Eficiência de tiacloprid para o controle de mosca-branca

Abstract

A mosca-branca, Bemisia argentifolii, foi observada no Brasil pela primeira vez em São Paulo, no início da década de 90 (Lourenção et al., 1999); no Distrito Federal foi encontrada em 1993, associada a cultivos de tomate e repolho (França et al., 1996); em 1996 o CASTELO BRANCO, M.; PONTES, L.A. Eficiência de tiacloprid para o controle de mosca-branca. Horticultura Brasileira, Brasília, v. 19, n. 01, ABSTRACT Efficiency of tiacloprid in controlling whiteflies.Effects of thiacloprid on adults, female fertility, egg hatch and nymph development of Bemisia argentifolii were determined in Brasília, Brazil. The first experiment was to evaluate the efficacy of tiacloprid in causing adult mortality. Cabbage leaves were treated with thiacloprid (96 g.a.i./ha), imidacloprid (14 g.a.i./ha), acephate (750 g.a.i./ha), deltamethrin (6 g.a.i./ha) and water. Adult whiteflies were released in cages containing the treated leaf. Adult mortality was evaluated after 72 h. The second experiment was to evaluate the impact of tiacloprid on female fertility. Cabbage leaves were treated with thiacloprid or water and put into the cage. About 50 adults were released into the cage for 24 h. After that time adults from each cage were transferred to a new cage containing a leaf free from insecticide treatment. Females were allowed to oviposit for 24 h. Then whiteflies were removed from the cage and the number of eggs on each leaf was counted. After counting, the leaves were transferred to a chamber and 10 days later the number of first instar nymphs was recorded. The third experiment evaluated the impact of tiacloprid on egg hatch. Whitefly eggs which were one and fiveday-old were treated with thiacloprid or water. After 10 days the number of first instar nymphs was determined. The fourth experiment evaluated the impact of tiacloprid on nymphs development. Second instar nymphs were treated with thiacloprid or water. After five days the number of third instar nymphs was determined. Thiacloprid and imidacloprid caused 99% adult mortality whereas acephate and deltamethrin caused less than 32% adult mortality. The results indicated that thiacloprid had good effect on adults. Egg viability was not affected when females had contact with leaves treated with the insecticide as more than 97% of the eggs hatched. More than 97% of the eggs treated with thiacloprid did not hatch, indicating that inhibition of egg hatch caused by tiacloprid has no connection with egg age. Thiacloprid affected nymph development. Only 1.2% of the second instar nymphs treated with the insecticide developed to the third stage.