Efeito translaminar, sistêmico e de contato de extrato aquoso de sementes de nim sobre Bemisia tabaci (Genn.) biótipo B em tomateiro

Abstract

The whitefly is one of the most important tomato pests. Considering the difficulty for its control with synthetic insecticides, alternative methods have been studied. The objective of this study was to determine the insecticidal action (translaminar, sistemic and topical) of aqueous extract from neem seeds, Azadiracta indica A. Juss, on nymphs of silverleaf whitefly in tomato plants. Water was used as control in all experiments. To evaluate the translaminar action, the extract was applied at the concentrations of 0.5, 1 and 5% on the adaxial side of leaves infested with 7-day old nymphs. The sistemic action was evaluated applying 50 ml of extract, at the concentrations of 1, 5 and 10%, on soil of pots containing plants infested with nymphs (7 days old). As the mortality was 100% even in small concentration, this experiment was repeated twice with concentrations of 0.5, 1 and 5% with 30 and 20 ml of extract per pot. The topical effect was evaluated applying 0.2 μl of aqueous extract at the concentrations of 0.5, 1 and 5% on nymphs of third instar. This experiment was repeated with the concentrations of 0.1, 0.3 and 0.5%. The aqueous extract of neem showed insecticidal action by translaminar, sistemic and topical via on silverleaf whitefly.