COMPORTAMENTO DE OVIPOSIÇÃO DE Helicoverpa zea (BODDIE, 1850) (LEPIDOPTERA: NOCTUIDAE) EM MILHO SEMENTE E SIMULAÇÃO DE CONTROLE

Abstract

Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae) is a major insect pest in corn seed. In orderto increase efficiency of its control, this research objectified to study the oviposition behavior in the field, aiming tosubsidize the spray of insecticides. The study was conducted in areas of corn seed production in the municipality ofSanto Augusto, Rio Grande do Sul, Brazil. After starting style-stigma emission, monitoring of the H. zea infestationwas performed by verifying the presence of eggs in these structures. Daily, 20 corn ears were sampled at 10 randomizedpoints of two areas. From the oviposition data curve, the most appropriate time to carry out chemical control of H.zea was determined, by simulating spray intervals of 4, 5, 6 and 7 days. In both study areas, at 14 days from the startof emission of styles-stigma, 70% of the corn ears were infested with eggs of H. zea. For the chemical control of H.zea, the best time for the first spray is 4 days after starting emission of styles-stigma, and reapplication after 4 days.In this simulation, 44.5, 48.5 and 7.0% of the corn ears will receive two, one or no spray of insecticide, respectively.

Keywords

• monitoring
• chemical control
• corn earworm
• Zea mays