2种拟除虫菊酯对荔蝽平腹小蜂的毒力

Toxicities of Two Pyrethroides to Anastatus japonicus Ashmead

40％杀灭菊酯、2.5％溴氰菊酯对荔蝽平腹小蜂成虫的LC_(30)分别为24.1×10^(-6)和35.41×10^(-6)。本试验分别取20×10^(-6)杀灭菊酯和35×10^(-6)溴氰菊酯作为亚致死剂量,对成蜂进行处理,结果表明其寿命缩短、寄生率下降。经t测验,与对照的差异极显著(1≥0.01)。用这2种农药的田间推荐使用浓度对荔蝽平腹小蜂的卵期、幼虫期、预蛹期及蛹期处理结果,最高死亡率不超过10％。因此当释放平腹小蜂的果园需要用药防治其它害虫时,可以选择使用这类农药,但要注意农药的残效作用对成蜂的影响,尽量选择平腹小蜂发育的前期喷药比较安全。

LC_(30) of Fenvalerate and Decamethrin for Anastarus japonicus Ashmcad equaled 24.1×10^(-6) and 35.41×10^(-6) respectively. In this test, the adult of A. japonicus was treated with a sublethal dose (20×10^(-6) of Fenvalerat and 35×10^(-6) of Decamethrin), which showed that the longevity of the treated adult was obviously shortened and its rate of parasitism declined. The difference between the treatmented and control groups was significant ( t>0.01). The recommended concentration of these insecticides slightly affected A. japonicus at the stages of the ovum, larva, prepupa and pupa. The maximum mortality of these stages caused by the insecticides did not exceed 10%. Therefore, these insectieides can be used to control the pests in the litchi orchards where wasps are releascd, but the rcsidual effect on the wasp must be paid attention to. It would be safe to spray the insecticides in the early development period of the wasp, if possible.