Wurdack Mareike, Polidori Carlo, Keller Alexander, Feldhaar Heike, Schmitt Thomas
Department of Animal Ecology and Tropical Biology, Biocenter, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Department of Evolutionary Biology and Animal Ecology, University of Freiburg, Hauptstrasse 1, D-79114 Freiburg, Germany.
Evolution. 2017 Nov;71(11):2562-2571. doi: 10.1111/evo.13322. Epub 2017 Oct 26.
The cuticle of insects is covered by a layer of hydrocarbons (CHC), whose original function is the protection from desiccation and pathogens. However, in most insects CHC profiles are species specific. While this variability among species was largely linked to communication and recognition functions, additional selective forces may shape insect CHC profiles. Here, we show that in Philanthinae digger wasps (Crabronidae) the CHC profile coevolved with a peculiar brood-care strategy. In particular, we found that the behavior to embalm prey stored in the nest with hydrocarbons is adaptive to protect larval food from fungi in those species hunting for Hymenoptera. The prey embalming secretion is identical in composition to the alkene-dominated CHC profile in these species, suggesting that their profile is adaptively conserved for this purpose. In contrast, prey embalming is not required in those species that switched to Coleoptera as prey. Released from this chemical brood-care strategy, Coleoptera-hunting species considerably diversified their CHC profiles. Differential needs to successfully protect prey types used as larval food have thus driven the diversification of CHCs profiles of female Philanthinae wasps. To the best of our knowledge, this is the first evidence of a direct link between selection pressure for food preservation and CHC diversity.
昆虫的表皮覆盖着一层碳氢化合物（CHC），其最初的功能是防止干燥和抵御病原体。然而，在大多数昆虫中，CHC图谱具有物种特异性。虽然物种间的这种变异性在很大程度上与通讯和识别功能有关，但其他选择压力可能会塑造昆虫的CHC图谱。在这里，我们表明，在掘土黄蜂亚科（Philanthinae，胡蜂科）中，CHC图谱与一种特殊的育幼策略共同进化。具体而言，我们发现，在那些捕食膜翅目的物种中，用碳氢化合物对储存在巢中的猎物进行防腐处理的行为具有适应性，可保护幼虫食物免受真菌侵害。在这些物种中，猎物防腐分泌物的成分与以烯烃为主的CHC图谱相同，这表明它们的图谱为此目的而适应性地保留下来。相比之下，在那些转而以鞘翅目为猎物的物种中，不需要对猎物进行防腐处理。由于摆脱了这种化学育幼策略，捕食鞘翅目的物种其CHC图谱有了很大的多样性。因此，成功保护用作幼虫食物的猎物类型的不同需求推动了雌性掘土黄蜂亚科黄蜂CHC图谱的多样化。据我们所知，这是食物保存选择压力与CHC多样性之间存在直接联系的首个证据。
