Population regulation and prey community impact of <i>Geolycosa rafaelana</i> (Chamberlin) (Araneae: Lycosidae)

TitlePopulation regulation and prey community impact of Geolycosa rafaelana (Chamberlin) (Araneae: Lycosidae)
Publication TypeThesis
Year of Publication1984
AuthorsConley MR
Number of Pages68
Date Published1984
UniversityNew Mexico State University
CityLas Cruces, New Mexico
Thesis TypePh.D. Dissertationpp
Call Number00035
Keywordsdissertation, dissertations, Geolycosa, SEE <SPIDER>, Geolycosa,food habits, spider, Geolycosa, spider, parasitism, spider, predation, spider, wolf spider,Geolycosa, theses, thesis
AbstractThe 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. Population survival rates were higher for nonreproducing adult females in one population with reduced density, and lower for nonreproducing females in one population with food supplementation. A pompilid wasp, Paracyphononyx funereus, was discovered as a parasitoid of G. rafaelana, producing 50-65% mortality in adult females during winter, and 4-5% mortality in adult females during summer. Predation (as indicated by absence of adult remains in burrow) was significantly higher in populations receiving food supplementation and accounted for 0-100% of the mortality in individual populations. The role of G. rafaelana as a structuring force in the arthropod community was examined with an experiment employing an additional eight 400 sq m plots. Adult spiders on these plots were censused during March 1983, and subsequently removed from four of the plots during June 1983. Spiders on the remaining four plots were left undisturbed and were monitored monthly for activity, during June - October 1983. Nocturnal ground-dwelling arthropods were sampled weekly, 29 June - 10 October, using pitfall traps on each plot. Ant colonies were censused on the eight plots in August 1983. Analyses of similarity in species composition, species diversity, and mean biomass indicated no consistent difference in arthropod community structure between control and removal plots. Additional comparisons for nine species of ants occurring on the plots disclosed no difference in colony densities on control versus removal plots.