Um imenso potencial para a produção de compostos secundários e potencial inseticida vem sendo estudado dentro da ampla diversidade que a flora brasileira apresenta. Dessa forma, o presente estudo objetivou apresentar informações sobre o potencial das plantas no controle de insetos, através de uma revisão bibliográfica. Os primeiros inseticidas botânicos utilizados foram a nicotina, a piretrina, a rotenona, a sabadilla e a rianodina. A partir de então foram estudados vários compostos e espécies, como a azadiractina, extraída do nim, alcaloides das Anonaceaes, rotenona em Derris urucu, Piperaceae com as amidas, entre outros registros com as espécies amazônicas. Observa-se então que as espécies amazônicas compõem uma rica fonte de pesquisa e muitos dos exemplares estudados mostraram-se promissores para o desenvolvimento de inseticidas. Entretanto, novas pesquisas, principalmente em campo, devem ser realizadas para prospecção de novas espécies, buscando compostos seletivos e consequentemente com menor contaminação ambiental, para utilização tanto direta, quanto para o desenvolvimento de novos inseticidas comerciais.
Currently, few active principles are authorized by the forest certification for the control of insect pests, with which it is necessary to develop new products, mainly aiming at lower environmental impact. The plants are able to develop substances called secondary metabolites, widely studied as an alternative form of pest control. Thus, the objective of this study was to evaluate the insecticidal potential of two Musa acuminata extracts, on the control of Atta sexdens rubropilosa. The extracts were obtained from the pseudostem of M. acuminata, which underwent drying and milling, producing two extracts: ethanolic (A1) and hydroethanolic rotaevaporate (A2) extract. For the analysis of the bioactivity of the extracts, a topical application of one milliliter of each extract on the ants was carried out, with the aid of spray, in the concentrations of: 2, 6, 10, 14, 18, and 20%, with distilled water (witness) applied to the test, analyzing the mortality and LC 50 , in different evaluation periods. At 24 hours the mortality of 90% at the concentration of 20% for the A1 extract was observed. From the 10% concentration there was 100% mortality in this same period for the A2 extract, and at 48 hours the 2% concentration caused 100% mortality. In the LC 50 analysis for 24 hours values of 7.94 and 1.09% were obtained for ethanolic extract and rotavaporated ethanolic extract respectively. And the LC 50 presented a decrease in values after 48 hours for the ethanolic extract presented value of 2.29%. Thus, it can be concluded that the A2 extract is the most efficient, since it allows the lower consumption of extract in the dilution for later application, due to the presence of insecticidal potential in low concentration.
The objective of this study was to evaluate the mortality of Aphis craccivora Koch (Hemiptera: Aphididae) submitted to different extracts with different concentrations of leaves of the native forest species: Tetragastris altissima (Aubl.) Swart (Burseraceae), Metrodorea flavida K. Krause (Rutaceae) and Cheiloclinium cognatum (Miers) AC Sm (Celastraceae) under laboratory conditions. Adults of Aphis craccivora were collected in Gliricidia sepium (Jacq.) Kunthe Walp. (Fabaceae), and separated into groups of ten individuals, transferred to Petri dishes and exposed to topical application of aqueous, alcoholic and leaf infusion extracts of Cheiloclinium cognatum, Metrodorea flavida and Tetragastris altissima. The extracts were applied at concentrations of: 3, 6, 9, 12 and 15%, with 1% dimethylsulfoxide (DMSO), using a control treatment 1 (distilled water + DMSO 1%) and control treatment 2 (fipronil). Evaluations were performed at 24, 48 and 72 hours after the application of the extracts by counting the dead insects. The experimental design was completely randomized, with five replicates, three types of extracts and five concentrations with controls. In all the studied species, the aqueous and infusion extracts presented a lower mortality (less than 52%), whereas the alcoholic extract in higher concentrations of Cheiloclinium cognatum, Metrodorea flavida showed a mortality of up to 100%. The species Tetragastris altissima reached an average mortality of 92%. The lethal concentration for the alcoholic extract of Cheiloclinium cognatum was LC50 6.43% and LC90 12.22%, Metrodorea flavida LC50 was 3.08% and LC90 7.05% and that for Tetragastris altissima LC50 5.58% and LC90 17.47%, after 72 hours. The use of the alcoholic extract of the species Metrodorea flavida at a concentration of 9% in the control of Aphis craccivora is indicated.
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