SOCIAL ATTRACTION MEDIATED BY BACTERIAL VOLATILES

Abstract

<p>Recent observations illustrate fruit fly larval attraction to the distinct odour emanating from food occupied by other larvae. Growing evidence of bacteria as influential microorganisms of hosts suggested the closer examination of host-microbial interactions. We investigated the origin of the volatiles that are attractive to flies. Focal larvae showed no difference in attraction to axenic used food with axenic larvae and axenic fresh food. Additionally, mated females showed no difference in attraction to axenic used food with axenic larvae and axenic fresh food. When we supplemented the axenic disks with <em>L. brevis</em>, larvae showed a significant preference for the axenic used food with axenic larvae and <em>L. brevis </em>over axenic fresh food. Also, the supplementation of <em>L. plantarum</em> to axenic disks also resulted in larvae showing a significant preference for the axenic used food with axenic larvae and <em>L. plantarum </em>over axenic fresh food. Focal larvae showed a significant preference for <em>L. brevis</em> on scratched MRS agar and axenic used food with axenic larvae, but did not show a significant preference for <em>L. brevis</em> on scratched axenic food. In a learning experiment, focal larvae showed no preference for novel odours previously paired with standard used food over novel odours previously paired with axenic used food. In order to test whether <em>L. brevis</em> improves food quality, the three fitness parameters observed, larval development rate, egg-to-adult survival, and adult body mass, revealed inexplicable findings. These results provide evidence for the role of bacterial volatiles in mediating the social attraction observed in fruit flies.</p>