Selective Elimination of Wolbachia from the Leafhopper Yamatotettix flavovittatus Matsumura.

Wolbachia infections affect the reproductive system and various biological traits of the host insect. There is a high frequency of Wolbachia infection in the leafhopper Yamatotettix flavovittatus Matsumura. To investigate the potential roles of Wolbachia in the host, it is important to generate a non-Wolbachia-infected line. The efficacy of antibiotics in eliminating Wolbachia from Y. flavovittatus remains unknown. This leafhopper harbors the mutualistic bacterium Candidatus Sulcia muelleri, which has an important function in the biological traits. The presence of Ca. S. muelleri raises a major concern regarding the use of antibiotics. We selectively eliminated Wolbachia, considering the influence of antibiotics on leafhopper survival and Ca. S. muelleri prevalence. The effect of artificial diets containing different doses of tetracycline and rifampicin on survival was optimized; high dose (0.5 mg/ml) of antibiotics induces a high mortality. A concentration of 0.2 mg/ml was chosen for the subsequent experiments. Antibiotic treatments significantly reduced the Wolbachia infection, and the Wolbachia density in the treated leafhoppers sharply declined. Wolbachia recurred in tetracycline-treated offspring, regardless of antibiotic exposure. However, Wolbachia is unable to be transmitted and restored in rifampicin-treated offspring. The dose and treatment duration had no significant effect on the infection and density of Ca. S. muelleri in the antibiotic-treated offspring. In conclusion, Wolbachia in Y. flavovittatus was stably eliminated using rifampicin, and the Wolbachia-free line was generated at least two generations after treatment. This report provides additional experimental procedures for removing Wolbachia from insects, particularly in host species with the coexistence of Ca. S. muelleri.

Effect of Wolbachia infection states on the life history and reproductive traits of the leafhopper Yamatotettix flavovittatus Matsumura.

Wolbachia is a maternally inherited bacterium of insects that can affect host reproduction and fitness. We examined the effect of Wolbachia infection on the life history and reproductive traits of the leafhopper Yamatotettix flavovittatus, which is a vector of the phytoplasma that causes white leaf disease in sugarcane. This investigation was performed using Wolbachia-infected and uninfected leafhopper lineages. Results revealed that Wolbachia infection did not significantly affect the survival of nymphal stages, male longevity, and sex ratio. However, Wolbachia-infected lineages had prolonged immature development periods and female longevity. In intrapopulation crosses, Wolbachia infection had no significant effects on occupation success, number of eggs laid, and female offspring, but the effect on egg-hatching varied. In interpopulation crosses, Wolbachia infection had no significant effect on occupation success and female offspring, but it did affect the number of eggs laid and egg-hatching rates. Assortative pairings regarding infection status resulted in normal egg deposition and hatching, whereas disassortative pairings resulted in lower egg deposition and no hatching. Wolbachia was thus shown to be highly vertically transmitted (>98% of the tested individuals). Our findings provide additional data on the interactions between Wolbachia in insect hosts. This evidence of perfect maternal transmission and strong reproductive incompatibility highlights the importance of further studies on the use of Wolbachia as a biological control agent for the leafhopper vector.