Synergism of insecticide activity to Heliothis zea (Boddie) (Lepidoptera: Noctuidae) by formanilides and formamidines

The toxicities of binary mixtures of formanilides and formamidines with nine insecticides to H. zea (Boddie) were investigated and compared to the toxicities of their individual components. The 21 formanilides were mono-, di-, or tri-substituted in the phenyl ring with chlorine, bromine, methyl, ethyl, nitro, or methoxy groups. The four N'-aryl-N,N-dimethylformamidines were substituted in the phenyl moiety with 4-ethyl, 2-trifluoromethyl, 3,4-methylenedioxy, or 2,4,6-trimethyl. Toxicity of cypermethrin, permethrin, fenvalerate, methyl parathion, chlorpyrifos, carbaryl, methomyl, and endrin was appreciably enhanced by some of the formanilides and formamidines; however, the activity of profenofos was synergistic only with one of the formamidines. These and related formamidines and formanilides may have practical applicability as insecticide synergists.