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 ® 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 ( Lumbricus 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 5 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. Copyright © 2003 Society of Chemical Industry