ChileanJAR

Corn (Zea mays L.) crops are damaged every year by corn earworm Helicoverpa zea (Boddie) larvae (Lepidoptera: Noctuidae). Two studies were carried out with the objective of defining the most adequate Trichogramma species to control the corn earworm. In the laboratory Trichogramma nerudai, T. maidis, T. evanescens, T. cacoeciae, T. pretiosum (strain 1) and T. pretiosum (strain 2) parasitism rates were compared on H. zea, Sitotroga cerealellaand Anagasta kuehniella eggs evaluating the percentage of parasitism at seven days after exposition. Native T. nerudai was effective or superior to the imported species, and it was, therefore, selected for field trials. The remaining tested Trichogramma species were less effective. In the field experiments the effect of four densities (200 000, 400 000, 800 000 and 1 600 000 parasitized eggs ha^-1) of the native T. nerudai was evaluated in a commercial corn crop. The corn earworm damage was reduced to close to 20% with the highest density as compared with 90.5% produced in the control treatment. Trichogramma was an effective parasitoid alternative for control of this pest.