EFFECTS OF TEBUFENOZIDE (RH-5992) FOR GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) SUPPRESSION ON NONTARGET CANOPY ARTHROPODS

In 1994 and 1995 we evaluated the impact of tebufenozide (RH-5992) app lication for experimental gypsy moth, Lymantria dispar (L.), suppressi on on nontarget canopy arthropods in mixed oak plots in Columbiana Cou nty, Ohio. Tebufenozide is an ecdysone agonist that has been shown to be highly efficacious against lepidopterous pests. Foliage samples wer e taken by pole pruners from the forest canopy in 9 plots. Pretreatmen t sampling in mid-May 1994 showed similar richness and abundance of ar thropods in all treatments. Tebufenozide was applied to 6 of the 9 plo ts on 21 and 22 May 1994. Three plots were treated with a high dose, 3 with a low dose, and 3 were left as untreated control plots. Analysis of variance with least significant difference mean separation was use d to analyze treatment differences for arthropod family richness and a bundance and macrolepidoptera larval richness and abundance. Target gy psy moth larvae were reduced in treated plots, but not significantly s o. No differences were seen among treatments for nontarget arthropod r ichness and abundance excluding macrolepidoptera. Macrolepidoptera ric hness excluding gypsy moth was significantly higher in control plots t han tebufenozide high dose plots for the early sample periods, but not the late sample periods, of both years. For macrolepidoptera abundanc e, numbers were significantly higher in control versus high dose plots for the early period in 1994 and control versus high and low dose plo ts for the late period in 1994 and early period in 1995. No difference s were seen in abundance for the late sampling period of 1995. Among t he most abundant caterpillar species showing treatment effects were me mbers of the families Noctuidae, Geometridae, Notodontidae, and Lycaen idae. If tebufenozide is applied in a way that is more effective for g ypsy moth control, effects on nontarget arthropods may be greater also .