Associação de defensivos natural e sintético a polímero para o controle de Alphitobius diaperinus (Panzer, 1797) (Coleoptera: Tenebrionidae) em sementes de amendoim.

Abstract

Under storage conditions, seeds can be attacked by pest insects. For their protection, the neem (Azadirachta indica A. Juss) has been shown as one alternative to synthetic products. In addition, seeds recovering has been a technique which guarantees insecticides and fungicides fixation and other materials on seeds surface, aiding the seeds germination. Thus, this work aimed evaluate the potential of synthetic and natural products associated to polymer to the control of Alphitobius diaperinus (Panzer, 1797) (Coleoptera: Tenebrionidae) on peanut seeds. Bioassays were carried out at the Laboratory of Entomology of Embrapa Cotton, Campina Grande, Paraíba. Peanut seeds (cultivar BR1) were treated with insecticide (imidaclroprid), fungicide (carboxin + thiram) and aqueous extract of neem leaves, associated or not to polymer, constituting the followed treatments: aqueous extract of neem, insecticides, fungicides, polymer, polymer + insecticide, polymer + fungicide, polymer + aqueous extract of neem (25%) and aqueous extract of neem (50%) and control (seeds without treatment). Three bioassays were accomplished. The first one about products efficiency on adult insects, evaluated the Number of Dead Insects, Eggs and punched seeds during 15, 30, 45, 60, 75 and 90 days of storage. The products efficiency on adult insects was calculated by Abbott method (1925). Data were submitted to Variance Analysis by F test (P ≤ 0,05) and means compared by Scott-Knott test (P ≤ 0.05), when necessary. Additionally, a correlation analysis between the principal variables, were realized. the second bioassay evaluated the products capacity in repelling A. diaperinus adults, by using circular arenas, with six recipients in its basis distributed in an equidistant way among them. Seeds without treatment and with one of the treatments mentioned before were distributed by alternative way. In the center of the arena 15 A. diaperinus couples were released and after 24 hours the number of insects in each recipient was recorded. A. diaperinus choices were analyzed using the ChiSquare test (P ≤ 0.05). The Repellence Index was also calculated, submitting it to Variance Analysis test (P ≤ 0.05) and means compared by Scott-Knott test (P ≤ 0.05) when necessary. The third bioassay evaluated larval survival kept in seed powder treated with the products of the first bioassay. Larvae survival until ten days after insect release in the substrate was evaluated. By the number of alive larvae in each treatment, a survival analysis using Logrank test (D. Collet Method) was accomplished, in which the survival of larvae submitted individually to products were compared to the survival of larvae in the control. The treatments with insecticide and fungicide, associated or no to polymer were efficient to control insects, reducing the number of eggs and punched seeds. For repellence, the association of insecticide e fungicide to polymer presented the best results for the Repellence Index. Larvae submitted o seeds powder treated with insecticide, fungicide and polymer + insecticide obtained their survival negatively altered, with 100% of mortality within 120 hours. Treatments with neem extract, associated or not to polymer, did not affected significantly on none of the variable.