温室白粉虱和烟粉虱常混合发生,危害严重.丽蚜小蜂是粉虱类害虫的重要寄生性天敌,被广泛应用于温室作物上粉虱的防控.本文分别以温室白粉虱和烟粉虱作为扩繁寄主,经多代连续扩繁,各自建立起稳定的丽蚜小蜂种群(分别以W1和W2表示),以这两种小蜂种群为天敌试虫,研究了其对不同寄主植物上混合发生的两种寄主粉虱若虫的寄生选择性及其后代蜂生长发育适应度表现.结果表明,番茄、茄子、菜豆上温室白粉虱和烟粉虱的同龄若虫同时存在时,小蜂W1和W2均偏好寄生于温室白粉虱,且寄生其若虫内后代蜂的发育历期显著短于寄生烟粉虱若虫内的发育历期;黄瓜上两种粉虱混合存在时W1偏好寄生于烟粉虱,且寄生其若虫内后代蜂的发育历期显著短于寄生温室白粉虱若虫内的发育历期,但寄主植物及粉虱对丽蚜小蜂的羽化率均无显著影响.综合来看,无论饲养寄主为温室白粉虱或是烟粉虱,丽蚜小蜂均偏好寄生温室白粉虱,且寄生温室白粉虱内的后代蜂发育适合度较高,这对指导寄生蜂的人工饲养及有效利用具有重要的理论意义和应用价值.%The parasitic wasp Encarsia formosa Gahan is a commercially available parasitoid used for the biological control of the whiteflies Trialeurodes vaporariorum Westwood and Bemisia tabaci Gennadius in vegetable greenhouses throughout the world. The two whiteflies often co-occur. Two strains of E. formosa, reared on T. vaporariorum and B. tabaci separately for several generations (represented as strain W1 and W2 respectively), were tested for their host-shift preference in the greenhouse. The two E. formosa strains preferred T. vaporariorum to B. tabaci in terms of high parasitism rate on tomato, eggplant and kidney bean co-infested by T. vaporariorum and B. tabaci. The offspring developmental duration of both wasp strains in T. vaporariorum nymphs was significantly shorter than that in B. tabacinymphs on the host plants of tomato, eggplant and kidney bean. In contrast, wasp W1 preferred B. tabaci to T. vaporariorum on cucumber, their offspring developed more quickly in nymphs of B. tabaci than in nymphs of T. vaporariorum, while offspring wasp emergence rate from the two whitefly species showed no difference. Generally, the two strains E. formosa prefer T. vaporariorum to B. tabaci in terms of higher parasitism and adaptability. This information may enhance the effectiveness and predictability of biological control using mass-reared E. formosa.
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