Too hard to swallow: a secret secondary defence of an aposematic insect
Too hard to swallow: a secret secondary defence of an aposematic insect
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DOI：
10.1242/jeb.172486
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发表时间：
2018-01-01
影响因子：
2.8
通讯作者：
Lin, Chung-Ping
中科院分区：
文献类型：
--
作者：
Wang, Lu-Yi;Huang, Wen-San;Lin, Chung-Ping
反捕食策略是被捕食物种适应的重要组成部分。警戒性的猎物被期望拥有与它们的警戒色同时进化的有效防御。本研究验证了Alfred Russel Wallace在近150年前提出的关于警戒性厚喙象甲硬体防御功能和生态学意义的假设。我们使用捕食试验与龙蜥树蜥蜴，以评估生存的“硬”（成熟）与“软”（teneral）和“爪”（完整）与“无爪”（手术切除）象鼻虫。通过评估象鼻虫的硬度，当地的猎物昆虫，和蜥蜴种群的咬合力的象鼻虫的硬体的生态意义进行了评估。采用气相色谱-质谱联用技术（GC-MS）检测了象甲中是否存在毒素或阻遏物。所有的硬象鼻虫，被咬上一口，立刻就被吐了出来，在蜥蜴的攻击下活了下来。相比之下，“软”象鼻虫被咀嚼，随后被吞咽。无论象鼻虫的跗爪是否存在，结果都是相同的。硬厚喙象甲的硬度显着高于其他猎物昆虫在同一生境中的平均硬度和当地蜥蜴的平均咬合力。经GC-MS鉴定的4种化合物对脊椎动物无毒性或驱避作用。这些结果表明，警戒性猎物的硬度功能作为一种有效的二级防御，他们提供了一个框架，了解脊椎动物捕食者和警戒性昆虫猎物之间的时空相互作用。
Anti-predator strategies are significant components of adaptation in prey species. Aposematic prey are expected to possess effective defences that have evolved simultaneously with their warning colours. This study tested the hypothesis of the defensive function and ecological significance of the hard body in aposematic Pachyrhynchus weevils pioneered by Alfred Russel Wallace nearly 150 years ago. We used predation trials with Japalura tree lizards to assess the survivorship of 'hard' (mature) versus 'soft' (teneral) and 'clawed' (intact) versus 'clawless' (surgically removed) weevils. The ecological significance of the weevil's hard body was evaluated by assessing the hardness of the weevils, the local prey insects, and the bite forces of the lizard populations. The existence of toxins or deterrents in the weevil was examined by gas chromatography-mass spectrometry (GC-MS). All 'hard' weevils were instantly spat out after being bitten once and survived attacks by the lizards. In contrast, the 'soft' weevils were chewed and subsequently swallowed. The results were the same regardless of the presence or absence of the weevil's tarsal claws. The hardness of 'hard' Pachyrhynchus weevils was significantly higher than the average hardness of other prey insects in the same habitat and the mean bite forces of the local lizards. The four candidate compounds of the weevil identified by GC-MS had no known toxic or repellent functions against vertebrates. These results reveal that the hardness of aposematic prey functions as an effective secondary defence, and they provide a framework for understanding the spatio-temporal interactions between vertebrate predators and aposematic insect prey.