Number of Trichogramma galloi released, simulating an application by airplane to control Diatraea saccharalis in sugarcane

The egg parasitoid Trichogramma galloi is used in large areas of sugarcane to control the sugarcane borer, Diatraea saccharalis, with greater efficacy than other control agents. However, the method of releasing pupae in small capsules is very costly and can compromise the entire program. This study evaluated the effectiveness of different numbers of pupae of T. galloi by the pupal-release technique to control eggs of D. saccharalis in two different sugarcane-growing regions, in 2013. In the first trial, in São Raimundo das Mangabeiras, Maranhão, 4 different numbers of pupae (50,000, 100,000, 150,000 and 200,000 ha^-1) in the soil and the release of 50,000 newly emerged adults ha^-1 as a control in a randomized block design. In the second trial, in Sertãozinho, São Paulo, the treatments were  50,000, 75,000, 100,000, 125,000 and 150,000 pupae ha^-1. In each 400 m² experimental plot pieces of paper with about 30 eggs of the sugarcane borer were attached to the leaves at different points in the plot. The parasitoid pupae were scattered on the ground two days before adult emergence; adults were released in the corresponding treatment only when emergence occurred in the other treatments. The release of T. galloi by the pupal-release technique in the sugarcane fields proved to be feasible and effective, and the number to be released was the same as recommended for adults and pupae in capsules (50,000 ha^-1).

Key words: ecology, biological control, egg parasitoid, Hymenoptera