WOLBACHIA INFECTION AND CYTOPLASMIC INCOMPATIBILITY IN DROSOPHILA SPECIES

Forty-one stocks from 30 Drosophila species were surveyed for Wolbachi a infection using PCR technology. D. sechellia and two strains of D. a uraria were found to be infected and were tested for the expression of cytoplasmic incompatibility, along with D. ananassae and D. melanogas ter strains, which are already known to be infected. D. ananassae and D. melanogaster show levels of incompatibility up to 25%, while D. aur aria and D. sechellia exhibit levels of egg mortality similar to 60%. A dot-blot assay using the dnaA sequence as probe was developed to ass ess the infection levels in individual males that were used in incompa tibility crosses. A positive correlation between bacterial density and cytoplasmic incompatibility was observed. The stocks examined can be clustered into at least two groups, depending on the levels of infecti on relative to the degree of cytoplasmic incompatibility exhibited. On e group, containing D. simulans Hawaii, D. sechellia, and D. auraria, exhibits high levels of cytoplasmic incompatibility relative to levels of infection; all the other species and D. simulans Riverside exhibit significantly lower levels of cytoplasmic incompatibility relative to levels of infection. These data show that, in addition to bacterial d ensity, bacterial and/or host factors also affect the expression of cy toplasmic incompatibility.