Effects of gypsy moth suppression tactics on litter- and ground-dwelling arthropods in the central hardwood forests of the Cumberland Plateau

This study assessed the impact of three gypsy moth suppression tactics on non-target arthropod abundance in the mixed mesophytic forests of the Cumberland Plateau prior to gypsy moth establishment in the region. Abundance of litter- and ground-dwelling arthropods was assessed in areas receiving applications of reduced rates of diflubenzuron and Bacillus thuringiensis var. kurstaki, simulating gypsy moth suppression programs, and compared to untreated controls, simulating a hands-off management approach. Study plots in southeastern Kentucky were aerially sprayed one time in May of 1997; control plots received no insecticide. In 1997 and 1998 we sampled arthropods in strata ranging from ground level to the forest canopy. Here we report the effects of the treatments on ground- and litter-dwelling arthropods. Gypsy moth suppression tactics negatively impacted litter-dwelling mites and thrips, with populations in diflubenzuron-treated plots significantly lower relative to untreated controls in the year of application. The abundance of predatory spiders and rove beetles was also affected by treatment applications. Treatment effects were evident 1 year post-application for populations of thrips, spiders, bark/ambrosia beetles, millipedes, and centipedes. The highly clustered distribution patterns of many arthropods, as well as variable weather patterns, may have confounded the effects of our treatments. Since the gypsy moth is not yet established in the region, results of this study will be useful to land owners and natural resource managers to enable them to make well-informed decisions regarding future gypsy moth infestations.