Stable composition of gut microbiome in the Asian ladybeetle Coccinella septempunctata reared on natural and artificial diets.

The Asian ladybeetle, Coccinella septempunctata, is an important insect of predatory natural enemy, which has a strong control effect and application prospects for aphids, whiteflies, mealybugs, and other small-sized pests of agriculture and forestry crops. Gut microbiota composition posed impacts on development of insects. In order to clarify the effect of artificial feed feeding on the intestinal microbial species and structure of C. septempunctata, we compared the intestinal microbial flora of C. septempunctata reared on bean aphids and artificial food for 15 days. Results show that Proteobacteria was the dominant component in all groups at phylum level, Rhodobacter, Methylovigula, Burkholderia, and Bradyrhizobium were the dominant bacteria among all groups at genus level. As to the differences in bacterial community structure and diversity, there is no significant difference between Shannon index and Simpson index, the principal components analysis of the bacterial communities, and the samples were roughly distributed in different regions. After 15 days of feeding, artificial diet did not significantly reduce the microbial diversity of the gut of C. septempunctata compared to the aphid group, and there was no significant effect on the abundance of dominant flora in the gut of C. septempunctata, C. septempunctata gut has a similar core microbiota. This study clarifies the effects in intestinal microbial diversity and composition structure of the C. septempunctata with artificial diet, and provides a theoretical basis for understanding the intestinal microorganisms and optimizating the artificial diet of C. septempunctata.

[Effects of neighbors with different sexuality and soil sterilization on biomass of Populus cathayana seedlings]. / 不同性别邻体和土壤灭菌对青杨幼苗生物量的影响.

Although plant-plant interactions have been intensively studied, few studies examined sex-related neighbor interactions in dioecious plant species. Here, we investigated the sexual diffe-rences in biomass accumulation, and analyzed the sexual neighbor effects and yields of sexual combination in Populus cathayana seedlings under the treatments of inter- and intra-sex neighbors and soil sterilization. The results showed that biomass accumulation of P. cathayana decreased in both of sexes when grown with an intra-sex neighbor. Females increased biomass accumulation under non-sterilization condition when grown with an inter-sex neighbor. Soil sterilization decreased biomass accumulation in both sexes of these plants, especially for females. Soil sterilization treatments did not significantly affect intra-sex interactions, but neutralized the positive effects in females and led the effects in males to turn from neutral to negative in inter-sex neighbors. The highest biomass in female-male combination under non-sterilization condition and the lowest biomass in male-male combination under sterilization condition were observed among combinations. These results indicated that the growth of female and male P. cathayana differed in their responses to their sexual neighbors, and that such neighbor effects were affected by soil microorganism. Our results could contribute to improve the productivity of poplar plantations in silviculture.

[Sublethal effects of fenpropathrin and avermectin on Panonychus citri (Acari: Tereanychidae).] / ç”²æ°°èŠé ¯å’Œé˜¿ç»´èŒç´ å¯¹æŸ‘æ©˜å ¨çˆªèž¨çš„äºšè‡´æ­»æ•ˆåº”.

A leaf disc bioassay was employed to examine the effects of fenpropathrin and avermectin with a sublethal concentration of LC20 on the development and reproduction of F0, F1 and F2 generations by means of life tables. The results showed that after the treatment of fenpropathrin at the sublethal concentration, the number of eggs laid per female significantly increased in F0 generation, the pre-oviposition duration was significantly shortened and the female ratio of offspring significantly increased both in F1 and F2 generations. The intrinsic rate of increase (rm) and finite rate of increase (λ) values all increased, and the generation time (T) and population doubling time (Dt) were shortened in F1 and F2 generations, with significant difference observed between F2 generations and the control. After exposure to avermectin, the number of eggs laid per female significantly decreased in F0 generation, and progeny (F1 and F2) also produced fewer eggs than the control, while the female ratio of offspring increased both in F1 and F2 generations and the pre-oviposition period was significantly shortened. The rm and λ values all increased, and the T and Dt were shortened in F1 and F2 generations. Such effects were more obvious on the F2 generation than the F1 generation. Generally, the effects of fenpropathrin and avermectin with a sublethal concentration of LC20 were not exactly the same on P. citri. Fenpropathrin could promote the development of the contemporary population, while avermectin had certain inhibition on the contemporary population, but both played a certain role in facilitating the development of future populations, which was of significance in developing integrated pest management strategies.

[Resistance realized heritability and risk assessment of Panonychus citri to avermectin and fenpropathrin].

On the basis of resistance breeding and selection in laboratory, and by using the threshold trait analysis in quantitative genetics, this paper studied the realized resistance heritability of Panonychus citri (McGregor) collected from Beibei of Chongqing to avermectin and fenpropathrin, and predicted the resistance risk of P. citri to these two acaricides. After 11- and 16-generations of selection with avermectin and fenpropathrin, the resistance of P. citri to the two acaricides increased by 3.8- and 29.9-fold, and the realized resistance heritability was 0.0475 and 0.1544, respectively. Under laboratory condition, to develop a 10-fold increase of resistance required 12-26 generations of selection for avermectin, and 7-16 generations of selection for fenpropathrin under the selection pressure of 50%-90% mortality for each generation. Under field condition, it would require more generations to develop the same resistance level. Comparing with bioacaricide avermectin, pyrethroid fenpropathrin had obviously higher resistance risk to P. citri. The results provided references for the resistance management of P. citri to acaricides.