Abstract: Wolbachia is widely distributed in arthropods and can manipulate the reproduction and fertility of its hosts. Antibiotics can effectively remove Wolbachia from host body. In this study, Wolbachia in Encarsia formosa was removed by feeding wasps with solution of 1, 5 and 10 mg tetracycline hydrochloride/mL sucrose water, and PCR technique was used to detect the completely removing of Wolbachia from female wasps. The numbers of eggs loaded and ovarian tubules of the females were investigated to evaluate the effect of Wolbachia on reproduction of E. formosa. The results indicated that there was no significant difference in the number of ovarian tubules among F0 female of different treatments (P=0.12), whereas there were 6 ovarian tubules in female wasps of Wolbachia free F1, F2 and F3 generations, significantly less than in female wasps of F0 generation (P<0.001). Egg load in F0 generation wasp from which Wolbachia was removed by feeding antibiotics was less than that in the untreated female of F0, but was more than that in F1, F2 or F3 generation (P<0.001). No significant difference in egg load among F1, F2 and F3 generations was found (P=0.59). E. formosa could produce male offsprings after Wolbachia was removed, but no mating behavior was found and females could produce female offsprings without mating. These results suggest that Wolbachia not only affects directly egg load of host but also affects the development of ovarian of host; however, removing of Wolbachia does not change the parthenogenetic reproductive mode of E. formosa.

Key words: Wolbachia, Encarsia formosa, reproduction, egg load, ovarian tubules, wsp gene