Characterization of a novel Wolbachia infection in Aedes albopictus (Diptera: Culicidae)

Wolbachia are maternally transmitted obligate intracellular bacteria that occur naturally in many arthropods. The phenotype observed in mosquitoes causes cytoplasmic incompatibility (CI), which results in reduced or absent egg hatch in crosses between individuals with different infections. Applied strategies propose that by releasing incompatible males infected with a Wolbachia strain that differs from the females in the host population, CI could suppress or replace mosquito populations. Using tetracycline treatment and embryonic microinjection, Ae. albopictus was cleared of its natural Wolbachia infection and artificially infected with a different strain from Ae. riversi. A series of crossing experiments were carried out to see if CI could be observed in crosses between naturally superinfected, artificially infected and uninfected strains of Ae. albopictus. Crosses between artificially infected and uninfected mosquitoes were as expected, exhibiting a classic unidirectional pattern, where the cross between uninfected females and artificially infected males resulted in no egg hatch. Crosses between naturally superinfected and artificially infected mosquitoes did not exhibit the classic CI pattern. Artificially infected females crossed with naturally superinfected males exhibited no decrease in egg hatch. Naturally superinfected females crossed with artificially infected males had a 30% reduction in egg hatch. This experiment indicates that host factors in addition to Wolbachia infection may play a role in CI.