Predation by cosmopolitan spiders upon the medically significant pest species Loxosceles reclusa (Araneae: Sicariidae): limited possibilities for biological control.
Interspecific predation of three cosmopolitan house spiders, Achearanea tepidariorum (Kock 1841) (Theridiidae), Steotoda triangulosa (Walckenaer 1802) (Theridiidae), and Pholcus phalangioides (Doleschall 1859) (Pholcidae), and the medically significant brown recluse spider, Loxosceles reclusa (Sicariidae) were examined to evaluate transitive predatory relationships and to explore the potential use of cosmopolitan spiders as effective biological control agents on L. reclusa. Fifty houses from northeastern Kansas were visually inspected from May to December 2002 for cosmopolitan spiders and L. reclusa. In 25 houses, insect monitoring traps were used to sample spider diversity and abundance. The remaining 25 houses were monitored to examine intraguild predation and spider behavior. If cosmopolitan spiders have the ability to regulate or decrease L. reclusa populations, houses with large cosmopolitan spider populations are expected to have significantly fewer L. reclusa than houses without cosmopolitan spiders. Predation and/or evidence of predation by all three cosmopolitan spiders on L. reclusa was detected in 68% of houses. Spearman's rank correlation analysis showed overall positive relationships between population densities of cosmopolitan spiders and L. reclusa. When evaluated independently, the presence of both A. tepidariorum and S. triangulosa showed negative, yet nonsignificant, relationships with L. reclusa densities, whereas P. phalangioides showed a positive nonsignificant relationship. Although statistical tests showed a decrease in L. reclusa population densities with increased population densities of two cosmopolitan species, alluding to a potential beneficial interaction for biological control, observations of spider behavior, web positioning (niche partitioning), and predation showed little possibility of biological control capabilities.
Sandidge
Jamél
J
Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA.
D000818:Animals; D001522:Behavior, Animal; D010572:Pest Control, Biological; D011156:Population Density; D011235:Predatory Behavior; D013112:Spiders / Q000502:physiology*