Resumo

ARAGON, Sandra; RODRIGUEZ, Daniel  e  CANTOR, Fernando. Release criteria of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) for the control of Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) on tomato. Agron. colomb. [online]. 2008, vol.26, n.2, pp.277-284. ISSN 0120-9965.

In order to take right decisions for the management of greenhouse whitefly, different strategies has been purposed, which pretend to reduce the impact generated by the indiscriminate use of pesticides. Nevertheless, those decision criteria are mainly useful for chemical control and their use is unknown in biological control programs. The goal of this work was to develop decision criteria for the biological control of greenhouse whitefly T. vaporariorum with the parasitoid Encarsia formosa considering its functional response and percentage of parasitism. In a completely randomized design, eight weeks old tomato plants were infested with 500 whiteflies scales and three plants were used as an absolute control. On each tomato plant, 0, 10, 20, 30, 40 and 50 adults of E. formosa were released, with three repetitions per density. The number of black pupae was registered after 12, 19 and 26 days after the first wasp liberation. At the end of the crop, the total number of white and black scales was counted. The results of this work suggest that in order to obtain a control near the 80%, one parasitoid for each 17 whiteflies scales of third instar must be released evaluating the control 35 days after. New releases of E. formosa should be made for the control of new scales found in the periodic sampling of the crop.

Palavras-chave : decision models; parasitic ability; biological control; action thresholds.

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