Variable fitness and reproductive effects of Wolbachia infection in populations of the two-spotted spider mite Tetranychus urticae Koch in China

摘要

Maternally inherited Wolbachia bacteria are widely distributed among insects, and their presence usually causes modifications of the host. To understand the evolutionary history of diverse host-Wolbachia associations, we investigated the symbiosis between Wolbachia and the two-spotted spider mite Tetranychus urticae Koch in China. The cytoplasmic incompatibility (CI) level, fecundity, female ratio, host longevity and host development time were examined. Our results indicate that Wolbachia bacteria had variable effects on the reproduction and fitness of Chinese populations of T. urticae. Variability of CI expression within T. urticae ranged from no CI to a strong level of CI in spite of the low variability of the wsp gene. Relative to uninfected mites, infected females in one of the three populations showed enhanced fecundity associated with the infection of Wolbachia. This is the first report of a Wolbachia infection promoting the fecundity of infected females in T. urticae. Furthermore, we found both positive and negative effects of Wolbachia infection on longevity and the development time. The differences in ecological characters may be attributed to both Wolbachia and host genotype.