ABSTRACT:The objective of this work was to evaluate the biological variables of Spodoptera frugiperda on species of cover crops. The experiments were conducted in laboratory and greenhouse using the following species: sunflower (Helianthus annuus), sun hemp (Crotalaria juncea), brachiaria (Urochloa decumbens e Urochloa ruziziensis), millet (Pennisetum americanum), black oat (Avena stringosa), white lupin (Lupinus albus), forage turnip (Rafanus sativus) and maize (Zea mays). In laboratory the S. frugiperda larval survival varied from 57%, on L. albus, to 93% on H. annuus and the survival of the pre-imaginal phase varied from 45% on U. decumbens to 81.6% on Z. mays. On C. juncea the larval biomass was lower and the development period of the young and larval stage was higher. The adaptation index was less on C. juncea in greenhouse and laboratory. In greenhouse the larval survival at 14 days was similar for all plants and at 21 days was the lowest on C. juncea. There was less accumulation of biomass at 14 days on C. juncea and at 21 days on C. juncea and A. stringosa. Regarding damage, C. juncea presented less susceptibility to Spodoptera frugiperda attack, which together with the other evaluated parameters, indicated this plant as the most appropriate for soil cover before cultivation of maize.

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Resumo -O objetivo deste trabalho foi avaliar os aspectos biológicos de Helicoverpa zea e Helicoverpa armigera (Lepidoptera: Noctuidae) em híbridos de milho com expressão de diferentes proteínas. Foram avaliadas as proteínas Cry1F, Cry1A(b), Cry1A.105 + Cry2Ab2 e Vip3A e seus respectivos isogênicos convencionais. As larvas foram alimentadas com espiguetas de milho Bt e convencional, trocadas a cada dois dias. Os parâmetros avaliados foram: sobrevivência 48 horas após eclosão, sobrevivência larval, peso de larvas e de pupas, período de desenvolvimento larval e período pré-imaginal. Observou-se efeito significativo da interação entre evento de milho Bt e espécie de Helicoverpa para todas as variáveis biológicas avaliadas. Larvas de H. armigera apresentaram maior sobrevivência 48 horas após eclosão em milho expressando a proteína Cry1F e a Vip3 em relação a H. zea. O período letal foi maior em H. armigera do que em H. zea, mas, em milho com expressão da proteína Cry1A(b), foi quatro vezes menor. Não houve sobrevivente para ambas as espécies de Helicoverpa em nenhum dos híbridos Bt avaliados. Nos isogênicos convencionais, o índice de adaptação de H. armigera foi superior ao de H. zea, o que indica maior facilidade de adaptação ao ambiente dessa espécie.Termos para indexação: biotecnologia, manejo de resistência de insetos, manejo integrado de pragas, Noctuidae, proteínas Bt. Development of Helicoverpa spp. in Bt maize expressing different proteinsAbstract -The objective of this work was to evaluate the biological responses of Helicoverpa zea and Helicoverpa armigera (Lepidoptera: Noctuidae) in maize hybrids expressing different proteins. The Cry1F, Cry1A(b), Cry1A.105 + Cry2Ab2, and Vip3A proteins and their isogenic conventional counterparts were evaluated. Larvae were fed on spikelets of Bt and conventional maize, which were changed every two days. The variables evaluated were: survival 48 hours after hatching, larval survival, larval and pupal weight, larval development period, and pre-imaginal period. There was a significant interaction between Bt maize event and Helicoverpa species for all evaluated biological variables. Helicoverpa armigera larvae showed higher survival 48 hours after hatching on maize expressing the Cry1F and Vip3 proteins when compared to H. zea. Lethal period was greater for H. armigera than for H. zea, but, in maize expressing Cry1A(b) protein, it was four times lower. There were no survivals for both Helicoverpa species in the evaluated Bt hybrids. In isogenic conventional counterparts, the adaptation index of H. armigera was higher than that of H. zea, which indicates greater ease of adaptation to the environment of that species.

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