高效液相色谱法检测菜蛾绒茧蜂幼虫体内多杀菌素残留

Detection and analysis of spinosad residue in the body fluid of Cotesia plutellae larvae with HPLC

应用高效液相色谱法检测施用于寄主幼虫的多杀菌素可否传递到在其体内发育的寄生蜂幼虫。以对多杀菌素高抗的小菜蛾Plutellaxylostella幼虫作为菜蛾绒茧蜂Cotesiaplutellae的寄主,待绒茧蜂发育到1龄幼虫时,将浓度为50mgL的多杀菌素点滴到寄主幼虫背板上,随后让寄主幼虫取食经50mgL多杀菌素处理过的甘蓝叶片,寄主幼虫和其体内的蜂幼虫再发育3天后,将寄主幼虫解剖取出蜂幼虫,用高效液相色谱法对经多杀菌素处理的小菜蛾幼虫体液以及绒茧蜂幼虫匀浆液进行检测,结果多杀菌素的2个活性成分spinosynA和spinosynD均被检测到,两者的多杀菌素残留浓度分别是2.79mgL和0.94mgL。这表明,通过寄主幼虫体壁接触和取食进入其体内的多杀菌素,可通过寄生蜂幼虫体壁浸透、蜂幼虫对寄主血淋巴的取食,或这两种途经一起进入蜂幼虫的体内,对蜂幼虫产生作用。

HPLC was used to investigate whether spinosad applied to parasitized host larvae could reach parasitoid larvae developing inside the hosts. Plutella xylostella larvae of a strain highly resistant to spinosad were used as hosts to rear the parasitoid Cotesia plutellae. When the parasitoids had developed to the stage of early instar larva, the host larvae were treated with 50 mg/L spinosad on the terga by topical application and then fed with cabbage leaves treated with 50 mg/L spinosad to allow the host larvae and the parasitoid larvae to develop. Three days after treatment, the parasitoid larvae inside the host were collected by dissecting the host larvae. The body fluid of P. xylostella and the bodies of parasitoid larvae were then analyzed with HPLC. Both of the active components, spinosyn A and spinosyn D, of spinosad were detected in the body fluid of host larvae and in the bodies of parasitoid larvae, and the residue concentrations were 2.79 mg/L and 0.94 mg/L in the host and the parasitoid respectively. The results demonstrate that spinosad applied to the host larvae can in turn reach inside the parasitoid larvae through penetration of cuticle and/or feeding of host hemolymph by the parasitoid larvae, and subsequently acts on the parasitoid larvae.