As plantas bioativas como estratégia à transição agroecológica na agricultura familiar: análise sobre a utilização empírica e experimental de extratos botânicos no manejo de afídeos em hortaliças

• Autor(a) principal: Lovatto, Patrícia Braga
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFPel - Guaiaca
• Texto Completo: http://repositorio.ufpel.edu.br/handle/ri/2365
• topic: Manejo de pulgões; Etnobotânica; Extratos; Bioensaios; Management of aphids; Ethnobotany; Extracts; Bioassays; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA

Knowledge about the use of bioactive plants for insect management has assisted in developing methods less harmful to the environment and human health, becoming a viable and environmentally sound strategy to be incorporated into agricultural production systems family that aims to sustainability. Thus, the active principles of plants can act in crop protection by acting as repellents, attractive and / or insecticides, representing a low-cost technology and reduced environmental impact, made from the recovery and maintenance of popular knowledge. Given these assumptions the research presented here was to order, identify, classify and contextualize the use of bioactive plants, used for the management of agroecossitemas by farmers in ecological basis of the Territory South Zone of RS, combining elements of research in ethnobotany research data experimental to legitimize the use of botanicals in the management of aphids on vegetable crops. Serving up the research participant and the phenomenological approach as qualitative tools for ethnobotanical research conducted with 33 farmers in ecological basis linked to the Cooperative Ecological and ARPA South-South, it was possible to infer the empirical use of 24 different plant species for management bioactive agroecosystems. Thus, the experimental study investigated the bioactivity of aqueous extracts of five plant species with the highest number of citations for the management of aphids: Melia azedarach (Meliaceae), Tagetes minuta (Asteraceae), Peteridium aquilinum (Dennstaedtiaceae), Ruta graveolens (Rutaceae) and Urtica dioica (Urticaceae), and the species Solanum fastigiatum var. acicularium (Solanaceae) on two species of horticultural importance, Brevicoryne brassicae and Myzus persicae (Hemiptera: Aphididae) under laboratory conditions. The bioassays included the evaluation of the repellent and insecticidal activity of extracts and assessment of survival, production of nymphs and instantaneous rate of population growth of insects, using as host cabbage, Brassica olareacea var. acephala. Jointly to the crude extract of fresh plant parts (30% w/v) and dried (5% w/v) dilutions were evaluated 30 and 10%, besides being distilled water and product test AGV Xispa pests. With respect to the bioactivity of the plants on aphid B. brassicae, the results showed that the repellent action of extracts prepared from fresh and dried leaves of R. graveolens, dry leaves and ripe fruits of M. azedarach, dry leaves of T. draft, leaves, flowers and twigs of U. dioica and fresh and dried leaves of P. aquilinum. The most representative insecticide was observed for extracts prepared from the dried leaves of R. graveolens, fresh and dried leaves of P. aquilinum, fresh leaves of S. fastigiatum var. acicularium and dried flowers of T. raw draft in the formulations and diluted to 30%. The reduction of survival and production of nymphs the most significant results were obtained with extracts prepared using the dried leaves of R. graveolens, dry leaves and unripe fruits of M. azedarach, dried leaves and flowers of T. draft, leaves, flowers and twigs of U. dioica, dried leaves of P. aquilinum and fresh leaves of S. fastigiatum var. acicularium. Already in bioassays on the instantaneous rate of population growth the most significant results were obtained with extracts prepared from dried leaves and flowers of T. minutes, dried leaves and unripe fruits of M. azedarach and dried leaves of P. aquilinum. Bioassays of the aphid M. persicae results pointed to the repellent action of aqueous extracts prepared from the dried leaves of the species R. and M. graveolens azedarach, in addition to those made from the leaves, flowers and twigs of the species U. dioica. The extracts prepared from dried leaves of R. graveolens dried unripe fruits of M. azedarach, dried leaves of P. aquilinum, dried flowers of T. draft and leaves, flowers and twigs of U. dioica also showed action on the biology of the aphid, significantly reducing the survival and reducing the offspring of M. persicae, confirming the results obtained with the species B. brassicae laboratory under similar conditions. The satisfactory results obtained with botanical extracts corroborate the agroecological knowledge, as well as indications of practical use of plants found within the manuals that guide the organic gardening and pointed between the techniques used by farmers in ecological basis, representing a viable alternative to preventing and control the occurrence of aphids in brassica crops. In this context, it is desirable that further investigative works are carried out with plants and their extracts in order to verify its action on the ecosystem as a whole, particularly as regards toxicity on non-target organisms, including humans, domestic animals and organisms beneficial, allow to expand the security and use of technology as a practice suited to agroecological management of crops.