health as well <pause dur="0.4"/> with special emphasis on the mad cow disease epidemic and its possible <pause dur="0.7"/> # the possible numbers of people who are going to be affected by <pause dur="0.6"/> # the human variant of mad cow disease which as you'll see from the

handout <pause dur="0.4"/> could be anything from <pause dur="0.3"/> a hundred to several thousand <pause dur="0.7"/> the data at the moment isn't <pause dur="0.2"/> isn't concrete enough to make an accurate prediction <pause dur="1.3"/> and then i'm going to say something briefly about ecotoxicology which is the way in which we can try and <pause dur="0.5"/> assess the environmental effects of chemicals <pause dur="0.4"/> before they're released into the environment using standard <pause dur="0.5"/> test animals <pause dur="0.4"/> but i'll go into that in a lot more detail after the break <pause dur="1.8"/><kinesic desc="puts on transparency" iterated="n"/> okay so <pause dur="0.5"/> first of all we're going to look at <pause dur="1.1"/> # the <trunc>c</trunc> <pause dur="1.7"/> couple of pesticides with obviously an environmental <pause dur="2.3"/> emphasis <pause dur="2.3"/> now <pause dur="0.5"/> <trunc>th</trunc> <trunc>th</trunc> the most important thing to <trunc>b</trunc> bear in mind throughout the lecture really is <pause dur="0.5"/> pest is a human definition <pause dur="0.8"/> and a pest is simply a plant <pause dur="0.7"/> or an animal which is living where man <pause dur="0.4"/> doesn't want it to live <pause dur="7.1"/> # and the best example i like to use of this is # is moles <pause dur="1.1"/> # i quite like moles i think they're quite cuddly cute little animals but of course they're considered to be a pest and it's quite legal to poison them and trap them <pause dur="0.7"/>

things like bats which i think are ugly <pause dur="0.5"/> little blighters <vocal desc="laughter" n="sl" iterated="y" dur="1"/> <pause dur="0.6"/> # have enormous protection and if you <pause dur="0.2"/> have bats in your loft bats in your belfry even <pause dur="0.4"/> you it's illegal to disturb them even if they're filling the <pause dur="0.4"/> the void of your loft space up with # <pause dur="0.3"/> bat droppings <pause dur="0.6"/> and you can't <pause dur="0.2"/> you can't disturb them and it's simply a # human perception of moles <pause dur="0.9"/> are not good and bats are good <pause dur="1.0"/> and # i saw this thing which has quite amused me which was # <pause dur="0.8"/><kinesic desc="changes transparency" iterated="y" dur="4"/> i'll put this back up in a second <pause dur="0.6"/> which was another thing from the innovations report <pause dur="0.8"/> # and it's a thing called the sonic <pause dur="0.6"/> mole chaser <pause dur="0.2"/> the idea is that it's an environmentally friendly <pause dur="1.5"/> way of getting rid of moles <pause dur="1.1"/> it says these <pause dur="0.3"/> what you do is you ram this thing into the ground <pause dur="0.5"/> and it <trunc>le</trunc> <pause dur="0.3"/> lets off a low frequency vibration and this annoys the moles and they move away <pause dur="0.7"/><vocal desc="cough" iterated="n"/> and there's a little <pause dur="0.7"/> cartoon here of a mole disappearing presumably into next door's garden <pause dur="0.8"/> it says <vocal desc="laughter" n="ss" iterated="y" dur="1"/> these <shift feature="voice" new="laugh"/> <trunc>sil</trunc> <shift feature="voice" new="normal"/> <reading>these silent and unobtrusive repellents <pause dur="0.5"/> are a humane way of persuading

moles to leave the area</reading> <pause dur="0.7"/> it's recommended by the Northern the widely read Northern Gardener magazine <pause dur="0.3"/><vocal desc="laughter" n="sl" iterated="y" dur="1"/> <pause dur="0.4"/> but the best one i heard was a # it was on the Gardeners' Question Time on the radio where apparently you <pause dur="0.9"/> if you want to get rid of moles what you do is you buy one of these Christmas cards or birthday cards that when you open it up it plays Greensleeves or something <pause dur="0.5"/> you take the little <pause dur="0.3"/> musical <pause dur="0.2"/> chip out of it <pause dur="0.7"/> these last for about three months apparently and you drop them down the hole <pause dur="0.7"/> and the moles get so annoyed <pause dur="1.5"/> or <pause dur="3.0"/><kinesic desc="reveals covered phrase on board" iterated="n"/> <vocal desc="laughter" n="ss" iterated="y" dur="2"/> that # <vocal desc="laughter" n="sl" iterated="y" dur="1"/> that # <pause dur="0.7"/><vocal desc="laughter" n="sf0220" iterated="y" dur="1"/> that they they go into next door's garden and these things <vocal desc="laughter" n="ss" iterated="y" dur="2"/> <shift feature="voice" new="laugh"/> last for about <shift feature="voice" new="normal"/> three months <pause dur="0.5"/> # and it's a sort of environmentally friendly way of # of getting rid of moles <vocal desc="laughter" n="ss" iterated="y" dur="1"/> <pause dur="0.4"/> and then <pause dur="0.2"/> three months later you <kinesic desc="changes transparency" iterated="y" dur="3"/> just buy another one <pause dur="2.3"/> right now then # it might surprise you to know <pause dur="0.2"/> that <pause dur="1.2"/> most pesticides have not been developed <pause dur="0.8"/> to <pause dur="0.8"/> kill off insects <pause dur="1.0"/> and in fact the main thrust of the <pause dur="0.7"/> of the G-M crops the genetically modified crops research <pause dur="0.5"/> has been not <pause dur="0.3"/> to develop

plants that resist insects although of course that is part of the <pause dur="0.4"/> research programme <pause dur="0.8"/> the main development is to do with <pause dur="0.5"/> the fact that most pesticides are used to kill off other plants <pause dur="1.4"/> and just to give you an </u><u who="sm0221" trans="overlap"> sorry can you repeat it </u><pause dur="0.5"/> <u who="nm0217" trans="pause"> pardon </u><u who="sm0221" trans="latching"> sorry can you repeat it </u><pause dur="0.7"/> <u who="nm0217" trans="pause"> which bit </u><pause dur="0.7"/> <u who="sm0221" trans="pause"> <gap reason="inaudible" extent="1 sec"/> </u><pause dur="0.5"/> <u who="nm0217" trans="pause"> # <pause dur="0.2"/> most </u><u who="sm0221" trans="overlap"> <gap reason="inaudible" extent="2 secs"/> </u><pause dur="0.3"/> <u who="nm0217" trans="pause"> # genetically modified crops </u><u who="sm0221" trans="overlap"> <gap reason="inaudible" extent="1 sec"/> thank you </u><pause dur="2.6"/> <u who="nm0217" trans="pause"> is that okay </u><pause dur="0.8"/> <u who="sm0221" trans="pause"> <gap reason="inaudible" extent="1 sec"/> </u><u who="nm0217" trans="overlap"> the whole <vocal desc="laughter" n="ss" iterated="y" dur="1"/> sentence <shift feature="voice" new="laugh"/> right <shift feature="voice" new="normal"/></u><u who="sm0222" trans="overlap"> <gap reason="inaudible" extent="1 sec"/> sentence </u><pause dur="0.6"/> <u who="nm0217" trans="pause"> # <pause dur="1.9"/> research into genetically modified crops you might think it was <trunc>main</trunc> mainly to do with <pause dur="0.4"/> developing crops that were resistant to insects </u><u who="sm0221" trans="latching"> mm </u><pause dur="0.5"/> <u who="nm0217" trans="pause"> the main in <trunc>p</trunc> but in fact the main <pause dur="0.2"/> <trunc>t</trunc> <pause dur="0.2"/> # <pause dur="1.3"/> traits that are being <pause dur="0.6"/> selected for are resistance to herbicides <pause dur="0.6"/> in plants <pause dur="2.2"/> okay </u><pause dur="1.1"/> <u who="sf0223" trans="pause"> <gap reason="inaudible" extent="1 word"/> </u><pause dur="1.5"/> <u who="nm0217" trans="pause"> and <pause dur="0.6"/> this is because in the U-K for example about eighty per cent <pause dur="0.6"/> of pesticide usage is for herbicides <pause dur="0.5"/> just for spraying for weeds <pause dur="1.0"/> and only about ten per cent is for fungicides and about ten per cent for insecticides and then a minor component <pause dur="0.7"/> for killing off other things for example <pause dur="0.5"/> pesticides for killing off rats of course are called rodenticides <pause dur="0.5"/> and i think

you've probably heard quite a lot about that in the course <pause dur="0.2"/> already <pause dur="1.6"/> # <pause dur="0.4"/> for herbicides <trunc>th</trunc> <pause dur="1.0"/> the usage is mainly to do with # direct drilling <pause dur="0.2"/> where <pause dur="0.5"/> in the past # historical past of course <pause dur="0.3"/> farmers would have always ploughed their fields before they planted the crops to kill off the weeds <pause dur="0.6"/> now they can spray the fields and kill off the weeds and then plant the seeds directly in the ground without having to <pause dur="0.4"/> to plough the <pause dur="0.2"/> plough the field and this saves them an enormous amount of money in labour <pause dur="1.0"/> this is called direct drilling <pause dur="1.0"/> # fungicides are used mainly for seed dressings <pause dur="0.7"/> when you collect seeds from a crop <pause dur="0.2"/> to store for the following year if you store them in a <pause dur="0.3"/> in a barn or something they can go mouldy quite quickly so if you <pause dur="0.2"/> cover the seeds in a very thin layer of <pause dur="0.4"/> of fungicide <pause dur="0.6"/> and this prevents them from going mouldy <pause dur="0.3"/> this is the main use of fungicides <pause dur="0.5"/> in the U-K <pause dur="0.9"/> insecticides have a have a <pause dur="0.5"/> much smaller usage <pause dur="0.5"/> because there aren't any really major insect pests of

crops <pause dur="0.6"/> and we don't in the U-K we don't get things like locusts swarms <pause dur="0.4"/> # coming in <pause dur="0.3"/> and it's only occasionally when you get things like Colorado beetles <pause dur="0.3"/> which is on the handout that i gave you <pause dur="0.4"/> arriving <pause dur="0.3"/> that # <trunc>tha</trunc> that you have to very seriously spray for insect pests <pause dur="0.8"/> so that's the sort of ratio that # <pause dur="0.5"/> of usage that you get <pause dur="1.8"/> now the <pause dur="0.3"/> ideal pest-killing chemical <pause dur="0.6"/> if it existed <pause dur="1.1"/><kinesic desc="changes transparency" iterated="y" dur="2"/> would <pause dur="0.5"/> do the following <pause dur="0.7"/> first of all it would only kill the target pest <pause dur="3.5"/> so <pause dur="0.5"/> if you have a pest <pause dur="0.9"/> problem <pause dur="1.0"/> you want your pesticide to be very specific to only target the specific thing that you're trying to <pause dur="0.3"/> kill off <pause dur="1.5"/> of course as we know that's not <pause dur="0.8"/> often # <pause dur="0.3"/> invariably not the case <pause dur="1.6"/> # <pause dur="2.5"/> they should have no short <pause dur="0.3"/> or long term health effects <pause dur="0.9"/> on non-target organisms and this of course includes people <pause dur="6.2"/> clearly you <pause dur="0.5"/> preferably don't want to kill off the natural predators <pause dur="1.0"/> of things so if you have had a <pause dur="0.3"/> problem with <pause dur="1.4"/> greenfly <pause dur="0.3"/> # aphids on a crop <pause dur="0.9"/> # clearly you don't want to kill off all the ladybirds because ladybirds eat lots

