Growth and nutritional physiology of Spodoptera frugiperda (Lepidoptera: Noctuidae) fed on Meliaceae fractions.
The effect of hexane, dichloromethane, ethyl acetate and hydroalcoholic fractions obtained from ethanolic extract of Trichilia pallida, T. pallens and Toona ciliata on growth and nutritional physiology of Spodoptera frugiperda was evaluated. First instar larvae were fed on a diet treated with fractions for ten days. The most active fractions were applied on the diet and offered to larvae until the pupal stage to verify effects on growth and survival. To calcúlate the nutritional indices, fractions were incorporated into the diet offered to fourth instar larvae for four days. The dichloromethane fraction of T. pallens stems affected growth and survival of S. frugiperda larvae, and fractions of T. pallida leaves and stems, and of To. ciliata leaves and fruits affected larval growth. Nutritional analysis indicated that the fraction of To. ciliata leaves acts mainly as a phagodeterrent, while dichlorometane fractions of T. pallida stems and leaves, To. ciliata fruits and T. pallens stems cause toxic effects after ingestion, reducing the efficiency of food conversion and increasing the metabolic cost to the larvae.