ARS | Publication request: ASCOSPHAERA AGGREGATA CONTAMINATION ON ALFALFA LEAFCUTTING BEES IN A LOOSE CELL INCUBATION SYSTEM

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2005
Publication Date: August 1, 2005
Citation: James, R.R., Pitts Singer, T. 2005. Ascosphaera aggregata contamination on alfalfa leafcutting bees in a loose cell incubation system. Journal of Invertebrate Pathology. 89:176-178.

Interpretive Summary: The alfalfa leafcutting bee has been used in large numbers to pollinate alfalfa seed crops since the 1960s. These bees are kept in nesting boards that are essentially a solid board with holes drilled or molded into them. However, bee reproduction has been greatly affected by chalkbrood, a larval disease caused by a fungus. In the U.S., attempts to control this disease have been fairly unsuccessful, but include removing the overwintering larvae from the nesting boards, and then disinfecting the boards with heat treatments or a fumigant before they are used again the next year. The bees that are removed from the nests are still in their cocoons inside the cells made by the mother bee, and this form of the bee is called 'loose cells.' We report here that adults emerging from the loose cells are heavily contaminated with A. aggregata spores. The contamination levels are not as high as previously reported for bees emerging from boards, but they are still a likely source for disease spread and may need to be targeted in chalkbrood control strategies.

Technical Abstract: The alfalfa leafcutting bee, a solitary bee used to pollinate alfalfa seed crops, is seriously affected by chalkbrood, a larval disease caused by the fungus Ascosphaera aggregata. One attempt to control the disease includes removing nests from the nesting boards (the 'loose cell' system). We report here that adults emerging from the loose cells are heavily contaminated with A. aggregata spores. The contamination levels are not as high as previously reported for bees emerging directly from the boards, but they are still a likely focus for disease spread and may need to be targeted in chalkbrood control strategies.