Ms. Goettel et al., PATHOGENICITY OF ASCOSPHAERA-LARVIS TO LARVAE OF THE ALFALFA LEAFCUTTING BEE, MEGACHILE-ROTUNDATA, Canadian Entomologist, 129(6), 1997, pp. 1059-1065
Laboratory assays and field surveys showed that Ascosphaera larvis (Bi
ssett) is a pathogen of alfalfa leafcutting bee larvae, capable of cau
sing high mortality in commercial populations. In one population over
21% of bees were found to be infected by A. larvis. However, overall l
evels of the disease are low and it is unlikely that this pathogen pos
es an immediate threat to commercial leafcutting bee populations in Ca
nada. The LD50 was determined to be 1.9 x 10(5) spores/bee. Elevated l
evels of CO2 are required for in vitro spore germination. The disease
can easily be diagnosed within bee cells by X-ray radiography, thereby
enabling disease levels to be monitored using conventional methods ut
ilized by the industry to monitor leafcutting bee quality.