Some Effects of Pesticide Residues on Trichogramma nubilale (Hymenoptera: Trichogrammatidae)1

Abstract

A laboratory bioassay was developed to assess the effects of pesticide residues on adult emergence and parasitism of the egg parasitoid Trichogramma nubilale Ertle and Davis. Tests were conducted on 1-,7-,14-, and 21-day greenhouse and field-weathered spray residues from pepper plants at two dosage rates of five pesticides. These were Bacillus thuringiensis Berliner, carbaryl, methomyl, methyl parathion, and permethrin. T. nubilale was highly sensitive to all the synthetic chemicals; methyl parathion was the most toxic. Permethrin residues had no adverse effects on parasitoid emergence, but parasitism rates were always significantly reduced. B. thuringiensis sprays, tested in the greenhouse only, did not reduce emergence from or parasitism of European corn borer (ECB), Ostrinia nubilalis (Hubner), eggs. Field-weathered carbaryl and methomyl residues did not reduce parasitoid emergence, but carbaryl residues reduced parasitism rates up to 21 days postspray. Parasitism increased over time at the lower dosage rate of methomyl.