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Title: NUCLEAR POLYHEDROSIS VIRUS PLUS AN EHANCER AS AN ARBORIST TREATMENT AGAINSTGYPSY MOTH (LEPIDOPTERA: LYMANTRIIDAE)

Author
item Webb, Ralph
item DILL, N - DELAWARE STATE UNIV
item MCLAUGHLIN, J - DELAWARE STATE UNIV
item KERSHAW, L - DELAWARE STATE UNIV
item PODGWAITE, J - USDA FOREST SERVICE
item Cook, Stephen
item Thorpe, Kevin
item FARRAR, R - UNIV MARYLAND
item Ridgway, Richard
item Fuester, Roger

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Blankophor BBH, a stilbene disulfonic acid derivative, had previously been shown to enhance the performance of Gypchek, the USDA Forest Service's registered formulation of the gypsy moth nuclear polyhedrosis virus (NPV) in laboratory and field bioassays. However, the amount of Blankophor needed to give control in the field had not been defined, and the combination of NPV + Blankophor BBH had not yet been demonstrated to give foliage protection or population suppression in a practical field test. Previous work indicated that the combination of NPV + Blankophor BBH would be useful as an arborist treatment using hydraulic spray equipment from the ground. Finally, the American Cyanamid Co. had a new formulation of Gypchek that it wished to evaluate under field conditions. Thus various combinations of Blankophor BBH and the American Cyanamid formulation of Gypchek were applied in a replicated experiment to individual trees in a gypsy moth infested woodlot. The experimental formulation proved substandard when used alone, but the addition of Blankophor BBH provided considerable enhancement, resulting in significant defoliation protection and population reduction. The minimum amount of Blankophor BBH needed to achieve enhancement was determined. In this study, the addition of Blankophor BBH compensated for an unexpected formulation deficiency, demonstrating that the use of an enhancing adjuvant can reduce the variability often seen with biopesticides, in this case resulting in a product that will give arborists a more reliable control of gypsy moths on high-value shade trees.

Technical Abstract: Doses of a commercial candidate formulation of gypsy moth nuclear polyhedrosis virus (LdMNPV) were applied with and without several concentrations of an enhancing adjuvant, Blankophor BBH, by an arborist to individual trees against natural gypsy moth populations. Amounts of Blankophor BBH adhering to foliage after application were measured at 1322, 227, and 37ug/g dry weight of leaf for the 0.5, 0.1, and 0.02% treatments, respectively. The highest dose of the candidate formulation used without the adjuvant failed to significantly increase first wave LdMNPV mortality above background levels, to reduce late season larval populations in the treated trees, or to provide any obvious foliage protection. However, when Blankophor BBH was added at a concentration of either 0.5% or 0.1% (wt/vol) to the formulation, levels of first wave LdMNPV were significantly increased, late-season larval populations in treated trees were significantly reduced, and significant foliage protection was achieved. Enhancement ceased to be significant when the concentration of Blankophor BBH fell to 0.02%.