Abstract

The whitefly Bemisia tabaci (Gennadius, 1889) is a major pest species in many agricultural crops worldwide. Growers from the Vale do Caí region, in Southern Brazil (Rio Grande do Sul state) have been facing severe economic losses due to the increasing damages caused by this sucking insect in their horticultural crops. Small-scale farming in the Vale do Caí region relies heavily on horticulture, with many families involved in the activity and a consumer market spread throughout the whole state. Virus transmission and other damages inflicted by B. tabaci are especially harmful to tomato plants, and the managing of the pest currently demands two thirds of all chemical insecticides used in the region. While chemical control remains the main strategy for whitefly management on tomato crops, control failures and lack of updated information have led tomato growers to raise the number of sprays per crop cycle, with selection of resistant populations and harmful effects on the environment as consequent risks. The aim of this work was to evaluate chemical compounds and bioinsecticides in the control of B. tabaci nymphs and adults on tomato plants grown in two different greenhouses and under natural infestation conditions. The most efficient treatment for the control of B. tabaci adults was cyantraniliprole + lambda-cyhalothrin (50+30 g a.i. ha^-1) with 64% of average control efficiency. As for nymph control, the most efficient treatment was the Embrapa formula, a bioinsecticide composed of 0.5% flaxseed oil + 0.5% neutral detergent + 0.3% sodium bicarbonate, which resulted in 72% of whitefly control in average.

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