The entomopathogenic fungi and were cultured on solid agar media containing different carbohydrate components (glycerol, glucose, trehalose or starch) at concentrations of ≤ 142.7 g added carbon I for 30 d at 25 °C. The water activity (a) of the media ranged from 0.925 to 0.998. Growth of and was stimulated between 0.975 and 0.995 a on glucose media and that of at 0.975 a on glycerol media. At < 0.970 a growth of each fungal species was significantly reduced ( < 0.05). Polyhydroxy alcohols (polyols) and trehalose were extracted from conidia produced on different media and quantified using HPLC. Total polyol content of conidia produced on glucose media varied between 5.2 and 52.2 mg g for , 77.3 and 90.3 mg g for , and 26.7 and 76.1 mg g for The amounts of specific polyols in conidia varied significantly from media of different glucose concentrations. Mannitol was the predominant polyol in conidia of all three species, with conidia of , for example, containing as much as 75.2 mg mannitol g when cultured on glucose media. The amount of the lower molecular mass polyols glycerol and erythritol was greater in conidia produced on glucose media with > 50.0 g added carbon I than that in conidia produced at lower glucose concentrations. Conidia contained between 10.8 and 20.8 mg glycerol plus erythritol g on glucose media with 142.7 g added carbon I, depending on species. Conversely, conidia of and contained maximum amounts of trehalose (≤ 23.5 mg g) when produced on glucose media with < 50.0 g added carbon I and trehalose content was considerably less at higher glucose concentrations. There were accumulations of glycerol and erythritol in conidia of all three species when grown on glycerol media with > 25.0 g added carbon I, conidia of contained up to 154.0 mg glycerol plus erythritol g. When and were grown on trehalose media, conidia contained up to 222.1 mg trehalose g. By contrast, conidia of contained < 17.0 mg trehalose g under all conditions tested. The water availability of solutions of different polyols is discussed in relation to their potential to act in osmotic adjustment during germination. The ability to manipulate polyol and trehalose content of fungal propagules may be critical in enhancing the storage life and efficacy of biological control agents.


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