Abstract

Laboratory experiments were conducted with the surface grasshopper, Chrotogonus trachypterus, to evaluate the effect of food plants on its growth and development. As indicated by a growth index for hoppers, in descending order of effectiveness were; lucerne, wheat, barley, mixed food, oats, chickpea, bermuda grass, spinach, nut grass and pigweed. On lucerne, hoppers took the shortest period (17.40 days) to develop into a fledglings, while on pigweed, development took the longest (25.25 days). Hoppers had 100 per cent survival on lucerne, wheat and barley; survival was lowest when reared on pigweed: 82.50, 72.50 and 67.50 per cent for hopper survival of the IV th , V th and VI th instars respectively). However, irrespective of the food plant, the sixth instar hoppers developed into fledglings, showing a cent (emergence the 100 per cent adult) per cent survival. The effect of different food plants on food utilization indices evinced that efficiency of conversion of ingested food (ECI) was high when the hoppers were reared either on wheat (36.53%) or mixed food (35.20%), but pigweed (16.21%) followed by nut grass (19.28) had lowest ECI. The approximate digestibility (AD) was high when the hoppers were reared on lucerne (45.20%) and significantly low in gram (38.39%). The efficacy of conversion of digested food (ECD) into body substances was significantly the maximum for hoppers raised on wheat (89.50%) and was significantly the lowest for hoppers on pigweed (42.14%).

Keywords: Surface grasshopper, Chrotogonus trachypterus, food plants, growth and development.