Relationships between Body Size and Parasitic Fitness and Offspring Performance of <i>Sclerodermus pupariae</i> Yang <i>et</i> Yao (Hymenoptera: Bethylidae)

The relationship between body size and fitness in parasitoid wasps has several effects on parasitic ability, reproductive behavior in female wasps, and progeny fitness. Female wasps with various body sizes were obtained by mass–rearing a gregarious ectoparasitoid, Sclerodermus pupariae, which is one of the excellent parasites to control the larvae and pupae of Buprestidae and Cerambycidae. We investigated the effects of body size of adult females introduced on Thyestilla gebleri (Coleoptera: Cerambycidae) larvae on their paralysis time, pre–oviposition period, oviposition period and fecundity, and the related fitness of their offspring. Results showed that small female wasps needed more time to paralyze a host and had a higher mortality rate than large female wasps. More offspring were produced by large female wasps than by small female wasps, and the percentage and body size of female offspring was not affected by maternal body size. The duration of the egg stage was not affected by foundress size, nor was that of the pupal stage, but the duration of the larval stage and generation time of small female wasps was longer than that of large females. Our findings suggest that the parasitic fitness and offspring performance are affected by maternal size, and there is need to choose reasonable body size of female wasps, to optimally utilize mass rearing and to control target pests with the lowest mortality cost.寄生蜂的体型与其适合度之间的关联，对其寄生能力、雌蜂繁殖行为以及子代适合度均存在多重影响。本研究通过大量饲养群栖外寄生蜂蛹肿腿蜂（Sclerodermus pupariae），获得了不同体型的雌蜂；该蜂是防治吉丁虫科（Buprestidae）与天牛科（Cerambycidae）幼虫及蛹的优秀寄生性天敌之一。本研究以接入Thyestilla gebleri（鞘翅目: 天牛科）幼虫的雌成蜂体型为研究变量，探究其对寄主麻痹时长、产卵前期、产卵期、繁殖力以及子代相关适合度的影响。研究结果显示，相较于体型较大的雌蜂，小型雌蜂麻痹寄主所需时长更长，且自身死亡率更高。体型较大的雌蜂所产子代数量多于小型雌蜂，且子代雌蜂的比例与体型均不受母体体型的影响。卵期时长不受产卵母蜂体型的影响，蛹期时长亦是如此；但小型母蜂所产子代的幼虫期时长与世代时长，均长于大型母蜂的子代。本研究结果表明，寄生适合度与子代表现均受母体体型的调控；因此，需合理筛选雌蜂体型，以优化大规模饲养流程，并以最低的致死成本防控目标害虫。