Hendrichs J, Katsoyannos B I, Wornoayporn V, Hendrichs M A
Entomology Unit, IAEA Laboratories, A-2444, Seiberdorf, Austria.
Department of Agriculture, University of Thessaloniki, Thessaloniki, Greece.
Oecologia. 1994 Sep;99(1-2):88-94. doi: 10.1007/BF00317087.
Predation is probably the most important male mortality factor in insect species with courtship displays that render males performing them conspicuous targets of predators. Sexually active Mediterranean fruit fly males, Ceratitis capitata (Wied.), aggregate in leks, where they participate in agonistic encounters and engage in visual, acoustic and pheromone-calling displays to attract receptive females. The objective of this study was to assess: a) whether sexually displaying C. capitata males in leks inside host and non-host foliage are subject to predation by the most prominent predators yellow-jacket wasps, Vespula germanica (F.), and if so, b) whether olfactory, visual or auditive stimuli are used by foraging wasps in locating male C. capitata prey. Studies were carried out in a citrus orchard and surroundings on the island of Chios, Greece. Observations were conducted using perforated containers hung within mulberry, fig or citrus foliage. Living C. capitata flies of different sex and either mature or immature were placed inside. Our results show that the yellowjacket wasps have learned to associate the presence of sexually active medfly males aggregated in leks with their prey's pheromone (kairomone). Foraging wasps, flying through the crowns of host trees, responded to the odour source of C. capitata male pheromone by approaching from downwind. Even inside dense citrus tree foliage, wasps keyed in on aggregations of pheromone-calling males using olfactory stimuli. Stimuli of visual and acoustic male signalling were only used at close range, after having followed the pheromone plume close to its source. Visual cues played a greater role in directing wasp foraging under more open and exposed host foliage conditions. Odour-based foraging of wasps inside host foliage in the mid-morning hours, when medfly male lekking activities peak, shifted gradually to a more visual-based host fruit patrolling in the afternoons to capture ovipositing and feeding medfly females. On ripe fruit, particularly fig, V. germanica visual prey hunting also included the capture of feeding medfly males, other feeding Diptera, as well as medfly larvae extracted from wasp-made perforations in the fruit.
在具有求偶展示行为的昆虫物种中，捕食可能是雄性昆虫最重要的死亡因素，因为求偶展示会使进行展示的雄性成为捕食者的显眼目标。性活跃的地中海实蝇雄性，即Ceratitis capitata (Wied.)，会聚集在求偶场中，在那里它们参与争斗遭遇，并进行视觉、听觉和信息素召唤展示以吸引处于接受期的雌性。本研究的目的是评估：a) 在寄主和非寄主树叶内的求偶场中进行性展示的C. capitata雄性是否会受到最主要的捕食者德国黄胡蜂Vespula germanica (F.) 的捕食，如果是这样，b) 觅食的黄蜂在定位雄性C. capitata猎物时是否使用嗅觉、视觉或听觉刺激。研究在希腊希俄斯岛的一个柑橘园及其周边地区进行。使用悬挂在桑树、无花果或柑橘树叶内的带孔容器进行观察。将不同性别、成熟或未成熟的活C. capitata果蝇放置在容器内。我们的结果表明，德国黄胡蜂已经学会将聚集在求偶场中的性活跃地中海实蝇雄性的存在与其猎物信息素（利它素）联系起来。觅食的黄蜂在寄主树冠中飞行时，会从下风处接近地中海实蝇雄性信息素的气味源。即使在茂密的柑橘树叶内，黄蜂也能利用嗅觉刺激锁定发出信息素召唤的雄性聚集群体。视觉和听觉的雄性信号刺激仅在靠近信息素羽流源头并接近源头后近距离使用时才会被利用。在更开阔和暴露的寄主树叶条件下，视觉线索在引导黄蜂觅食方面发挥了更大作用。在上午中旬，当地中海实蝇雄性求偶活动达到高峰时，黄蜂在寄主树叶内基于气味觅食，到了下午逐渐转变为更多基于视觉的寄主果实巡查，以捕捉正在产卵和取食的地中海实蝇雌性。在成熟果实上（特别是无花果），德国黄胡蜂的视觉猎物捕猎还包括捕捉正在取食的地中海实蝇雄性、其他取食的双翅目昆虫，以及从黄蜂在果实上钻出的孔中取出的地中海实蝇幼虫。
