DETOXIFICATION ENZYMES AND THE EFFECTS OF TEMPERATURE ON THE TOXICITY OF PYRETHROIDS TO THE FALL ARMYWORM, SPODOPTERA-FRUGIPERDA (LEPIDOPTERA, NOCTUIDAE)

1. The effects of temperature on the topical toxicity of cypermethrin and fenvalerate to fifth-instar larvae of the fall armyworm, Spodoptera frugiperda, were investigated, as well as their effects on ataxia and prostration. Activities of carboxylesterase and glutathione S-transferase were also assessed. 2. Pyrethroid toxicities were characterized by a negative temperature coefficient (TC) between 15 and 27-degrees-C, and a positive TC between 27 and 38-degrees-C. Fenvalerate was more toxic at all test temperatures. 3. The median time for the onset of ataxia and prostration decreased as temperature increased. 4. Activity (mu mol/min/mg protein) of carboxylesterase and glutathione S-transferase was significantly lower for fenvalerate-treated insects (217.4 and 17.2, respectively) than for cypermethrin (344.7, 39.7).