of aphids lots of greenfly <pause dur="1.0"/> but if you spray the crop to kill off the aphids then you'll kill off their natural predators as well <pause dur="0.5"/> so the pest problem in the long term can in fact become worse <pause dur="2.1"/> so ideally you'd want to target a specific # <pause dur="0.5"/> specific organism that was causing the problem <pause dur="3.6"/> # the third <pause dur="0.2"/> factor is you'd want them to break down rapidly into harmless components better rub this off while i remember hadn't i <pause dur="0.4"/><event desc="wipes board" iterated="y" dur="1"/><vocal desc="laughter" n="sl" iterated="y" dur="1"/> <pause dur="2.4"/> break down into harmless components <pause dur="0.6"/> so that you spray your <pause dur="0.6"/> or you apply your chemical to the crop <pause dur="0.4"/> it kills the pest <pause dur="0.3"/> and then it breaks down very quickly <pause dur="1.5"/> and # one as we'll see one of the problems of pesticides that were used <trunc>s</trunc> <trunc>s</trunc> historically in in the past <pause dur="0.7"/> was that many of them were extremely persistent <pause dur="0.9"/> you remember when we did the practical on D-D-T <pause dur="0.3"/> the <pause dur="0.3"/> D-D-T was shown to cause eggshell thinning <pause dur="0.9"/> eggshell thinning in birds of prey <pause dur="0.8"/> and i'll come back that to that in a bit more detail later on <pause dur="0.7"/> but the pesticides which are being developed nowadays

tend to have a much shorter half-life in the environment <pause dur="0.6"/> and some of them will in fact break down instantly when they touch the soil <pause dur="0.5"/> so # they're very effective <pause dur="0.3"/> when you spray them but they break down very quickly so there aren't such long term <pause dur="0.5"/> effects <pause dur="1.3"/> a fourth # factor is quite important <pause dur="0.7"/> although difficult to control <pause dur="0.2"/> i mean <trunc>i</trunc> the ideal <trunc>pe</trunc> # pesticide should prevent <pause dur="0.9"/> the development of genetic resistance to target <pause dur="0.4"/> organisms <pause dur="1.9"/> and i'll come back to this in more detail later on <pause dur="0.8"/>

but # <pause dur="0.9"/> there are several species of insects which have become resistant <pause dur="0.5"/> to a <trunc>w</trunc> a wide range of pesticides <pause dur="0.5"/> and these are have very difficult to control <pause dur="0.6"/> in the field without # <pause dur="0.3"/> massive applications of pesticides which become ecologically <pause dur="0.4"/> unacceptable <pause dur="1.6"/> finally <pause dur="0.2"/> # <pause dur="0.4"/> farmers of course are all in in a business <pause dur="0.2"/> as as we hear <pause dur="0.7"/> <trunc>i</trunc> increasingly nowadays <pause dur="0.6"/> and the use of pesticides <pause dur="0.4"/> should save money compared to making no effort to control pest species <pause dur="2.8"/> and # pesticides are relatively have been relatively cheap <pause dur="0.2"/> # and it's <pause dur="0.3"/> in the <trunc>farm</trunc> <pause dur="0.2"/> been in the farmer's interest to spray the crops very regularly <pause dur="0.6"/> without actually <pause dur="1.0"/> doing doing without the scientific back-up to to <pause dur="0.7"/> # know whether or not this # is an an effective way of controlling the pests <pause dur="1.4"/> sometimes you can get away with much fewer with with many fewer <pause dur="0.3"/>

applications of pesticides if you look for example at the climate <pause dur="0.4"/> and the the weather conditions <pause dur="0.3"/> and # <trunc>th</trunc> the natural population fluctuations of the pests rather than just spraying <pause dur="0.4"/> say every <pause dur="0.3"/> on the first Monday of every month <pause dur="0.5"/> because your farmhand happens to have that allocated in his diary <pause dur="0.6"/> look at the population structure of the pests <pause dur="0.7"/> look at the weather <pause dur="0.3"/> what's the best time to spray to have the most effective effect rather than just <pause dur="0.7"/> # <pause dur="1.3"/> spraying just because it happens to be that time of the month <pause dur="2.3"/><kinesic desc="changes transparency" iterated="y" dur="9"/> okay now i want to say something very briefly about the different <trunc>th</trunc> the three main <pause dur="1.3"/> types <pause dur="1.0"/> of pesticide <pause dur="1.5"/> just to illustrate the sort of <pause dur="0.5"/> problems that you can have environmental problems that you can have <pause dur="4.7"/> now <pause dur="0.9"/> the most or <pause dur="0.3"/> one of the most effective herbicides <pause dur="0.2"/> that's a <pause dur="0.2"/> pesticide for killing other plants <pause dur="0.6"/> is a <trunc>s</trunc> chemical called two-four-five-T <pause dur="1.5"/> and this was very widely used in farming <pause dur="1.0"/> and was also unfortunately very widely used in the Vietnam War <pause dur="0.2"/> where it became known as Agent

Orange <pause dur="1.1"/> and the American Army sprayed <pause dur="0.5"/> # vast areas of the Vietnamese jungle <pause dur="0.7"/> with two-four-five-T <pause dur="0.8"/> # <pause dur="0.3"/> in an attempt to actually wipe out the jungle completely so the Viet Cong <pause dur="0.5"/> had nowhere to hide <pause dur="1.4"/> couldn't hide in the jungle and <trunc>l</trunc> vast tracts of Vietnam were laid waste by the spraying of this chemical <pause dur="0.8"/> and unfortunately during the manufacturing process <pause dur="0.8"/> there's an impurity which <pause dur="1.7"/> evolves <pause dur="0.3"/> in the in the chemical process called dioxin and dioxin is extremely toxic <pause dur="0.9"/> and <pause dur="0.2"/> many of the American servicemen who were involved in spraying this chemical <pause dur="0.4"/> and also farm workers who were spraying two-four-five-T <pause dur="0.6"/> # <pause dur="0.7"/> got some symptoms of dioxin poisoning <pause dur="0.6"/> which is a general sort of # aching of the body aching of the limbs <pause dur="0.4"/> # acne develops on the skin you get quite severe acne <pause dur="0.6"/> # and eventually headaches # and # it can be quite dehabilitating <pause dur="0.8"/> of course what happened to the <pause dur="0.2"/> poor Vietnamese who were in the <shift feature="voice" new="laugh"/> jungle <shift feature="voice" new="normal"/> <pause dur="0.7"/> when they got sprayed i mean they've got very badly affected as well so # <pause dur="0.6"/> the

effects of dioxin <pause dur="0.3"/> <trunc>ca</trunc> # have been quite serious <pause dur="0.4"/> so one of the problems with <pause dur="0.2"/> pesticides is that can contain impurities which cause effects <pause dur="0.4"/> which are nothing to do with the <pause dur="0.9"/> # <trunc>th</trunc> <trunc>th</trunc> the pest-killing <pause dur="0.7"/> status <pause dur="2.0"/><kinesic desc="changes transparency" iterated="y" dur="3"/> # <pause dur="0.3"/> for fungicides <pause dur="0.5"/> there is an example <pause dur="0.3"/> quite a <trunc>sev</trunc> <trunc>s</trunc> # serious example <pause dur="0.4"/> in Iraq in nineteen-seventy where <pause dur="0.7"/> # seeds were dressed with mercury <pause dur="0.2"/> it was quite common a common practice to dress seeds with mercury as a fungicide <pause dur="1.0"/> <trunc>ev</trunc> even in the U-K up until # <pause dur="0.3"/> the early nineteen-nineties it was still legal to do this <unclear>no doubt</unclear> now it's been stopped <pause dur="1.5"/> but # in Iraq in nineteen-seventy <pause dur="0.7"/> # the mercury which had been dressed <trunc>s</trunc> <pause dur="0.3"/> <trunc>w</trunc> <pause dur="0.3"/> <trunc>ha</trunc> was by mistake sent to a bakery <pause dur="0.5"/> and # loads of bread were made out of this <trunc>brea</trunc> this these seeds <pause dur="0.6"/> and # before it was discovered <pause dur="0.7"/> # <pause dur="0.3"/> that that this <pause dur="0.9"/> had # had occurred # about a thousand people died of mercury poisoning <pause dur="0.3"/> and many others were # <pause dur="0.4"/> dehabilitated by the mercury <pause dur="3.1"/> so you have to be very careful with these things with # that that that

that they don't get <pause dur="0.7"/> move in the wrong direction in the food chain <pause dur="8.6"/><kinesic desc="changes transparency" iterated="y" dur="6"/> okay now thirdly <pause dur="0.3"/> insecticides <pause dur="1.9"/> # insecticides have been <pause dur="0.6"/> again very widely <pause dur="0.4"/> used and they're they've been studied quite intensively because of their potential effects on # high levels in the food chain <pause dur="1.3"/> and <pause dur="0.2"/> historically chemicals like D-D-T which were <pause dur="0.3"/> developed <pause dur="1.9"/> # <pause dur="0.8"/> some some years ago now have have had a long half-life so <pause dur="0.3"/> D-D-T technically has a half-life <pause dur="0.5"/> of two-point-eight years <pause dur="0.6"/> and <pause dur="0.9"/> the ninety-five per cent breakdown <pause dur="0.8"/> is about ten years <pause dur="0.6"/> but # this can be much longer if <pause dur="0.3"/> the D-D-T is in a <pause dur="0.4"/> a cold environment or a dry environment <pause dur="1.2"/> <trunc>th</trunc> the breakdown is very <trunc>affecti</trunc> # is very # affected by the temperature and the climatic conditions so these this is a sort of average figure <pause dur="0.4"/> it can be much longer <pause dur="0.5"/> now more modern insecticides like aldrin <pause dur="0.5"/> # have a much shorter half-life <pause dur="1.1"/> and they tend to break down more quickly and the very modern ones <pause dur="0.2"/> will break down often in a period of days <pause dur="1.6"/><kinesic desc="changes transparency" iterated="y" dur="3"/> and of course the

problem with these insecticides is that they can accumulate in the food chain <pause dur="0.7"/> now you don't need to copy this <pause dur="0.2"/> down because you've had it on the # on the handout that i gave you for the practical but just to <pause dur="0.6"/> # <pause dur="1.0"/> reiterate again the problem about the eggshell thinning <pause dur="1.3"/> the # D-D-T which was used very widely for <trunc>sp</trunc> for spraying crops <pause dur="0.3"/> as an insecticide <pause dur="0.6"/> was accumulated through the food chain <pause dur="0.8"/> and # birds of prey like peregrine falcons and sparrow hawks which were eating <pause dur="0.5"/> # <pause dur="0.3"/> small small mammals and birds which had <pause dur="0.3"/> accumulated D-D-T <pause dur="0.7"/><vocal desc="cough" iterated="n"/> became # badly affected because their <pause dur="0.5"/> the D-D-T would <pause dur="0.2"/> would interfere with the calcium metabolism of the birds <pause dur="1.4"/> so if you remember from the practical when we measured the egg <pause dur="0.2"/> eggshells <pause dur="0.4"/> # i've just put up the peregrine falcon data <pause dur="0.5"/> # we saw a thinning of the peregrine falcon <pause dur="1.0"/> eggs that had been removed from <pause dur="0.3"/> abandoned nests <pause dur="0.5"/> # in the sort of nineteen-fifties nineteen-sixties and there has quite been quite good recovery <pause dur="0.5"/> # in recent years although we did still find a

few eggs that were <pause dur="0.3"/> were thinned <pause dur="2.4"/> okay so <pause dur="1.3"/> there can be impurities in these pesticides they can <pause dur="0.7"/> get # into the human food chain if <kinesic desc="changes transparency" iterated="y" dur="9"/> if you're not very careful <pause dur="0.5"/> and the insecticides can also affect <pause dur="0.3"/> things if they pass up through the food chain <pause dur="1.9"/> now D-D-T it might interest you to know you'd think that D-D-T would have been banned but in fact this is an article from New Scientist <pause dur="0.4"/> on the eighteenth of September <pause dur="0.4"/> last year <pause dur="0.8"/> and it says here <reading>proposals to ban the pesticide D-D-T by two-thousand-and-seven <pause dur="0.6"/> have been dropped <pause dur="0.9"/> for fear of harming efforts to fight malaria <pause dur="0.7"/> instead countries negotiating to limit persistent organic pollutants <pause dur="0.5"/> agreed in Geneva last week to achieve elimination over time</reading> which is a good <pause dur="0.2"/> politician's fudge phrase <pause dur="0.5"/> <reading>on condition that poor countries get help <pause dur="0.3"/> finding alternatives <pause dur="1.3"/> # World Wide Fund <pause dur="0.2"/> for Nature says combinations of safer insecticides bed nets and draining of mosquito breeding areas <pause dur="0.2"/> control malaria just as well <pause dur="0.7"/> but the World

