Predation versus resource limitation in survival of adult burrowing wolf spiders (Araneae: Lycosidae).

The influences of food supply and density on adult survival were examined in the burrowing wolf spider Geolycosa rafaelana (Lycosidae), using manipulations of spider populations on eight 400 sq m experimental plots. A total of 110 adult spiders were captured, weighed, marked, and returned to their burrows during April-May 1983. Treatments of (1) food supplementation, (2) density reduction, (3) food supplementation combined with density reduction, and (4) no manipulation (control) were applied to the eight populations, and adult survival and reproduction were monitored during May-October 1983. Survival rates were higher for nonreproducing adult female populations with reduced density, and lower for nonreproducing females in populations with food supplementation. A pompilid wasp, Paracyphononyx funereus, was documented as a parasitoid of G. rafaelana, producing 50%-65% mortality in adult females during winter, and 4-5% mortality in adult females during summer. The observed survival responses were correlated with variations in predation, while parasitism did not appear to be strongly density-dependent.