Chlorpyrifos residue levels in avian food items following applications of a commercial EC formulation to alfalfa and citrus

Two 10-day field residue studies were conducted to measure the amount of chlorpyrifos residue found in typical avian food following applications of a commercial 480 g liter(-1) EC (Lorsban(R) 4E) at 1.1 kg AI ha(-1) (1 lb AI acre(-1)) to alfalfa and at 2.3 kg AI ha(-1) (2.0 lb AI acre(-1)) to citrus. Avian food items used in these studies included: crickets (Acheta domestica (L)), earthworms (Lumbvicus terrestris L), darkling ground beetle larvae (Tenebrio molitor L), seed heads (Triticum sp), and naturally occurring flying and ground-dwelling insects. The studies incorporated a design involving three main study plots placed within larger treated areas of an alfalfa crop and a mature orange grove. The three main study plots represented three replications and each contained four sub-plots. One sub-plot, on each study plot, was sampled on day 0 (2-h post-application), day 1, day S and day 10 post-application. Chlorpyrifos residues were present in all avian food sampled following the application; however, residue levels were lower than estimated residue values typically used by the US EPA to establish expected environmental concentration (EEC) used in screening assessments of risk to terrestrial wildlife. (C) 2003 Society of Chemical Industry.