LABORATORY EVALUATION OF SELECTED SPRAY ADJUVANTS AS ULTRAVIOLET LIGHT PROTECTANTS FOR THE NUCLEAR POLYHEDROSIS VIRUS OF THE CELERY LOOPER (LEPIDOPTERA:NOCTUIDAE)

Authors: Farrar, Robert; RIDGWAY, RICHARD - RETIRED

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Commercial agriculture continues to rely heavily on chemical pesticides for insect pest control, despite problems with environmental contamination, worker exposure, and residues in agricultural products. Nuclear polyhedrosis viruses (NPVs) are naturally occurring viruses, each of which infects only a certain few species of insects or other arthropods. They are promising alternatives to pesticides for many important pests, especially caterpillars. They are usually sprayed onto crop plants, where insects eat them, become infected, and die. However, NPVs are quickly destroyed by the ultraviolet light (UV) in sunlight while on the surface of a plant, and so are often gone before the insects eat them. We tested in the laboratory materials that can be added to virus sprays to protect the virus from UV. Several materials, including Lignosite AN (a lignin product), Blankophor BBH, (a fluorescent brightener) and Coax (a feeding stimulant) protected an NPV from damage by UV, though none gave complete protection. We expect our results to be useful to people looking for non-chemical controls for pests. A spray additive that protects NPVs from UV will help growers obtain better pest control. Better and more consistent results can be expected to lead to wider adoption of NPVs as pest management tools. This can, in turn, reduce the use of chemical pesticides and problems of contamination, worker exposure, and residues.

Technical Abstract: Four spray adjuvants were tested in the laboratory as ultraviolet light (UV) protectants for the nuclear polyhedrosis virus of the celery looper, Anagrapha falcifera (Kirby) (AfMNPV) against the beet armyworm, Spodoptera exigua (Hubner). Adjuvants tested included a sodium lignin sulfonate (Lignosite AN), two diaminostilbene disulfonic acid-derived fluorescent brighteners (Blankophor BBH and Blankophor HRS), and a nutrient-based feeding stimulant (Coax). Lignosite AN had activity as a UV protectant; Blankophor BBH, both as an enhancer and a UV protectant; Blankophor HRS, as an enhancer only; and Coax, as a UV protectant only. Lack of an effect of Coax as a feeding stimulant may be due to the design of the bioassay, in which larvae were confined on small pieces of foliage. The practical utility of some, if not all, of these materials may be limited by the cost of the amounts required to achieve the desired effects, however.