A defined artificial diet for the larvae of Manduca sexta

The tobacco hornworm, Manduca sexta (Johannson) (Lepidoptera: Sphingidae), has become an important and widely used laboratory animal. It was first cultured on the foliage of its host plants (Waldbauer et al., 1964; Hoffman et al., 1966), but is now typically cultured on undefined artificial diets that contain such complex substances as wheat germ and yeast (Yamamoto, 1969; Bell & Joachim, 1976; Baumhover, 1985). A diet that includes such ingredients, each containing the gamut of nutrients, is useful for maintaining cultures but is not appropriate for most nutritional studies, including studies of dietary self-selection. We here describe a defined diet (containing no ingredients that are chemically less well characterized than linseed oil) that is suitable for studies of self-selection and other aspects of nutrition. To the best of our knowledge, no defined diet for M. sexta has been previously published. The defined diet (Table 1), a modification of Vanderzandt's (1968) diet, is prepared as follows: The group A ingredients, water and agar, are poured into a flask that is capped with aluminum foil, autoclaved for 20 min, cooled for 10 min, poured into a blender with the group B ingredients, and then thoroughly mixed. When the mixture cools below 60 ~ the group C ingredients are added, the diet is blended for 5 min and then poured into plastic molds. After the diet has cooled to room temperature, each mold is wrapped with aluminum foil and stored at 4 ~ until used. Table 1. Composition of defined diet for rearing Manduca sexta larvae