ARS | Publication request: Studies on the interaction of water with three granular biopesticide formulations

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2010
Publication Date: June 2, 2010
Citation: Lyn, M.E., Burnett, D., Garcia, A.R., Gray, R. 2010. Studies on the interaction of water with three granular biopesticide formulations. Meeting Abstract.

Technical Abstract: Two obstacles for biopesticide commercialization, long shelf-life and reliable efficacy, are both affected by moisture availability or more specifically, water activity. In the present study, the moisture sorption isotherms of three clay-based biopesticide delivery systems denoted as TRE-G, Pesta, and PEC-G were analyzed using a dynamic vapor sorption analyzer and were fitted with the GAB and Young & Nelson models. The objectives were to evaluate the usefulness of the dynamic vapor sorption technology to biopesticide research and to investigate the water uptake/loss behavior of the three biopesticide formulations over the 0 to 90% relative humidity range at 25.0°C. The formulations sorbed up to 12.7% moisture. In rehydrating from 0 to 90% RH, TRE-G and PEC-G were =63% and =58% faster than Pesta, respectively. In losing moisture from 90 to 0% RH, Pesta was 3.4x and 2.3x slower than TRE-G and PEC-G, respectively. For all three formulations, the moisture-sorption mechanism appears to be dominated by bulk absorption. The GAB model was inadequate for describing the moisture sorption of all three formulations. However, the Young & Nelson model showed good correlation (r > 0.990) for all three formulations. Moisture distribution for all formulations was obtained. The implications of the findings as they relate to shelf-life and dew period requirements of biopesticides are discussed.