BIOLOGICALLY BASED TECHNIQUES FOR MANAGEMENT OF VEGETABLE PESTS
Location: Vegetable Research
Title: Field Evaluation of a Kudzu/Cottonseed Oil Formulation on the Persistence of the Beet Armyworm Nucleopolyhedrovirus
Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 23, 2012
Publication Date: July 23, 2012
Citation: Shapiro, M., El Salamouny, S., Jackson, D.M., Shepard, B. 2012. Field evaluation of a kudzu/cottonseed oil formulation on the persistence of the beet armyworm nucleopolyhedrovirus. Journal of Entomological Science. 47:197-207.
Interpretive Summary: The beet armyworm is a major pest of many vegetable and field crops in the United States. Crops are sprayed excessively with insecticides to control this pest and even then, control is sometimes unsatisfactory. Thus, there is a need for new biologically-based control tactics, such as insect viruses, to combat beet armyworms. Naturally occurring insect viruses are quite effective against beet armyworms; however, commercial virus formulations are quickly deactivated by ultraviolet light from the sun. We found that a formulation of a kudzu extract in cottonseed oil was effective in protecting an insect virus from degradation by ultraviolet light in a field experiment. This new control method is of interest to private companies developing biocontrol measures to use against pests like the beet armyworm.
A plant extract (kudzu) was tested as a UV protectant for SeMNPV, with and without the addition of an oil/emulsifier (cottonseed oil/lecithin) formulation. Aqueous and oil emulsion formulations of the beet armyworm, Spodoptera exigua (Hübner), nucleopolyhedrovirus SeMNPV were applied to collards and residual virus activity was determined for 7 days. Sunlight exposure of SeMNPV resulted in an activity loss of 42%, 85%, and 95% at days 2, 4, and 7, respectively. The addition of the oil/emulsifier to SeMNPV did not provide UV protection. At days 2, 4, and 7, activity losses were 67%, 84%, and 92%, respectively. While the addition of kudzu (5%) to SeMNPV provided significant UV protection during the sunlight exposure period, activity losses of 17%, 62%, and 76% occurred at days 2, 4, and 7, respectively. The greatest UV protection for SeMNPV was achieved when cottonseed oil/lecithin were used in conjunction with kudzu. In this formulation, activity losses were 2%, 40%, and 55% at days 2, 4, and 7, respectively. Although, the mode of action is unknown at this time, the addition of cottonseed oil to kudzu resulted in an increase of both UVB (280-320 nm) and UVA (320-400 nm) absorbance.