黑胸茧蜂寄主范围初步研究

A Primary Study on Host Range of Bracon nigroru fum

室内试验及田间调查结果表明，黑胸茧蜂除寄生棉红铃虫及梨小食心虫外．豆荚螟是又一新发现的重要寄主。黑胸茧蜂对棉红铃虫寄生率高，豆荚螟，梨小食心虫次之．在湖北。黑胸茧蜂越冬代５月上旬开始羽化．５月中旬寄生二代梨小食心虫，６月中、下旬越冬代大量羽化集中寄生春大豆上第二代豆荚螟，７月上、中旬转移至棉田寄生第一代棉红铃虫。８月上、中旬又向棉田四周的夏大豆田转移寄生第三代豆荚螟，９月上、中旬迂回棉田寄生第三代棉红铃虫直至越冬。

Results from lab experiment and field investigation showed that lima pad borer, Etiellazinckenella(Treitschke)was a new host of Bracon nigrorufum (Cushman) whose known hosts comprised cotton boll-worm,Pectinophora gss ypiella Saunders and oriental fruit moth. Graphotitha molesta Busek.Parasitization of P.grssypiella by B. nigrorufum were greater than that of anoter two pest insects,This Parasite wasp had a greater par-asite rate to E. zinckenella than to G. molesta, Every year in Hubei Province ,hibernating generation of the waspspecies began to emerge in the lst decade and parasitized the 2nd generation larval of G. mkolesta in the 2nd decadeon May.The wasp parasitized mainly the 2nd generation of E,zinckenella which infested spring soybean in the latertwo decades on June and migrated to cotton field to utilize the lst generation of P.gossypiella as host in the earlytwo decades on July.In the early two decades of August ,the wasp entered summer soybean field to parasitize the3rd generation of E. zinckenella,then came back to cotton field for the 3rd generation of P.goss ypiella in earlySeptember and over wintered in late October.