Effects of Tebufenozide (Rh-5992) for Gypsy Moth (Lepidoptera: Lymantriidae) Suppression on Nontarget Canopy Arthropods

Abstract

In 1994 and 1995 we evaluated the impact of tebufenozide (RH-5992) application for experimental gypsy moth, Lymantria dispar (L.), suppression on nontarget canopy arthropods in mixed oak plots in Columbiana County, Ohio. Tebufenozide is an ecdysone agonist that has been shown to be highly efficacious against lepidopterous pests. Foliage samples were taken by pole pruners from the forest canopy in 9 plots. Pretreatment sampling in mid-May 1994 showed similar richness and abundance of arthropods in all treatments. Tebufenozide was applied to 6 of the 9 plots 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 used to analyze treatment differences for arthropod family richness and abundance and macrolepidoptera larval richness and abundance. Target gypsy moth larvae were reduced in treated plots, but not significantly so. No differences were seen among treatments for nontarget arthropod richness and abundance excluding macrolepidoptera. Macrolepidoptera richness excluding gypsy moth was significantly higher in control plots than tebufenozide high dose plots for the early sample periods, but not the late sample periods, of both years. For macrolepidoptera abundance, numbers were significantly higher in control versus high dose plots for the early period in 1994 and control versus high and low dose plots for the late period in 1994 and early period in 1995. No differences were seen in abundance for the late sampling period of 1995. Among the most abundant caterpillar species showing treatment effects were members of the families Noctuidae, Ceometridae, Notodontidae, and Lycaenidae. If tebufenozide is applied in a way that is more effective for gypsy moth control, effects on nontarget arthropods may be greater also.