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Chrysoperla externa (Neuroptera: Chrysopidae) and Utetheisa ornatrix (Lepidoptera: Arctiidae) on organically grown Crotalaria juncea (Fabaceae) Chrysoperla externa (Neuroptera: Chrysopidae) e Utetheisa ornatrix (Lepidoptera: Arctiidae) sobre Crotalaria juncea (Fabaceae) cultivada organicamente

DOI: 10.1590/s0100-83582012000300001

Keywords: controle biológico , lagarta-das-crotalárias , crisopídeo , aduba o verde , Manejo Integrado de Pragas , biological control , crotalaria month , green lacewing , green manure , Integrated Pest Management

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Abstract:

Chrysoperla externa (Neuroptera: Chrysopidae) larvae can avoid foraging on plants of Crotalaria juncea (Fabaceae) after the issuance of floral buds, when the prey of Utetheisa ornatrix (Lepidoptera: Arctiidae) incorporate toxic pyrrolizidine alkaloids from this plant. This reduces the predation and favors increasing the number of adults and eggs of this defoliator on crops of this plant. The aim of the present paper was to evaluate some biological and ecological aspects of C. externa and U. ornatrix on the organic crop of C. juncea in the EMBRAPA Maize and Sorghum in Sete Lagoas, Minas Gerais State, Brazil. Chrysoperla externa and U. ornatrix were more abundant in the vegetative and flowering stages of C. juncea, respectively, with caterpillars of this defoliator feeding on leaves and seeds of this plant. The duration of the stages/instars, survival, lifetime fecundity, and oviposition showed that the branches of C. juncea are a suitable food for U. ornatrix. The abundance of adults and larvae of C. externa was lower in the flowering and pods stages of C. juncea, respectively, when the postures of U. ornatrix are present, probably due to the toxicity of the eggs of this prey to this predator. During these stages, C. externa may be reared with alternative hosts, and when the crops of C. juncea are scarce, an artificial diet should be used for rearing this defoliator in the laboratory for biological research and the development of biological control tactics. Larvas de Chrysoperla externa (Neuroptera: Chrysopidae) podem evitar o forrageamento sobre plantas de Crotalaria juncea (Fabaceae) após a emiss o de bot es florais, quando presas de Utetheisa ornatrix (Lepidoptera: Arctiidae) incorporam alcalóides pirrolizidínicos tóxicos dessa planta. Isso reduz a preda o e favorece o aumento do número de adultos e ovos desse desfolhador sobre cultivos dessa planta. O objetivo deste trabalho foi avaliar alguns aspectos biológicos e ecológicos de C. externa e U. ornatrix sobre cultivo organico de C. juncea na EMBRAPA Milho e Sorgo, em Sete Lagoas, Minas Gerais, Brasil. Chrysoperla externa e U. ornatrix foram mais abundantes nos estádios vegetativo e de florescimento de C. juncea, respectivamente, com lagartas desse desfolhador se alimentando sobre folhas e sementes dessa planta. A dura o dos estágios/estádios, sobrevivência, fecundidade de vida e oviposi o mostraram que ramos de C. juncea é um alimento adequado para U. ornatrix. A abundancia de adultos e larvas de C. externa foi menor nas fases de flora o e vagens de C. juncea, respectivamente, quando posturas de

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