Microflora associated with the alfalfa leafcutting bee, Megachile rotundata (Fab) (Hymenoptera: Megachilidae) in Saskatchewan, Canada

Abstract - The microflora associated with Megachile rotundata was isolated from adult bees, larval cadavers, cell provisions, bee cell surfaces, and nest material. Dominant fungi included Alternaria alternata, Aspergillus niger, Eurotium chevalieri, Mucor sp, Penicillium spp, Saccharomyces sp, Trichoderma citrinoviride, and Trichosporonoides sp. Bacteria commonly isolated included Bacillus circulans, Bacillus mycoides, Enterobacter agglomerans, and Pseudomonas spp. These microorganisms may be involved in activities such as spoilage of provisions, production of enzymes, antibiotics, mycotoxins, and growth factors (vitamins, amino acids), metabolic conversion of provisions, and inhibition of competing microorganisms. Microbial succession was observed involving yeast and bacterial fermentation of provisions followed by mould overgrowth of cell contents; this process was often associated with larval mortality. The microflora isolated likely has a range of beneficial and deleterious effects on M rotundata. Some fungal species reported here may also be potentially harmful to the health of leafcutting bee managers.