Volume 8, Issue 1 (January 2011)
Improving Formulations for Biopesticides: Enhanced UV Protection for Beneficial Microbes
As environmentally conscious consumers push for environmentally friendly pest control, interest in controlling insects with microbial-based biopesticides increases. Specific bacteria, fungi, and viruses can provide effective pest control when sprayed onto plants. However, these microbes are rapidly degraded by sunlight, which limits their field efficacy. One strategy to combat this degradation is to develop formulations to protect the beneficial microbe from sunlight energy, specifically the ultraviolet (UV) wavelengths. Formulation technologies (ingredients and processes) continue to be developed and adapted to provide UV protection. We have been conducting research on soyscreen and lignin as formulation ingredients to provide UV protection to a variety of insect pathogens. Soyscreen consists of feruloylated soy glycerides (FSG) specifically developed to absorb UV energy. Previous research demonstrated that FSG in oil-based formulations protected the viability of hydrophobic fungal conidia of Beauveria bassiana exposed to simulated sunlight, but not when applied in the field to oil absorbing substrates, including cabbage and tree bark. To prevent the FSG from being absorbed, the oil was encapsulated in starch using a jet cooking process forming a product with improved UV absorption. These starch-FSG composites may be useful to formulate aqueous-based systems without synthetic surfactants to deliver and protect microbial biopesticides. Lignin has been used with a spray-drying process to encapsulate insecticidal viruses, which are extremely sensitive to degradation by sunlight. The insoluble particles remain intact during application and can extend insecticidal activity by several days. 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. These technologies are considered to be environmentally benign and are intended to fit in the biopesticide concept. The versatility of combining various products and processes provides variable formulations, some of which are suitable for specific biopesticide applications.