ARS | Publication request: Evaluating spray adjuvants to extend residual activity of microbiol pesticides`

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: December 9, 2007
Publication Date: N/A

Technical Abstract: Based on requests to improve the residual efficacy of baculovirus applications, a commercial adjuvant (Nu-Film 17(R) and an experimental lignin adjuvant were evaluated for resistance to environmental degradation. Nu-Film is a commercial product derived from pine resin; and lignin is a by-product of the paper industry, both with claims of resistance to wash-off and degradation by sunlight. As a model system, unformulated and a lignin encapsulated formulation (known to protect from sunlight degradation with no rainfastness) of the baculovirus, (Anagrapha falcifera MNPV), were used as the active agents. In the laboratory, treatments were applied to potted cotton plants and exposed to simulated rain (5 cm) using a spray chamber. Efficacy was based on mortality of Trichoplusia ni larvae fed treated leaf tissue. When adding Nu-Film and lignin adjuvant as tank mixes with unformulated and encapsulated baculovirus, Nu-Film improved resistance to wash-off, although the lignin adjuvant was less effective. When treatments were exposed to simulated (xenon) sunlight, treatments with the lignin adjuvant maintained some residual activity, but treatments with Nu-Film did not. When applied to field-grown cabbage and evaluated for efficacy 2, 6, 26, and 50 hours after application, treatments with lignin (encapsulated formulation or with adjuvant) provided significantly greater mortality than the control through the 26-h evaluation. Unformulated virus treatments (with and without Nu-Film) were not significantly different from the control at the 6-hour evaluation. These data support claims that environmental degradation of microbial pesticides may be addressed by the careful selection of adjuvants.