Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 27, 2010
Publication Date: January 19, 2011
Citation: Behle, R.W., Compton, D.L., Kenar, J.A., Shapiro Ilan, D.I. 2011. Improving formulations for biopesticides: Enhanced ultraviolet protection for beneficial microbes. Journal of ASTM International. 8(1):137-157. Interpretive Summary: Microbial insecticides have not been widely accepted by growers partly because of the rapid degradation of activity when exposed to sunlight. This manuscript describes the results of research on formulations that protect beneficial microbes from degradation by sunlight. Two technologies were evaluated: Soyscreen™ added to oil-based formulations protected viability of Beauveria bassiana conidia in laboratory experiments; and lignin formulated as an adjuvant formulation for water-based applications extended residual insecticidal activity of baculovirus applications to field crops. Protecting microbes from degradation by sunlight will improve pest control with these environmentally friendly pesticides and help reduce grower dependence on chemical pesticides.
Technical Abstract: As society pushes for environmentally friendly production practices in agriculture, control of insect pests of plants often focuses on developing microbial-based biopesticides. Specific bacteria, fungi, and viruses have the potential to provide effective control of pests when applied to plants using techniques similar to those used for chemical pesticide applications. Yet, these microbes all suffer from rapid degradation when exposed to sunlight, which drastically limits their field efficacy. One effective solution is to develop biopesticide formulations to protect the beneficial microbe from sunlight energy, specifically the Ultraviolet (UV) wavelengths. Technologies (ingredients and processes) continue to be developed that may provide UV protection in a variety of formulations. Soyscreen™ consists of feruloylated soy glycerides (FAG) specifically developed to absorb UV energy by covalently modifying soybean oil with ferulic acid (a ubiquitous plant component from lignin). Although originally designed for the cosmetic industry, FAG has potential to benefit oil-based formulations such as for hydrophobic fungal conidia of Beauveria bassiana or Metarhizium anisophliae. Furthermore, FAG can be used with a starch-oil composite technology, known as Fantesk™, to encapsulate FAG oil in a jet cooked starch matrix that improves FAG’s UV absorption and efficacy. These starch-FAG composites may be useful to formulate aqueous-based systems without synthetic surfactants to deliver and protect microbial biopesticies. Insecticidal viruses that are extremely sensitive to degradation by sunlight have been effectively encapsulated within water insoluble lignin particles using a spray-drying process; this process prevents disassociation of microbe from the protective agent when diluted in the spray tank. Techniques are currently being developed to produce an adjuvant formulation with water soluble lignin in an effort to provide UV protection for a broader range of commercial pesticides (thus bypassing EPA registration of individual pesticide formulations).