Effect of an insecticide,chlorpyrifos on the activity density of wolf spiders (Araneae: Lycosidae) in guava orchard

Effect of chlorpyrifos (lorsban) has been studied on the mean activity density and body measures (i.e.,total body length,carapace length,carapace width and wet weight) of wolf spiders in the field. significant difference was recorded in the mean activity density of wolf spiders in the treated and control field. mean activity density of wolf spiders collected from different distances from field's margin of both fields (i e.,treated and control) also differed significantly. chlorpyrifos did not show any negative effect on the growth of pardosa burmanuca simon. 1884,while it affected the growth of carapace and wet weight in lycosa terrestris butt et al.,2006. it is concluded that application of chlorpyrifos in the fields may reduce the density of wolf spiders not only because of direct mortality but also due to disturbance and emigration,thus reducing the pest control potential of this important predatory group. copyright 2010 zoological society of pakistan.