Growth and reproductive performance of edible grasshopper (Ruspolia differens) on different artificial diets

Ruspolia differens (Serville) (Orthoptera: Tettigoniidae), also known as the 'edible grasshopper', 'African edible bush-cricket', and 'nsenene', is regarded as one of the most promising edible insect species that can be used for food, particularly in Sub-Saharan Africa. However, there is insufficient information on suitable diets and their effects on survival, adult weight, fecundity, and developmental time of this species, which are preconditions for large-scale production. In this study, we experimentally evaluated the effects of 12 diets (wheat bran, rice seed head, finger millet seed head, soya bran, maize bran, fresh maize comb, millet flour, chicken feed egg booster, simsim cake, sorghum seed head, powdered groundnut, and germinated finger millet), that are known to be accepted by R. differens, on their growth and reproductive parameters. The survival rate, developmental time, and adult weight varied considerably on the various diets. The highest nymphal survival rates, shortest development times, and highest adult weights were recorded for both sexes when fed fresh maize comb and germinated finger millet diet. Lifetime fecundity of females fed on germinated finger millet also was, on average, more than twice higher compared to other diets. The present study demonstrated that relatively inexpensive and locally available germinated finger millet, fresh maize seed (at the silking stage on the comb), sorghum seedhead, and finger millet seedhead could be successfully used to rear and sustain populations of R. differens. Our findings contribute to the future design of an effective mass-rearing system for this economically important edible insect.