Grohmann Constanze, Henze Miriam Judith, Nørgaard Thomas, Gorb Stanislav N
Proc Biol Sci. 2015 Jun 22;282(1809):20142976. doi: 10.1098/rspb.2014.2976.
Insects have developed different structures to adhere to surfaces. Most common are smooth and hairy attachment pads, while nubby pads have also been described for representatives of Mantophasmatodea, Phasmida and Plecoptera. Here we report on the unusual combination of nubby and smooth tarsal attachment structures in the !nara cricket Acanthoproctus diadematus. Their three proximal tarsal pads (euplantulae) have a nubby surface, whereas the most distal euplantula is rather smooth with a hexagonal ground pattern resembling that described for the great green bush-cricket Tettigonia viridissima. This is, to our knowledge, the first report on nubby euplantulae in Orthoptera and the co-occurrence of nubby and smooth euplantulae on a single tarsus in a polyneopteran species. When adhering upside down to a horizontal glass plate, A. diadematus attaches its nubby euplantulae less often, compared to situations in which the animal is hanging upright or head down on a vertical plate. We discuss possible reasons for this kind of clinging behaviour, such as morphological constrains, the different role of normal and shear forces in attachment enhancement of the nubby and smooth pads, ease of the detachment process, and adaptations to walking on cylindrical substrates.
昆虫已经进化出不同的结构来附着在表面上。最常见的是光滑和多毛的附着垫，而对于螳䗛目、竹节虫目和襀翅目的代表物种，也有瘤状垫的描述。在此，我们报告了纳拉蟋蟀Acanthoproctus diadematus跗节附着结构中瘤状和平滑结构的不寻常组合。它们跗节近端的三个垫（真跗垫）表面有瘤状，而最远端的真跗垫相当光滑，有六边形的底色图案，类似于大绿螽斯Tettigonia viridissima的描述。据我们所知，这是直翅目昆虫中瘤状真跗垫的首次报道，也是多新翅类物种单个跗节上瘤状和平滑真跗垫同时出现的首次报道。与动物垂直悬挂或头朝下挂在垂直板上的情况相比，当A. diadematus倒挂在水平玻璃板上时，其瘤状真跗垫附着的频率较低。我们讨论了这种附着行为的可能原因，如形态限制、法向力和剪切力在瘤状和平滑垫附着增强中的不同作用、脱离过程的难易程度以及对在圆柱形基质上行走的适应性。
