小菜蛾的生物防治问题

本文应用种群数量发展趋势指数和干扰作用控制指数，研究不同菜场的小菜蛾Ｐｌｕｔ－ｅｌｌａｘｙｌｏｓｔｅｌｌａ（Ｌ．）种群动态。在大量而频繁施用广谱性杀虫剂的菜场，小菜蛾的种群数量发展趋势指数高达２９．３。在应用苏云金杆菌制剂代替广谱性杀虫剂的菜场，经过若干世代以后，小菜蛾的种群数量发展趋势指数下降为４．８８，接近于不使用化学杀虫剂的小区的水平（３．４０）。在试验中，散放赤眼蜂Ｔｒｉｃｈｏｇｒａｍｍａ（Ｔ．ｃｏｎｆｕｓｕｍＶｉｇｇｉａｎｉ，＝Ｔ．ｃｈｉｌｏｎｉｓ，Ｎａｇａｒａｊａ，ｎｅｃ．Ｉｓｈｕ）使小菜蛾种群干扰作用控制指数下降为０．２４。施用苏云金杆菌制剂使小菜蛾的种群数量发展趋势指数下降为０．２９，这两种措施在种群数量发展趋势指数比较低的情况下可以防治小菜蛾。散放赤眼蜂和施用苏云金杆菌制剂的处理，种群数量发展趋势指数下降为０．０６，表达了两者相辅相成的作用。即使在种群数量发展趋势指数高达２９．３，也可能受到良好的效果。

Biological Control of HiamondbackMOth Plutella xylostella(L.)

in this peper,by means of the indices of populztion trend and the interference indicesof pepulation control,the population dynamies of diamondback moth Pbuella xylostella (L.)(DBM)in various vegetable fields were investigated.When it was intensively sprayed wide-spec-trum insecticides,the index of popula`uon tretid was as high as 29.3.in other words,the popula-tion size of next generation would incrased in 26.3 times against that generation,It gave raise todiffitttilties in DBM control.In the vesetable field sprayed Bacillus tharingiensis(B.t)to controlthe pest insects,instead of the wide-spectrum insecticides,a few generation later,the index of popu-lation trend decreased to 4. 88.In the experiment,UPC in the trea:nient of releasing Trichogramma(T.confusum Viggiani=T.chilonis,Navoaraja, nec.Ishu)increased in 0.24.UPC in the treatment of spayins B.t.in-creased in 0.29.UPC in the ircatmnent of PxGV increased in 0. 23. These biological control asentsmay be used to control DBM in the condition uf low level of uidex of population trend.UPC in thetreatment of releasing Trichogranima and sprayins B.t.increased in 0. 06,showed the complinientary effect of each other of these two biological control agents.It may be use.d to control DBMeven in the level of index of population trend as high as 29. 3.