Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2007
Publication Date: 9/19/2007
Citation: Jackson, M.A., Payne, A.R. 2007. Evaluation of the desiccation tolerance of blastospores of Paecilomyces fumosoroseus (Deuteromycotina: Hyphomyces)using a lab-scale, air-drying chamber with controlled relative humidity. Biocontrol Science and Technology. 17(7):709-719. Interpretive Summary: The survival and shelf-life of biopesticides for use in controlling insects and weeds is often enhanced through drying. Our air-drying studies with the insect-killing fungus Paecilomyces fumosoroseus have shown that the relative humidity (RH) of the drying air can enhance the survival and shelf-life on this fungus. Drying air with RH above 40 percent supported high rates of survival (~80 percent) after drying and drying air with RH above 55 percent significantly improved the shelf-life of the fungus. The pH of the spent medium or the rinsing of spent media from the fungus prior to air-drying had no significant impact on survival. A lab-scale, air-drying chamber that delivers air flow over the sample and that can be operated at controlled-RH was developed and is described. These studies have provided researchers and biopesticide producers with air-drying conditions that improve biopesticide survival after drying and a lab-scale, drying chamber that allows researchers to screen potential microbial biopesticides amenable to air-drying.
Technical Abstract: The stabilization of living microbial agents for use as biological control agents is often accomplished through desiccation. The drying process must be conducive to the survival of the living microbial agent during desiccation and storage. Our air-drying studies with liquid culture-produced blastospores of the entomopathogenic fungus Paecilomyces fumosoroseus have shown that the relative humidity (RH) of the drying air significantly impacts the desiccation tolerance and storage stability of these propagules. Drying air with RH above 40 percent was shown to support high rates of initial blastospore survival (~80 percent) after drying; and drying air with RH above 55 percent, significantly improved the shelf-life of the blastospore preparations. The pH of the spent medium or the rinsing of spent media from the blastospore preparation prior to air-drying had no significant impact of blastospore desiccation tolerance. A lab-scale, air-drying chamber that delivers air flow over the sample and that can be operated at controlled-relative humidity is described.