Effect of Media on the Mycelial Growth of Honey Bee Fungal Pathogen Ascosphaera apis Mating Types

The fungal pathogen Ascosphaera apis significantly impacts the honey bee Apis mellifera by causing larval mortality and reducing colony productivity. Understanding the growth dynamics of A. apis under different media conditions is crucial for advancing research on its biology and pathogenicity. This study evaluates the effect of eight artificial media namely Potato Dextrose Agar (PDA), Carrot Dextrose Agar (CDA), Beetroot Dextrose Agar (BDA), Tender Coconut Water (TCW) media, Sabouraud Dextrose Agar (SDA), Sabouraud Dextrose Agar Yeast (SDAY), Sabouraud Maltose Agar Yeast (SMAY), and Malt Extract Agar (MEA) on the mycelial growth and reproductive structure formation of A. apis’s two mating types. Results indicated significant differences in mycelial growth across media. SDA (75.40 mm dia) and SDAY (74.83 mm dia) supported maximum growth for mating type 1 (MAT1) and, SDA (72.72 mm dia) and BDA (68.17 mm dia) yielded the maximum growth for mating type 2 (MAT2). The TCW resulted in the least growth for MAT1 (44.19 mm dia) and MAT2 (41.25 mm dia). The growth patterns showed that media supplemented with sugars generally enhanced A. apis growth, whereas non-sugar media did not. Furthermore, reproductive structures formed faster on PDA and CDA than on other media. The study confirms that media composition, particularly sugar content, critically influences the growth and development of A. apis, providing insights that could help to develop better management strategies for controlling chalkbrood disease in honey bee colonies.