Diversificação vegetal como estratégia de redução de Lipaphis erysimi (Kalt., 1843) (Hemiptera: Aphididae) e incremento de predadores no cultivo orgânico de couve (Brassica oleracea L. var. acephala)

Abstract

Two field experiments were performed which presented the same experimental arrangement with 5 treatments and 5 replicates. The treatments were monocrop of kale (Brassica olearceae L. var. capitata) associated to four floriferous plants: coriander (Coriandrum sativum L.), fenel (Anethum graveolens L.), marigold (Tagates erecta L.) and calendula (Calendula officinalis L.). In the first experiment it was found that the marigold was more attractive to predators only in F1, but the treatment did not affect the population of L. erysimi during F1 and F2. The relationship density dependent between predator and L. erysimi was verified throughout the crop cycle, being that the larvae of Syrfidade were dominant. In the second, companion plants did not affect on the population of predators compared to monoculture of kale, but it was possible to verify the effect of predation on L. erysimi by means of OCs and CCs. In this case the spiders were the dominant taxonomic group. Both works showed that the arthropod population in a form differentiated from that of companion plant phenology and climatic conditions, altering the population dynamics in regard to abundance, diversity, richness and insect dominance. In the third experiment we tested the olfactory response of L. erysimi to the odors of kale, forage-turnip (Raphanus sativus L.), and mustard (Brassica juncea). According to the results, the mustard was shown to be as attractive as the kale. Therefore, the mustard deserves to be studied at field level as a trap plant. Accordingly, further tests with the marigold and mustard must be carried, because these species may be promising in reducing L. erysimi and increase of natural enemies in diversified systems as strategy "push-pull".