Arachnids (Arachnidae) in a Spring Wheat Agrocenosis in Southern Sverdlovsk Oblast and the Effect of Treatment with Decis, a Pyrethroid Insecticide, on Their Populations

摘要

Arachnids are active predators. Due to their abundance, they are an important component of arthropod communities in both natural and man-made ecosystems. It has been proposed to use some species of spiders as indicators of the effects of various economic activities on the state of the environment. In particular, this concerns pesticide treatment, a powerful factor of anthropogenic impact on ecosystems (Everts et al., 1986; Pristavko and Zhukovets, 1987; Aukema et al., 1990; Esyunin and Batalin, 1995). Russian publications on the species composition of arachnids in agrocenoses and their responses to the effects of pesticides are scarce, and the corresponding data on Sverdlovsk oblast are absent. Such studies are important both for determining the type and strength of responses to toxic influences and for choosing proper indicator species of arachnids. The purpose of this work was to study the species composition of arachnids (true spiders and harvestmen) in a spring wheat agrocenosis and the responses of their populations to crop treatment with Decis, a pyrethroid insecticide. Our tasks were as follows: to amend the list of spider and harvestmen species inhabiting the spring wheat fields in the vicinity of Yekaterinburg, to study the seasonal population dynamics of individual species in the corresponding agrocenosis, and to determine the patterns of their responses to the treatment of wheat crops at the booting stage with Decis.