THE EFFECTS OF WOLBACHIA ON THE AGGRESSION OF MALE FRUIT FLIES

Elizabeth Bondy , Chelsie E. Rohrscheib, Dr. Jeremy C. Brownlie

THE EFFECTS OF WOLBACHIA ON THE AGGRESSION OF MALE FRUIT FLIES

Wolbachia is a genus of alpha-proteobacteria that is found as an intracellular endosymbiont in nematodes and arthropods. Around 40% of all insect species are infected (Zug & Hammerstein 2012), including the common fruit fly Drosophila melanogaster, a model organism commonly used in neuro-genetic and behavioral studies. Wolbachia’s omnipresence and unique ability to manipulate host reproductive and sex determination systems have generated great interest in studying the details of the symbiotic relationships between Wolbachia and its hosts. Wolbachia are known to infect the brains of insect hosts, including D. melanogaster, yet relatively little is known about what effect such infections have on behavior. One important behavioral aspect to consider is how Wolbachia affects host aggression, an important behavior used to secure sexual partners or resources. The aggression of male fruit flies was determined for males that were uninfected (controls), infected with a benign Wolbachia strain (wMel), or infected with a pathogenic strain (wMelPop) known to establish high infection density within the brain. The results showed that wMel infected flies demonstrated no difference in aggression with their uninfected counterparts, whereas flies infected with wMelPop had significantly reduced aggression compared to uninfected flies. wMel is the most prevalent Wolbachia strain in the wild, so the findings can support how wMel has been able to spread amongst populations. The decreased aggression caused by wMelPop, on the other hand, leads us to question if the results parallel with other strains of Wolbachia and their respective hosts. This is the first time any research has been performed on how Wolbachia effects aggression, so extensive future experiments can follow, involving more environmental manipulations or different species. Recently, Wolbachia has been pondered as a potential biological control agent, therefore it is critical to ascertain potentially negative behavioral effects that Wolbachia exerts on its hosts. This work has been supported by a grant from the National Institutes of Health (MD0014277) through the BRAVO! program.

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