A comparison of adaptations to running, pushing and burrowing in some adult Coleoptera: especially Carabidae

A wide range of compromises between maximum speed attained and pushing force exerted are exhibited by various Coleoptera. Some structural and functional parameters are quoted for two beetles at the extreme ends of this range: the rapid tiger beetle Cicindelu cumpestris and the powerful dung beetle Geotrupes stercorarius. Additionally, maximum sprint speeds and pushing forces were obtained for 105 species selected from 22 families of beetles. To compare the relative speed (u R ) and relative force (F R ) abilities of different sized species, a simple means of scaling was used in which u R = u/W 0'33 (where u is the maximum sprint speed, and W the weight of a beetle) and F R = F/W 0'67 (where F is the maximum forçe exerted by the beetle. measured by pulling). The best speed/force adapted species lay along a limiting front where u R a F R and u. F/W.k = 1 (where k is a constant). This gave a measure of the locomotory capability of a beetle in terms of I, the index of speed/force specialization. The specialists exhibited an index close to 1·0, but that of most beetles tested lay between 1·0 and 0·01. The Carabidae was analysed more closely as it contains many locomotor specialists. It was possible to define three structural/functional groups which showed different combinations of running and pushing abilities. The possible evolutionary relationships of these habit groups was discussed, and some speed and force comparisons were made between beetles and some other terrestrial arthropods.