The economic and technical efficiency of controlling the South American tomato pinworm (Tuta absoluta) by the parasitoid Trichogramma pretiosum was evaluated in protected environment, in Luziania, Goiás State, Brazil, during the summer of 1999-2000. The research was conducted in two greenhouses, each one submitted to the following pest control regimes: (1) habitual farmer practices: pesticides sprayed based on presence/absence of the pest and rotation of products (deltamethrin; abamectin; Bacillus thuringiensis (at the recommended dose); and soap at 0,5% concentration). (2) inundative release of T. pretiosum associated with weekly sprays of Bacillus thuringiensis as an emulsifiable concentrate formulation (at the recommended dose). Insecticide sprays and parasitoid mass release were initiated just after the first adults were observed. Mass release consisted of weekly display of two cards (20x30 cm) of parasitized eggs by T. pretiosum that were gradually increased until the reached six cards each week, by the time of tomato harvest. Once a week, 50 leaflets were collected in each greenhouse. The number of eggs was determined in the laboratory and kept inside chambers to determine the number of larvae or the percentage of parasitism. Tomato production and damage to the fruits were determined weekly from 50 tomato plants randomly chosen in each treatment. The productivity of the treatment using biological control was 6,160 polystyrene trays/600g and 6,833 trays/600g when chemical control was used. The variable costs of production were R$ 3,9 thousands and R$ 4,7 thousands for the biological control and chemical control, respectively. The loss limit in each cropping season for both production systems, estimated by the technical-economic efficiency, was higher for the biological control (61,7%). The coefficient of economic efficiency was significant (2.62) and the internal rate of return (24.9%) confirmed that the system of production that used the biological control by T. pretiosum was economically efficient.
Tuta absoluta; Lycopersicon esculentum; Trichogramma pretiosum; Bacillus thuringiensis
