Aged pesticide residues are detrimental to agrobiont spiders (Araneae)

Spiders are among the most abundant arthropods in agroecosystems, playing an important role as natural enemies of various pests. In this study we evaluated residual activity of selected pesticides on the mortality and behaviour of four spider species (Dictyna uncinata, Pardosa palustris, Philodromus cespitum and Theridion impressum). We used three pesticides: a herbicide Command (clomazone), and insecticides Decis (deltamethrin) and Nurelle (chlorpyrifos and cypermethrin). Mortality was recorded after exposure of spiders to fresh (2-h), 5, 10, 15 and 20-day-old residues. For each residue mortality was evaluated after 24-72 h. Residual effect differed between preparations and, in some cases, between spiders. All of the Nurelle residues (fresh to 20-day-old) caused 100% mortality in all spider species. Residues of Command were rather harmless (causing