Residuos de tiametoxam, aldicarbe e de seus metabolitos em folhas de cafeeiro e efeito no controle de Leucoptera coffeella (Guerin-Meneville) (Lepidoptera: Lyonetiidae)

The coffee leaf miner Leucoptera coffeella (Guerin-Meneville), one of the major pests of coffee crops in Brazil, is mainly controlled with insecticides. The objective of this study was to evaluate the residues and the translocation of the insecticide thiamethoxam in coffee leaves, as well as to study its effect on the coffee leaf miner control, comparing it with aldicarb, used as standard. One experiment was set up in the county of Garca, SP from December/2001 to August/2002. The treatments used were: aldicarb 150 G at the rates of 2.25 and 4.50 g a.i./pit, thiamethoxam 10 GR, at the rates of 0.15 and 0.30 g a.i./pit and check. Twig samples were collected prior to and 30 , 60, 90, 120, 150, 180, 210 and 240 days after the application, at three coffee plant heights (lower, middle and upper third), and the percentage of mined leaves was evaluated. The determination of aldicarb residues, including their sulphoxide and sulfone metabolites and of thiamethoxam were performed by gas chromatography with a nitrogen-phosphorus and mass spectrometer detectors, respectively. The results indicated a uniform translocation of both insecticides in all three thirds of the coffee plants when applied to the soil. A higher persistence of thiamethoxam was verified with its residues being found for as far long as eight months following the application, while aldicarb residues, including the sulphoxide and sulfone metabolites, were found only until four to six months after the application. Control of the coffee leaf miner was observed with both insecticides.