TOLERANCE OF PYRETHROID-RESISTANT TOBACCO BUDWORM (LEPIDOPTERA, NOCTUIDAE) LARVAE TO GOSSYPOL AND PIPERONYL BUTOXIDE

Diets containing 0, 0.025, 0.05, and 0.2% gossypol with 0 and 0.06% pi peronyl butoxide were fed to 1-, 3-, and 5-d-old tobacco budworm, Heli othis virescens (F.), larvae representing three populations: a pyrethr oid-resistant, a susceptible, and a resistant x susceptible cross. Eff ects on growth were measured. Gossypol was toxic to the 1- and 3-d-old larvae, but the 5-d-old insects tolerated higher levels. Piperonyl bu toxide was toxic to the 1-3-, and 5-d-old larvae, although less to the older insects. When both gossypol and piperonyl butoxide were added t o the diet, we observed further decreases of growth. The pyrethroid-re sistant strain of tobacco budworm was more tolerant to gossypol than t he susceptible strain.