共生菌Wolbachia在中国二斑叶螨种群中的扩散规律

A comparative study of the dynamics of Wolbachia infection in different populations of Tetranychus urticae(Acari: Tetranychidae)

共生菌Wolbachia在中国二斑叶螨Tetranychus urticae Koch中分布广泛,所有的地理种群中均感染Wolbachia。以二斑叶螨湖南长沙(HN),辽宁兴城(LN)和江苏徐州(JS)3个地理种群为实验材料,经筛选获得100%感染和不感染Wolbachia的品系后,人工设置Wolbachia感染率为50%的品系,通过PCR技术检测二斑叶螨连续世代Wolbachia感染率动态变化,研究Wolbachia在二斑叶螨种群中的扩散规律。结果表明:3个地理种群的垂直传播效率都为100%;HN种群Wolbachia感染率上升速度最快,F7代达到100%感染;LN种群F12达到100%感染;而JS地理种群中Wolbachia感染率速度上升最慢,在F20代达到100%感染,其后感染率均能稳定在100%。LN种群Wolbachia通过诱导胞质不亲和的策略,JS种群的Wolbachia通过提高寄主适合度的策略,而HN种群Wolbachia则通过诱导胞质不亲和与提高寄主适合度两者相结合的策略,最终达到在二斑叶螨中维持感染状态并扩散传播的目的。本研究结果为今后利用Wolbachia的扩散规律控制有害生物及疾病传播提供了基础。

Maternally inherited Wolbachia bacteria are widely distributed in Chinese populations of the two-spotted spider mite Tetranychus urticae Koch （Acari： Tetranychidae）. All populations were found to be infected with Wolbachia. Using the Hunan （HN）, Liaoning （LN） and Jiangsu （JS） populations of T. urticae as experimental subjects, 100% Wolbachia-infected and 100% uninfected spider mite lines were obtained by screening. This study investigated the dynamics of Wolbachia spread in the two-spotted spider mite. Infection frequencies of Wolbachia among the progenies of the artificial populations, initiated with 50% infected and 50% uninfected female adults, were monitored by PCR. The results show 100% maternal transmission in all three populations. The rate of spread was fastest in the HN population in which the infection rate reached 100% by the F7 generation. The infection rate in the LN population reached 100% by the Fl2 generation but took until the F20 generation to do so in the JS population. Wolbachia appeared to use different strategies to invade and spread in the different populations. In the LN population, Wolbachia invaded and spread by inducing cytoplasmic incompatibility （CI）. In the JS population, Wolbachia invaded and spread by enhancing mite survival and host fitness. In the HN population, inducing CI was the dominant strategy. The enhanced fecundity associated with Wolbachia helped to promote the spread of infection. These results could provide a foundation for using Wolbachia-based strategies to control insect pests and disease vectors.