ABSTRACT

The acute toxicity of several novel insecticides was tested against two important natural enemies of cotton pests: the parasitic wasp Cotesia marginiventris, and the predatory bug, Orius indisiosus. The wasp is an important natural enemy of many caterpillar pests, particularly armyworms. The predatory bug is an effective predator of small pests, feeding heavily on thrips, mites, aphids, and eggs and small caterpillars. The tests were conducted in the laboratory and greenhouse, utilizing several bioassay techniques. The pesticides studied were Karate (l-cyhalothrin), Novaluron, Tracer (spinosad), Steward (indoxacarb), Centric (thiamethoxam), Intruder (acetamiprid), Trimax (imidacloprid), Denim (emamectin benzoate), and the numbered compounds S-1812 (a Valent insecticide targeting caterpillars), F-0570 (an FMC pyrethroid also targeting caterpillars), and the novel compound flonicamid (FMC's F-1785, targeting sucking pests).

The novel insecticides generally were less toxic than the standard insecticides, represented here by the pyrethroid Karate. Centric, however, was highly toxic to O. insidiosus, not differing significantly from Karate in its toxicity. Intruder and Trimax were toxic to O. insidiosus, though less so than was the case with Centric or Karate. Intruder exhibited no toxicity to C. marginiventris in previous tests. Flonicamid exhibited little or no toxicity to Orius insidiosus at any of the rates tested, although there were indications from the Leaf Trial that some mortality may occur after prolonged exposure to treated foliage. Novaluron was essentially non-toxic to O. insidiosus. Tracer was highly toxic to C. marginiventris, but not to O. insidiosus. Steward exhibited some toxicity to C. marginiventris after prolonged exposure to treated foliage, unlike observations in previous tests. Toxicity of Steward may require additional attention. Denim and S-1812 were not toxic to C. marginiventris.