The bacterium Wolbachia is known to infect a large number of the world's insect species (among other terrestrial invertebrates), with important effects on the biology of its animal hosts. In many insects, Wolbachia causes a kind of bacteria-induced reproductive failure called "cytoplasmic incompatibility" (CI), a phenomenon that favors the survival of Wolbachia-infected insects by a mechanism that, despite intense study, is still poorly understood. Having made a recent, surprising discovery of CI in a second bacterium, Cardinium, that is unrelated to Wolbachia, the investigators in this study will probe the CI mechanisms of Cardinium in parasitic wasps. This project represents the first study of CI mechanisms in a bacterium other than Wolbachia; through the tractability of this experimental system and the comparative insights it can provide, this investigation will ultimately enhance understanding of CI in Wolbachia as well as Cardinium. To address these questions, the investigators will analyze the expression of genes in male and female Cardinium-infected wasps. They will also conduct a microscopic analysis of the mortality of embryos due to CI-causing Cardinium. The insights into CI will contribute to the effective manipulation of CI-causing bacterial symbionts for management of important insect pests and disease vectors. The project will also contribute to middle school science education and training with a curriculum supplement on insects and microbe interactions. Lastly, the project will result in research training (including international training) of a graduate student, two undergraduates, as well as training of two graduate students in K-12 science outreach.
