Impact of the insecticids chlorfenapyr and methamidophos on arthropods community associated with Bean crops

Este trabalho objetivou estudar o impacto dos inseticidas clorfenapir e metamidofós sobre a comunidade de artrópodes do feijoeiro com uma e duas aplicações e foi realizado em Coimbra, MG de março a junho de 2005. Os tratamentos foram estabelecidos em arranjo fatorial 2 x 2 (inseticidas x número de aplicações) além da testemunha. O delinemanto foi em blocos casualizados com cinco repetições. Avaliaram-se as populações de artrópodes fitofagos, predadores, parasitóides e detritívoros no dossel da planta, sobre o solo e no interior do solo. A comunidade de artrópodes foi avaliada um dia antes e 1, 8, 16, 24, 32, 40 e 48 dias após a aplicação dos tratamentos. A primeira aplicação ocorreu em 30/04/2005 e a segunda três semanas após. Os inseticidas clorfenapir e metamidofós foram aplicados na dose recomendada 0,18 L de i.a/ha e 0,45 L de i.a/ha respectivamente. A avaliação dos artrópodes associados ao dossel foi realizada pela batida de plantas em bandeja plástica. Na avaliação dos artrópodes sobre o solo foi usada armadilha do tipo pitfall. Para a avaliação dos artrópodes no interior do solo foi retirada amostra de solo com 30 cm de profundidade e 10 cm de diâmetro e posteriormente colocados em funis Berleze por 48 horas. Na análise estatística dos dados foram usadas análises de variáveis canônicas, teste F (p < 0,05), distância de Mahalanobis e análise de variância por medida repetida. Os principais insetos associados ao dossel do feijoeiro afetados inseticidas clorfenapir e metamidofós foram o desfolhador Cerotoma arcuata (Coleptera: Chrysomelidae) e o fitossucívoro Caliothrips phaseoli (Thysanoptera: Thripidae). O clorfenapir e o metamidofós reduziram o ataque de C. arcuata e C. phaseoli ao feijoeiro até 16 dias após a aplicação. Os principais artrópodes sobre o solo na cultura do feijão afetados pelo clorfenapir e metamidofós foram os detritívoros Isotoma sp. e Emtomobryidae (Collembola) e Scheloribatidae (Acari). O clorfenapir e metamidofós reduziram as populações dos detritívoros Isotoma sp., Emtomobryidae e Scheloribatidae sobre o solo. Os principais artrópodes no interior do solo afetados pelo clorfenapir e metamidofós foram os detritívoros Hypogastrura sp. (Collembola), Galumnidae sp.1 e Scheloribatidae (Acari) e o predador Hypoaspis sp. (Acari). O clorfenapir e metamidofós reduziram as populações dos detritívoros Hypogastrura sp., Galumnidae sp.1 e Scheloribatidae e do predador Hypoaspis sp. Verificou-se uma rápida recuperação desses taxa logo após as aplicações dos inseticidas na comunidade de artrópodes do dossel da planta e que vivem sobre o solo. Entretanto o metamidofós após a segunda aplicação, não se observou à recuperação dos artrópodes até o final do experimento.This work aimed to study the impact of the insecticides chlorfenapyr and methamidophos on arthropods community of the bean crops with one and two applications. This experiment was carried out on commercial beans farming placed in Coimbra city, Minas Gerais state, Brazil during period from March until June, 2005. The treatments were established in factorial arrangement 2 x 2 (insecticides x number of applications) and control (no application). The Randomized Block Design was used with five replications. The arthropods phytophagous, predators, parasitoids and soil-dwelling on the plant canopy, soil surface and soil interior were evaluated. The arthropods community one day before application and 1, 8, 16, 24, 32, 40 and 48 days after the application of the treatments were sampled. The first application of the treatments was in 04/30/2005 and the second application after three weeks was done. The dosage used on treatments were 0,18 L a.i/ha and 0,45 L a.i/ha respectively. The arthropods associates to the plant canopy, were sampled by beating a white plastic tray in the apex of five bean plants. The arthropods community from the soil surface were sampled by pitfall traps. Also were sampled the population of arthropods of the soil interior, being