我国不同地区草地贪夜蛾内共生菌感染和耐寒能力差异研究

Difference in endosymbiont infection and cold tolerance among different geographical populations of Spodoptera frugiperda

本研究旨在明确我国不同地区草地贪夜蛾Spodoptera frugiperda共生菌感染差异和耐寒能力差异。采用16S或23S rDNA等定性检测方法,鉴定草地贪夜蛾共生菌种类并测定其感染率,通过邻接法(Neighbor-joining)构建系统进化树,进行共生菌系统发育分析。从我国8个地区采集的草地贪夜蛾幼虫中鉴定出2种内共生细菌,分别为Arsenophonus和Cardinium。两种共生菌在不同地理种群中的感染率存在显著差异,其中Arsenophonus感染率总体较低,云南保山种群感染率最高,为20.0%,其次是广西南宁种群(15.5%),贵州贵阳和江苏盐城的种群感染率均为1.7%,而广东广州、江苏无锡以及湖北宜昌和孝感种群中均未发现Arsenophonus的感染;Cardinium感染以江苏无锡种群最高,达96.7%,云南保山和广东广州种群感染率分别为93.3%和86.7%,贵州贵阳种群为53.3%,湖北孝感和宜昌感染率则分别为30.0%和18.3%,江苏盐城种群感染率也为18.3%,而广西南宁种群中未发现该共生菌。对8个地区草地贪夜蛾的耐寒能力比较表明,江苏盐城和湖北孝感种群耐寒能力最弱,-6℃下死亡率分别为76%和69%,显著高于其它6个种群,后6个种群间无显著差异,死亡率在35%~49%之间。我国不同地区草地贪夜蛾在共生菌感染和耐寒能力上均存在差异,但未发现共生菌感染与耐寒能力的相关性。

The study aims to clarify the difference in endosymbiont infection and cold tolerance among different geographical populations of Spodoptera frugiperda(Lepidoptera∶Noctuidae),which will be beneficial to further analysis on functions of the symbionts.The species of endosymbionts and their infection rate were detected by diagnostic PCR method with primers targeting the 16S or 23rDNA sequence,and the phylogenetic trees were constructed using the neighbor-joining method.Two species of endosymbiont,Cardinium and Arsenophonus,were detected from 8 field populations collected in China,and there was significant difference in the infection rate among different populations.The infection incidence of Arsenophonus in Baoshan Yunnan population was 20.0% which was the highest among all tested populations,and the infection rate in Guiyang Guizhou and Yancheng Jiangsu populations were all only 1.7%,whereas no individuals in the other 4 populations were found to be infected with Arsenophonus.The infection incidence of Cardinium in Wuxi Jiangsu population was up to 96.7%,and that in Baoshan Yunnan population and Guangzhou Guangdong population were 93.3% and 86.7%,respectively,the incidence in Yicang Hubei and Yancheng Jiangsu were all 18.3%,Cardinium was not present in Nanning Guangxi population.Comparison on cold tolerance showed that,the mortality of Yancheng Jiangsu and Xiaogan Hubei population under -6℃ exposure was 76% and 69%,which was significantly higher than that of the other 6 populations,and there was no significant difference among the 6 populations,the mortality under -6℃ exposure ranged from 35% to 49%.Our results indicated that endosymbiont infection and cold tolerance varied with geographical populations of S.frugiperda,and endosymbiont infection had no relationship with cold tolerance.