Agricultural pest insect control: combining genetics, resistance management and dynamics

Lead Research Organisation: Imperial College London
Department Name: Life Sciences

Abstract

The public and consumers increasingly want to see more sustainable methods used to control pests and there is general concern to promote sustainability and biodiversity in agricultural ecosystems.
Diamondback moth (DBM) is a major worldwide pest of brassicas (e.g. broccoli, cabbage) causing economic losses of $4-5bn annually through management costs and crop damage. DBM has evolved resistance to all known classes of synthetic chemical insecticides and to at least two bio-pesticides based on Bt, Bacillus thuringiensis. Bt toxins typically have specific action against particular insect Orders (e.g. Lepidoptera), have unparalleled environmental safety and have been widely engineered into transgenic crops. The evolution of resistance to Bt toxins is a real challenge to the sustainable exploitation of this key bio-pesticide. DBM has not only evolved resistance to Bt many times in the field, but is also a proven laboratory system for testing evolutionary theory.
Our industry partner, Oxitec Ltd (an Oxford spin-out), is pioneering genetically engineered "sterile" insects to suppress populations of agricultural or public health pests. Released "RIDL" male insects find mates in the wild and their offspring inherit a genetic construct that prevents them developing to adulthood. Our theoretical work predicts that a female-specific version will not only reduce insect numbers (daughters die so there are fewer females to lay eggs) but also help dilute any resistance in the population (sons inherit Bt-susceptible alleles from released males).
Our cross-disciplinary research project brings together experts in ecology and evolution of the DBM-Bt system and world-leading biotechnologists to explore the management of insect resistance to bio-pesticides and the interplay with genetic insect control.
Novel RIDL strains of DBM will be developed, in addition to Oxitec's prototypes, and a phased series of experiments will be conducted on their biology, genetic traits, and performance for suppressing DBM populations and managing resistance to Bt. Key performance traits include male mating competitiveness, sperm competition with wild-type males, longevity, dispersal, the ability to find mates and suitability for mass-rearing. These will be analysed at increasing levels of detail and realism, from small laboratory cage experiments to experiments in simulated (field cage) and actual field conditions, progressively identifying and prioritizing the most suitable strains.
We will perform a series of experiments involving competition and selection to explore the effect of RIDL male releases on the evolution of DBM resistance to Bt bio-pesticides. The experiments will incorporate key features of existing resistance management strategies, such as Bt-free refuges to provide a source of Bt-susceptible genes alongside Bt diet (this is a key feature of current measures to manage resistance to Bt crops), populations with non-homogeneous spatial structure and various ecological conditions, and mixtures of different toxins (multiple toxins are used in spray treatments and engineered into some plants). These experiments will provide direct tests of theoretical predictions about the evolution of resistance and provide information about the system's dynamics to inform the formulation and parameterization of further mathematical models.
Our empirical experiments will be supported by a range of novel mathematical models to gain a fuller understanding of the bio-economics of integrated pest management approaches combining bio-pesticides with genetic pest control. We will explore the potential cost-effectiveness and policy options for integrated biologically-based management of agricultural pests such as DBM.

Technical Summary

This is a cross-disciplinary collaborative LINK project, with commercial partner Oxitec Ltd, with the objective of optimizing a biotechnological solution for the management of insect resistance to bio-pesticides. We will combine genetic technological developments with mathematical models, laboratory and field experiments to develop an integrated research approach for novel methods of insect pest management.
Oxitec pioneered the development of RIDL - Release of Insects carrying a Dominant Lethal genetic system - a novel approach to insect pest management based on the sterile insect technique.
Oxitec has recently developed transgenic RIDL DBM strains with female-specific lethality. Theoretical modelling has predicted that RIDL releases can mitigate resistance by reducing pest population size and driving pesticide-susceptible genes into a population through the male line.

Our project aims to build on these recent advances. We will test this novel theory using experimental evolution and competition assays to simulate existing resistance management strategies (work packages 1 and 2). We will extend testing to scenarios that are predicted to increase the impact of RIDL releases on resistance management. These scenarios will be increased spatial structure and exposure to multiple toxins. In work package 3 the fitness and field-suitability of new RIDL DBM strains will be investigated through fitness and mating competition assays. Performance of these strains will carefully evaluated in an experimental series that culminates in the field. This will be thoroughly supported by a range of novel mathematical models that will provide a detailed understanding of the evolution of resistance to Bt and its toxins in diverse and heterogeneous agro-ecosytems and also of the cost-effectiveness of genetic control methods for agricultural pests such as DBM (work package 4).