Wildlife Fund dropped calls for a ban by two-thousand-and-seven <pause dur="0.4"/> because arguments over the date got in the way of the more important goal <pause dur="0.4"/> of helping poor countries adopt alternatives</reading> <pause dur="0.7"/> so <pause dur="0.2"/> the proposal to ban D-D-T by two-thousand-and-seven <pause dur="1.1"/> has in fact been <pause dur="1.3"/> dropped <pause dur="0.9"/> so D-D-T is still being used <pause dur="0.4"/> in # developing countries <pause dur="2.2"/> and of course if we have birds which # migrate <pause dur="0.3"/> like the osprey which migrate from Scotland <pause dur="0.6"/> down to # <pause dur="0.8"/> to Africa <pause dur="0.6"/> then they can pick up the D-D-T <pause dur="0.2"/> when they're in Africa and then when they come back to the U-K and start laying eggs <pause dur="0.5"/> that can cause problems <pause dur="0.7"/> if the eggshells are thinned <pause dur="2.6"/><kinesic desc="changes transparency" iterated="y" dur="3"/> okay <pause dur="0.5"/> so how are pesticides evolved there are three main generations of pesticides <pause dur="0.4"/> the third of which has <pause dur="0.7"/> arisen in the last few years <pause dur="0.7"/> but the first generation pesticides <pause dur="0.3"/> pesticides have been around for a very long time <pause dur="2.6"/> # <pause dur="0.7"/> before nineteen-forty <pause dur="0.5"/> which is a good sort of cut-off point <pause dur="1.9"/> pesticides were <pause dur="0.6"/> invariably natural products <pause dur="3.7"/> and the pesticide pyrethrum <pause dur="0.7"/> which is an extract from <pause dur="0.3"/> #

flowers of a <pause dur="0.3"/> pyrethrum plant so you pick the <pause dur="0.2"/> the flowers from the pyrethrum plant <pause dur="0.7"/> # and they would be soaked in water and then you could spray that onto crops and the natural defence of the plant would also protect against insects <pause dur="0.7"/> and there's evidence that the Chinese were doing this # two-thousand years ago so <pause dur="0.4"/> many quite ancient cultures <pause dur="0.5"/> have been using pesticides for <pause dur="0.2"/> some considerable time <pause dur="2.1"/> but # <pause dur="1.1"/> <trunc>s</trunc> <pause dur="0.2"/> just <trunc>bef</trunc> before and after the Second World War <pause dur="0.2"/> there was a an explosion in the chemical industry <shift feature="voice" new="laugh"/> # not an explosion <pause dur="0.2"/> expansion <shift feature="voice" new="normal"/> <pause dur="0.7"/><vocal desc="laughter" n="ss" iterated="y" dur="1"/> in the <trunc>chemi</trunc> well probably was an explosion as well though <trunc>w</trunc> though i <pause dur="0.3"/> talk about explosions later on <pause dur="0.5"/> # there was a persistent <pause dur="0.8"/> # <trunc>th</trunc> <trunc>th</trunc> the persistent <trunc>organ</trunc> inorganic chemicals were developed <pause dur="0.9"/> and it was thought at the time that # <pause dur="0.6"/> in the sort of white heat of technology <pause dur="0.7"/> that existed that # this was the answer to all pesticide problems <pause dur="0.6"/> and that # if you had a pesticide problem you could just go and spray it with these chemicals and the problem would

disappear <pause dur="0.7"/> of course as we know that hasn't happened <pause dur="3.1"/> # <pause dur="0.5"/> some of the <pause dur="0.2"/> chemicals which were used <pause dur="1.3"/> in <pause dur="0.5"/> in Victorian times <pause dur="0.3"/> were quite toxic and in up to relatively recent times <pause dur="0.8"/> # these include things like Bordeaux mixture <pause dur="0.7"/> which is named after the <pause dur="0.2"/> fact that it was used extensively for spraying vines in France <pause dur="0.5"/> grape vines <pause dur="0.8"/> and these are <trunc>b</trunc> <pause dur="0.2"/> basically just solutions of of metal salts like copper <pause dur="0.4"/> and arsenic <pause dur="2.0"/> and these are very persistent # and these would be sprayed on on <pause dur="0.3"/> crops <pause dur="0.6"/> and # <pause dur="0.4"/> would be quite good at resisting <pause dur="0.8"/> insect attack <pause dur="1.6"/> # i always think it's ironic that if you go a garden centre and you go to the organic <pause dur="0.4"/> sort of gardening section <pause dur="0.7"/> they include <pause dur="0.4"/> Bordeaux mixture as a traditional organic remedy which <shift feature="voice" new="laugh"/> in fact it's <shift feature="voice" new="normal"/> <pause dur="0.3"/> probably about the worst thing you could spray on your <pause dur="0.5"/> on your garden because it is very persistent <pause dur="0.7"/> and # if you analyse soil <pause dur="0.5"/> from gardens and houses of more than <pause dur="0.3"/> say before about nineteen-ten nineteen-twenty <pause dur="0.6"/> they invariably have very high concentrations of <pause dur="0.7"/> # copper

and lead and arsenic because people would traditionally just use this Bordeaux mixture as a traditional remedy <pause dur="0.7"/> # the house we used to live in off the Oxford Road in <gap reason="name" extent="1 word"/> which was built in about nineteen-hundred <pause dur="0.5"/> i analysed the soil <pause dur="0.5"/> from from the back garden and it had about between five and ten times the normal background level of copper <pause dur="0.6"/> and it's almost certainly because people had been spraying Bordeaux mixture <pause dur="0.5"/> on their # on their roses or <shift feature="voice" new="laugh"/> whatever they were growing there <shift feature="voice" new="normal"/> <pause dur="0.7"/> at # the turn of the century <pause dur="5.6"/> okay <pause dur="4.4"/> now the second generation pesticides which have developed from the Second World War onwards are mainly synthetic <pause dur="0.8"/> organic chemicals <pause dur="0.9"/> so for example D-D-T came into <pause dur="0.5"/> widespread use <pause dur="0.5"/> from nineteen-thirty-nine onwards <pause dur="1.8"/> and # <pause dur="0.6"/> it was a very <pause dur="0.2"/> important # chemical it it its <trunc>n</trunc> <pause dur="0.2"/> <trunc>s</trunc> it <trunc>i</trunc> # its use has certainly saved <pause dur="0.7"/> # millions of lives <pause dur="0.7"/> particularly for control in in wartime conditions where you get <pause dur="0.4"/> where you get high concentrations of people soldiers or refugees or <pause dur="0.5"/>

whatever people in very impoverished conditions or difficult <pause dur="0.3"/> cramped conditions <pause dur="0.4"/> you can get <pause dur="0.2"/> diseases # <pause dur="0.2"/> diseases like # typhoid <pause dur="0.6"/> transmitted very easily and and <pause dur="0.3"/> if you have <pause dur="0.4"/> # mites <pause dur="0.5"/> for example which or lice which are transmitting the diseases <pause dur="0.7"/> # these were controlled quite effectively by D-D-T <pause dur="0.8"/> and # this this # <pause dur="0.2"/> had a big effect on # saving many a people's lives <pause dur="0.4"/>

particularly during the war <pause dur="0.8"/> so although <pause dur="0.2"/> these <pause dur="0.2"/> chemicals clearly have have major problems environmentally they have saved a lot of lives <pause dur="1.7"/> now worldwide <pause dur="1.1"/> something like two-point-five-millions tons <pause dur="0.6"/> of second generation pesticides <pause dur="0.6"/> are used every year <pause dur="0.8"/> so the massive <pause dur="0.5"/> massive quantities it's a huge # industry which is economically <pause dur="0.9"/> is very important <pause dur="0.9"/> but # eighty-five per cent of these are used <pause dur="0.9"/> in the most developed countries like # America and <pause dur="0.3"/> Western Europe <pause dur="2.0"/> most farmers in developing countries <pause dur="0.6"/> don't # use <pause dur="1.1"/> as # pesticides <pause dur="0.3"/> very <pause dur="1.2"/> extensively because they're they're expensive <pause dur="0.4"/> and # <pause dur="1.0"/> there are cases of them being used <pause dur="0.4"/> locally of course but # <pause dur="0.2"/> in general <pause dur="0.4"/> most of the pesticides are used <pause dur="0.4"/> in developed countries <pause dur="4.3"/> # there are something like fifty-thousand different types of second generation pesticides <pause dur="0.7"/> which have been developed <pause dur="1.4"/> and of course this has <pause dur="0.4"/> <trunc>implicatio</trunc> environmental implications because it's really would be impossible to test <pause dur="0.7"/> every single <pause dur="1.4"/> pesticide on every single potential species in the wild <pause dur="0.6"/> and ways of getting around this problem i'll come back to later on when we <pause dur="0.2"/> we talk about ecotoxicology after

the break <pause dur="0.7"/> so there are large numbers of of these chemicals <pause dur="0.6"/> and the usage is more or less the same as it is in the U-K <pause dur="1.6"/> about eighty-five per cent <pause dur="0.5"/> of herbicides <pause dur="0.2"/> <trunc>o</trunc> of <trunc>c</trunc> pesticides used in the world are herbicides <pause dur="1.5"/> and of that eighty-five per cent about twenty-five per cent <pause dur="0.2"/> sorry twenty per cent is used on golf courses <pause dur="0.4"/> and gardens <pause dur="1.0"/> i read some statistic once that said that five per cent of all <pause dur="0.6"/> herbicides in the world were sprayed on Japanese golf courses <pause dur="0.8"/> and they just drench them with <pause dur="0.4"/> chemicals to kill off the weeds <pause dur="0.5"/> so they have this very very <pause dur="0.5"/> particularly on the golf greens <pause dur="0.4"/> they have this very very pure # <pause dur="0.3"/> grass <pause dur="0.3"/> on a <pause dur="0.5"/> on a specific <pause dur="0.5"/> culture of grass which is mowed to within a couple of millimetres of <shift feature="voice" new="laugh"/> the soil <pause dur="0.6"/> <shift feature="voice" new="normal"/> so the golfers can <pause dur="1.2"/> knock their balls in the holes <pause dur="2.2"/> another reason reason for <pause dur="0.4"/> banning golfers # <pause dur="0.5"/><vocal desc="laughter" iterated="y" dur="1"/> <pause dur="0.8"/><shift feature="voice" new="laugh"/> # <shift feature="voice" new="normal"/> <pause dur="2.5"/> ten per cent are used # for insecticides <pause dur="0.8"/> and about five per cent for fungicides <pause dur="1.5"/> so # <pause dur="0.6"/> again we can see that the vast majority of chemicals are used for # <pause dur="0.2"/> for herbicides <pause dur="2.7"/>

