Stability of a Bacillus sphaericus formulation under different storage temperatures

Abstract

The stability of a Bacillus sphaericus formulation on granular corncob stored at two diferent temperatures (room temperature and 50°C) during 12 months was evaluated. A concentrated spore-cristal suspension was stored under the same conditions and used for comparison. The larvicidal activity of fresh corncobs and concentrated pathogen formulations were similar when inoculated onto artificial Culex quinquefasciatus breeding sites. Periodic analysis showed, however, higher spore viability in the corncob formulation under both conditions over a period of 12 months. The corncob formulation stored under high temperature (50°C) permitted a higher spore viability (30%) and larvicidal activity up to 60 days. Under the same conditions, the concentrated spore-cristal suspension showed total loss of both spore viability and larvicidal activity.