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Gemma Hough

I was a PhD student at the Warwick Crop Centre at The University of Warwick. My research focused in the area of entomology, particularly the study of aphids (commonly known as greenfly).

My interest in entomology began during my undergraduate degree at the University of Birmingham where I undertook a small research project looking at the physiology of the Peach Potato Aphid (Myzus persicae). Following this I decided to further my knowledge and undertake my own research project in a similar area.

My Research

Thesis Title: Biology and Control of Currant-Lettuce Aphid (Nasonovia ribisnigri)

Supervisor: Dr. Rosemary Collier 

Funded by the Horticultural Development Company (HDC)

Of the four species of aphid which infest lettuce, N. ribisnigri is the most economically significant. This is due to its preference to feed and live in the heart of lettuce heads where it is sheltered from the effects of certain insecticides and natural enemies, making its control difficult. As a result growers often suffer financial losses, as the presence of aphids leads to unmarketable heads.

Currently the control of N. ribisnigri is restricted to a limited number of insecticides. Unfortunately, like many other aphid pests the over-application of insecticides has led to the selection of N. ribisnigri expressing resistance to several insecticides. This then led to research into alternative methods of control which resulted in lettuce varieties with resistance to N. ribisnigri. Available commercially, these varieties have a single gene, known as the Nr gene, which provides complete protection against N. ribisnigri. Until 2007, these varieties controlled N. ribisnigri successfully. However, since then, certain clones of N. ribisnigri have overcome the resistance in these varieties. Therefore the future control of N. ribisnigri is uncertain.

My research focused on dermining the developmental, overwintering and population biology of both resistance-breaking (Rb) and wild type (WT) N. ribisnigri to provide essential information to create more effective control measures.



Gemma Hough


 Nasonovia ribisnigri