Residues of thiamethoxam, aldicarb and its metabolites in coffee leaves and effect on the control of the coffee leaf miner Leucoptera coffeella (Guérin-Mèneville, 1842) (Lepidoptera:Lyonetiidae)

Author(s)

Gabriela Inés Diez Rodriguez

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2005-02-23
• Advisor: Gilberto Casadei de Baptista

Abstract

The coffee leaf miner Leucoptera coffeella (Guérin-Mèneville, 1842), one of the major Brazilian coffee crop pests , is especially controlled with insecticides. The objective of this study was to evaluate the residues and the translocation of thiamethoxan insecticide in coffee (Coffea Arabica L.) leaves, as well as to study its effect on the coffee leaf miner control, comparing it with aldicarb, used as the standard. Two experiments were set up in the county of Garça-SP in the periods of December/2001-August/2002 and December/2002-August/2003. The treatments used were: aldicard (Temik 150), at the dosages of 2.25 and 4.50 g a.i./pit and 3 and 6 g a.i./pit, thiamethoxan (Actara 10 GR), at the dosages of 0.15 and 0.30 g a.i./pit and 0.20 and 0.40 g a.i./pit and check (no application) for the first and second experiments, respectively. Twig samples were taken in pre-count and 30, 60, 90, 120, 150, 180, 210 and 240 days after the application (DAA) at three coffee plant heights (lower, middle and upper third), and the percentage of mined leaves was evaluated. The analytical method consisted of the extraction of aldicarb residues and their sulphoxide and sulfone metabolites, with an acetone/water mixture; clean by gel permeation chromatography and quantitative determination by gas chromatography equipped with a nitrogen-phosphorus detector (NPD). Thiamethoxam residues extraction was performed with acetate, with extracts being cleaned-up through the gel permeation chromatography (GPC) technique and quantitative determination by gas chromatography, using a mass spectrometer detector (MSD). The limits of quantitation (LOQs) of the methods, determined by fortification and recovery studies, were 0.5 mg.kg-1, for aldicarb and metabolites, and 0.02 mg.kg-1, thiamethoxam. The results indicated a uniform translocation of both insecticides in all three thirds of the coffee plants when applied to the soil in the month of December. Also it was observed the higher persistence of thiamethoxam, whose residues were found as far as eight months following the application, while the aldicarb sulphoxide and sulfone metabolites were found three to six months after the application. Both insecticides were efficient in the control of the coffee leaf miner, however, the period provided by Actara 10 GR was longer than of by Temik 150. (AU)