The Population Dynamics of an Australian Wolf Spider, Geolycosa godeffroyi (L. Koch 1865) (Araneae: Lycosidae)

Abstract

The life cycle and population structure of a burrow inhabiting wolf spider, G. godeffroyi, were examined in the Australian Capital Territory. The phenology of the life cycle was similar to that of the much smaller lycosid, Lycosa (Pardosa) lugubris, in Scotland [United Kingdom]. The females produced egg sacs in the summer and the young from these egg sacs over-wintered twice before maturity, about 15 instars later. These females died by the end of the 3rd winter. The burrowing habit of the spiders enabled the field determination of growth rates and of fecundity. The females produced an average of 1.8 cocoons, each containing an average of 338 eggs. About 7.8% of the eggs were estimated to die before the spiderling stage. Two periods of parasite induced mortality occurred, the 1st in the eggs, caused by scelionid Hymenoptera and the 2nd at size classes 11 and 12, caused by acrocerid dipterans. The population was estimated using a combination of quadrat counts and trapping over a period of 599 days. No spiders were removed permanently from the population. The population was divided into 15 size classes on the basis of the field-determined growth increment through the instars. A stationary age distribution was indicated in the population. The number of spiders passing through each size class was used to estimate the mortality of the spiders. The spiders had a fairly constant size class specific mortality of 34%. The general mortality schedule, although unexpected, was similar to those derived for other spiders and resulted in a Slobodkin Type III survivorship curve.