Toxicity and Persistence of Some Organophosphorus Insecticides and Permethrin on Apple Fruits for the Control of Codling Moth, Laspeyresia Pomonella (L.)
Eight organophosphorus insecticides and the synthetic pyrethroid, permethrin, were tested for their intrinsic toxicity as residues in apple fruits to the neonatal larvae of codling moth (Laspeyresia pomonella) in the laboratory. There was a 60-fold variation in the LD50 values between the most toxic (the pyrethroid) and the least effective chemical. A field trial with six of the O.P. insecticides and permethrin, on three apple cultivars, showed that persistence was a critical factor. The period during which the organophosphorus compounds were effective varied between 15 and 29 days. Permethrin was effective for a period in excess of 70 days when applied at the same rate. All harvest residues were within acceptable limits.