Fatores naturais que influenciam o ataque da mosca-branca em pimentão

Abstract

Resumo -Este trabalho objetivou determinar os efeitos da pluviosidade, da temperatura, da umidade relativa, dos predadores e parasitóides, da idade das plantas, dos compostos químicos foliares (cromatógrafo a gás acoplado a espectrômetro de massa -CG/EM), dos níveis de N e de K foliares sobre a intensidade do ataque de Bemisia tabaci biótipo B (Genn.) (Homoptera: Aleyrodidae) em pimentão (Capsicum annuum) var. Myr-10. As correntes totais de íons dos picos 28,178 min. (tempo de retenção) e 42,755 min. (tempo de retenção) correlacionaram-se positivamente com as ninfas e adultos da mosca-branca, respectivamente, e a corrente total de íons do pico 36,352 min. (tempo de retenção) correlacionou-se negativamente com ninfas deste inseto.Termos para indexação: Capsicum annuum, Bemisia tabaci, aleloquímico, nitrogênio, potássio. Natural factors influencing whitefly attack in sweet pepperAbstract -The objective of this work was to determine the effect of rainfall, temperature, relative humidity, predators, parasitoids, plant age, leaf chemical composition (GC/MS-gas chromatographic-mass spectrometric analysis of hexane extract) and levels of N and K on the intensity of attack by Bemisia tabaci biotype B (Genn.) (Homoptera: Aleyrodidae) on sweet pepper (Capsicum annuum) var. Myr-10. Out of the four peaks detected in the hexane extract on GC/MS analysis, areas of the peak eluting at 28.178 and 42.755 min correlated positively to the nymph and adult population, respectively. The peak eluting at 36.352 min correlated negatively with the nymph population.

Hosting Capacity of Horticultural Plants for Insect Pests in Brazil

“…Trichome density was determined on one expanded leaf from the apical, medium, and bottom canopy strata of 10 plants per crop (three leaves per plant), which were collected monthly in Guidoval and Viçosa, prepared on slides, and the trichome assessed (Leite et al, 2001a;2001b;2002a;2002b;2002c;2005a;2005b;2005c;2006a;2011). Leaf N and K levels were determined monthly in the laboratory from one expanded leaf of the upper parts of 10 plants per crop in both municipalities.…”

“…These leaves were dried and ground, K was determined with a flame photometer, and N analyzed by the Nessler method. Fully expanded apical leaves of 10 plants per crop were sampled monthly in both municipalities by gas chromatography/mass spectrometry (GC/MS) and hexane analyses were performed as in Leite et al (2001a;2001b;2002a;2002b;2002c;2005a;2005b;2005c;2006a, 2011. Morphological, nutritional, and chemical analyses were made with three independent monthly evaluations for each plantation.…”

“…Leaf N and K levels, allelochemicals, trichomes (type and density), natural enemy and pest populations, and weather effect on the main vegetables cultivated in Brazil, such as Abelmoschus esculentus (L.) Moench (Malvaceae), Brassica oleracea L. vars. acephala and capitata (Brassicaceae), Capsicum annuum L. (Solanaceae), Cucurbita moschata (Duchesne), C. maxima Duchesne and Cucumis sativus L. (Cucurbitaceae), Lycopersicon esculentum Mill., Solanum gilo Raddi and S. melongena L. (Solanaceae), and Phaseolus vulgaris L. (Fabaceae), have been studied (Leite et al, 2001a;2001b;2002a;2002b;2002c;2005a;2005b;2005c;2006a;2011) with the objective of comparing host capacity of those plants for insect pests, the relationships of these pests with their morphologic, nutritional, and chemical features, their natural enemies, and weather conditions in order to propose crop rotation and management procedures of neighboring plants to reduce insect damage.…”

Impact of insecticides on non-target arthropods in watermelon crop

“…One week after seed germination the arthropod populations sampling started and were weekly assessed throughout the crop cycle. To evaluate the number of arthropods found in the canopy of watermelon plants it was used a direct counting technique (LEITE et al, 2002), where all leaves of each plot were examined, without foliage disturbance, and the arthropods were counted and registered.…”