关键词: 二化螟, 抗药性种群, 中肠, 变形梯度凝胶电泳, 16S rDNA文库, 细菌群落多样性

Abstract: Bacterial community in midguts of larvae of four populations of the striped stem borer, Chilo suppressalis, with different levels of resistance to insecticides was detected and analyzed using PCR-DGGE and 16S rDNA libraries. The bioassay showed that compared to the susceptible strain, the Heilongjiang population (HLJ population), the Lianyungang population (LYG population) had low to middle resistance level to monosultap, chlorpyrifos and triazophos, the Rui’an population (RA population) and Zhuji population (ZJ population) had middle to very high resistance level to the above three insecticides, and the latter three populations all were susceptible to avermectins. DNA sequence analysis indicated that the PCR-amplified 16S rDNA genes represented 21 bacteria phylotypes, and most of them belonged to the genus Streptococcus. Bacterial community in larval midgut of four different resistant populations was mainly the genus Enterococcus, except that the dominant bacteria in ZJ population were Lactococcus garvieae, L. lactissubsplactis and Ochrobactrum anthropic. The DGGE profiles demonstrated that the bands of HLJ population were simple, those of LYG population were the most abundant, and the band richness of ZJ population was similar to that of RA population. The common bacteria in the four populations were Enterococcus faecium, E. hirae and Arthrobacter sp., and the main bacteria were the genus Enterococcus. The results suggest that there is difference in bacterial abundance in larval midgut of C. suppressalis with different levels of resistance to insecticides, which may be related to the difference of resistance to insecticides among different populations of C. suppressalis.

Key words: Chilo suppressalis, resistant population, midgut, PCR-DGGE, 16S rDNA libraries, bacterial community diversity