these samples collected by removing of soil blocks with approximately 30 cm of depth and 10 cm of diameter and then submitted to the funnels of Berleze. The set of were submitted to the canonical variate analysis, Mahalanobis Distance statistic and multivariate analysis by repeated measures. The main insects associates to the canopy of the bean crops affected to clorfenapir and methamidophos are the phytophagous pests Cerotoma arcuata (Coleptera: Chrysomelidae) and Caliothrips phaseoli (Thysanoptera: Thripidae). Chlorfenapyr and methamidophos reduced the attack of C. arcuata and C. phaseoli to the bean plant up to 16 days after application. The main arthropods on the soil surface affected by clorfenapir and methamidophos are the soil-dwelling Isotoma sp., Emtomobryidae (Collembola) and Scheloribatidae (Acari). Chlorfenapyr and methamidophos reduced the populations of the soil-dwelling Isotoma sp., Emtomobryidae and Scheloribatidae on the soil surface. The main arthropods in the soil interior affected by clorfenapir and methamidophos are the soil-dwelling Hypogastrura sp. (Collembola), Galumnidae sp.1, Scheloribatidae (Acari) and the predator Hypoaspis sp. (Acari). Chlorfenapyr and methamidophos reduced the populations of the soil-dwelling Hypogastrura sp., Galumnidae sp.1 and Scheloribatidae and of the predator Hypoaspis sp. A fast recovery of this arthropods densities associated to the canopy plant and soil surface were observed after the insecticides applications. However after the second application of the methamidophos, was not observed to the recovery of the arthropods density until to the end of experiment.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Impact and determinants factors of pests attack in Phaseolus vulgaris

Os objetivos deste trabalho foram determinar os componentes críticos e os fatores chave de perdas na cultura do feijoeiro (Phaseolus vulgaris) e identificar os fatores que determinam o ataque de pragas a esta cultura. Para tanto, foram realizados cultivos de feijão nas épocas de primavera-verão, verão-outono e inverno- primavera em plantio direto e convencional nos anos agrícolas de 2005/2006 e 2006/2007 em Coimbra, MG. Durante os cultivos monitoraram-se as perdas nos componentes de produção do feijoeiro e as densidades de insetos praga, de inimigos naturais e de artrópodes detritívoros. Os componentes críticos de perdas foram as flores, vagens e óvulos. Os fatores chave de perdas foram o abortamento de flores e a má formação de vagens e óvulos. As perdas por abortamento de flores estiveram associadas ao ataque de Bemisia tabaci, Caliothrips phaseoli, Empoasca kraemeri e Frankliniella occidentalis. As perdas por má formação das vagens estiveram v ii associadas ao ataque B. tabaci, Cerotoma arcuatus e Diabrotica speciosa. Já as perdas por má formação de óvulos estiveram associadas ao ataque de Thrips tabaci. Os fatores determinantes do ataque de insetos praga ao feijoeiro foram as épocas de cultivo, sistemas de plantio, os elementos climáticos, o estádio fenológico das plantas e os inimigos naturais. Os elementos climáticos que influenciaram a intensidade de ataque de insetos praga ao feijoeiro foram as chuvas, a temperatura do ar e o fotoperíodo. Os inimigos naturais, cujas densidades estiveram associadas a intensidade de ataque de insetos praga ao feijoeiro, foram o parasitóide Encarsia sp., os predadores aranhas, Calosoma sp., formigas, Geocoris sp., Nabis sp. e Orius incidiosus. Os insetos detritívoros Collembolla influenciaram positivamente as populações de aranhas, formigas e Calosoma sp.The aim of this work were to determine the critical yield components and key factors of yield losses on common bean (Phaseolus vulgaris) and identify the factors that determine pest attack in this culture. The bean crops was cultivated in three growing seasons, the spring-summer, summer-autumn and winter-spring arranged in two planting system, no-tillage and conventional. The experiment was carried out at the experimental field of UFV located in Coimbra, MG over 2005/2006 and 2006/2007. Losses in