Planned Impact

see lead document

Related Projects

Project Reference Relationship Related To Start End Award Value
BB/L00819X/1 31/03/2014 29/02/2016 £275,764
BB/L00819X/2 Transfer BB/L00819X/1 01/03/2016 31/03/2017 £102,323
 
Description The aim of the experimental part of this proposal was to demonstrate, in contained mesocosms, that the release of genetically modified sinsects for biocontrol can also have benefits for the evolution of resistance to pesticides.

This is because some female specific GM technologies involve releasing large numbers of males - which mate with wild insects and kill all female descendents. The males however can survive and reproduce, and if release in sufficient numbers can flood local populations with their genes, including those that convey susceptibility to pesticides.

Thus far we have explored the conditions under which this holds true for insects which are evolving resistance to Bacillus thuringiensis toxins in conditions which simulate the use of GM crops in the field. The first substantive paper has now been published (in addition to other collaborative publications) while a second will be submitted shortly.

We have now addressed all the objectives of our original proposal, although results in-project meant that we revised the plans for the final objective and focussed more on the importance of structure in insect populations rather than on the combined use of multilple toxin agents.
Exploitation Route These findings may be valuable in promoting more diverse uses of GM insects in pest management. Since these self-limiting technologies are available for mosquito vectors of disease these data could have wider relevance for the use of biotechnology in the sustainable control of vector management.
Sectors Agriculture, Food and Drink,Communities and Social Services/Policy,Environment,Pharmaceuticals and Medical Biotechnology

 
Description Advising stakeholders & EU commission on biosafety of microbial pesticides
Geographic Reach Europe 
Policy Influence Type Gave evidence to a government review
Impact Certain EU members states have been agitating for tightening up the regulations on the application of microbial bicontrol agents in particular Bacillus thuringiensis (Bt). This position was in part driven by misconstruing the basis of some food poisoning incidents in Germany. I presented evidence to industry and to a meeting involving regulators, scientists and stakeholders. My evidence and analysis confirms the excellent safety record of Bt and unpicked the very poor evidence linking Bt to food poisoing or other disease. Following this consultation the EU have not taken the decision to tighten up regulations, a decision that faciltates the use of environmentally friendly biological alternatives to chemical insecticides. My responses to the European Food Safety Authority on the biological safety of Bt have been published in FEMS Microbiology and Ecology.
 
Description Helped ADAS draft "Crop Action" document on control of diamondback moth during the 2016 outbreak: issue 29
Geographic Reach National 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
Impact We anticipate that advice on the largest influx of a key Brassica pest for 40 years would have had some impact on farmer's ability to control this pest over that season, although these would be very hard to quantify
 
Description Membership of ACRE- DEFRA committee on release of GMOs and biological control agents
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description Co-developing risk assessment across disciplines and borders: gene drive mosquito field trials in Uganda
Amount £49,585 (GBP)
Organisation The British Academy 
Sector Academic/University
Country United Kingdom
Start 01/2019 
End 07/2020
 
Description Demography and the evolution of resistance 
Organisation University of Oxford
Country United Kingdom 
Sector Academic/University 
PI Contribution We are in the process of developing models and proposals to continue this avenue of research and incorporate research theoretical work on population growth and resistance.
Collaborator Contribution The collaboration is at at early stage- we are developing outline proposals.
Impact n/a
Start Year 2019
 
Description Industrial Partnership - (as part of BBSRC IPA award) 
Organisation Dow AgroSiences
Country United Kingdom 
Sector Private 
PI Contribution My team will be engaged in producing mutants with increased virulence to resistant insect pests, as well as screening strain collections and toxin libraries for novel or improved isolates and proteins.
Collaborator Contribution The partner will be providing access to a sequenced strain collection as welll as to additional sequencing / molecular characaterization services.
Impact not yet....project began end of Feb 2019
Start Year 2019
 
