Innovative approaches to pest management

Lead Research Organisation: Rothamsted Research
Department Name: Unlisted

Abstract

We will exploit long established and acclaimed expertise in the identification and development of pheromones and other semiochemicals for use in crop protection. The work now embodies molecular genetic approaches and specifically targets delivered through seed via breeding and GM technologies. Semiochemicals are small lipophilic molecules (SLMs) that can be generated as plant secondary metabolites and represent a more flexible and robust alternative to current pest control targets for GM, which are mostly direct gene products. Only now do we have the necessary analytical and molecular tools to exploit SLMs by modifying secondary plant metabolism with the advantage that we can use non-toxic signalling mechanisms as alternatives to toxic modes of action, as embodied in semiochemicals. Thus, the main thrust is to exploit semiochemicals as secondary metabolites. Where defensive metabolites are already present in crop species, but acting by direct physiological methods, this will be included, though usually with uplift support.

This will be achieved through the following objectives:

1: Identification of signalling chemicals involved in interactions between insects and between insects and their host plants.

2: Investigation of molecular interactions between the signals and their recognition proteins.

3: Elucidation of the molecular basis of natural stress-related induction of plant defences to insects.

4: Deployment of semiochemical strategies at the farm scale.

Publications

10 25 50

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Anderson JA (2016) Emerging Agricultural Biotechnologies for Sustainable Agriculture and Food Security. in Journal of agricultural and food chemistry

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Babikova Z (2013) How rapid is aphid-induced signal transfer between plants via common mycelial networks? in Communicative & integrative biology

 
Description This programme identified and developed pheromones and other small lipophilic molecule (SLM) semiochemicals for use in crop protection, embodying targets for delivery through seed via breeding and GM technologies.

Avoidance of crop plants by insect pests and recruitment of their natural enemies, eg parasitoids (parasitic wasps), is mediated by key secondary metabolites including 6-methyl-5-hepten-2-one (MHO) and the homoterpenes (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT). We have shown that production of the homoterpenes can be primed by either airborne or rhizosphere stress signalling from neighbouring insect-damaged plants. We have identified a novel lipid-derived elicitor, produced by pest insects, of homoterpene production produced by pest insects, using advanced spectroscopic techniques (MS, NMR) and electrophysiological recordings hyphenated to high resolution chromatography (GC, LC), and chemical synthesis. Our hypothesis that production of the metabolites is via CYP450-mediated oxidative stress has been tested using next generation sequencing (comparative RNA-seq) to show differential expression of putative CYP450 genes upon either insect colonisation or elicitor treatment. The challenge will be to understand the underlying mechanisms of the plant signalling processes at the chemical and genetic level to underpin practical development.

We have demonstrated that emerging synthetic biological approaches can be used in the design of novel semiochemicals and genes for their biosynthesis. This is exemplified by the production of analogues of (S)-germacrene D, a potent aphid repellent, which cannot be rationally designed from docking studies with the associated olfactory proteins from the insects. We have recorded neurophysiological responses using GC-coupled electrophysiology from the olfactory receptor system, ie, antennae, of aphids, and shown that products generated by feeding of non-natural substrates to the plant synthase enzyme, have sufficient similarity to achieve activity on a rational basis. The challenge will be to explore the generality of the approach with other plant-derived signals such as the homoterpenes mentioned above, and to utilise this approach in the rational identification of new chemical ecological tools for pest management that overcome resistance by pests or beneficial organisms to existing semiochemicals.

Our field trials with genetically modified (GM) wheat emitting the aphid alarm pheromone (E)-B-farnesene showed that constitutive expression failed to reduce aphid populations or increase aphid parasitism. The challenge will be to develop an engineered wheat using an ecologically relevant release of the pheromone, via gene promoter sequences associated with newly identified stress-related elicitors and aphid colonisation. The onward route for GM will also include production and field testing of crops that produce either homoterpenes, and other new identified targets, and the challenge will be to demonstrate activity of modified crops expressing these metabolites, initially in the laboratory, but at a later stage in the field. Successful pest management via GM crop plants will require effective management of ecosystem services, requiring elucidation and exploitation of volatile plant signalling from wild grasses in providing parasitoid populations for conservation biological control in arable crops.
Exploitation Route Globally, sustainable intensification of crop production systems requires the delivery of new crop protection tools via seed, ie. GM, and the enhancement of ecosystem services, i.e. beneficial natural enemies, from land set aside as natural habitats. The findings here underpin the practical development of new crop protection interventions based on chemical ecology, specifically plant defence signalling, and which can deliver crop protection via smart plants, sentinel technology and recruitment of ecosystem services i.e. beneficial natural enemy populations for conservation biological control.
Sectors Agriculture, Food and Drink

 
Description GCRF-IAA
Amount £33,439 (GBP)
Funding ID BB/GCRF-IAA/18 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 02/2017 
End 02/2017
 
Description International Congress of Entomology Meeting 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited Keynote presentation at International Congress of Entomology Meeting, Orlando, USA, September 2016. "Prospects for Robust Insect Resistance in Crops Using Plant Genetic Engineering".
Year(s) Of Engagement Activity 2016