The objective of this work was to evaluate the susceptibility of caterpillars of the biotypes corn and rice of Spodoptera frugiperda, to insecticides with different action manners. The insects were collected in corn and in irrigated rice in the lowland, county of Pelotas, area that produces corn and irrigated rice (side by side). The experiments were conducted, in controlled conditions of temperature (25 ± 1°C), relative humidity (70 ± 10%) and photophase (14 hours), with leaves of the corn hybrid Pionner 30F33 (40 days after the emergency). The leaves were powdered in Potter tower gauged for application of a volume of 1.7 ± 0.305mg cm-2, they were put in containers of plastics with cover, and individualized 25 caterpillars of 3rd instar of each biotype of S. frugiperda. The insecticides and concentrations evaluated were: chlorpyrifos [Lorsban 480 BR, 0.960g a.i. L-1 (Chlorophosphate)], lambda-cyhalothrin [Karate Zeon 50 CE, 0.003g a.i. L-1 (synthetic Piretroid)], lufenuron [Match CE, 0.006g a.i. L-1 (Acilureis)], methoxyfenozide [Intrepid 240 SC, 0.158g a.i. L-1 (Diacylhydrazine)] and spinosad [Tracer, 0.960g a.i. L-1 (Naturalyte)]. The evaluation of the mortality was accomplished 24, 48, 72, 96 and 120 hours after the treatment. The biotype corn of S. frugiperda was less susceptible to the insecticides lambda-cyhalothrin, lufenuron and methoxyfenozide. The insecticides chlorpyrifos and spinosad were efficient in the control of the caterpillars of the biotypes corn and rice of S. frugiperda.
Insecta; fall armyworm; chemical control
