管氏肿腿蜂雌性抚育中幼虫转移行为的启动和节律

Initiation and rhythm of larva-translocation behavior during maternal care in an ectoparasitoid Sclerodermus guani (Hymenoptera: Bethylidae)

为深入理解肿腿蜂雌性抚育的行为学特征,在室内连续观察了雌性管氏肿腿蜂Sclerodermus guani对子代幼虫的转移行为,旨在明确雌蜂在子代蜂幼虫发育到哪一阶段时启动转移行为,以及幼虫转移行为是否有节律。以黄粉虫Tenebrio militor蛹期在24h内的蛹体为寄主,根据子代蜂幼虫发育进程将其划分为低龄幼虫(1-2龄)、高龄幼虫(3-4龄)、老熟幼虫(自然脱落)和吐丝幼虫(开始吐丝结茧)等4个时期,采取人工剥离(早期幼虫)或自然脱离(晚期幼虫)的方法处理子代蜂幼虫,观察雌蜂对所表现出的行为反应;然后以子代蜂高龄幼虫为对象,连续观察雌蜂的30次幼虫转移行为过程。结果表明:雌蜂对所有发育时期子代蜂幼虫均用触角拍打进行探测;但不转移低龄幼虫,只转移其他阶段幼虫,转移老熟幼虫和吐丝幼虫的瞬间概率分别是转移高龄幼虫的4.09倍和7.69倍。雌蜂转移高龄、老熟和吐丝幼虫的比例分别为96%,100%和100%,没有显著差异(P≥0.05);对高龄幼虫、老熟幼虫和吐丝幼虫转移耗时平均分别为27.96,34.04和32.49s,没有显著差异(P≥0.05);平均转移距离依次为4.19,7.18和9.43mm,对吐丝幼虫的转移距离显著大于高龄幼虫(P<0.05),但在高龄和老熟幼虫之间没有显著差异(P≥0.05)。对雌蜂连续30次幼虫转移行为的趋势和节律分析表明:幼虫转移前探测的幼虫数总体上随幼虫转移次序增加而减少,在间隔1次和2次之间存在显著自相关,幼虫转移耗时在间隔1次之间存在显著自相关,但幼虫转移距离未表现出明显的节律。本研究结果说明,管氏肿腿蜂雌性抚育中的幼虫转移行为只在子代蜂幼虫发育到较高龄期时启动,且幼虫转移中的某些行为特征具有节律性。

Experiments in the laboratory were conducted by continuously observing the larva-translocation behavior during maternal care in an ectoparasitoid Sclerodermus guani, with the goal of determining the developmental stage of offspring when larva-translocation behavior is initiated and exploring the rhythm of the behavior. Tenebrio militor pupae aged less than 24 hours were used as the host. The parasitoid larvae were divided into four groups according to their developmental maturity, i.e., young larva （1st-2nd instar）, old larva （3rd-4th instar）, mature larva （naturally dislodged） and spinning larva （starting spinning cocoon after dislodged）. Parasitoid larvae treated were dislodged artificially （for young larvae） or naturally （for old larvae） from the host. A female wasp was continuously recorded for larva-translocation behaviors using video camera, and then analyzed by playbacks. The results showed that the female wasp patted larvae of all stages with its antennae, but did not move the young larva. The female exhibited a strong tendency to move the mature larva, with an instant probability of 4.09 times as high as that to move the old larva. The instant probability of moving the spinning larva was 7.69 times as high as that of moving the old larva. The proportion of larvae moved was 96% for the old larva and 100% for both mature and spinning larvae, without a significant difference between them （P≥0.05）. The time the female parasitoid spent on a larva-translocation was on average 27.96 s for the old larva, 34.04 s for the mature larva, and 32.49 s for the spinning larva, without significant differences between them （P≥0.05）. The larva-translocation distance, the direct length by which a larva was moved, was 4.19, 7.18, and 9.43 mm for the old, mature, and spinning larva, respectively; there was no significant difference between the first two （P≥0.05）, but there was between the first two and the last （P〈0.05）. The linear trend analysis showed that there was a significant decreasing trend in the number of larvae tapped before translocation, but not in the larva-translocation duration and distance. There was a significant autocorrelation at lag 1 and 2 in the number of larvae tapped before translocation, and at lag 1 in the larva-translocation duration, but not in the larva-translocation distance. The results of this study suggest that S. guani females do not initiate larva-translocation behavior until their offspring larvae mature, and some behaviors of larva-translocation may be rhythmic.