الفهرس 
Studies on factors affecting the stability of certain biopesticides
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Abstract
Biopesticides especially the entomopathogenic bacterium Bacillus thuringiensis (B.t) has been used in crop protection for the last 70 years, but most of the biopesticides have macromolecules containing several chemical active groups causing the compounds to be easily broken down, as also less stable under environmental conditions. So, the current study was directed to evaluate the influence of certain environmental conditions on the stability and biological activity of two commercial formulations of B.t (Dipel 2X 6.4% WP and Protecto 9.4% WP), two commercial formulations of spinosyns (Tracer 24% SC and Radiant 12% SC) in addition to, two commercial formulations of emamectin benzoate (Proclaim and Broact 5% SG). The tested biopesticides were stored under accelerated hot storage, outdoor and ambient shelf storage. Also, photolysis studies were carried out by exposing samples to UV and sunlight in aqueous solutions. Parallel a bioassay test was carried out to assess the biological activity of each bioinsecticide against neonate and the 2nd larvae instar of the cotton leafworm Spodoptera littoralis. The results revealed that the loss% of all tested bioinsecticides after storage for two years was above the permissible limits of WHO and FAO specifications except Dipel 2X. In accordance with this trend, the bioassay tests revealed decreased in their biological activity (LC50{u2019}s) against neonate and the 2nd instar larvae of cotton leafworm. Moreover, biological activities of the samples stored under direct sunlight and UV were reduced to half values of their LC50