Project Number: 5428-21000-013-11
Project Type: Specific Cooperative Agreement

Start Date: Aug 24, 2006
End Date: Jul 31, 2011

Objective:
Chalkbrood and other diseases cause significant mortality in bees, especially the alfalfa leafcutting bee, a pollinator that is key to successful production of alfalfa seed crops. Chalkbrood and other unidentified diseases are the primary reason that US seed growers are unable to produce enough of their own bees and must import them from Canada every year. A better understanding of the phylogenetic relationship between bees and the Ascosphaera (the causative agents of chalkbrood) will improve our understanding of the evolution of host/pathogen relationship. In addition, we would like to gain knowledge on the genetics of the immune response of the bees to pathogen invasion to develop effective disease control strategies to assist in breeding more resistant bee populations.

Approach:
Phylogeny Work. Fungi in the genus Ascosphaera are known to occur only in association with bees. A better understanding of the phylogeny of this unusual group will aid in identifying host specificity and pathogenicity factors. Sequence information has previously been published for the ITS gene in most known species of Ascosphaera, but phylogenies based on one gene are incomplete. We will obtain sequence information for three other genes for a number of Ascosphaera species. We will obtain ~50 kb of double-stranded sequence data using the CIBS DNA sequencing facility at Utah State University. Genetics of Immune Response. Temperature significantly affects the immune response of bees, where conditions of heat-shock make the bees less susceptible to infection from Ascosphaera infections. Microarrays will be used to identify upregulation of genes during heatshock and during pathogen invasion to look for commonalities and to identify key genes responsible for increased immunity. Once key compounds have been identified in the alfalfa leafcutting bee in response to A. aggregata and A. proliperda invasion, we will test whether a similar immune response occurs in honey bees when they are challenged with A. apis.