Effect of alternative rearing substrates and temperature on growth and development of the cricket Modicogryllus conspersus (Schaum)

Abstract

The increasing demand for animal protein in sub-Saharan Africa has led to insects being considered an alternative protein source for food and feed. In Uganda, chicken mash, containing fish meal as the protein source is commonly used to rear crickets. However, fishmeal is an expensive protein source that is also human food. This study therefore aimed at establishing an alternative preferred (consumed in the highest quantity) plant leaf diet for raising the Modicogryllus conspersus cricket, and the most suitable temperature for hatchability and egg development. The effect of (a) three diets (cassava leaves + cocoyam leaves + milk weed leaves; cassava leaves + pumpkin leaves + wandering Jew; and cassava leaves + lablab + Cinderella weed) on growth; and (b) incubation temperature (26, 28, 30, 32, and 34 °C) on egg hatchability and egg development time were studied. Cassava, pumpkin and milk weed leaves were the most ‘preferred’ of the tested plant leaves. Egg development time was longer at lower temperatures, ranging between 7-14 days across a 26-34 °C temperature range. The highest hatchability (95%) was observed at 28 °C, below and above which hatchability decreased. The maximum nymph weight (1.58 mg) at hatching was observed at 26 °C and decreased with increasing egg incubation temperature. The plant leaf diet containing leaves with highest protein content (pumpkin, wandering Jew and cassava) led to the highest growth and growth rate comparable to the control diet (broiler chick mash). Temperature had a significant effect on egg development time (P<0.001) and nymph weight at hatching (P<0.001) while the food type significantly influenced growth (P<0.001) and moulting time. The possibility of formulating a nutrient balanced, cost-effective, compound feed for cricket production should be investigated.