now <pause dur="0.2"/> the third generation pesticides <pause dur="0.7"/> which have come into <pause dur="0.6"/> being in the last <pause dur="0.8"/> few years of course are genetically modified <pause dur="0.5"/> crops or G-M crops <pause dur="3.3"/> and if i asked any people in this room whether they would eat genetically modified crops i would guess that most people would say no they wouldn't <pause dur="0.9"/> and # the fact is that we've all eaten <trunc>gemet</trunc> genetically modified crops and we've been doing so for at least two or three years <pause dur="0.7"/> and this is because <pause dur="1.0"/> most of the soya <pause dur="0.9"/> that's used <pause dur="0.7"/> in # in food <pause dur="0.3"/> processing for a very very wide range of things like <pause dur="0.2"/> cakes <pause dur="0.9"/> baked beans # <pause dur="1.1"/> sauces # biscuits <pause dur="0.4"/> tons of things <pause dur="0.6"/> are made with the <pause dur="0.2"/> <trunc>h</trunc> have soya added as a as a part of the food # <pause dur="0.3"/> preparation process <pause dur="0.6"/> and most of the soya that's used is now genetically modified soya <pause dur="1.5"/> so we've all been eating it <pause dur="0.8"/> # <pause dur="0.3"/> whether or not we whether we like it or not <pause dur="1.3"/> and the main thrust for the development of the genetically modified crops is to develop <pause dur="1.5"/> crops which are resistant to herbicides <pause dur="0.5"/> which may sound rather peculiar <pause dur="1.6"/> but # the

point of it is that if you can <pause dur="0.5"/> make your crop resistant to herbicides then you can spray <pause dur="0.3"/> # larger quantities of herbicides on a crop <pause dur="0.5"/> you can make them grow faster because you can get <trunc>r</trunc> rid of the weeds more easily <pause dur="0.6"/> # and this is because you <trunc>cou</trunc> if you for example if you spray twice as much herbicide <pause dur="0.4"/> on a herbicide resistant crop <pause dur="0.5"/> in theory you can get rid of the weeds twice as fast <pause dur="0.5"/> because your genetically resistant crop is able to survive much higher doses of herbicide <pause dur="0.9"/> this is very good for the <pause dur="0.2"/> the manufacturers of herbicides because they can sell more <pause dur="0.8"/> basically that's the that's the <trunc>th</trunc> idea behind the <pause dur="0.4"/> the problem <pause dur="1.4"/> and # on the handout one of the handouts i've given you this is # <pause dur="0.8"/> # <pause dur="1.2"/> on the one about Colorado beetle <trunc>i</trunc> i'll come back to Colorado beetles later on <pause dur="1.6"/> # the one that's on sideways on the bottom this is from yesterday's New Scientist so this this <trunc>t</trunc> course is nothing if not # topical <pause dur="0.9"/> and # there's a little article here which says resistance is useless <pause dur="0.7"/>

and it's confirmed that in fact the major fear <pause dur="0.2"/> of the development of these herbicide resistant crops <pause dur="0.5"/> is that the genes for resistance can pass from the crops to the weeds <pause dur="1.2"/> if you then get <pause dur="0.4"/> weeds which are <pause dur="0.4"/> resistant to herbicides you can imagine the potential financial implications for farmers <pause dur="0.9"/> because if you <pause dur="0.7"/> # if you've got <pause dur="0.4"/> # <pause dur="0.4"/> weeds in a crop and you can no longer when you spray them with herbicides the weeds are no longer killed <pause dur="0.6"/> it means that you might have to go back to the # <pause dur="0.7"/> to a traditional method of farming <pause dur="0.2"/> <shift feature="voice" new="laugh"/> again which is <pause dur="0.2"/> of course might be quite good but # <pause dur="0.7"/><shift feature="voice" new="normal"/> but # has enormous economic implications <pause dur="3.7"/><kinesic desc="changes transparency" iterated="y" dur="13"/> now # in in America <pause dur="0.3"/> there well let's just <pause dur="0.3"/> do this where are we <pause dur="0.3"/> properly <pause dur="0.2"/> here we are <pause dur="0.9"/> if we look at # <pause dur="0.8"/> a couple of recent articles this is one from <pause dur="1.7"/> this is from Nature back in November <pause dur="0.6"/> this says # <reading>area under transgenic crops <pause dur="0.2"/> shoots up forty-four per cent <pause dur="1.4"/> it's the area of land planted with <pause dur="0.2"/> G-M crops is expected to increase dramatically <pause dur="0.3"/> particularly in China Argentina

Canada and South Africa <pause dur="0.4"/> according to Monsanto the U-S <pause dur="0.5"/> agri-biotechnology company <pause dur="1.0"/> # the <pause dur="0.2"/> company <pause dur="0.4"/> said that almost forty-million hectares <pause dur="0.4"/> will be planted with G-M crops this year</reading> so we're not talking about a sort of fringe industry this has become a major thing <pause dur="1.0"/> # says <pause dur="0.4"/> <reading>G-M crops were planted commercially in Portugal and the Ukraine for the first time this year <pause dur="0.9"/> Teng was speaking at the Asian rice <pause dur="0.3"/> conference in the Philippines</reading><pause dur="0.9"/><vocal desc="laugh" iterated="n"/><pause dur="0.5"/> so # <pause dur="0.8"/> worldwide these things are really taking off # but in the U-K <pause dur="0.5"/> # there is <trunc>b</trunc> a <trunc>hol</trunc> the British government has put a hold on it <pause dur="0.8"/> # there's a cartoon down here it looks like President Reagan actually i'm not sure as to who is it supposed to be but # <vocal desc="laugh" iterated="n"/><pause dur="0.6"/> it says all we ask for is a level playing field <pause dur="0.7"/> with a <trunc>r</trunc> roller with genetically modified crops <pause dur="0.2"/> written on it squashing a <pause dur="0.5"/> squashing a butterfly <pause dur="0.9"/><kinesic desc="changes transparency" iterated="y" dur="9"/> # <pause dur="0.4"/> so <pause dur="0.2"/> the <pause dur="0.4"/> implication is that the the the the companies who develop these things <pause dur="0.5"/> are roller-coasting this thing through <pause dur="1.3"/> but as i said in the U-K there is now a

voluntary ban <pause dur="0.6"/> on growing <trunc>ge</trunc> genetically modified crops in Britain until two-thousand-and-two <pause dur="1.3"/> so # <pause dur="0.6"/> that's that's been put on hold <pause dur="0.3"/> in the U-K but in the rest of the world it's it's really taking off <pause dur="0.3"/> and in America <pause dur="0.6"/> # more than half <pause dur="0.4"/> of of the <trunc>acrea</trunc> of the <pause dur="0.2"/> of the area <pause dur="0.4"/> growing certain <trunc>c</trunc> types of crops like # cotton for example are now genetically modified <pause dur="0.5"/> at least they include genes to make them resistant to <pause dur="0.4"/> to insects or resistant to herbicides <pause dur="2.0"/> okay now # <pause dur="0.8"/> what i thought i'd do next was to go through the major types of insecticides <pause dur="2.7"/><kinesic desc="changes transparency" iterated="y" dur="3"/> because # if you're reading around this subject which hopefully you you will # you'll come across these terms and it's useful to have the definitions in one <pause dur="0.6"/> place <pause dur="4.3"/> okay now the major types of insecticides <pause dur="0.8"/> are there's four main types there's <pause dur="0.3"/> first of all chlorinated hydrocarbons <pause dur="3.6"/> and # examples of these are D-D-T <pause dur="0.6"/> and aldrin they're also known as # <pause dur="0.5"/> organochlorines of course <pause dur="0.8"/> and the persistence of chlorinated hydrocarbons <pause dur="0.8"/> is quite high <pause dur="0.5"/> up to

fifteen years or more <pause dur="9.9"/> okay the second type of insecticides are organophosphates <pause dur="1.4"/> we're sort of going through a sequence of of development here in terms of the <pause dur="0.3"/> <trunc>t</trunc> <pause dur="0.3"/> historically how they developed <pause dur="1.5"/> the the second type of insecticides are organophosphates and an example of an organophosphate is malathion <pause dur="1.0"/> and these are tend to be <trunc>l</trunc> <pause dur="0.2"/> these tend to be less persistent <pause dur="1.1"/> up to # <pause dur="1.3"/> to a year or so <pause dur="0.3"/> <trunc>de</trunc> again depending on the <pause dur="0.2"/> the sort of climatic conditions <pause dur="1.5"/> and then <trunc>th</trunc> the final two <pause dur="1.0"/> have low persistence <pause dur="0.4"/> carbamates <pause dur="1.0"/> # <pause dur="1.1"/> an example of which is carbaryl <pause dur="0.7"/> has a low persistence typically of weeks <pause dur="1.0"/> and pyrethroids <pause dur="0.9"/> again have a low <pause dur="0.6"/> persistence of days or weeks <pause dur="2.1"/> but # <trunc>py</trunc> most of the pyrethroids that are used now <pause dur="0.4"/> in farming are synthetic pyrethroids <pause dur="0.7"/> and # one of the ways in which these insecticides have been developed <pause dur="0.8"/> is that scientists have looked at the <pause dur="0.5"/> chemical structure the molecular structure <pause dur="0.6"/> of naturally occurring <pause dur="0.4"/> chemicals like pyrethrum <pause dur="0.7"/> and they have then synthesized a molecule

which is very very similar but then <trunc>th</trunc> they've tweaked it to make it more toxic <pause dur="0.9"/> so what they did with the synthetic pyrethroids was to look at the chemical structure of pyrethrum which is a <trunc>chemic</trunc> a naturally occurring chemical <pause dur="0.6"/> in pyrethrum flowers <pause dur="0.5"/><vocal desc="cough" iterated="n"/><pause dur="0.7"/> synthesize it <pause dur="0.4"/> # <pause dur="0.3"/> synthesize it in the laboratory <pause dur="0.5"/> and then change <pause dur="0.2"/> change the structure of or slightly or maybe add or take off a hydrogen atom or something <pause dur="0.6"/> # and then test this and <trunc>ma</trunc> # to to find whether it's more toxic <pause dur="1.3"/>

