Whitefly is one of the main pests of melon in the Northeast area of Brazil. In this research, the effect of leaf and seed aqueous extracts of the neem plant (Azadirachta indica A. Juss.) and a formulation containing azadirachtin compared to buprofezin were studied as a spray application against nymphs of the silverleaf, Bemisia tabaci biotype B, whitefly in greenhouse conditions on melon cv. Torreon. Three independent essays were performed using a completely randomized design, with seven treatments each and replication varying from five to seven. Each plant was considered as an experimental unit. On the first essay the treatments were: absolute control (water), Neemazal® (1.2% Azadirachtin) at doses of 12; 24; 48; 96 and 192 ppm of azadirachtin. On the second: absolute control (water) and seed extract using 1; 2; 4; 8 and 16 g/100 ml. On the third, leaf extract was applied at the same rate as for seeds. For each essay a positive control was added by using the commercial product Applaud® (Buprofezin) at 1.5 g.c.p./L, which corresponds to 0.375g of the active ingredient (i.a.)/L of water. Azadirachtin at all dosages was effective and caused up to 98% reduction on alive nymphs number. When applied over 24 ppm, this compound showed the same efficiency as the standard buprofezin. The seed extracts, when used at 1; 2; 4; 8 and 16g/100 ml, significantly reduced the alive nymphs number showing the same performance as the standard insecticide. The leaf extracts did not show a significant effect on nymphs.
Bemisia tabaci biotipo B; Azadirachta indica; Cucumis melo; alternative control; insecticide
