從視覺生態角度探討蜘蛛捕食者與昆蟲獵物間之行為互動 (1/3)(國科會 94-2311-B-029-004)

摘要

Bright body colorations of orb-weaving spiders have been hypothesized to be attractive to insects and thus function to increase foraging success. However, the colour signals of these spiders are also considered to be similar to those of the vegetation background, thus the colorations function to camouflage the spiders. In this study, we evaluated these two hypotheses by field experiments and by quantifying the spiders’ visibilityto insects. We first compared the insect interception rates of orbs constructed by the orchid spider Leucauge magnifica with and without the spider. Orbs with spiders intercepted significantly more insects than orbs without. Such a result supported the prey attraction but ot the camouflaging hypothesis. We then tested whether bright body colorations were responsible for L. magnifica’s attractiveness to insects by manipulating the spiders’ colour signals with paint. Alteration of colour signals significantly reduced L. magnifica’s insect interception and consumption rates, indicating that these spiders’ bright body parts were attractive to insects. Congruent with the finding of field manipulations were the colour contrasts of various body parts of these spiders. When viewed against the vegetation background, the green body parts were lower but the bright parts were significantly higher than the discrimination threshold. Results of this study thus provide direct evidence that bright body colorations of orb weavers function as visual lures to attract insects.

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更新:Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).