Beetles of the superfamily Curculionoidea (Coleoptera) in a complex semi-desert in relation to climate changes in the North Caspian region

Abstract

In desert and steppe habitats of the complex North Caspian semi-desert, more than twofold differences in the number of hortobiont Curculionoidea species (33 and 75 species, respectively) were observed between the “dry” (1972–1974) and “humid” (2003–2005) climatic phases. The abundance of most species changed. Polyphagous steppe weevils of the subfamily Entiminae (Otiorhynchus velutinus, Euidosomus acuminatus, Omias verruca, and O. rotundatus) with spring activity of adults were the most stable, representing the main dominants of the spring communities both in the 1970s and 2000s. Nearly all of the weevils that changed their abundance since the 1970s were specialized herbivores with summer adult activity. In the more humid 2000s, the abundance of some desert-steppe weevils dominating the desert communities (Phacephorus nebulosus, Metadonus anceps and especially Ptochus porcellus) dropped drastically. Most of the species whose abundance increased most strongly (Phyllobius brevis, Trachyphloeus amplithorax, Archaeophloeus inermis, Stenopterapion tenue, Sitona inops, S. longulus, Tychius spp.) are associated with Medicago romanica, the plant that considerably raised its density in the microdepressions during the “humid” phase. The data show an evident reduction of the most xerophilic (desertsteppe) components of the weevil community and an increase in the fraction of mesophilic species. These changes seem to follow a cyclic pattern.