Tested cohorts of the parasitoid Fopius arisanus (Sonan) were reared on a strain of the host, Bactrocera doralis (Hendel), which was sensitive to spinosad. The toxicity tests showed that the LC50 of spinosad for female and male adults of F. arisanus was 0.090 8 mg/mL and 0.027 4 mg/mL, respectively, while the LD50 was 1.0041 mg and 0.804 3 mg, respectively. The effects of diluted 1 000, 2 000 and 3 000 times of spinosad as sublethal concentrations on F. arisanus were observed. The results revealed that all sublethal concentrations could significantly shorten the longevity of F. arisanus, reduce the total fecundity of females and the average fecundity when compared to the control. The parasitism rate and the emergence rate of adults of offspring also decreased with the sublethal concentration increasing of spinosad, but the sex ratio of offspring had no notable difference compared to the control. The simulated equation of the effect of F. arisanus on the eggs of B. doralis corresponded to Holling Ⅱ type model, but the instantaneous attack rate reduced, the handling time prolonged and the searching efficiency declined with the increasing of sublethal concentrations of spinosad. These results suggested that the sublethal concentrations of spinosad would affect significantly the bio-control effect of F.arisanus on B. doralis.%以对多杀菌素敏感的橘小实蝇实验种群做寄主饲养阿里山潜蝇茧蜂,毒力测定结果显示,多杀菌素对阿里山潜蝇茧蜂雌蜂和雄蜂的LC50分别为0.0908 mg/mL和0.0274 mg/mL,LD50分别为1.0041 mg和0.8043 mg.分别用1 000、2000、3 000倍液的多杀菌素处理阿里山潜蝇茧蜂成蜂,与对照相比,不同倍液的多杀菌素亚致死剂量均使阿里山潜蝇茧蜂的寿命显著缩短;雌蜂的总产卵量、平均产卵量、寄生率、子代成蜂羽化率等均随着多杀菌素浓度的增大而减少;但子代雌雄性比之间差异不显著;阿里山潜蝇茧蜂寄生橘小实蝇卵的拟合方程符合Holling圆盘方程Ⅱ型,处理寄主的时间随着多杀菌素浓度的增大而增加、瞬时攻击率、搜寻效应等均随着多杀菌素浓度的增大而减少.结果表明,多杀菌素的亚致死剂量可通过缩短寿命、降低繁殖力、改变功能反应参数等影响阿里山潜蝇茧蜂,从而影响生物防治的效果.
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