Symbiotic associations with microbes are nearly ubiquitous across insects and might be exploited to serve as a method of pest control. One such association, with the bacterium Wolbachia, is of interest to biological and vector control programs due to the bacterium’s ability to spread in insect populations and modify reproduction and physiology, resulting in small pest populations, more effective biological control agents, or protection against pathogens. Wolbachia is being transferred to target insects such as mosquitoes, resulting in the reduced transmission of dengue. Similar programs are in development for agricultural pests such as Drosophila suzukii. In Trichogramma wasps, Wolbachia improves the efficacy of biological control, as the entire population is female, the effective sex for parasitization of pests. It is clear Wolbachia can both: (A) improve biological control, or (B) act as a biological control agent. However, we know relatively little about the mechanisms by which Wolbachia infects and alters hosts. We use genome-wide functional investigations of how Wolbachia establishes infection and manipulates diverse insects. Our approaches are versatile, using systems level approaches to identify candidate genes, but also establishing model systems to interrogate how this intracellular bacterium has evolved to infect and manipulate arthropods of agricultural importance. Below are some of the systems we use to understand Wolbachia biology and evolution.
Drosophila melanogaster frequently harbor Wolbachia strains that can cause sperm-egg incompatibilities. Additionally, these Wolbachia can make their host insect recalcitrant to secondary infections with RNA viruses, and are being transferred to mosquitoes for use in vector control programs. The genetic tools available for Drosophila allow us to ask mechanistic questions about how Wolbachia establishes infection and manipulates its host.
Trichogramma wasps are minute in size and parasitize the eggs of moths and butterflies. They often harbor Wolbachia strains that convert them to a form of asexual reproduction. This can improve the efficacy of biological control, as only females kill pests. Additionally, this conversion to asexuality can be permanent: wasps rely upon their resident Wolbachia for the continued production of females.
Insect Cell Culture
Insect cell culture systems allow us to easily move Wolbachia between host contexts, visualize the localization of the bacteria, and track the progress of infection. There is a suite of molecular tools available for insect cells lines that facilitate genetic and microscopic studies of the host-Wolbachia relationship.