THE INFLUENCE OF PREY AVAILABILITY AND HABITAT ON ACTIVITY PATTERNS AND ABUNDANCE OF ARGIOPE-KEYSERLINGI (ARANEAE, ARANEIDAE)

I examined habitat relationships and prey abundance to determine which (if either) of these factors was more important in determining the local density patterns of the Saint Andrew's Cross spider, Argiope keyserlingi Karsch. Focusing on the relationship between a predator and its prey distribution presupposes that prey capture rate is crucial to the biology of the predator. I also studied the influence of prey capture on survival, reproduction and behavior of A. keyserlingi as a test of this assumption. Reproduction of females was influenced by food availability under laboratory conditions. Survival was higher among individual females provided with supplemental food in a field experiment. Adult female A. keyserlingi moved less frequently when they were provided with supplemental food. Features of vegetation were correlated with patterns of spatial distribution of this spider. There was a highly significant correlation between spider density on the study plots and the density of the understory shrubs that were favored as web sites. On a broad scale, seasonal phenology of activity in A. keyserlingi was positively correlated with potential prey abundance. At the scale of individual study plots, there is evidence that prey distribution was unpredictable in both time and space and that neither the activity patterns nor local density of Argiope keyserlingi tracked these fluctuations.