Qualidade nutricional e metabólitos de folhas e legumes de soja: preferência alimentar e desempenho biológico de Helicoverpa armigera

Abstract

Helicoverpa armigera (Lepidoptera: Noctuidae: Heliothinae) is one of the most devasting pests in the world. In the soybean crop, H. armigera can be an initial pest attacking the cotyledons, sprouts, seedling leaves, as well as later consume vegetables and grains. As herbivorous and polyphagous species, their requirements as food preferences as in terms of species like organs of some plants require more comprehension and investigation. The objective of this study was to examine the influence of soybeans organs in the food preferences, in the quantitative nutrition and in the biological performance of H. armigera. Experiments were carried out in acclimatized chamber (25 ± 2 ºC, relative humidity 60±10% and photoperiod of 12 hours), in the Entomology Laboratory, of the Agronomy and Veterinary Medicine Faculty, of the University of Passo Fundo, in Passo Fundo. It was found that the bromatological and secondary composition varies with the organs of the soybean plant. In general, the protein concentration it was higher in the leaves in growth and grains fully developed. The matter of phenolic acids was bigger in leaves. The isoflavones in the aglycones glycitein forms and genistein were found only in leaves. The isoflavones in the daidzin glycitein forms and genistein and in the forms malonic mal - daidzin, mal-glycytin presented variations in concentration among the vegetative and reproductive organs. It could be observed that the H. armigera larva in the first instar prefer expanding leaves instead of new and old leaves, when it were offered new, old leaves, vegetables well developed with grains in the beginning of the development of the grain and vegetables well developed with completely developed grains. Larvae of fourth and fifth instar did not present a defined preference among vegetative or reproductive soybean structures. The best nutritional indexes were reached when fourth, fifth and sixth instar H. armigera larvae fed on new plus old leaves blended. The best biological performance of H. armigera was observed when both vegetative and reproductive structures were simultaneously offered in the larval stage.