Potencial inseticida de extratos aquosos de plantas ocorrentes na Amazônia Oriental sobre pulgão da couve (Hemiptera: Aphididae).

Abstract

The objective of this work was to verify the insecticide potential of aqueous extracts from native or occurring plants in the Amazon Region. First, field interviews were carried out with producers of vegetables in two municipalities in the Pará Northeast (Castanhal and Cametá) in order to obtain information about the pests, the main methods of control and the use or knowledge of plants with insecticidal effect. After, the effect of aqueous extracts of plants occurring in the region on the aphid Erisymi sp. in cabbage plants was evaluated in the laboratory. For this, the leaves of these plants were oven dried at 40ºC for up to 48 hours and ground to obtain powder. The treatments consisted of aqueous extracts (g. mL-1) of Mansoa standleyi, Momordica charantia, Quassia amara and distilled water (control). The experimental design was completely randomized, with five replicates, ten insects per plot. The number of dead nymphs and adults were counted 24 hours and 48 hours after spraying, the results were submitted to analysis of variance and the means were compared by the Tukey test at 5% probability. Through the interviews it was verified that 95% of the producers declared to have some type of problem with the occurrence of pests in their area of cultivation. Regarding the control methods used by the producers, 80% of the interviewed producers use chemical control as the main method and the pests that cause the most damages to the cultivated vegetables are the caterpillars (Lepidoptera), mole cricket (Orthoptera), spittlebugs (Hemiptera), slugs , whitefly (Hemiptera, Aleyrodidae) and aphid (Hemiptera, Aphididae). In relation to the laboratory evaluation of the aqueous extracts was verified the insecticidal effect of the extract of Q. amara on the aphid Erisymi sp. in the phases of nymph and adults. The M. standleyi extract had an insecticidal effect only at the nymph stage of aphids. The number of dead insects after spraying with M. charantia extract did not differ from the control treatment. The extract of Q. amara shows an insecticidal effect on the aphid, a key pest in vegetables, in the phases of nymph and adult.