关键词: 异色瓢虫, 苯氧威, 保幼激素类似物, 毒性, 胚胎发育, 蛹发育, 杀卵作用

Abstract: 【Objective】 This study focused on the effects of fenoxycarb, a juvenile hormone analog (JHA), on the ladybird Harmonia axyridis and discussed its mechanisms of action, so as to evaluate the risks of fenoxycarb application and provide theoretical basis for rational use of the JHA. 【Methods】 Toxicity of fenoxycarb to egg, 2nd instar larva, pupa and adult of H. axyridis was determined in the laboratory by using the methods of dipping, topical contact and residual film, respectively. 【Results】 Fenoxycarb significantly disrupted embryonic development of newly-laid eggs at the minimum concentration of 0.0001 μg/mL, but when the 2 d-old eggs were treated, the larvae could hatch even at the highest concentration of 20 000 μg/mL. The mortality of 2nd instar larvae was very low even at the highest concentration of 4 000 μg/mL. When pupae were treated, fenoxycarb had significant effects on pupal development with adult eclosion blocked, and pupa-adult intermediate and abnormalities of adults emerged at the minimum concentration of 0.0001 μg (a.i.)/larva. The adult vitality was affected significantly at 24 h after contact with fenoxycarb at the concentration of 0.0125 μg/mL. 【Conclusions】 Fenoxycarb had an obvious ovicidal action on newly-laid eggs of H. axyridis, seriously blocked the larval-pupal metamorphosis and affected the survival of the adults. When fenoxycarb is used in fields, the susceptible developmental stages of the ladybird should be avoided.

Key words: Harmonia axyridis, fenoxycarb, juvenile hormone analog, toxicity, embryonic development, pupal development, ovicidal action