Efeito de inseticidas sistêmicos aplicados no solo na produção do feijoeiro

Este trabalho objetivou o estudo dos componentes de produção na cultura do feijoeiro (Phaseolus vulgaris L.), quando se utilizaram os inseticidas sistêmicos Aldicarb 150 G (6 kg/ha) e Fosthiazate 100 G (10, 20, 30 e 40 kg/ha), além da testemunha. A pesquisa foi desenvolvida na Universidade Federal de Viçosa, Viçosa (MG), em abril-julho de 1994. O delineamento experimental foi em blocos casualizados com quatro repetições, sendo a unidade experimental constituída de 500 plantas. Avaliaram-se altura das plantas, número de nós, mortalidade de plantas, número de flores, vagens, óvulos e grãos danificados (identificando-se os causadores dos danos). Foi estimada a produtividade média de cada tratamento, as perdas ocorridas e suas causas. A partir desses dados, confeccionou-se tabela de vida para a cultura. Não se verificou efeito dos inseticidas Aldicarb e Fosthiazate quanto à altura e ao número de nós das plantas de feijoeiro. O componente de produção que mais sofreu perdas foi a vagem devido ao ataque de Etiella zinckenella (Treitschke) (Lepidoptera: Pyralidae)] seguido da mortalidade de plantas na fase vegetativa e grãos (pelo ataque do fungo Colletotrichum lindemuthianum). A flutuação de perdas totais foi mais influenciada pela mortalidade de plantas seguida pelo abortamento de flores. Ocorreu menor mortalidade de plantas na fase vegetativa com o aumento na dosagem de Fosthiazate

MORTALITY OF ANTICARSIA GEMMATALIS (LEPIDOPTERA: NOCTUIDAE) CATERPILLARS POST EXPOSURE TO A COMMERCIAL NEEM (AZADIRACHTA INDICA, MELIACEAE) OIL FORMULATION

The velvetbean caterpillar, Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae), is the most important defoliator of soybean (Glycine max L. Merrill, Fabaceae) crops in Brazil. Early-instar caterpillars of this pest are the main target of control. The objective of this work was to evaluate the toxicity of a commercial product, Bioneem (R) [neem oil (Azadirachta indica A. Juss., Meliaceae)], sprayed on A. gemmatalis caterpillars. Bioneem (R) was sprayed on soybean plants and 3 h later specific branches were enclosed by organza bags in a greenhouse with third-instar A. gemmatalis caterpillars. Ten replications with 80 caterpillars were used per treatment. The mortalities of A. gemmatalis caterpillars (mean 3rd to 6th instars) was 3.17, 7.18, 5.00, 11.25, 16.74, and 18.15%, whereas the respective mortalities of the pupae obtained from treated the caterpillars were 20.57, 22.79, 29.64, 39.16, 51.50, and 59.17%. The viabilities until the pre-pupal stage were 76.26, 70.03, 65.36, 49.59, 31.76, and 22.68% with 2.5, 5, 10, 15, 20, and 25% of the neem oil, respectively. The larval stage of this pest (3rd instar to pre-pupa) lasted longer in the 20% neem oil treatment than at the other rates, but its longevity was not affected. Anticarsia gemmatalis pupae presented developmental interruptions and anomalies at all concentrations of neem oil. The commercial product Bioneem (R) (neem oil) can therefore be used as a suitable alternative to synthetic insecticides to control A. gemmatalis.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Rice-Straw Mulch Reduces the Green Peach Aphid, Myzus persicae (Hemiptera: Aphididae) Populations on Kale, Brassica oleracea var. acephala (Brassicaceae) Plants

Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21-36(circle)C and to 18-32(circle)C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30(circle)C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Does environmental diversity affect hymenopteran galling insects and their natural enemies on Caryocar brasiliense trees (Caryocaraceae)?.

Caryocar brasiliense (Malpighiales: Caryocaraceae) trees, protected by Brazilian federal laws, are the main income source in many communities. The transformation of the Cerrado (savanna biome) into grazing or agricultural areas has been isolating these trees species in an agro-urban landscape. We studied the effects of environmental diversity on the abundance of galling insect communities inhabiting C. brasiliense trees in three different environments: Cerrado, pasture, and an urban area. Eurytoma sp. (Hymenoptera: Eurytomidae) adults and their galls, its parasitoid Sycophila sp. (Hymenoptera: Eurytomidae) and the predator Zelus armillatus (Hemiptera: Reduviidae) were present in larger numbers on the C. brasiliense leaflets in the urban area. The percentages of totally galled leaflets (exhibiting all kinds of galls) and the number of trees were negatively correlated. Greater habitat diversity favored that of galling insect species and their natural enemies