The objective of this work was to analyze the biology of Spodoptera frugiperda (J.E. Smith) populations in corn and irrigated rice leaves. Caterpillars from four populations from Rio Grande do Sul state were collected from isolated areas (distant more than 300 km apart), from the counties of Santa Rosa (M/SR) and Uruguaiana (A/U), traditional areas of corn and irrigated rice production, respectively, and in adjacent areas in Pelotas county, where corn (M/P) and rice (A/P) are grown side by side. In the laboratory, 150 caterpillars were individualized in glass vials containing leaves of the Pioneer 30F33 corn hybrid and the cultivar of the irrigated rice Pelota, under controlled temperature (25 ± 1ºC), relative humidity (70 ± 10%) and photophase (14h). After adult emergence, 20 couples were individualized in cylindrical PVC cages, covered inside with paper towels, and fed with a 10% honey aqueous solution. All populations of S. frugiperda collected from corn and rice, regardless their place of origin, showed unique physiological needs, as evidenced by the different biological parameters evaluated. The Populations M/SR and M/P (maize) and A/U and A/P (irrigated rice), did not differ physiologically. Based on the results, both "corn" and "rice" S. frugiperda biotypes are present in Rio Grande do Sul.
Insecta; fall armyworm; host plant; biotype
