Parasitismo de larvas da mosca-minadora Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae) pelo parasitóide Opius sp. (Hymenoptera: Braconidae) na cultura da batata com faixas de feijoeiro intercaladas

Abstract

The bean plant (Phaseolus vulgarisL.), in southern M inas Gerais State, in any period of the year, have practically only its cotiledonary leaves and few leaflets infested by the leaf miner Liriomyza huidobrensisBlanchard (Diptera: Agromyzidae), being that the parasitism level of its larvae by Opius sp. (Hym enoptera: Braconidae) gets up to 100%. Thus, the effect of bean strips in a potato culture (Solanum tuberosum L) on the parasitoid/pest relationship was evaluated. The experiment was set up in June 1997, at the winter planting, time of greatest occurrence of the leaf miner, in Alfenas county, with the cultivar Achat. The experimental design was that in strips, in a total of six, each of 30 x 5m (length x width), divided into 10 subplots of 3m and a rranged in the field in two sets: one with four strips 0.5, 5, 10 and 15 m away from the bean plants strip and the other with two strips, being this last set separated from the bean plant by 150 m of culture of the potato itself. The bean plants strip planted close to the first set was of equal length and had a wid th of 3 m, containing six planting lines. The two sets of strips were compared between them as to the parasitism level of the pest and within the first set, it was evaluated how far there was influence of the bean plant. Twelve leaves were randomly collected from each split plot, weekly, until the end of the cycle of the crop. From these leaves, the pupae of the miner were col lected and later the number of adult flies and their parasitoids emerged from them was evaluated. An increase of around 212% was verified at the parasitism level in the strip that received the bean plant as compared to that which did not. There was no significant difference on parasitism among potato strips 0.5, 5, 10 and 15 m away from the bean plants strip. The above-quoted mixture pr oved to be a feasible practice to decrease both the infestation and damage caused by the insect.