The Recognition Of Bacteria-Infected And-Uninfected Armyworms,Mythimna Separata By The Endoparasitoid Wasp,Microplitis Mediator

As important biological agents,parasitic wasps control agricultural and forestry pests and play an indispensable role in production.Understanding the chemical communication between the parasitic wasp and its host will promote positioning of the parasitic wasp to the host,and further strengthen the application of parasitic wasps in the field.In addition,using of bacteria to infect the host,based on the interaction between parasitic wasp-host-bacteria,will provide basis for the construction of ecological control of important agricultural pests.In order to explore the selection bias of parasitic wasps on infected and uninfected bacterial hosts,this study first infected the host insect Microplitis mediator with bacteria Micrococcus luteus and Enterobacter cloacae and then examined the phenoloxidase activity and expression of the antimicrobial peptide gene Gloverin 3 in the hosts.Next,we observed and recorded the spying,oviposition and development of the parasitic wasp in the infected and uninfected hosts.Finally we analyzed the change of the hydrocarbon composition of the host integument after infection.Our main results are as follows:1.After infection with M.luteus and E.cloacae,the expression of the antimicrobial peptide gene Gloverin 3 in the Mythimna separata was up-regulated.After 6 h,12 h infection with M.luteus,the activity of PO was increased significantly,After 12 h,24 h infection with E.cloacae,the activity of PO was also increased significantly.2.After 12 h infection with M.luteus and E.cloacae,the number of spying on Mythimna separata was less than healthy host.Compared with healthy Mythimna separata,there was no difference in the number of eggs laid by the Microplitis mediator after 3 hours infection with E.cloacae;6 h and 12 h post infection,he number of eggs laid by the Microplitis mediator in the healthy Mythimna separata was significantly higher than that of the infected host.After 6hours infection with M.luteus,there was no significant difference in the number of eggs laid by Microplitis mediator.However,after 12 h and 24 h infection,the number of eggs laid in the healthy Mythimna separata was significantly higher than that of the infected host.3.In the Mythimna separata infected with E.cloacae,the larval stage of the wasp was shortened to a certain extent,in the Mythimna separata infected with M.luteus,the larval stage was basically the same as in the healthy host.The developmental status of the first and second instar larvae in the bacterial-infected host is basically the same as the one in the healthy host.However,in the bacterial-infected host,the third instar larvae have enlarged and transparent tail vesicles.The tail vesicles of the third-instar juveniles in healthy hosts are darker and shrunken.The eclosion rate of parasitic wasp that developed in the host infected with E.cloacae was slightly higher than that developed in the healthy host.The eclosion rate of parasitic wasp that developed in the host infected with M.luteus was basically same as that developed in the healthy host.4.After infection with M.luteus and E.cloacae,the composition and content of hydrocarbons on the body surface of Mythimna separata were changed.Trihexadecane was detected on the surface of the infected Mythimna separate.And 2,4-Di-tert-butylphenol,3-dodecane,3-octadecene,dibutyl phthalate,(7Z)-7-hexadecene,Oleamide,Bis(2-ethylhexyl)adipate,triacontane,and tetratetracontane content were increased.In summary,compared with the Mythimna separata infected with bacteria,the parasitic wasp has a preference for laying eggs on healthy host.After infection with M.luteus and E.cloacae,the composition and content of hydrocarbons on the body surface of Mythimna separata were changed.