Environmental fate of spinosad. 1. Dissipation and Degradation in Aqueous systems

Spinosad is a bacterially derived insect control agent consisting of two active compounds, spinosyns A and D. The objective of this paper is to describe the environmental fate of spinosad in aquatic systems. To this end, several studies performed to meet regulatory requirements are used to study the fate and degradation in individual environmental media. Specifically, investigations of abiotic (hydrolysis and photolysis) and biotic (aerobic and anaerobic aquatic) processes are described. Understanding developed from the laboratory-based studies has been tested and augmented by an outdoor microcosm study. Understanding of aquatic fate is a building block for a complete environmental safety assessment of spinosad products (Cleveland, C. B.; Mayes, M. A.; Cryer, S. A. Pest Manag. Sci. 2001, 58, 70−84). From individual investigations, the following understanding of dissipation emerges:  (1) Aqueous photolysis of spinosad is rapid (observed half-lives of <1 up to 2 days in summer sunlight) and will be the prim...