感染微孢子虫的棉铃虫幼虫对化学杀虫剂的敏感性

为明确棉铃虫微孢子虫Nosema sp.与杀虫剂混用的效果及其机理,采用感染饲喂和微量点滴法,研究了感染微孢子虫的棉铃虫幼虫对辛硫磷、溴氰菊酯的敏感性变化.健康幼虫与感病幼虫对辛硫磷LC50之比为4.855,对溴氰菊酯LC50之比为7.953.随着微孢子虫感染时间和感染剂量的增加,棉铃虫对杀虫剂的敏感性进一步增强;感染微孢子虫5天,健康幼虫与感病幼虫对辛硫磷的LC50之比为3.278,与感染3天处理相比差异显著;当剂量为107个孢子/mL时,健康幼虫与感病幼虫对辛硫磷的LC50之比为4.090.经微孢子虫处理后,棉铃虫幼虫体内的羧酸酯酶、谷胱甘肽-S-转移酶和乙酰胆碱酯酶的比活力均增高.

Sensitivity of Helicoverpa armigera larvae infected by microporidian to chemical insecticides

To elucidate the insecticidal activity and mechanism of the mixture of Nosema sp.with insecticides against Helicoverpa armigera,the sensitivity of H.armigera larvae infected byNosema sp.to phoxim and deltamethrin was tested with the diet infection and topical applica-tion.When healthy larvae and infected larvae were treated with phoxim,the ratio of LC_(50)was4.855,while treated with deltamethrin,the ratio was 7.953.As the time of infection by Nose-ma sp.was prolonged and the number of microporidian infecting H.armigera larvae increased,the larvae became more sensitive to insecticides.The ratio of LC_(50)of phoxim to healthy larvaeand to the larvae 5 days after infection with microporidian was 3.278,which was significantlyhigher than the ratio of LC_(50)of phoxim to healthy larvae and to the larvae 3 days after infectionwith microporidian.The ratio of LG_(50)of phoxim to healthy larvae and to infected larvae was4.090 when the concentration of microporidian reached 10~7/mL.It was found that the activityof AChE,CarE and GST increased in larvae infected by Nosema sp.