yield components and densities of insect pests, natural enemies and detritivores were monitored during experimental period. The critical components of losses were flowers, pods and ovules. The key factors was incomplete formation of pods, flower and ovule abortion. The flower abortion was associated with the pest attacks of Bemisia tabaci, Caliothrips phaseoli, Empoasca kraemeri and Frankliniella occidentalis. The incomplete formation of pods was correlated with the pest densities of B. tabaci, Cerotoma arcuatus and Diabrotica speciosa. The period of highest attack of Thrips tabaci was associated with ovule abortion. The growing seasons, planting system, climatic elements, developmental stage of plants and natural enemies were determinants factors of pest attacks. The climatic elements rainfall, temperature and photoperiod influenced the seasonality and pests densities. The natural enemies, whose densities were associated with the densities of pests were Encarsia sp., spiders, Calosoma sp., Ants, Nabis sp. and Orius incidiosus. Collembolla positively influenced the populations of spiders, ants and Calosoma sp.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

ATRIBUTOS QUÍMICOS DE SUELO EN SISTEMAS DE USOS DIFERENTE, ITACOATIARA-AM, BRASIL

The use of soil to implement several management systems, such as agriculture, livestock farming and agroforestry activities contribute to the depletion of the soil and the forest, reducing or increasing the levels of soil chemical attributes, such as calcium, magnesium, potassium, and phosphorus and increase or decrease of active (pH) or exchangeable (Aluminum) acidity. This study aimed to evaluate macronutrients (calcium - Ca2+, magnesium - Mg2+, potassium - K+ and phosphorus - P), as well as aluminum - Al3+ and soil pH, under use systems: agroforestry system - SAFs and pasture - PA, comparing them to Primary Forest - PF, in the Rosenthal community in Itacoatiara-AM, Brazil. The soils were sampled in layers 0-10 cm and 10-20 cm deep, with samples composed of six single samples each. The distribution of nutrient contents (Ca2+, Mg2+, K+ , and P) considering the 0-10 and 10-20 cm layers showed little variation, except for phosphorus, which obtained the highest concentration in the prospected layers. The distribution of calcium, magnesium, and potassium nutrients in the sampled soil layers decreased with depth. However, an inverse pattern was observed in&nbsp;the elevation of active soil acidity and aluminium levels. Soil macronutrients showed medium to high concentrations, with forest and SAFs as systems that preserve good levels of fertility.El uso del suelo para implementar varios sistemas de gestión, como la agricultura, la ganadería y las actividades agroforestales contribuyen al agotamiento del suelo y del bosque, reduciendo o aumentando los niveles de los atributos químicos del suelo, como el calcio, el magnesio, el potasio y fósforo y aumento o disminución de la acidez activa (pH) o intercambiable (aluminio). El objetivo de este estudio fue evaluar los macronutrientes (calcio – Ca2+, magnesio – Mg2+, potasio – K+ y fósforo -, P), así como aluminio - Al3 + y pH del suelo, bajo sistemas de uso: sistema agroforestal - SAF y pastos - AP, comparándolos con el bosque primario - FP, en la comunidad Rosenthal en Itacoatiara, estado de Amazonas, Brasil. Los suelos se muestrearon en capas de 0-10 cm y 10-20 cm de profundidad, con muestras compuestas de seis muestras individuales cada una. La distribución del contenido de nutrientes (Ca2+, Mg2+, K+ y P) considerando las capas de 0-10 y 10-20 cm mostró poca variación, a excepción del fósforo, que obtuvo la concentración más alta en las capas prospectadas. La distribución de nutrientes de calcio, magnesio y potasio en las capas de suelo muestreadas disminuyó con la profundidad. Sin embargo, se observó un patrón inverso en la elevación de la acidez activa del suelo y los niveles de aluminio. Los macronutrientes del suelo tienen concentraciones de media a altas, con bosques y SAFs como sistemas que preservan buenos niveles de fertilidad