and the commercially available synthetic pyrethroids <pause dur="0.4"/> are more <pause dur="0.2"/> toxic <pause dur="0.4"/> to <trunc>ins</trunc> more toxic to insects than a naturally occurring <pause dur="0.5"/> pyrethrum <pause dur="0.8"/> <trunc>t</trunc> </u><u who="sf0223" trans="overlap"> <gap reason="inaudible" extent="1 sec"/> change the <gap reason="inaudible" extent="1 sec"/><pause dur="0.5"/> <gap reason="inaudible" extent="1 sec"/></u><u who="nm0217" trans="overlap"> yeah </u><u who="sf0223" trans="overlap"> does that mean they can then patent it </u><pause dur="1.0"/> <u who="nm0217" trans="pause"> # <trunc>y</trunc> # yes <pause dur="1.1"/> yes so then most of these chemicals are patented <pause dur="0.9"/> that's why there probably why there's fifty-thousand <pause dur="0.5"/> 'cause what they tend to do is they'll produce <pause dur="1.0"/> you know if they come up with a new chemical in the lab <pause dur="0.4"/> <trunc>th</trunc> # they might not have <trunc>e</trunc> any evidence that it's useful but if they patent it <pause dur="0.4"/> in ten years time </u><u who="sf0223" trans="overlap"> yeah </u><u who="nm0217" trans="overlap"> <pause dur="0.5"/> or at the end of the <pause dur="0.2"/> field

trials they might find that it's useful <pause dur="0.4"/> 'cause these things take <pause dur="0.5"/> typically new chemicals nowadays and drugs as well take about ten years <pause dur="0.3"/> from <pause dur="0.6"/> discovery to final commercial approval <pause dur="0.4"/> because they have to go through a wide range of <pause dur="0.9"/> of # tests <pause dur="0.7"/> before they do that </u><pause dur="2.3"/> <u who="sf0224" trans="pause"> with things like the chlorinated hydrocarbons and you say they're <pause dur="0.4"/> persistent can't you alter the persistence <gap reason="inaudible" extent="2 secs"/></u><u who="nm0217" trans="overlap"> yeah that's what these these more <pause dur="0.4"/> well <pause dur="1.0"/> organochlorines tend to be very stable molecules <pause dur="0.5"/> because of <pause dur="0.6"/> the the nature of the <pause dur="0.4"/> atoms </u><u who="sf0224" trans="overlap"> <gap reason="inaudible" extent="3 secs"/></u><u who="nm0217" trans="overlap"> <pause dur="0.3"/> yeah you and and it's difficult too <pause dur="0.4"/> that's why these new chemicals have been <pause dur="1.0"/> have been developed which are less <pause dur="1.2"/> persistent <pause dur="0.6"/><kinesic desc="changes transparency" iterated="y" dur="11"/> organochlorines in general are <pause dur="0.3"/> persistent chemicals just 'cause of the nature of the <pause dur="0.8"/> of the structure <pause dur="0.3"/> the of the chemical <pause dur="0.2"/> they're <trunc>diffi</trunc> more difficult to break down <pause dur="3.9"/> okay now the major types of herbicides are three <pause dur="0.7"/> main types of these <pause dur="3.0"/> # first of all <pause dur="0.4"/> contact <pause dur="0.3"/> herbicides <pause dur="1.6"/> an example of which is atrazine <pause dur="2.1"/> and these things you spray them on the crops and they will kill the foliage <pause dur="1.1"/> # because they block photosynthesis <pause dur="12.0"/> # second type of

herbicides you get are <trunc>sys</trunc> so-called systemic <pause dur="1.2"/> herbicides and this is what <pause dur="0.3"/> two-four-five-T is it's a <trunc>sys</trunc> systemic <pause dur="1.0"/> herbicide <pause dur="5.1"/> and the systemic herbicides interfere with the <pause dur="0.5"/> natural hormones in the plants <pause dur="1.2"/> and essentially they make them grow too fast <pause dur="1.0"/> so <pause dur="0.8"/> the plants can't take in enough nutrients <pause dur="0.6"/> from the or water from the soil <pause dur="0.6"/> to make to <trunc>sus</trunc> sustain the very rapid growth rates that <pause dur="0.3"/> that they <pause dur="0.4"/> that are induced by the spraying of these chemicals <pause dur="3.4"/> and the third type <pause dur="1.0"/> are <pause dur="1.4"/> things called soil sterilants <pause dur="3.1"/> an example of which is trifluralin <pause dur="0.8"/> and this <pause dur="0.4"/> these chemicals will kill soil microbes essential for plant growth <pause dur="0.9"/> so if plants have mycorrhizal <pause dur="0.9"/> # fungi around the roots <pause dur="0.5"/> or if they're nitrogen-fixing <pause dur="0.9"/> for example <pause dur="0.5"/> these soil sterilants will kill off these <pause dur="0.2"/> microbes and the plants won't grow so well because they don't have this # symbiotic <pause dur="0.3"/> these <pause dur="0.3"/> symbiotic <pause dur="0.4"/> fungi or microbes <pause dur="0.6"/> around the roots <pause dur="3.8"/> so those are the main <pause dur="0.4"/> the main types <pause dur="11.3"/><kinesic desc="changes transparency" iterated="y" dur="10"/> okay now <pause dur="0.4"/> pesticides i've <pause dur="0.4"/> given them a <pause dur="0.2"/> pretty bad press <pause dur="0.9"/> so far <pause dur="2.0"/> but

# of course pesticides can be <pause dur="0.5"/> are are have been very useful <pause dur="1.4"/> in a wide range of situations and if we just <pause dur="0.6"/> present the case for the defence for a <trunc>s</trunc> for a moment <pause dur="0.7"/> for a moment before we get on to the problems <pause dur="0.6"/> # pesticides have clearly saved <pause dur="1.2"/> # millions of lives <pause dur="0.6"/> controlling diseases <pause dur="2.3"/> # for example malaria the spraying of pesticides managed to <pause dur="0.7"/> <trunc>ho</trunc> <pause dur="0.7"/> <trunc>con</trunc> <trunc>con</trunc> contain <pause dur="0.6"/> <trunc>m</trunc> # malaria outbreaks quite successfully <pause dur="0.6"/> for # a number of years <pause dur="1.8"/> unfortunately we'll come we'll come back to this later but unfortunately of course # mosquitoes have <trunc>m</trunc> <pause dur="0.3"/> become resistant <pause dur="0.2"/> resistant to many of the pesticides that are used <pause dur="0.5"/> and in some <trunc>ar</trunc> areas malaria has <pause dur="0.3"/> returned <pause dur="0.5"/> # because of this resistance <pause dur="1.2"/> # the second <pause dur="0.6"/> point is that <pause dur="0.6"/> pesticides have <pause dur="0.7"/> # increased food production <pause dur="1.5"/> # lots of # # <pause dur="0.2"/> crops have been saved by the spraying of pesticides because they would otherwise have been eaten by insects <pause dur="0.6"/> # and it's <trunc>estimi</trunc> estimated that worldwide <pause dur="0.7"/> about # fifty per cent of all crops <pause dur="0.3"/> are lost to pests <pause dur="2.6"/> #

incidentally another <pause dur="0.2"/> another twenty-five per cent is thrown away <pause dur="1.5"/> so of of the food which is grown <pause dur="1.6"/> in the world <pause dur="1.0"/> only about twenty-five per cent of it <pause dur="0.8"/> actually ends up in a inside us <pause dur="0.2"/> inside humans <pause dur="2.0"/> one of my ex # <pause dur="0.3"/> PhD students <pause dur="0.4"/> <gap reason="name" extent="1 word"/> <pause dur="0.4"/> who # <pause dur="0.9"/> left a few years ago went to work for Tesco's because <shift feature="voice" new="laugh"/> he <trunc>w</trunc> <shift feature="voice" new="normal"/> <pause dur="0.5"/> he realized that if he wanted his <trunc>w</trunc> he wanted a Porsche <pause dur="0.5"/> and he realized that if he stayed in academic life there was absolutely no chance <pause dur="0.7"/> and # <pause dur="0.6"/> so he went to work for Tesco's he's now in the working in the office which plans new Tesco's <pause dur="0.2"/> stores which is quite interesting <pause dur="0.7"/> anyway he was <pause dur="0.2"/> for a while when he was on the management training course <pause dur="0.5"/> they put him in charge of the fresh fruit department in Tesco's in Broadmead in Bristol <pause dur="0.2"/> which he said was like working in a <pause dur="0.5"/> prisoner of war camp or something he said it was just unbelievably stressful <pause dur="0.5"/> # for about eighteen months just to sort of test him out to make sure he could <pause dur="0.3"/> could hack it <pause dur="0.5"/> before they put him into the office and he said

that they used to throw away about half of the <trunc>f</trunc> <pause dur="0.4"/> half of the fresh <pause dur="0.3"/> produce was thrown away <pause dur="1.2"/> only half of it was sold because things like tomatoes particularly <pause dur="0.4"/> more than half of the tomatoes <pause dur="0.4"/> that you see on the display that people pick out by themselves are thrown away because they <trunc>s</trunc> <pause dur="0.2"/> go past their sell-by date <pause dur="0.5"/><vocal desc="cough" iterated="n"/> or because people damage them when they're handling them <pause dur="0.6"/> so <pause dur="0.2"/> on average about half of the food that's grown is lost to pests and of that that <trunc>s</trunc> <pause dur="0.2"/> survives about half of it <pause dur="0.6"/> is thrown away <pause dur="0.3"/> which is <pause dur="1.0"/><kinesic desc="changes transparency" iterated="y" dur="6"/> not good news really but # <pause dur="2.4"/> okay <pause dur="1.1"/> now one of the # <pause dur="0.5"/> major problems with using pesticides of course is the development of genetic resistance <pause dur="1.5"/> and <pause dur="0.2"/> something like five-hundred insect species are resistant <pause dur="0.7"/> to some insecticides <pause dur="1.3"/> and <pause dur="0.6"/> twenty insect species are resistant to some extent to all <pause dur="0.6"/> insecticides <pause dur="4.2"/> and this is a a clearly is a major problem <pause dur="0.6"/> # to to to put it into context <pause dur="1.0"/> # in the U-K there are periodically there are outbreaks of # <pause dur="0.6"/> scratching my head i shouldn't do that <pause dur="0.3"/>

outbreaks of head lice <pause dur="0.4"/> instinctively scratching <pause dur="1.3"/> and # my children had it a couple of times when they were # <pause dur="0.6"/> you know when they were at <trunc>sc</trunc> <pause dur="0.2"/> school when they were about # <pause dur="0.2"/> think once when they were about six and once when they were about # <pause dur="0.3"/> ten <pause dur="1.1"/> # haven't had it for a quite a long time i should reassure you about that but # <vocal desc="laugh" iterated="n"/> <pause dur="0.7"/> so i don't have it now but # it's very widespread and you very often # <pause dur="0.5"/> friends of ours who've got children will often mention oh there was an outbreak of head lice at school today <pause dur="0.5"/> and head lice <pause dur="0.4"/> has <pause dur="0.5"/> re-emerged in the last <pause dur="0.9"/> fifteen <trunc>t</trunc> <pause dur="0.3"/> ten to fifteen years <pause dur="0.5"/> as a <trunc>p</trunc> as a problem <pause dur="0.7"/> and this is because the head lice have become resistant to the chemicals that are used <pause dur="0.4"/> in their control <pause dur="1.3"/> and # when our kids had head lice you have to go to <pause dur="0.3"/> to Boots the chemists and # buy some <pause dur="0.5"/> head lice lotion and you rub it some of you probably know about this who probably don't want to admit it but <pause dur="0.6"/> you have to rub it in your hair and leave it for a <pause dur="1.0"/> # half an hour or something

