Comparison of release techniques of Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae) to control Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)

Abstract

We compared five different release techniques of Tricchogramma galloi Zucchi in the field to control the sugarcane borer, Diatraea saccharalis (Fabricius). The tests were carried out in June, November, and December of 1998, in Piracicaba, state of São Paulo. We evaluated the average daily egg parasitism in 25 equidistant infestation sites within 400 m2 plots artificially infested with D. saccharalis eggs, with only one release of parasitoids. The percentage of parasitism and active period of T. galloi observed after adults were spread over the plot was similar to that obtained when adults were released in a single place. Besides, no differences were observed between releases of adults or non-protected pupae. However, the techniques using releases of protected pupae were superior to the others and were not affected by the weather conditions. Temperature and rain were the factors that most affected the release efficiency of the other four techniques. The release of protected pupae at three different ages did not increase the active period of the parasitoid. The spatial distribution of T. galloi was not affected by the release technique. Regardless of the technique used, the active period of the parasitoid lasted for six days.