Effect of three larval diets on the development of the armyworm, Spodoptera latifascia Walker, 1856 (Noctuidae, Lepidoptera)

Some biological effects of feeding larvae of the armyworm Spodoptera latifascia with leaves of three plant species (cotton, soybean and lettuce) have been studied. Some indicative measurements were utilized to determine the host suitability of these three plant species. Cotton leaves (Gossypium hirsutum) were found to be better than soybean (Glycine max) for the development and growth of this insect. Lettuce leaves (Lactuca sativa) were incapable of sustaining this insect. Moreover, the stress of the latter diet was associated with a latent microbial disease, a mixed infection caused by Vairimorpha sp. and a nuclear polyhedrosis virus (NPV). Cotton leaves can be recommended as a suitable diet for mass rearing of this insect species. Due to recent outbreks of S. latifascia observed in the States of São Paulo, Santa Catarina and Paraná and because of the frequent applications of wide spectrum chemical insecticides, it can be expected that this insect will soon become one of the important pests threatening cotton and other economic plantations in Brazil