EFFECT OF DIFLUBENZURON ON NONTARGET CANOPY ARTHROPODS IN CLOSED, DECIDUOUS WATERSHEDS IN A CENTRAL APPALACHIAN FOREST

In a 6-yr study (1989-1994), we evaluated the impact of diflubenzuron on the diversity and abundance of arthropods in the Fernow Experimenta l Forest in West Virginia. Diflubenzuron is commonly used in gypsy mot h, Lymantria dispar (L.), suppression programs in eastern forests. For the evaluation, foliage samples were taken with pole pruners from the forest canopy an 4 small deciduous watersheds: burlap bands were used on tree trunks on all watersheds. Pretreatment sampling was conducted mid-May through mid-August 1989 through 1991, Diflubenzuron was appli ed by helicopter to 2 watersheds; the 2 remaining watersheds served as control plots. Analysis of variance was used to compare treatment mea ns. Gypsy moth larvae were reduced on the treated watersheds, particul arly during the treatment and posttreatment year, Possible nontarget a rthropod effects were researched for 27 mo after treatment. A signific ant reduction in the diversity of arthropod families was observed bene ath burlap bands in treated plots. However, no reduction was observed for arthropod abundance. The diversity and abundance of macrolepidopte ra larvae also were reduced by diflubenzuron during the treatment lear On foliage, overall arthropod family diversity and abundance, and num bers of macrolepidoptera and beetles were reduced significantly in tre ated watersheds. No significant reduction was seen for macrolepidopter a larvae diversity on foliage. At 27 mo after treatment, total arthrop od abundance and macrolepidoptera abundance on foliage remained signif icantly reduced. Declines were seen on treated watersheds far Carabida e, Gryllacrididae, Psocoptera, Phlaeothripidae, and some sapfeeders bu t were nonsignificant.