Department of Evolutionary Biology of Invertebrates, Institute for Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 28E, D-72076 Tübingen, Germany.
Zoology (Jena). 2012 Apr;115(2):117-27. doi: 10.1016/j.zool.2011.09.006. Epub 2012 Mar 24.
The adhesive prey-capture apparatus of the representatives of the rove beetle genus Stenus (Coleoptera, Staphylinidae) is an outstanding example of biological adhesive systems. This unique prey-capture device is used for catching elusive prey by combining (i) hierarchically structured adhesive outgrowths, (ii) an adhesive secretion, and (iii) a network of cuticular fibres within the pad. The outgrowths arise from a pad-like cuticle and are completely immersed within the secretion. To date, the forces generated during the predatory strike of these beetles have only been estimated theoretically. In the present study, we used force transducers to measure both the compressive and adhesive forces during the predatory strike of two Stenus species. The experiments revealed that the compressive forces are low, ranging from 0.10 mN (Stenus bimaculatus) to 0.18 mN (Stenus juno), whereas the corresponding adhesive forces attain up to 1.0 mN in S. juno and 1.08 mN in S. bimaculatus. The tenacity or adhesive strength (adhesive force per apparent unit area) amounts to 51.9 kPa (S. bimaculatus) and 69.7 kPa (S. juno). S. juno beetles possess significantly smaller pad surface areas than S. bimaculatus but seem to compensate for this disadvantage by generating higher compressive forces. Consequently, S. juno beetles reach almost identical adhesive properties and an equal prey-capture success in attacks on larger prey. The possible functions of the various parts of the adhesive system during the adhesive prey-capture process are discussed in detail.
代表步甲科隐翅虫属的粘性猎物捕捉装置是生物粘性系统的杰出范例。这种独特的猎物捕捉装置用于捕捉难以捉摸的猎物，它结合了 (i) 分层结构的粘性突起、(ii) 粘性分泌物和 (iii) 垫内的角质纤维网络。这些突起起源于垫状表皮，并完全沉浸在分泌物中。迄今为止，这些甲虫捕食性攻击过程中产生的力仅在理论上进行了估计。在本研究中，我们使用力传感器来测量两种 Stenus 物种捕食性攻击期间的压缩力和粘合力。实验表明，压缩力很低，范围在 0.10 mN（ Stenus bimaculatus）到 0.18 mN（ Stenus juno）之间，而相应的粘合力在 S. juno 中可达 1.0 mN，在 S. bimaculatus 中可达 1.08 mN。韧性或粘性强度（每单位表观面积的粘性力）达到 51.9 kPa（ stenus bimaculatus）和 69.7 kPa（ stenus juno）。S. juno 甲虫的垫表面积明显小于 S. bimaculatus，但通过产生更高的压缩力似乎弥补了这一劣势。因此，S. juno 甲虫在攻击较大猎物时达到几乎相同的粘合力和相同的猎物捕获成功率。详细讨论了粘性猎物捕捉过程中粘性系统各部分的可能功能。
