The role of the microbiota in mediating invasions

Background:
Invasions of pest species are increasingly a problem, partly due to an increasingly globalized world, partly due to climate change allowing range expansion. Two recent invasions that been particularly devastating have been of the fruit fly Drosophila suzukii across the Americas and Northern Europe, and of the fall armyworm, Spodoptera frugiperda, across Southern Africa. The former is a pest of soft fruit crops such as cherries and grapes; where it is a major problem as, unusually for a fruit fly, it infests ripening fruit rather than rotting fruit. S. frugiperda is a pest of grain crops, like rice and corn. In both cases, economic impacts in recent years have been vast. There is reason to suggest that changes in the gut microbiota have assisted in their rapid invasion. Additionally, in D. suzukii, preliminary results suggest that the changes in diet that would be expected when invading a novel host, can impact negatively on mating behavior, as a result of changes in the expression of adipokinetic hormone.

Objectives:
The objective of the proposed project is to investigate the role of the gut microbiota in mediating invasion events, utilizing D. suzukii and S. frugiperda as model systems.

Novelty:
Very little is known about the basic biology of D. suzukii, and although the life history of S. frugiperda has been well studied, little is known regarding its microbiota. The proposed project has the potential to have an important impact on our understanding of invasions, and how climate change is likely to mediate them.

Timeliness:
Earlier this year S. fruiperda invaded, and swept through, Southern Africa, to devastating effect. D. suzukii too, has further expanded its range. Such invasions and range expansions are becoming ever more commonplace, and therefore the project is both important, and extremely timely, not least given climate change predictions.