Description Microbial ecology and insect fitness 
Organisation Oxitec Ltd
Country United Kingdom 
Sector Private 
PI Contribution We have produced preliminary data indicating that intestinal microbiota make a significant contribution to insect fitness, especially the ability to compete for mates. This could have significant implications for the Oxitec's technology and plans to release insects for pest population reduction.
Collaborator Contribution The partner Oxitec provided GM insects and made suggestions for protocols/ rearing methods.
Impact At the moment we are considering options for how to follow up on these data- this may mean applying for additional grant/studentship funding.
Start Year 2016
 
Description Wuhan plasmid project 
Organisation Huazhong Agricultural University
Department State Key Laboratory of Agricultural Microbiology
PI Contribution Shaped research questions, wrote paper, shaped and informed analysis
Collaborator Contribution Collected genomic data, analysed data, co-wrote paper
Impact This has resulted in a publication in mBio (Zheng et al)- and is a collaboration between molecular biologists and myself as an evolutionary ecologists. Other projects related to this collaboration are still ongoing.
Start Year 2016
 
Description Biological control workshop in Brazil 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Neil Crickmore and I were invited to run a small workshop, funded by FAPESP, at the University of Jaboticabal in Brazil. We gave a series of talks over 2 days on biological, Bacillus thuringiensis, and the evolution of resistance. It was primarily attended by postgraduate students and local academics.
Year(s) Of Engagement Activity 2014
 
Description IBMA Copa-Cogeca workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Safety and regulation of Bt based biopesticides were discussed with stakeholders and presented to representatives of EU commission
Year(s) Of Engagement Activity 2017
URL http://www.ibma-global.org/en/news/ibma-and-copa-cogeca-workshop-to-explore-the-implications-of-baci...
 
Description IBMA industry conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact This is the international biocontrol manufacturers annual meeting and very much an industry meeting rather than an academic conference. I was invited to give a talk on the safety on micro-organisms in biocontrol
Year(s) Of Engagement Activity 2017
URL http://www.abim.ch
 
Description Invited talk at Siconbiol biological control conference in Brazil 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Gave invited talk at Biological control meeting near Rio and again in Sao Paolo State in 2017
Year(s) Of Engagement Activity 2015,2017
 
Description Open days 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact The Penryn campus runs a series of open days throughtout the year designed to engage with prospective students and their families. This gives us a venue in which to talk about our research generally and that of the campus. In an event last summer, for instance, I discussed the recent invasion of diamond back moth and met with a local cabbage farmer and talked about pest control issues associated with this species.
Year(s) Of Engagement Activity 2016,2017,2018
 
Description Radio interviews relating to diamondback moth outbreak 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact We put out a press release relating to the 2016 diamonndback moth outbreak and since Cornwall is a Brassica growing region and this is a Brassica pest I also directly contacted local radio stations. This lead to a series of radio interviews on BBC Local Radio (Laurence Reed Show); Heart FM and was picked by the Mark Forrester show - a pick of local radio program broadcast nationally.
Year(s) Of Engagement Activity 2016
 
Description Science of Christmas 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact This is a children focussed event designed to build enthusiasm in a young / very young audience for science in general. The event is a series of Christmas themed talks- my contributution discussed gift giving in animals and bacteria and introduced the idea of unwanted presents and also touched on current antiobiotic resistance themes. As well as the regional audience parts of this show received some national media interest.
Year(s) Of Engagement Activity 2016
 
Description Silwood Bugs Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact 100-200 members of the public attended a Silwood Park open day focussed on entomological research at Imperial. As well as academic staff local research organizations, charities and conservation organizations had stands. The local MP and councillors also attended.
Year(s) Of Engagement Activity 2015
 
Description Visit and planning meeting with biopesticide producers 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Attended meeting at eNema HQ in Kiel, Germany. eNema are one of the largest producers of biopesticides in the EU. We discussed my recent results with nematodes and Bacillus and agreed to collaborate on a BBSRC proposal investigating nematode improvement for corn rootworm pests.
Year(s) Of Engagement Activity 2015
 
Description Visit to Chinese Academy of Science Institute for Plant Protection 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact My post doc and I were invited to visit Bejing to give talks, share ideas and develop future collaborative interests. Future projects are currently under discussion.
Year(s) Of Engagement Activity 2015
 
Description Workshop meeting with CABI 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Third sector organisations
Results and Impact 5-6 members of staff from Silwood Park attended a workshop run by CABI, a leading international biological control organization based in Egham. The purpose of the meeting was to explore future avenues for collaboration between academia and the needs of this sector.
Year(s) Of Engagement Activity 2015