Ecophysiological studies on the utilization of food in the paddy field grasshopper Oxya velox

Abstract

The paddy field grasshopper Oxya velox fed ad libitum on fresh leaves of the grass Digitaria is reared in the laboratory from hatching to death. A female grows to a maximum size of 218±40 mg wet weight on the 240th day, while a male attains a maximum of 132±17 mg weight on the 149th day. Total food intake amounts to 1341 and 557 mg dry grass for a single female and a single male respectively. Feeding rate averages 167 mg wet grass/g wet weight of grasshopper/day. Assimilation efficiency amounts to 27% in both sexes. Unassimilable faeces amount to 1 g for a female and 0.4 g for a male. About 32% of the assimilated food is used for total growth in either sex. Exuviae amount to 4% and 5% of the assimilated food in the female and the male respectively. The average amount of (dry) body substance used for reproduction is 82 mg in fertilized and 10 mg in the parthenogenetic female. A fertilized female consumes more food than a virgin. A female produces 3.5, egg pods on a average, each containing about 4 eggs. About 14% of the assimilated food energy is required for reproduction by a female and 3% by a male. At death the male contains 26% and the female 12% of the assimilated food energy respectively. The energy budget of O. velox is discussed in comparisn with that of Bombyx mori, a lepidopteran.