FULLY FUNDED PROJECT: The manipulation of olive fly gut microbiota for improved pest control

The olive fly, Bactrocera oleae (Diptera: Tephritidae), is the primary pest of olives globally. Current control relies on intensive spraying of insecticides. However, larvae feed on the fruit, causing major crop losses in Greece, Spain and Italy. In Greece, the olive fly is considered the most serious agricultural insect pest. Current control methods rely overwhelmingly on insecticides. SIT is a species-specific and environmentally friendly method of pest control. Current SIT relies on irradiation to sterilise the target pest species but this can have a negative impact on the released insects’ performance. This and other problems associated with current SIT programmes could be overcome by the use of recombinant DNA methods. Oxitec Ltd is the world leader in developing such approaches and has developed a technique called RIDL (Release of Insects carrying a Dominant Lethal), which uses transgenic technology to overcome limitations of SIT. At Oxitec, we have developed RIDL female lethal strains for olive fly. This project seeks to build on this success by optimising the strains for eventual olive fly control in the field.

Implementation of SIT requires simple, efficient and cost-effective mass-rearing system that produces high-quality insects. Although, artificial diets have been developed that can replace olive as larval food, to permit large-scale factory rearing, they are expensive and not very effective. The objective of this studentship is to define the gut bacterial and fungal communities across developmental stages of Bactrocera oleae (larvae, pupae and adults) and understand the impact of gut microbial communities on the fitness of cultured and wild olive flies with the aim of improving diets for mass rearing.

The central hypothesis of this study is that the olive fly’s monophagic feeding behaviour is linked to specialised/symbiotic gut microbiota which facilitates the utilisation of the insect’s diet. This leads to the hypothesis that changes in this gut flora will result to changes in insect fitness. The student will fully profile the gut microbiota of olive flies from wild and lab populations in order to understand the gene composition and function of these communities. Comparing the gut flora of laboratory-reared and wild insects will further permit identification of bacterial species that are depleted by artificial diet. The student will also investigate how these communities affect host traits like metabolism, fecundity, immunity, mating and longevity.

Training:
The student will gain expertise in molecular biology, microbial analysis and culture, high-throughput sequencing and metagenomic analysis at the University of Liverpool, while will also benefit from the unique expertise of Oxitec in developing RIDL strains – microinjections, insect rearing and manipulation - and taking these strains to field cage and open-field assessment. The student will work closely with collaborations in Crete, Morocco and Spain who will permit the timely provision of wild olive fly from different locations for the purposes of this research.