Related Experiment Video
Updated: Aug 15, 2026
On-site DNA Detection of Trypanosomatid Parasites and Nosema ceranae Through Alkaline Lysis Coupled to RPA/CRISPR/Cas12a System
Published on: July 18, 2025
PCR diagnostic methods for Ascosphaera infections in bees
1USDA-ARS Bee Biology and Systematics Laboratory, Logan, UT, USA. rjames@biology.usu.edu
Abstract:
Fungi in the genus Ascosphaera are the causative agents of chalkbrood, a major disease affecting bee larval viability. Identification of individual Ascosphaera species based on morphological features has been difficult due to a lack of distinguishing characteristics. Most identifications are based on the size and shape of the ascomata, spore balls and conidia. Unfortunately, much overlap occurs in the size of these structures, and some Ascosphaera species will not produce sexual structures in vitro. We report a quick and reliable diagnostic method for identifying Ascosphaera infections in Megachile bees (leafcutting bees) using PCR markers that employ genus-specific primers for Ascosphaera, and species-specific primers for species known to be associated with Megachile spp. Using these methods, species identifications can be performed directly on bees, including asymptomatic individuals. Furthermore, the PCR markers can detect co-infections of multiple Ascosphaera species in a single host. We also identified a marker for Ascosphaera apis, the predominant cause of chalkbrood in Apis mellifera, the honey bee. Our diagnostic methods eliminate the need for culturing samples, and could be used to process a large number of field collected bee larvae.
Insights
Diagnosing chalkbrood disease in bees is now easier with new PCR markers. These molecular tools accurately identify Ascosphaera species, improving bee health management for leafcutting and honey bees.
Area of Science:
- Mycology and Apiculture: Focuses on fungal pathogens impacting bee health.
Background:
- Ascosphaera fungi cause chalkbrood, a significant bee larval disease.
- Traditional identification methods are unreliable due to morphological overlap and in vitro culture limitations.
Purpose of the Study:
- To develop a rapid and accurate diagnostic method for Ascosphaera species in bees.
- To enable direct detection of infections in both symptomatic and asymptomatic bee individuals.
Main Methods:
- Utilized genus-specific and species-specific PCR markers for Ascosphaera identification.
- Developed primers targeting Ascosphaera species commonly found in Megachile and Apis mellifera.
Main Results:
- Established a reliable PCR-based diagnostic for Ascosphaera in Megachile bees.
- Successfully identified Ascosphaera apis marker, the primary honey bee chalkbrood agent.
- Demonstrated detection of multiple Ascosphaera species co-infections within a single host.
Conclusions:
- PCR methods offer a faster, more reliable alternative to traditional diagnostics for Ascosphaera.
- These molecular tools facilitate efficient screening of field-collected bee larvae for chalkbrood pathogens.