then you wash it all out and then you have to do it the same thing again a week later to kill off the eggs or anything that's hatched out <pause dur="1.0"/> and # what they do in Boots <pause dur="0.3"/> <trunc>o</trunc> in all the chemists is there is a national programme to <pause dur="0.3"/> change the <pause dur="0.6"/> active ingredient in this shampoo <pause dur="0.5"/> # about every month or two <pause dur="0.7"/> and the idea behind it is to prevent the head lice from becoming resistant to one particular chemical <pause dur="1.0"/> so for one month they may use # malathion <pause dur="0.8"/> as the active ingredient and then a couple of months later they'll change from malathion to another chemical <pause dur="0.6"/> and the idea is to prevent the head lice from becoming resistant to <pause dur="0.8"/> to # <pause dur="0.7"/> to these insecticides <pause dur="0.9"/>

the # the <trunc>nowad</trunc> <pause dur="0.3"/> in the last year or two <pause dur="0.4"/> head lice have become resistant to all the chemicals that have been used and it's now become very difficult to get rid of them <pause dur="0.6"/> and # people are recommending that you go back to the traditional methods <pause dur="0.4"/> of of <pause dur="0.6"/> of # combing with a very fine comb <pause dur="0.4"/> on a regular basis to try and get rid of them but it's not <pause dur="0.5"/> nothing like as effective as dousing them with <pause dur="0.6"/> chemicals <pause dur="0.5"/> so head lice is a is a <pause dur="0.2"/> <trunc>m</trunc> <pause dur="0.4"/> major problem at the moment <pause dur="2.3"/> another problem with pesticides of course is that you tend to kill off natural enemies <pause dur="1.7"/> if you spray a crop you'll kill off things like ladybirds and # <pause dur="1.3"/> fly larvae that are eating eating things <pause dur="1.4"/> and of course # you can kill off <pause dur="0.9"/> # <pause dur="1.4"/> wildlife <pause dur="3.7"/> and there are <pause dur="0.2"/> clearly threats to # <pause dur="0.2"/> to wildlife if you're spraying a crop particularly on a windy day <pause dur="1.2"/> less than ten per cent of the <pause dur="0.3"/> pesticide that you spray will settle on the crop most of it will get <pause dur="0.3"/> land on the soil or will get

blown away <pause dur="0.5"/> to adjacent <pause dur="0.3"/> # land and if of course if you've got farming surrounding a nature reserve <pause dur="0.6"/> it's possible that you could get quite severe mortality of <pause dur="0.5"/> of # insects <pause dur="0.9"/> if the pesticide blows on to the nature reserve <pause dur="2.2"/> and of course there are threats <pause dur="0.4"/><vocal desc="cough" iterated="n"/> excuse me to wildlife and humans through passage up through the food chain <pause dur="3.1"/> # <trunc>f</trunc> <pause dur="0.4"/> last of all the problems # you do get occasionally get major disasters the worst one that's occurred is the explosion which i <pause dur="0.4"/> referred to earlier on <pause dur="0.7"/> and this was at a place called Bhopal <pause dur="0.7"/> a Union Carbide factory in India <pause dur="1.2"/> and here three-thousand-three-hundred people were killed <pause dur="0.7"/> by release of thirty-six tons of <pause dur="0.6"/> methyl <pause dur="0.4"/> isocyanate gas <pause dur="1.5"/> this is in nineteen-eighty-four <pause dur="0.5"/> and about twenty-thousand serious injuries occurred <pause dur="0.5"/> so <pause dur="0.5"/> # you you can get major disasters that <pause dur="0.4"/> in with the chemical industry <pause dur="0.2"/> associated with <pause dur="1.1"/> # leakages of <pause dur="0.4"/> toxic chemicals <pause dur="9.9"/> of course cyanide is also in the news at the moment because of this there's a been a major <pause dur="0.3"/> release of

cyanide from a gold <pause dur="0.5"/> mine in Romania <pause dur="0.2"/> and it's <pause dur="0.4"/> seems to have killed almost everything in the Danube <pause dur="0.8"/> in the last week or two <pause dur="6.2"/><kinesic desc="changes transparency" iterated="y" dur="10"/> okay <pause dur="0.9"/> now <pause dur="1.0"/> before we go on to look at a few slides <pause dur="2.9"/> what are alternative methods of pest control without using chemicals <pause dur="7.4"/> okay now the first of these is is <pause dur="0.3"/> biological control <pause dur="2.8"/> and with biological control <pause dur="0.5"/> you can encourage the <trunc>na</trunc> <trunc>p</trunc> <pause dur="0.3"/> instead of just spraying <pause dur="0.3"/> the pests you can encourage natural predators <pause dur="0.6"/> to try and bring the pests under control <pause dur="0.8"/> # for example you can now commercially buy little packets of <pause dur="0.3"/> of eggs of <pause dur="0.2"/> parasitic wasps <pause dur="0.6"/> which you can hang up among crops <pause dur="0.5"/> and when these hatch out these will parasitize the pests <pause dur="0.7"/> particularly # aphids <pause dur="1.6"/> and # they lay eggs inside the <trunc>p</trunc> the aphids and the aphids <pause dur="0.2"/> die because the larvae eat <pause dur="0.2"/> eat them <pause dur="1.1"/> eat them from the inside out <pause dur="2.2"/> but these <pause dur="0.9"/> methods really only work very well in glass houses where you can <pause dur="0.3"/> <trunc>p</trunc> <pause dur="0.2"/> where you can confine the <pause dur="0.5"/> pest and the <pause dur="0.3"/> predator <pause dur="0.2"/> or the parasite <pause dur="0.7"/> if you try it in the field <pause dur="0.4"/> the

the the the the the density of the parasites isn't sufficiently high <pause dur="0.3"/> to control the pest because they tend to fly away <pause dur="0.6"/> so that works pretty well <pause dur="0.8"/> in # in glasshouses <pause dur="1.9"/> course you can also introduce <pause dur="0.6"/> diseases <pause dur="0.8"/> into <pause dur="0.9"/> pests <pause dur="1.3"/> # particularly virus diseases <pause dur="0.7"/> and this can also be <trunc>ef</trunc> <pause dur="0.2"/> effective <pause dur="2.6"/> and there's a thing called bacillo virus which is <pause dur="0.5"/> quite widely used commercially as a pesticide which contains a bacterial toxin <pause dur="0.9"/> which will <pause dur="0.7"/> kill off <pause dur="0.6"/> insect pests particularly <pause dur="0.2"/> caterpillars <pause dur="3.8"/> now <pause dur="0.2"/> another <pause dur="0.2"/> way which is quite a cunning way and this is a good example of where basic biological knowledge <pause dur="0.2"/> zoological knowledge is used <pause dur="0.5"/> in an applied sense <pause dur="0.7"/> and this is what's called <trunc>insa</trunc> insect sterilization <pause dur="0.7"/> and this has been quite effective in controlling a pest <pause dur="0.2"/> rather disgusting pest <pause dur="0.4"/> called the screw worm fly <pause dur="0.8"/> in America <pause dur="0.7"/> this fly lays its eggs on the back of a <pause dur="0.4"/> back of a cow <pause dur="0.6"/> and the larvae hatch out and then burrow through the skin of the cow and live in a sort of chamber underneath with a breathing

hole <pause dur="0.2"/> it's a revolting <pause dur="1.0"/> <trunc>sty</trunc> lifestyle <pause dur="0.6"/> <shift feature="voice" new="laugh"/> really <shift feature="voice" new="normal"/> <pause dur="0.5"/> and # and this apart from causing intense irritation to the cow <pause dur="0.7"/> # means that you can't sell the hide afterwards 'cause it's full of holes <pause dur="1.2"/> and what they do here is they will <pause dur="0.3"/> breed <pause dur="0.7"/> screw worm flies in the lab <pause dur="1.2"/> they <pause dur="0.2"/> expose them to irradiation and this sterilizes them <pause dur="0.3"/> so you end up with large numbers of sterile male flies <pause dur="1.2"/> # you then release <pause dur="0.4"/> thousands and thousands of these sterile flies into the field <pause dur="0.6"/> and they will mate with the females and of course because they're sterile the females' eggs are not fertilized <pause dur="0.6"/> and # when the females come to lay the eggs there are no larvae to hatch out <pause dur="0.6"/> and although this doesn't get rid of the problem completely it reduces it to such a low level that it becomes commercially viable <pause dur="0.7"/> # and is is a very good way of controlling the <pause dur="0.5"/> the pests <pause dur="2.2"/> now another way is to attract <pause dur="1.8"/> pests <pause dur="0.5"/> <trunc>u</trunc> # sort of hijacking their natural <pause dur="1.1"/> <trunc>s</trunc> # <pause dur="1.0"/> attractive attract <pause dur="0.2"/> # sexual attractant system <pause dur="1.7"/> and of course many species of moths <pause dur="0.6"/> # the

males will be attracted to the females because the females give off this pheromone <pause dur="0.3"/> sort of come and get me <pause dur="0.2"/> chemical <pause dur="0.7"/> and what you can do is you can either <pause dur="0.2"/> you you can have a <pause dur="0.5"/> in the field you can have a <pause dur="0.2"/> you know like those # <pause dur="1.2"/> ultraviolet traps you get in butchers' shops and things and food shops with a <pause dur="0.6"/> ultraviolet light and an an electrified grille <pause dur="0.9"/> and the fly comes in and sort of oh there's a ultraviolet light and then go she-oo pssh whack <pause dur="0.2"/> zap you hear this crack as the thing gets <pause dur="0.4"/> instantly electrocuted well you can do the same thing with moths and you can put a <pause dur="0.5"/> a female moth behind one of these grilles <pause dur="0.6"/> and the males come flying in thinking thinking they're about to have sex and then they <pause dur="0.6"/> whack zap they get <pause dur="0.2"/> electrocuted on the electric <shift feature="voice" new="laugh"/> grille <vocal desc="laughter" n="ss" iterated="y" dur="1"/> <pause dur="0.7"/> and # <shift feature="voice" new="normal"/> of course <pause dur="0.2"/> one female can attract <pause dur="0.2"/> hundreds thousands of males <pause dur="0.5"/> and # this is very effective at reducing the <pause dur="0.5"/> the # incidence of males in the population <pause dur="0.6"/> and can <trunc>ha</trunc> kind of be quite effective <pause dur="1.3"/> now there was something again in yesterday's

