Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/1998
Publication Date: N/A
Citation: Interpretive Summary: Gypchek, the nuclear polyhedrosis virus product registered by USDA Forest Service against the gypsy moth, is specific to the gypsy moth and thus is the material of choice for gypsy moth control where a high degree of target specificity is desired. Until recently, Gypchek was applied in a standard tank mix consisting of a lignosulfate powder, molasses, a sticker, Gypchek, and water. While efficacious, the tank mix was awkward to use. A new, ready to use, formulation has been developed that has several properties that are superior to the standard tank mix, including enhanced protection of the virus from harmful UV radiation (sunlight), improved anti-evaporative properties, and ease of mixing and spraying. The present paper documents the fact that the new formulation provides equal or better efficacy than the tank mix, when applied under field conditions, as measured by virus kill and foliage protection. The paper also reports that the new formulation can be applied once rather than the previously recommended two applications, and in a reduced volume of water, without significant loss of efficacy in either case, which will lead to improved operational efficiency and reduced costs.
Technical Abstract: A ready-to-use spray adjuvant (Carrier 038) has been developed that is superior to the standard Forest Service lignosulfonate-molasses formulation in ease of mixing and spraying and also provides enhanced protection of the virus from sunlight. In an aerial application trial in Virginia we evaluated: Control (no spray, STD (double application of the Forest Service standard formulation at 5 X 1011 viral inclusion bodies [OB] in 19 liters/ha), 038 (double application of 5 X 1011 OB in 9.5 liters/ha), 038/2 (double application of 5 X 1011 OB in 4.8 liters/ha), and 038/1AP (single application of 1 X 1012 OB in 9.5 liters/ha). Treatment evaluations showed (=0.05) no significant differences in NPV mortality in larvae collected from either the STD treatment plots (80%) the 038 treatment plots (86%), or the 038/2 treatment plots (83%). However, the single application treatment (68%) was significantly lower than the other 038 treatments. All Gypchek treatments were significantly different than the control (19%). Defoliation differences (18-23%) between Gypchek treatments were not significant, but all were significantly lower than the control (37%). Similarly, numbers of surviving larvae were not significantly different between Gypchek treatments but were significantly different from the control. These results indicate that a Carrier 038 formulation of Gypchek applied twice at either 9.5 liters/ha or 4.8 liters/ha provides a level of efficacy comparable to the standard formulation applied twice at 19 liters/ha. Thus Carrier 038 is an attractive alternative to the latter for use in gypsy moth management programs.