Suscetibilidade de Spodoptera frugiperda (Lepidoptera: Noctuidae) a metaflumizone na cultura do milho: bases para o manejo da resistência / Susceptibility of Spodoptera frugiperda (Lepidoptera: Noctuidae) to metaflumizone in maize: basis for resistance management

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Metaflumizone is a new insecticide, belonging to the new chemical group semicarbazone, with excellent activity against many species of Lepidoptera Order. The product acts in the nervous system of insects blocking the sodium channels without metabolic activation, in other words, the molecule is toxic on its original form. The mechanism of action of metaflumizone is distinguished to the pyrethroids that act as sodium channel modulators. To know the activity of metaflumizone against Spodoptera frugiperda (J.E. Smith) and to establish proactive strategies of resistance management to preserve the lifetime of that product, the main objectives of this work were: (a) to establish the baseline susceptibility of metaflumizone in populations of S. frugiperda collected in maize crop in different regions of Brazil; (b) to define diagnostic concentrations (LC95 e LC99) for the susceptibility monitoring of S. frugiperda populations; (c) to verify the possibility of cross-resistance between metaflumizone and lambda-cyhalothrin; and (d) to verify the agronomic efficacy of metaflumizone in the control of S. frugiperda under field conditions. The bioassay method was the surface treatment of an artificial diet with pesticides by using 3rd instar larvae. The diagnostic concentrations of 32 e 100 µg of metaflumizone/mL of distilled water (ppm) were defined for the susceptibility monitoring of S. frugiperda populations to metaflumizone. Significant differences in susceptibility to metaflumizone were found for the two diagnostic concentrations in the populations, with survival percentage from 5.3 to 16.73% in the concentration of 32 ppm and from 0.42 to 10.37% in the concentration of 100 ppm. To verify the cross-resistance between metaflumizone and lambda-cyhalothrin, the characterization of dose-mortality curve to metaflumizone was done in a lambda-cyhalothrin-resistant population of S. frugiperda (R) and the results were compared to the response of the susceptible population (S). The results suggested no existence of cross-resistance. The agronomic efficacy of metaflumizone under field conditions was verified in 2 field trials in maize crop infested with S. frugiperda at high level of pyrethroids resistance frequency (40%), with two applications of insecticides, at seven days interval. The treatments were: 1-untreated; 2-metaflumizone 200 g A.I./ha, 3-metaflumizone 240 g A.I./ha; 4-indoxacarb 75 g A.I./ha; and 5-lambda-cyhalothrin 7,5 g A.I./ha. The lower defoliation levels were achieved by the treatments of indoxacarb at 75 g A.I./ha and metaflumizone at 240 g A.I./ha, at 7 days after the second application of the insecticides, confirming its efficacy against S. frugiperda. Therefore, metaflumizone can be used as an alternative for the resistance management of S. frugiperda to insecticides.

ASSUNTO(S)

fitossanidade metaflumizone pesticidas - resistência. spodoptera frugiperda lagartas milho cross-resistance manejo integrado resistance management.

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