This work was conducted in corn fields in the silking stage, in Sete Lagoas, MG, (EMBRAPA/CNPMS). In one experiment, different numbers of virgin females of Helicoverpa zea were compared to a commercial synthetic pheromone formulation using a Pherocon 1C sticky trap from the USA. In another experiment, calling behavior and nocturnal activity of adults were observed during the fall, winter, summer and spring using virgin females. There were no significant differences in the adult catches, using one, three or five females/trap. Three females were considered the best number, taking in count that the use of five females/trap was impractical and there is the possibility of death or physiological malfunction of the female in case of the lowest density. There were no H. zea catches in traps with the synthetic pheromone which, instead, captured the noctuid Mythimna. Mating activity of H. zea started soon after the scotophase and the catching peak occurred after midnight. The field reproductive activity was related to ambiental temperature.
Insecta; natural sexual pheromone; Zea mays; Noctuidae