EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 94 (4): 453-459, 1997

Experiments on the foraging behaviour of the hunting spider Pisaura mirabilis (Araneae: Pisauridae): Utilization of single prey items

LANG A., KLARENBERG A.J.

N/A

Feeding experiments with female Pisaura mirabilis were carried out in the laboratory. Several species of Diptera, ranging in their size from small fruitflies to large blowflies, were offered. Each spider received a single fly, and then the absolute as well as the relative amount of prey consumption was recorded. Absolute consumption was measured as the amount of a fly consumed by the spiders. Relative consumption, i.e. the utilization rate, was calculated as amount of fly consumed by the spiders divided by the initial mass of the fly. Absolute consumption was positively correlated with the mass of the fly, i.e. the larger the fly the more the spider consumed. No satiation effects were observed. P. mirabilis ingested on average 75% of the prey item, but was able to extract up to 95%. The relative consumption showed no relationship with mass of fly, i.e. the prey size did not influence the utilization rate. Also, neither body size nor age of spiders affected absolute or relative consumption. Furthermore, the fly remnants discarded by the spiders, and uneaten control flies were analysed for their C and N contents. Fly remnants showed a significantly higher C and N content, whereas their C/N ratio was lower. The results show that in the single-prey situation P. mirabilis increases absolute biomass intake with increasing amount of prey available. However, low values and a high variance of the utilization rate indicated that it is not only prey quantity which may be essential for the spiders. We therefore conclude that in future studies the nutritional qualities of prey should be considered more closely.

Keywords: Pisauridae, Pisaura mirabilis, spider, predator, feeding behaviour, prey size, partial consumption

Accepted: December 18, 1996; Published: October 1, 1997  Show citation