Performance of the wheat armyworm, Pseudaletia sequax Franclemont, on natural and artificial diets

Armyworms in the genus Pseudaletia Franclemont are important pests of cereal crops worldwide. The development of pest management strategies is largely dependent on studies involving the relationship among the pest, its host plants and natural enemies, as well as its susceptibility to chemical and biological control strategies. Part of these studies requires rearing the species of interest under laboratory conditions, which can be greatly facilitated by the use of artificial diets. In the present study, the effects of three artificial diets on development, survival, reproduction and demographic parameters of P. sequax were compared to a natural host plant, Pennisetum clandestinum. A diet based on pinto beans, wheat germ and torula yeast provided the best results in comparison to those obtained with the host plant. The most important life history parameters used in the evaluation of the nutritional quality of the diets were fecundity, egg viability and pupae deformities. The intrinsic rate of increase and the net reproductive rate were higher when individuals were fed on the artificial diet if compared to the host plant, indicating the suitability of the tested diet for the rearing of P. sequax. This artificial diet has been used successfully for the rearing of P. sequax without any fitness effect for over 18 consecutive generations.