Translocation of the insecticide thiamethoxam in the phloem of castor bean and coffee plants. / TranslocaÃÃo do inseticida tiametoxam no floema de mamoneira e cafeeiro.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

It was aimed in this work to investigate the translocation of thiamethoxam in the phloem of castor bean plant, used as model plant, the influence of adjuvants on the penetration of this insecticide in the leaves of this plant and its translocation in the phloem of coffee plant. Castor bean plants with three weeks of age, growing in nutrient solution and coffee seedlings growing in pots, in a greenhouse, and five-year-old coffee plants, growing in the field, were used. The castor bean plants received an aqueous solution of thiamethoxam, through injection in the petioles, or spraying of an aqueous suspension of a formulation of the insecticide, with and without adjuvants, on the developed leaves. The coffee seedlings were treated through foliar spray and adult plants were treated through drench application in the trunk basis. The quantitative determinations of thiamethoxam were performed by high performance liquid chromatography. Thiamethoxam was shown to be transported both in the xylem and in the phloem of castor bean plant and to be redistributed inside the plant, either when injected in the petioles or when sprayed on the leaves. The tested adjuvants did not influence expressively the penetration of thiamethoxam in the castor bean leaves. A low rate of penetration of thiamethoxam was observed when sprayed on coffee leaves, being the compound quite exposed to photo degradation and consequently little available for transport in the phloem. In the field, it was observed that the transport of thiamethoxam to coffee fruits takes place not only through the xylem, but also in the phloem, from developed leaves. Thiamethoxam contents found in coffee grains were in conformity with those tolerated for these grains and the residue levels found in the hulls do not indicate problems with regard to the use of these hulls in animal feeding. The transport of thiamethoxam to the fruits provided a partial control of the coffee berry borer, when fruits collected in the field were exposed to adult females of this pest.

ASSUNTO(S)

inseticida sistÃmico transporte no floema penetraÃÃo foliar controle de pragas entomologia agricola foliar penetration coffee pests pragas do cafeeiro phloem transport pest control systemic insecticide

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