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Antifeeding effect of cypermethrin and permethrin at sub‐lethal levels against Pieris brassicae larvae

1981; Wiley; Volume: 12; Issue: 6 Linguagem: Inglês

10.1002/ps.2780120606

1096-9063

K. H. Tan,

Insect-Plant Interactions and Control

Abstract An antifeeding (feeding deterrent) response by first‐ and fifth‐instar larvae of Pieris brassicae was shown to be significant at sub‐lethal levels of cypermethrin and permethrin, using leaf‐discs treated with the pyrethroids by dipping. Permethrin was slightly more effective than cypermethrin both as an insecticide and as an antifeedant against fifth‐instar larvae, but the reverse order of effectiveness was observed, with a marked difference in mortality, against newly‐hatched larvae. When 1‐day‐old fifth‐instar larvae were continuously given leaf discs treated with a solution of the pyrethroid (1 mg litre −1 ), up to the time of pupation, both cypermethrin and permethrin induced a significant extension of the larval period, with a reduction in the maximum larval and pupal weights, as well as a reduction in the total leaf‐area consumed. However, at higher levels of both pyrethroids, lowering the temperature induced some irritancy, as indicated by regurgitation and frequent uncoordinated wriggling movements of the fifth‐instar larvae. The advantages of cypermethrin as a protectant and as an antifeedant over permethrin are discussed.