Effects of Chronic Metal Exposure on the Morphology of Beetles Species Representing Different Ecological Niches

To test effects of metal contamination on beetles morphology, specimens from species representing herbivores (Strophosoma capitatum), carnivores (Carabus arcensis and C. violaceus) and detritivores (Anoplotrupes stercorosus) were collected from an area polluted with zinc, lead and cadmium and from a control site. Both the length and width of elytra and pronotum were compared. Females of all species from the polluted area were smaller than those from the control site with the average difference of 2.7% (range 0.7%–6%). In contrast, males responded less consistently among species: A. stercorosus showed lower size of elytra and pronotum at the polluted area, while in C. arcensis only the elytra length and pronotum width were smaller. C. violaceus males exhibited smaller elytra length and pronotum length and width at the polluted area. In contrast, no differences between the two sites were found for S. capitatum males. Sex differences may originate from different energy investment strategies in females and males related to the reproduction needs. Even if the observed differences in body size were small, the smaller body size in females of all studied species, irrespectively of the guild, is striking and may indicate on lower fitness of a range of species inhabiting metal polluted areas.