ABSTRACT Weevil is one of the main pests of stored corn. The adults feed on intact and broken seeds or bran, while the larvae develop by feeding on the inside of the seeds, resulting in a reduction in weight and physiological quality. The objective of this study was to evaluate the effects of Sitophilus zeamais infestation on corn seeds during storage. Corn seeds were infested using insect densities: 0, 36, 72, 108, and 144 individuals per 240 g of seeds. The infested seeds were placed in individualized plastic containers and covered with voile fabric. The seeds were stored for 60 days under laboratory conditions with an average temperature of around 27 °C and relative humidity of 85%. Initially and every 15 days of storage for 60 days, the seeds were evaluated using the parameters: number of S. zeamais individuals, total number of infested seeds, seed weight loss, germination test and seedling emergence in the tray. The population increase of S. zeamais causes a decrease on the physical and physiological quality of stored corn seeds, but the deterioration rate does not increase in the same proportion as the weevil population growth rate.

RESUMO Nesta pesquisa objetivou-se avaliar os aspectos biológicos e o comportamento alimentar de Aphis gossypii em cultivares de melancia submetidas à aplicação de silício. O experimento foi conduzido no Instituto de Educação, Agricultura e Ambiente da Universidade Federal do Amazonas, Humaitá, Brasil. Utilizaram-se o delineamento experimental inteiramente ao acaso e o esquema fatorial 2×3 (sem silício e com silício; cultivares Crimson Sweet, Fairfax e Charleston), com dez repetições. A aplicação do ácido silícico (1%) foi realizada diretamente no substrato, com dose equivalente a 1 ton SiO2·ha-1, 25 dias após a semeadura. Os pulgões da criação foram mantidos em plantas de pepino, cultivar Caipira. Foram conduzidos ensaios de biologia do inseto para avaliação da duração dos períodos pré-reprodutivo, reprodutivo e pós-reprodutivo, longevidade, número de ninfas e comportamento alimentar por meio da técnica de secreção de honeydew. Realizou-se a análise de variância dos dados utilizando-se o programa estatístico SISVAR e as médias foram comparadas pelo teste de F e Scott–Knott (p ≤ 0,05). A aplicação de silício em plantas de melancia afeta a reprodução e a alimentação de A. gossypii. Plantas de melancia do cultivar Crimson Sweet tratadas com silício apresentam alta resistência à alimentação por A. gossypii.

ABSTRACT This research aimed to evaluate the biological aspects and the feeding behavior of Aphis gossypii in watermelon cultivars submitted to silicon application. The experiment was conducted at the Institute of Education, Agriculture and Environment of the Federal University of Amazonas, Humaitá, Brazil. The experimental design was completely randomized in a 2×3 factorial (with and without silicon; cultivars Crimson Sweet, Fairfax and Charleston), with ten replications. The application of silicic acid (1%) was carried out directly on the substrate using dose equivalent to 1 ton SiO2·ha-1, 25 days after sowing. The rearing of aphids was kept in cucumber plants, cultivar Caipira. Insect biology tests were conducted to evaluate the duration of the prereproductive, reproductive and postreproductive periods, longevity, number of nymphs, and feeding behavior using the honeydew secretion technique. Analysis of variance was performed using the statistical program SISVAR and the means were compared by the F and Scott–Knott test (p ≤ 0.05). The silicon application to watermelon plants affects the reproduction and feeding of A. gossypii. The watermelon plants cultivar Crimson Sweet treated with silicon has high resistance to feeding by A. gossypii.

Objetivou-se, neste trabalho avaliar os efeitos de alguns fungicidas protetores utilizados na cultura de pepino sobre o pulgão Aphis gossypii Glover, 1877. Os experimentos foram conduzidos em condições controladas (Temp.: 25±2º C; UR: 70±10% e fotofase de 12 h). O delineamento experimental foi inteiramente ao acaso com quatro tratamentos (fungicidas e testemunha) e 45 repetições, sendo cada parcela composta por um indivíduo. Os fungicidas utilizados e suas respectivas dosagens em g i.a.L-1, foram: enxofre 800 PM (1,6), mancozebe 800 PM (1,6) e oxicloreto de cobre 840 PM (1,49). A testemunha foi composta por água destilada. Todos os produtos avaliados não influenciaram na duração em dias da fase ninfal e adulta, períodos pré-reprodutivos e reprodutivos de A. gossypii. Houve efeito do enxofre e do oxicloreto de cobre sobre o período pós-reprodutivo desse pulgão, constatando-se um período 4,5 vezes superior àquele da testemunha e mancozebe. A fecundidade foi influenciada pelos fungicidas testados, ocorrendo aumento de 1,25 vezes na produção total de ninfas, sendo então os fungicidas testados favoráveis ao inseto.

The objective of this work was to evaluate the toxic effects of some protecting fungicides used in cucumber crop on the aphid Aphis gossypii Glover, 1877. The experiments were conducted in controlled conditions (Temp.: 25±2º C; RH: 70±10% and 12 h photophase). The experimental design was completely randomized with four treatments (fungicides and control) and 45 replicates, each plot comprised of one individual. The used fungicides and their respective dosages in g a.i. L-1 were: sulfur 800 PM (1.6), mancozeb 800 PM (1.6) and copper oxichloride 840 PM (1.49). The control was composed of water. None of the tested products influenced the duration in days of the nymphal and adult phases, or the pre-reproductive and reproductive periods of A. gossypii. Sulfur and copper oxichloride affected the post-reproductive period of the aphid, which showed a period 4.5 times longer than that of the control and mancozeb. Fecundity was influenced by the tested fungicides, with a 1.25 fold increase in the total production of nymphs, so that tested fungicides were favorable to the insect.