Variables Influencing Laboratory Energy Budgets of Geolycosa godeffroyi (Araneae)

Abstract

The assimilation efficiency of food energy in Geolycosa godeffroyi (L. Koch) was unaffected by a series of constant temperatures, by a cyclical temperature regime or by spider weight above the first three instars. Assimilation efficiency varied directly with the feeding rate but within the range of feeding rates of field spiders the expected variation was less than 1 %. Production had a caloric value consistent with assimilated food passing to fat storage. The characteristic relationship between weight and respiration was similar whether respiration was measured directly or indirectly through feeding experiments. Cyclical temperatures increased the respiration rate above the resting level and was cumulative with an increase in respiration resulting from feeding alone. More prey were killed under cycling temperatures than would be expected from the number killed at a series of constant temperatures. Feeding relationships were influenced by the number of prey presented at each feed and by behavioural interactions between the spider and the food species. Feeding ceased for a time before the moult, the period being directly related to the spider weight.