The Selection Behavior And Field Control Effect Of Microplitis Similis (Hymenoptera:Braconidae) On The Infected Larvae Of Spodoptera Litura

In this study,the parasitism behavior of Microplitis similis to healthy and infected Spodoptera litura larvae by Heliothis virescens ascovirus 3h(HvAV-3h)and the influence of different learning experience on the parasitic selection of the wasp were studied,and its comprehensive recognition ability to healthy and infected hosts was evaluated.The effects of M.similis on the selection behaviors of healthy and infected larvae and their accessory substances,as well as the effects of different learning experiences on the selection behaviors were studied.Under the condition of filed cage experiment,the effect of control of S.litura was studied.The main results are as follows:(1)The M.similis with learning experience can improve their search efficiency a certain extent,and also have a certain impact on the ability of wasps to identify their hosts.In terms of attack times,within 1-2 d of the infected larvae,the wasps with no experience and with the experience of the infected larvae tended to attack the healthy host more frequently,and in 3-6 d after infection,the wasps of the three treatments gradually tended to attack the infected host more frequently.In terms of first attack rate,the first attack rate of wasps without experience on infected larvae for 1-7 d is on the whole increasing trend.The first attack rate of wasps with the heathy lavae experience on infected lavae for 1-5 d is continuously higher than that of healthy larvae,and the first attack rate of wasps with the infected lavae experience on infected lavae for 3-6 d is continuously higher than that of healthy larvae.(2)The wasps without experience or healthy host experience showed obvious preference for healthy hosts and its’appendages,while those with infected larvae experience showed no obvious preference for healthy and infected hosts and its’appendages.In 1-3 d,there was no obvious selection tendency for infected and healthy host in the wasps without experience or with experience of healthy host,and in 4-6 d,the wasps have obvious selection tendency to healthy host.But there was no obvious selection tendency for the wasps with infected host experience between infected within 1-7d and healthy host.The wasps without experience and with healthy host experience had obvious selection tendency to feces and haemolymph of the infected host for 4-7 d,but the wasps with the infected host experience had no obvious selection tendency.(3)Only M.similis or the combination of M.similis and HvAV-3h can both significantly inhibit the damage of S.litura to cabbage.When only healthy host larvae were put into the field,the larval feeding leaf area was restrained about 38.02 cm~2,and the yield increased by 10.22%by the wasp with no HvAV-3h,and the larval feeding leaf area was 42.54 cm~2,and the yield increased by 9.19%by the wasp with HvAV-3h.When the healthy and infected larvae were both put in the field,the area of leaf feeding was restrained about 32.86 cm~2,and the yield increased by 18.61%by the wasp with no HvAV-3h.