ABSTRACT
Insects provide rich and diverse arenas for various microbes. A considerable proportion of insect species harbor endosymbionts—bacteria, protists, and viruses—in their gut or cells. This chapter reviews various case studies in which endosymbionts were shown to have profound effects on their hosts, with special emphasis on chemical ecology. Gut bacteria in locusts and cockroaches play important roles in the production of fecal aggregation pheromones. Gut bacteria in Drosophila flies have critical effects on the biosynthesis of hydrocarbons, which act as contact sex pheromones, thereby having a potentially important role for mate-recognition leading to speciation. Some bacteria exert their effects as chemical defense against predators, parasites, or pathogens in a variety of insects. Besides this, there are numerous cases where direct or indirect contribution of microorganisms to insect chemical ecology is suspected. The utility and benefit of the hologenomic concept in the light of microbe-associated chemical ecology is also discussed.
