Environmental Chemistry, Ecotoxicity, and Fate of Lambda-Cyhalothrin

Lambda-cyhalothrin is a pyrethroid insecticide. Pyrethroids are synthetic chemical analogues of pyrethrins, which are naturally occurring insecticidal compounds produced in the flowers of chrysanthemums (Chrysanthemum cinerariaefolium). Insecticidal products containing pyrethroids have been widely used to control insect pests in agriculture, public health, and homes and gardens (Amweg and Weston 2005; Oros and Werner 2005). In agriculture, target crops include cotton, cereals, hops, ornamentals, potatoes, and vegetables, with applications made to control aphid, coleopterous, and lepidopterous pests. Pyrethroids are important tools used in public health management where applications are made to control cockroaches, mosquitoes, ticks, and flies, which may act as disease vectors. Residential use of pyrethroid products has increased because of the suspension of organophosphate products containing chlorpyrifos or diazinon (Oros and Werner 2005; Weston et al. 2005).

Lambda-cyhalothrin is the active ingredient (a.i.) in several brand name products: Warrior, Scimitar, Karate, Demand, Icon, and Matador. Annual agricultural use of lambda-cyhalothrin in California has been consistent at approximately 30,000 lbs a.i. per annum from 2000 to 2003 and increased to ~40,000 lbs a.i. per annum between 2004 and 2006 (CDPR 2006). Residues of lambda-cyhalothrin have been detected in irrigation and storm runoff water and in their associated sediments. Residues have been detected in runoff resulting from agricultural, public health, and residential applications. For example, lambda-cyhalothrin was detected in water at 0.11–0.14 μg/L from agricultural watersheds in Stanislaus County, California. Lambda-cyhalothrin residues were detected in sediments obtained from sites sampled in Imperial, Monterey, Stanislaus, and Placer Counties. Residues in sediment ranged from 0.003 to 0.315 μg/g of dry wt (Starner 2007).