Wolbachia-mediated "Memory" Deprivation Manipulates Parasitic Behaviors Of Trichogramma Dendrolimi Matsumura

Trichogramma dendrolimi is a kind of egg parasitoids which can control many agricultural and forestry lepidopteran pests.How to identify host is particularly important for egg parasitoids.Parasitoids will mark the host as parasitized by markers when they parasitism,and acquire the ability to distinguish such markers through acquired learning,so as to avoid repeated parasitism to the same host.The "memory" generated by such learning is affected by many factors.Among them,some studies suggest that Wolbachia can weaken the "memory" of Trichogramma and make it prefer to superparasitism,and the horizontal transmission of Wolbachia may occur in the process of superparasitism.Therefore,it is suggested that Wolbachia may increase its tendency to superparasitism by depriving its host of "memory",thus expanding its spread.To test this hypothesis,the present study investigated the effects of Wolbachia and two "memory" inhibitors on "memory" ability and "memory"-related genes(CREB)of T.dendrolimi,a male and parthenogenetic female strain of Trichogramma.Influence of expression,the superparasitism frequency of T.dendrolimi under the influence of Wolbachia and "memory" inhibitor was calculated.The results are as follows:The difference in "memory" of Trichogramma pinus and Trichogramma pinus were investigated.The scent selection and residence time of females of the two reproductive strains were calculated after association learning at different time intervals.It was found that the experimental group was significantly higher than the control group after 12 hours of association learning.After 24 h of association learning,the male and female reproductive lines were still higher than the control group,but there was no difference between the parthenogenetic female lines and the control group.After 36 h of association learning,there was no significant difference between the experimental group and the control group.To investigate whether infection with Wolbachia affects the "memory" ability of T.dendrolimi.After associative learning "memory" test in parthenogenetic female reproductive lines,the proportion of odor selection in females of non-infected Wolbachia was significantly higher than that of females of infected Wolbachia.The "memory" inhibitors actinonin D and anisomycin were used to reduce the "memory" ability of T.dendrolimi in both Wolbachia-infected and non-infected females.However,the "memory" ability of T.dendrolimi was decreased only in females of the non-infected Wolbachia-infected females,but in females of the infected females.This did not occur in female bees of HIA strain.The expression difference of CREB 1 gene in T.dendrolimi was investigated.Both Wolbachia-infected and non-infected Trichogramma strains were fed with "memory" inhibitors actinonin D and anisomycin,and actinonin D inhibited the expression of CREB 1gene more significantly than anisomycin.The effects of Wolbachia,actinone D and anisomycin on the superparasitism frequency of Trichogramma SPP.By feeding actinosterone D and anisomycin to hermaphroditic and parthenogenetic lines,it was found that the superparasitism frequency of Wolbachia-infected lines was higher than that of hermaphroditic lines.Feeding inhibitors increased the frequency of Trichogramma superparasitism.In this study,two T.dendrolimi caterpillar strains were fed with "memory" inhibitors,and the frequency of "memory" superparasitism and the expression of CREB 1 gene were compared between the two strains.It was confirmed that Wolbachia could increase the tendency of "memory" superparasitism through "memory" deprivation.The results will help us better understand the effects of Wolbachia on the neurobiology of invertebrate hosts,lay a foundation for further revealing the molecular mechanism of the effects of Wolbachia on the "memory" behavior of Trichogramma,and contribute to better use of parasitic wasps for pest control,which is of great significance.