Effects of pvriproxyfen spray, powder, and oral bait treatments on the relative abundance of nontarget arthropods of black-tailed prairie dog (Rodentia : Sciuridae) towns

Separate black-tailed prairie dog, Cynomys ludovicianus (Ord), towns on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, were treated wi th technical pyriproxyfen (Nylar) spray, powder, and oral bait. The treatme nts were applied to reduce relative abundance of the plague vector Oropsyll a hirsuta (Baker). Because pyriproxyfen is a juvenile hormone analog, we we re also concerned with the effects of the treatments on nontarget arthropod s, which is the focus of this study. Pitfall traps and sweep net sampling w ere used to measure relative abundance of arthropod populations pre- and po sttreatment. Nontarget arthropod sampling produced a large number of statis tical comparisons that indicated significant declines (P < 0.05) in relativ e arthropod abundance. Many of the significant declines were probably becau se of natural fluctuations in arthropod populations rather than treatment e ffects. Because arthropod populations appeared to fluctuate randomly, we on ly made inferences about highly significant (P<0.001) declines. In doing so l we hoped to abate some of the confusion created by the natural fluctuatio n in arthropod abundance and increase our chance of correctly attributing a population reduction to a treatment effect. Only Homoptera at the pyriprox yfen powder site exhibited highly significant reductions that appeared to b e attributed to the treatments. Pyriproxyfen spray treatments did not signi ficantly reduce relative arthropod abundance.