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PhD Project: Mealybug control in cocoa to reduce the vectoring of the Cocoa Swollen Shoot Virus Disease (CSSVD)


Warwick Supervisor: David Chandler (University of Warwick)

Industrial Supervisor: Dr Clare Stirling (Mondelez International)

Primary research partners: Dr Jayne Crozier and Dr Steve Edgington (CABI UK)

Start date: 4 October 2021

Location: Working independently in Ghana for part of the year and working in the UK with the CABI Biopesticide Team for part of the year.


This 4 year PhD is funded by a BBSRC Collaborative Training Partnership with Mondelez to be delivered jointly by the University of Warwick and CABI UK. The funding covers Tuition fees and pays an annual stipend of at least £15,609 (tax free paid monthly in advance). See Funding Eligibility below for more information. Part time study will be considred.

Application deadline: 6 September 2021

Project description:

Cocoa production in West Africa is threatened by a number of constraints including black pod disease, mirids, and increasingly, by cocoa swollen shoot virus disease (CSSVD). CSSVD is responsible for substantial economic losses in Ghana and Cote d’Ivoire in the last 20 years. Current efforts for managing the disease focus on eradication of millions of cocoa trees in ‘cut and replace’ campaigns and other cultural practices such as use of barrier crops yet the disease has continued to spread.

The virus is vectored by several species of mealybugs, with Formicococcus njalensis, Planococcus citri and Ferrisia virgata identified as the most important species. Despite their importance in virus spread there are a number of constraints to mealybug management. Some chemical pesticides are known to be effective but their use is challenging due to the cryptic nature of the mealybug and extensive treatment is needed to access all individuals on an affected tree. The extensive use of chemical pesticides also has a detrimental effect on non-target organisms including on mealybug predators and cocoa pollinators.

Biological control could be an alternative management strategy for managing mealybugs and thereby limiting the spread of CSSVD. The development of mycoinsecticides could provide an option for sustainable management of mealybug populations as they use naturally occurring entomopathogenic fungi (EPF) that can be formulated to enhance their capacity to overcome mealybug defences. The use of mycoinsecticides would be compatible with many existing integrated crop management (ICM) techniques already in use with cocoa including crop sanitation, cultural practices, mixed cropping and ant control.

PhD Aims:

This PhD aims to help reduce the spread of CSSVD by reducing the numbers of mealybugs using fungal biopesticides. The work will include:

  1. Bioprospecting field populations for suitable fungal isolates that may potentially control mealybugs.
  2. Screening of local, field collected isolates (from 1) and commercially available biopesticide products registered for use on mealybugs in other African countries, to determine which ones are the most pathogenic.
  3. Mass production potential of any natural isolates showing potential from 2 vs commercial equivalent. Isolates examined for their potential to mass produce spores in high volume.
  4. Non-target effects of the chosen isolates to ensure there is no harm to pollinators or natural predators.
  5. Field trials of suitable isolates after successful lab trials.
  6. Population dynamics of the mealybug to determine when is the best time to apply the biopesticide.
  7. Link with cocoa farmers to evaluate attitudes towards using biological control products.

This PhD is looking for a dynamic student who can work independently and as part of a team in Ghana and the UK. For part of the year the student will be working in Ghana on various activities as mentioned above. For this time the student will be primarily be working on their own and will need to have strong discipline to push the work forward. The remaining part of the year the student will be based in the UK working with the CABI Biopesticide Team on learning key skills in biopesticide development.

Funding Eligibility

UK and International students are eligible to apply.

Home (UK) students who have been ordinarily resident in the UK for at least three years can apply for a full award covering tuition fees and annual stipend for living costs.
International students (including EU Students) can apply for a jointly funded award covering tuition fees in full and annual stipend for living costs.
BBSRC CTP funding will provide annual stipend for living costs and tuition fees at the UK rate. The difference between UK tuition fee rate and international tuition fee rate will be covered by University funding.

Entry Requirements

The University’s standard entry requirements are as follows:

  • You must hold an upper second class UK honours degree (2:1) or M.Sc. in an appropriate discipline - Overseas Qualifications: UK equivalency
  • You must be able to provide 2 satisfactory academic references
  • Submit an English Language test certificate (if appropriate). Please note: It is a requirement that overseas students will show that their ability to understand and express themselves in both written and spoken English is sufficiently high for them to derive the full benefit from the PhD. Please note that the requirement for admission is IELTS 6.5 (with no component below 6.0) or equivalent. More information can be found at:

How to apply

  • Informal project enquiries can be made to David Chandler via email: Dave dot Chandler at warwick dot ac dot uk
  • Complete the online application form - selecting course code: P-C1PB - PhD Life Sciences
  • Upload a transcript from your current or previous study and any other documents that you feel would support your application.
  • Ask your referees to submit a reference for you. Note: when you submit your application, an email will automatically be sent to your referees requesting a reference for you. This email will contain a secure link for your referee to upload a reference for you.
  • The deadline for applications is 6 September 2021

For further information about applying to Warwick see the application FAQ's page”