New Scientist which is <pause dur="0.6"/> # <pause dur="0.4"/> very similar to this <pause dur="0.7"/> if you read the article <pause dur="0.3"/> you'll get it in more detail but the Colorado beetle which is a major <pause dur="0.3"/> pest <pause dur="0.3"/> of potatoes <pause dur="1.2"/> # they're suggesting # using the same technique but rather than using a sex attractant <pause dur="0.4"/> to find out what the active smell is in potato leaves <pause dur="0.6"/> and # again use this as a as a trap mechanism you put the <pause dur="0.3"/> the chemicals in a trap <pause dur="0.8"/> and # the Colorado beetles think oh it's a potato <pause dur="0.5"/> and they come <pause dur="0.3"/> flying in <pause dur="0.4"/> to the # to the trap and then of course they get killed because # <pause dur="0.4"/> because they're # <pause dur="1.8"/> 'cause it's not a potato <trunc>a</trunc> at all it's just a chemical to attract them <pause dur="2.0"/>

and # <trunc>f</trunc> finally insect hormones <pause dur="1.8"/> # <pause dur="1.0"/> you can mess up the biochemistry of <pause dur="0.2"/> insects by spraying them with chemicals which mimic <pause dur="0.3"/> chemicals within their bodies <pause dur="1.2"/> # within <pause dur="1.4"/> <trunc>ca</trunc> # caterpillars for example <pause dur="0.4"/> there's a <sic corr="hormone">cormone</sic> called juvenile hormone <pause dur="1.4"/> and the animals secrete juvenile hormone <pause dur="0.5"/> until the end of the fifth instar <pause dur="0.6"/> and then it the juvenile hormone <pause dur="0.5"/> production stops and then they then pupate <pause dur="0.2"/> into a pupa and then of course into a butterfly or a moth <pause dur="1.7"/> if you <pause dur="0.3"/> spray the insects with these juvenile hormones or or mimics of the juvenile hormone synthetic versions of these hormones <pause dur="0.5"/> you can prevent the caterpillar from pupating <pause dur="1.1"/> so it gets to the <trunc>fi</trunc> fifth instar and then it just keeps growing <pause dur="0.3"/> moults into a sixth instar and eventually it will die because # <pause dur="0.5"/> because the other <pause dur="0.7"/> components of its biology <pause dur="0.7"/> think it's <pause dur="0.3"/> turning into a pupa when it's

still a still a caterpillar <pause dur="0.7"/> so you can <pause dur="0.3"/> # <pause dur="0.4"/> target the pesticides to <pause dur="0.4"/> hit particular aspects of the <kinesic desc="changes transparency" iterated="y" dur="7"/> biochemistry of the animal <pause dur="3.2"/> okay <pause dur="0.3"/> right final <pause dur="1.1"/> overhead before we # look at some slides <pause dur="6.2"/> whoops <pause dur="3.4"/> okay now this is a schematic <pause dur="0.3"/> # <pause dur="0.4"/> diagram <pause dur="0.2"/> don't want to # show you that yet <pause dur="1.2"/> schematic diagram which illustrates the principle of biological <pause dur="0.3"/> pest control <pause dur="1.0"/> if we have time along the X-axis and pest density along the Y-axis <pause dur="1.0"/> the purple line <pause dur="0.7"/> is the density of the pest <pause dur="0.7"/> and the orange line is the economic threshold <pause dur="0.9"/> if we can get the population of the pest <pause dur="0.5"/> well below the economic threshold <pause dur="0.6"/> then # <pause dur="0.2"/> then it's <pause dur="0.4"/> if there's a small amount of pest damage it doesn't really matter if the <trunc>dif</trunc> if the overall <pause dur="2.5"/> level of damage is acceptable <pause dur="2.2"/> so if you've got the pest <pause dur="0.5"/> density going along here it's clearly <trunc>t</trunc> <pause dur="0.3"/> above the economic threshold line which is <pause dur="0.4"/> too high <pause dur="0.6"/> # <pause dur="0.6"/> if we introduce some method of biological control <pause dur="0.6"/> some of the methods which we # <pause dur="1.4"/> mentioned above <pause dur="1.8"/> we can get the pest population to get down below the economic

threshold <pause dur="4.5"/> and <pause dur="0.2"/> this means that we have to accept a small amount of pest damage <pause dur="0.5"/> but the damage is not sufficiently great to significantly affect the the income <pause dur="0.9"/> of the farmer <pause dur="3.7"/><kinesic desc="changes transparency" iterated="y" dur="5"/> but <pause dur="0.4"/> if we do biological control we have to accept some damage i'm giving away my age here but # <pause dur="1.5"/> most of you probably haven't heard of Joni <trunc>mitch</trunc> Joni Mitchell but there's a song that you hear <trunc>ev</trunc> every so often Big Yellow Taxi and <pause dur="0.4"/> one of the lines is <pause dur="0.5"/> <reading>give me spots on my apples but leave me the birds and the bees</reading> <pause dur="0.9"/> and # every time if you go shopping in the supermarket and you're picking out apples for example from a <pause dur="0.4"/> a big display of apples <pause dur="0.5"/> if you pick one up and it's got a small imperfection on it <pause dur="0.5"/> a hole or a small scab or something <pause dur="0.4"/> if you put it back you're encouraging <pause dur="0.5"/> the over-use of pesticides because you are only accepting perfect fruit <pause dur="0.7"/> and the environmental consequences of perfect <pause dur="0.4"/> fruit and vegetables <pause dur="0.4"/> is an increased use of pesticides <pause dur="0.7"/> so # <pause dur="0.4"/> we have to if we want to use

less pesticides and <pause dur="0.7"/> use <trunc>biologic</trunc> <pause dur="0.5"/> biological control <pause dur="0.2"/> we have to be able to accept <pause dur="0.5"/> that # some of the things that we eat may not be # absolutely perfect <pause dur="8.3"/> okay <pause dur="0.7"/> let's look at some slides before we stop <pause dur="42.7"/><event desc="turns on slide projector" iterated="n"/> right <pause dur="1.0"/> has everybody finished with this <pause dur="2.1"/> yep <pause dur="3.3"/><event desc="turns off overhead projector" iterated="n"/> okay <pause dur="0.2"/> about another ten minutes or so then you can have a </u><pause dur="0.5"/> <u who="sm0225" trans="pause"> <unclear>really</unclear> </u><pause dur="0.7"/> <u who="nm0217" trans="pause"> <vocal desc="laughter" iterated="y" dur="1"/> <unclear>what's <trunc>s</trunc></unclear> who said all right <vocal desc="laughter" iterated="y" dur="1"/><pause dur="0.6"/> can have a nice # <pause dur="1.0"/> # a coffee break <pause dur="4.2"/> right <pause dur="0.7"/> now then # of course pests as i said aren't just used for killing <pause dur="0.5"/> insects <pause dur="1.7"/> # <pause dur="0.5"/> this is a <pause dur="0.4"/> Forestry Commission <pause dur="0.4"/> plantation just south of Reading at a place called Heath Warren near Bramshill <pause dur="1.1"/> and <pause dur="0.2"/> when they <pause dur="0.4"/> clear the trees when they chop down the trees as a commercial product <pause dur="1.3"/> # what's left behind is # <pause dur="0.2"/> is a <pause dur="0.2"/> bare ground because the light doesn't penetrate very well here and you get a very rapid growth of things like birch trees and # general <pause dur="0.8"/> # low <pause dur="0.2"/> growing plants <pause dur="0.8"/> and they can control these by spraying <pause dur="1.0"/><kinesic desc="changes slide" iterated="n"/> and this is just an example here this is the <pause dur="0.5"/> an area which has been felled <pause dur="0.9"/> and after they've felled it # they put this notice

up i've got a <pause dur="0.5"/> higher <kinesic desc="changes slide" iterated="n"/> magnification picture of it here <pause dur="0.5"/> here we are <pause dur="1.3"/> # this is a <pause dur="0.6"/> this area has been sprayed to control weeds <pause dur="0.7"/> and there's a <pause dur="0.5"/> says herbicide applied do not eat fruit <pause dur="0.2"/> and there's a <trunc>pi</trunc> just in case you don't know what <pause dur="0.3"/> fruit looks like there's a <vocal desc="laughter" n="sl" iterated="y" dur="2"/> picture of it <pause dur="0.8"/> and # if you were a kid and you had an I Spy book <pause dur="0.4"/> I Spy Signs <pause dur="0.2"/> that would probably be worth about two-hundred marks <vocal desc="laughter" n="ss" iterated="y" dur="2"/> 'cause it's a <pause dur="0.6"/><shift feature="voice" new="laugh"/> 'cause it's a <shift feature="voice" new="normal"/> <pause dur="0.6"/> couple of blackberries with a line through <pause dur="0.5"/> so # <pause dur="0.7"/> they spray the area instead of <pause dur="0.2"/> going around for somebody physically going around and chopping all this stuff down <pause dur="0.4"/> it's obviously much cheaper <pause dur="0.2"/> for them to spray <pause dur="0.4"/> spray it # to allow the baby <pause dur="0.5"/> pine trees <pause dur="0.5"/> the chance to grow up because if they don't do that then the pine trees get # <pause dur="0.3"/> get smothered by this very rapid growing <pause dur="0.5"/> # vegetation <pause dur="2.8"/><kinesic desc="changes slide" iterated="n"/> now # one method of biological control <pause dur="0.3"/> is to encourage <pause dur="1.6"/> natural predators of pests to <pause dur="0.8"/> migrate into crops <pause dur="0.2"/> and in <pause dur="0.4"/> some farms nowadays the farmers will leave a strip quite a

wide strip around the field <pause dur="0.5"/> and this acts as a reservoir for things like carabid beetles and # natural predators <pause dur="0.8"/> and during the night they can crawl from this area this refuge into the crop <pause dur="0.5"/> and # help to control the pests <pause dur="0.9"/> it's not a # a complete substitute for spraying <pause dur="0.6"/> but certainly it has been shown that there are significantly lower numbers of pests <pause dur="0.4"/> in the margins of these fields than there are <pause dur="0.4"/> in the centre <pause dur="0.4"/> and what <trunc>th</trunc> some of them <pause dur="0.3"/> # <pause dur="0.2"/> very organic farms <pause dur="0.3"/> do is they will put strips of these sort of set-aside strips <pause dur="0.5"/> right through the crop <pause dur="0.5"/> # so that the <pause dur="0.2"/> natural predators have a refuge all throughout the crop and this does significantly reduce the <pause dur="0.5"/> incidence of pests <pause dur="2.9"/><kinesic desc="changes slide" iterated="n"/> okay now just something briefly about the D-D-T problem <pause dur="1.6"/> # the D-D-T didn't didn't just affect birds of prey this is a <pause dur="0.8"/> picture of a a nest of a brown pelican <pause dur="0.7"/> and this is a <pause dur="0.4"/> double-crested cormorant <pause dur="0.7"/> which <pause dur="0.2"/> became deformed in the egg the egg managed to hatch but as it grew <pause dur="0.5"/> this the beak was very badly

deformed <pause dur="0.5"/> you can see the upper part of the beak here is curled <pause dur="1.6"/> and here the eggs have become squashed by the female because the eggshells have become thin because of the interference with the calcium <pause dur="0.2"/> and metabolism by the D-D-T that was used in the area <pause dur="2.5"/><kinesic desc="changes slide" iterated="n"/> in the U-K <pause dur="0.6"/> # this is <pause dur="0.3"/> changes in the status of sparrow hawks in relation to agricultural land use <pause dur="0.9"/> this is a proportion of land which is farmed <pause dur="0.3"/> # <pause dur="1.0"/> intensively and you can see the black areas here in East Anglia particularly <pause dur="0.4"/> of very intensive farming <pause dur="0.7"/> and this is the # populations of sparrow hawks <pause dur="0.9"/> around the time when D-D-T was being used <pause dur="0.9"/> and you can see there's an almost mirror image here in the <pause dur="0.2"/> in the terms of the intensity of farming <pause dur="0.5"/> and the populations of sparrow hawks <pause dur="0.3"/> sparrow hawks manage to <pause dur="0.7"/> # persist <trunc>qu</trunc> in quite high populations in Wales and south-west England where the farming intensity is lowest <pause dur="0.9"/> but # during the maximum period of usage of D-D-T the sparrow hawks died out almost completely <pause dur="0.4"/> from East Anglia <pause dur="0.3"/>

