Efeito do silício na preferência para oviposição de Bemisia tabaci biótipo B (Genn.) (Hemiptera: Aleyrodidae) em plantas de feijão (Phaseolus vulgaris L.)

Abstract

The biotype B of Bemisia tabaci stands out among the main pests of the bean plant. The objective of this work was to evaluate the resistance induction to the whitefly by silicon application in bean plant. The experimental design was completely ranlomized with 4 treatments, in a 2 (cultivar Carioca and Brave) x 2 (with and without silicon application) factorial outline and 6 repiicates. Ten days after the emergence of the seedlings, 500 ml of 1% silicic acid solution was applied in the soil, at a dosage equivalent to 2 t SiO2/ha. Ten days after the silicon application, the plants were infested with non-sexed whitefly adults in an acclimatized room, wiht 100 whiteflys/vase. For the non-choice test, the same procedure was used, with each vase covered by cages of organza cloth. Previously to the infestation, a plant of each vase was removed, oven-dried to constant weight for the evaluation of phenol levels. After 48 hours of infestation, the liberated adults were removed from the plants for evaluation of the number of eggs. For that, a leaf of a plant/vase was chosen, selecting the third completely developed apical leaf. After fifteen days, the number of nymphs of 3rd and/or 4th instar were evaluated. There was no response among cultivars of common bean to silicon application. A lower number of eggs and lower number of nymphs were observed in the plants treated with silicon in the test with chance choice. In the no-choice test the silicon application did not affect the oviposition of the whitefly and the nymph development, as well as the phenol levels.