ABSTRACT
Melon plant is one of the most important exportable agricultural commodities in Northeastern region of Brazil. Its main pest is the silverleaf whitefly, Bemisia tabaci biotype B. In order to control this pest, insecticides of wide spectrum and, in some cases, nonregistered pesticides, have been used. This practice has brought severe outbreaks and pest resistance problems. This work was undertaken under greenhouse and field conditions aiming to reduce the use of insecticides by studying the efficiency of natural products. The experiments were set up using a completely random design with four replicates and seven treatments: T1-Non control, T2-pirolenhoso extract (Pironat), T3-timbó extract (Rotenat), T4-Beauveria bassiana (Bovenat), T5-Metarhizium anisopliae (Metanat), T6-neem oil (Natuneem), and T7-imidacloprid (Confidor 700g GrDA). Mean number of nymphs, and adults and nymphs were evaluated under greenhouse and field experiments, respectively. Under greenhouse conditions the neem oil (66.49%) and the natural extract Pironat (67.35%) were the most efficient in the control of whitefly nymphs. However, under field conditions, the neen oil presented the best results as a natural insecticide for the control of whitefly adults and nymphs. The products based on entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, had better effect on nymphs, M. anisopliae being more efficient than B. bassiana. The natural extract "timbó" presented more efficiency on whitefly adults in the beginning of the plant development, while the natural extract Pironat was more efficient in the control of the nymphs during the plant development.
KEY WORDS
Neem oil; natural extract; timbó extract;
Beauveria bassiana
;
Metarhizium anisopliae