although now of course they've returned <pause dur="2.4"/><kinesic desc="changes slide" iterated="n"/> and # this illustrates the <pause dur="0.5"/> whole problem this is the <pause dur="0.7"/> same thing with peregrine <pause dur="0.3"/> falcons <pause dur="0.6"/> relative to nineteen-thirty you can see that the population of peregrines declined <pause dur="0.6"/> during the usage <pause dur="0.9"/> of # <trunc>s</trunc> these pesticides <pause dur="1.2"/> and has recovered <pause dur="0.3"/> quite substantially since <pause dur="2.2"/> the # <pause dur="1.1"/> D-D-T was in fact banned throughout the <trunc>E</trunc> European Community <trunc>f</trunc> in nineteen-eighty-one although in the U-K it was banned <pause dur="0.6"/> banned earlier <pause dur="1.0"/> than that <pause dur="3.0"/><kinesic desc="changes slide" iterated="n"/> and this is the eggshell thickness index # just reiterates <pause dur="0.4"/> what we saw on the overhead and we saw in the practical class that there was a distinct thinning <pause dur="0.8"/> during the period of maximum <pause dur="0.5"/> D-D-T use <pause dur="1.7"/><kinesic desc="changes slide" iterated="n"/> and that # if we relate the thickness of eggshells <pause dur="0.5"/> to the D-D-E content which is the <pause dur="0.9"/> # <pause dur="0.7"/> # metabolic breakdown <pause dur="0.3"/> product of D-D-T <pause dur="0.6"/> we can see there's a very clear correlation <pause dur="0.7"/> between the thickness of the eggshell <pause dur="0.2"/> and the concentration <pause dur="0.5"/> of D-D-E <pause dur="4.8"/> okay <pause dur="0.6"/> so now i just want to show some general slides to back up the <pause dur="1.1"/> idea of

pests <pause dur="0.8"/> # this is <pause dur="0.4"/> over in chemistry this is the where the manic mole used to # <vocal desc="laugh" iterated="n"/><pause dur="0.7"/> do its stuff there's a big <pause dur="0.2"/> huge <trunc>ar</trunc> there's this big area of daffodils which are about to come out now <pause dur="0.7"/> but # <pause dur="0.2"/> every so often the mole manages to get across the road and then it <shift feature="voice" new="laugh"/> causes all these little # <shift feature="voice" new="normal"/><pause dur="0.4"/> little hummocks <pause dur="0.4"/> but again it's a <pause dur="0.3"/> the concept to the fact that the moles are a pest because they're in an area that # <pause dur="0.4"/> the ground staff don't want them to be so they <pause dur="0.3"/> they're defined as a pest <pause dur="0.6"/> whereas if they were a <trunc>t</trunc> colony of bats <pause dur="0.4"/> living in the <pause dur="0.3"/> top of the # Chemistry department up here then we wouldn't be able to do anything about it because they'd be legally <pause dur="0.4"/> protected even though they might be covering the floor in <pause dur="0.2"/> # bat droppings <pause dur="0.5"/><vocal desc="laugh" iterated="n"/><pause dur="2.4"/><kinesic desc="changes slide" iterated="n"/> okay here's some more pests this is a <pause dur="1.0"/> # an example where you can have a an animal which has a natural <pause dur="1.8"/> its natural food # is a plant which grows wild in the environment but # if it manages to cross that barrier and start eating other plants then it becomes a serious

pest this is a large white butterfly caterpillar <pause dur="0.4"/> which of course is a very <pause dur="0.3"/> # severe pest of cabbages <pause dur="0.3"/> but it will <trunc>s</trunc> will also eat nasturtiums this is a one on a nasturtium leaf <pause dur="0.5"/> in our back garden <pause dur="0.5"/> so these things can <trunc>cres</trunc> pests can cross <pause dur="0.4"/> # species barriers and eat <pause dur="0.4"/> # <pause dur="0.3"/><kinesic desc="changes slide" iterated="n"/> plants which they wouldn't naturally have evolved to <pause dur="0.7"/> here's another pest this is a sawfly larvae <pause dur="0.3"/> this is a larvae of a of a wasp rather than a moth or a butterfly <pause dur="1.6"/> and if you don't know the difference between them the way to tell the difference between a sawfly larvae and a <pause dur="0.6"/> caterpillar a butterfly or moth is that sawflies have seven <pause dur="0.7"/> pairs of prolegs one two three four five six seven <pause dur="0.6"/> as opposed to <pause dur="0.3"/> butterflies and moths which have five <pause dur="1.7"/> but # these sawfly larvae are quite serious pests of <trunc>u</trunc> of a range of crops <pause dur="0.5"/> and # <pause dur="0.3"/> when you annoy them they will <pause dur="0.5"/> exhibit this characteristic alarm behaviour which is to raise their bottoms in the air and # <pause dur="1.0"/> apparently it's supposed to to scare off # <pause dur="0.2"/> potential <pause dur="0.6"/><kinesic desc="changes slide" iterated="n"/> attackers <pause dur="1.5"/>

okay # greenfly this is a <pause dur="1.6"/> <trunc>w</trunc> one of the main problems with aphids is that they can reproduce very rapidly and <pause dur="0.3"/> they can reproduce parthenogenetically <pause dur="0.5"/> which means that <pause dur="0.3"/> they don't have to have males <pause dur="0.5"/> the females can produce <pause dur="0.5"/> baby greenflies little baby greenfly here <pause dur="0.2"/> aren't they sweet </u><u who="sf0226" trans="latching"> mm </u><u who="nm0217" trans="latching"> <vocal desc="laughter" iterated="y" dur="1"/> <pause dur="0.7"/> # without without mating with a male so they can increase their population <pause dur="0.3"/> density extremely rapidly <pause dur="1.4"/> # exponentially in fact # <pause dur="0.6"/> in under certain circumstances <pause dur="0.4"/><kinesic desc="changes slide" iterated="n"/> and of course if you spray the crops then you'll kill off <pause dur="0.5"/> the natural predators of <pause dur="0.5"/> of these things like two-spot and seven-spot ladybirds <pause dur="0.5"/> these here are munching their way through some <pause dur="0.5"/> # cherry aphids on a cherry # <pause dur="0.2"/> cherry tree in our <trunc>b</trunc> <pause dur="0.2"/> again in our back garden at home <pause dur="1.1"/> so they a ladybird can eat <pause dur="0.4"/> between fifty and eighty greenfly a day so they really are major # <pause dur="0.4"/> pests # <pause dur="0.2"/> major predators of pests <pause dur="2.4"/><kinesic desc="changes slide" iterated="n"/> here's another one this is a hoverfly larvae <pause dur="1.2"/> # sorry not a hoverfly larvae a lacewing larvae <pause dur="0.3"/> eating a eating a fly here and these again are major pests

of # <pause dur="0.6"/> <trunc>pred</trunc> predators of of of pests particularly greenfly <pause dur="0.9"/><kinesic desc="changes slide" iterated="n"/> and here's one here this is a business end here which has <pause dur="1.4"/> grabbed on to this this # fly <pause dur="2.4"/> so all these things will get killed <kinesic desc="changes slide" iterated="n"/> if you spray the crop <pause dur="0.4"/> with a general purpose insecticide <pause dur="1.2"/> okay now <trunc>the</trunc> wasps are good examples of animals which are <pause dur="0.7"/> most of us would consider to be pests but <pause dur="0.3"/> but in fact are on balance very very beneficial because they themselves will eat lots of pests <pause dur="1.0"/> this wasp here is in a place where <pause dur="0.2"/> i don't want it to be because it's it's # <pause dur="0.7"/> rasping its way through our garden bench <pause dur="1.2"/> and # when you're sitting out there in the summer reading a book or something you can hear this sort of <vocal desc="scraping noise" iterated="y" dur="1"/> scraping noise what the hell's that you look around and there's a wasp <pause dur="0.7"/> scraping away at the bench and # <pause dur="0.6"/> this is made of teak <pause dur="0.4"/> i should have <pause dur="0.3"/> environmentally friendly teak i should point out <pause dur="0.7"/> approved by Friends of the Earth <pause dur="0.6"/> so this must have about the hardest wasps' nest in <gap reason="name" extent="1 word"/> 'cause it's <pause dur="0.9"/> scraping away the wood

to take away to make its # make its nest <pause dur="0.9"/> but that's clearly in that situation the wasp is a pest <pause dur="0.9"/><kinesic desc="changes slide" iterated="n"/> # also <pause dur="0.4"/> if you get wasps on # <pause dur="0.3"/> apples they're a pest <pause dur="0.8"/> 'cause you might end up with <pause dur="0.6"/> # with one in your mouth <pause dur="0.4"/> but on balance wasps are very useful animals because they eat very large numbers <pause dur="0.4"/> of pests themselves <pause dur="2.1"/><kinesic desc="changes slide" iterated="n"/> okay this is a <pause dur="0.6"/> a head louse <pause dur="1.1"/> # which isn't from my hair i should point out <shift feature="voice" new="laugh"/> it's from somebody who <trunc>c</trunc> <shift feature="voice" new="normal"/><pause dur="0.5"/> who sent it to me <pause dur="0.5"/> and # if you remember these these <pause dur="0.3"/> # head lice have become very <pause dur="0.6"/> resistant in recent years to # to pesticides <pause dur="0.6"/> and # one of the problems is that they will lay their that <pause dur="0.2"/> you can rid of the <pause dur="0.2"/> the adults themselves <pause dur="0.3"/> but they lay eggs on the hair shafts <pause dur="0.8"/> and these eggs are very very resistant to the pesticides so you have to have two applications of the pesticide to kill off the <pause dur="0.5"/> the # the <pause dur="0.2"/> the baby head lice which hatch out of the <pause dur="0.2"/> out of out of the eggs <pause dur="3.4"/><kinesic desc="changes slide" iterated="n"/> okay

flies <pause dur="0.4"/> most people would <trunc>sco</trunc> would consider flies to be pests <pause dur="0.5"/> but of course flies are # <pause dur="0.5"/> very important in decomposition <pause dur="2.1"/><kinesic desc="changes slide" iterated="n"/> and as <pause dur="0.2"/> maggot larvae <pause dur="0.8"/> # if we didn't have flies around <pause dur="0.4"/> then # <pause dur="0.2"/> we'd have dead bodies lying all over the place dead animals <pause dur="0.4"/> because flies are extremely important in breakdown of materials so <pause dur="0.4"/> it's another example of an animal which is a pest <pause dur="0.6"/> from one point of view in that you don't like them buzzing around <trunc>anno</trunc> <pause dur="0.4"/> getting on your food <pause dur="0.6"/> but if they were absent then there would be # real problems in terms of <pause dur="0.2"/> a slowdown in decomposition of dead animals <pause dur="2.2"/><kinesic desc="changes slide" iterated="n"/> it's just a load more there <pause dur="0.6"/> the pupae down here <pause dur="3.7"/><kinesic desc="changes slide" iterated="n"/> right finally this is today's joke <pause dur="0.8"/> anybody guess what that is <pause dur="1.5"/> fly in the ointment <pause dur="0.2"/> yeah # <pause dur="0.4"/><vocal desc="laughter" n="sl" iterated="y" dur="3"/> <pause dur="0.7"/> right okay i think we'll stop there and if we restart at # <pause dur="0.8"/> do you want a long coffee break today </u><pause dur="0.9"/><u who="sm0227" trans="pause"> yeah </u><pause dur="0.4"/> <u who="nm0217" trans="pause"> shall we restart at eleven </u><pause dur="0.6"/> <u who="ss" trans="pause"> <gap reason="inaudible, multiple speakers" extent="1 sec"/> </u><pause dur="0.3"/> <u who="nm0217" trans="pause"> okay