VARIATION IN SUSCEPTIBILITY OF TREE-FEEDING INSECT SPECIES TO PHOTOACTIVATED THIOPHENE INSECTICIDES

The contact toxicity of the plant-derived phototoxin, alpha-terthienyl (alpha-terthienyl) and its cyano-derivative (CN-derivative) was exami ned with respect to 16 terrestrial, primarily tree-feeding insect spec ies by topical application followed by exposure to near-UV light. The sensitivity of these species to alpha-terthienyl varied 500-fold. Lepi doptera larvae were sensitive, with the exception of black army cutwor m. For 2 species, white marked tussock moth and spruce budworm, the ma terial was more toxic than fenitrothion and carbaryl but less toxic th an permethrin. Sawfly species varied widely in susceptibility, whereas adults of coleopteran species were tolerant. The activity of the CN-d erivative was generally similar to the parent alpha-terthienyl to 6 le pidopteran species, in contrast to previously reported results of its higher activity to mosquito larvae.