Repelência de produtos fitossanitários usados na cana-de-açúcar e seus efeitos na emergência de Trichogramma galloi

Abstract

Trichogramma galloi Zucchi is an important parasitoid of Diatraea saccharalis (Fabricius), a major pest of sugarcane. As various chemical products are used in the management of this crop, this study aimed to evaluate the repellence of some pesticides on adults of the parasitoid T. galloi, and its effect on the emergence of their offspring. The tests were carried out in a climatic chamber at 23 ± 2 ºC, with a relative humidity of 60 ± 10% and a photo period of 14 hours. The products evaluated were: insecticides clorantraniliprole, ethiprole, thiamethoxam, triflumuron, lambda-cyhalothrin+thiamethoxam, fipronil and Metarhizium anisopliae; the herbicides clomazone and diuron+hexazinone; and the plant-growth regulators methyl-sulfometuron, and ethyl-trinexapac, at the highest concentrations recommended for sugarcane. To evaluate the repellence of each product, a free-choice test was carried out with, where 30 eggs of D. saccharalis were immersed in distilled water and another 30 in a mixture of the product to be tested. Each mass of eggs from the two treatments was transferred to a glass tube, these being connected by a paper connector with a central hole through which a smaller tube was attached to allow the release of three females of T. galloi which had previously been fed. The experimental design was completely randomized, with fifteen repetitions for each product evaluated. Repellence, average number of parasitised eggs per female and emergence rates were all evaluated. Clorantraniliprole, triflumuron and methyl-sulfometuron did not repel the parasitoid nor affect the number of parasitized eggs. As for emergence, it was found that M. anisopliae, thiamethoxam, clomazone, diuron+hexazinone and methyl-sulfometuron did not affect this biological characteristic.