Chalkbrood

Drone brood with Chalkbrood.

Drone brood with Chalkbrood.

Chalkbrood (Ascosphaera apis) is typically observed during the spring but symptoms can be seen throughout the year. Chalkbrood contaminates larvae when the spores are mixed with brood food. The fungus will outcompete larvae for food and eventually turn the larvae into a “chalk-like” mummy. The color of chalkbrood ranges from white to grey then starts to turn black-this is when the fungus is producing fruiting bodies. This is the most infectious stage of chalkbrood. The black looking mummies are often what you see outside on the entrance board or in front of the hive. At this point these mummies can spread spores to other colonies in the area. Lack of population may be a contributing factor in the colonies ability to ventilate properly. Proper hive ventilation should prevent chalkbrood.

Chalkbrood taking over a drone larvae.

Chalkbrood taking over a drone larvae.

Symptoms:
• Spotty brood pattern.
• Chalk-like mummies at the colony entrance, chalk-like mummies in open brood.
• Early stages of chalkbrood look very similar to SBV but the head is less defined and more round with a sunken appearance.

Brood frame riddled with chalkbrood mummies.

Brood frame riddled with chalkbrood mummies.

Different ages of Chalkbrood.

Different ages of Chalkbrood.

Larvae being replaced by fungal mycelium.

Larvae being replaced by fungal mycelium.

Treatment:
Apiguard or a thymol based treatment is active against chalkbrood. Vitafeed Green contains thymol and also works against chalkbrood. Beevital Chalkbrood is another product available for treating chalkbrood. Increased ventilation in the hive will help prevent chalkbrood.

Written By: Rob Snyder

Rob Snyder has written 62 post in this blog.

I currently work out of the Butte County Cooperative Extension in Oroville, CA as a Crop Protection Agent. I received my B.S. in biology from Delaware Valley College, PA. There I attained a majority of my entomological knowledge from Dr. Chris Tipping and Dr. Robert Berthold. After graduation, I was an apiary inspector for 2 years at the Department of Agriculture in Pennsylvania. In my third year there, I still inspected some colonies but I mainly focused on The Pennsylvania Native Bee Survey (PANBS) where I pinned, labeled, entered data and identified native bees to genus species. Leo Donavall assisted me in learning the basics on positive Identifications of the native bees. Around the same time I began working on coordinating kit construction and distribution for the APHIS National Honey Bee Survey. I was also fortunate to conduct many of these surveys with fellow co-worker Mike Andree and Nathan Rice of USDA/ARS throughout California. All of these experiences have led me to where I am today, working to assist beekeepers in maintaining genetic diverse colonies resistant to parasites while reducing the use of chemical treatments in colonies. The BIP Diagnostic Lab at the University of MD is in an integral part of this process by generating reports in which we can track change and report to beekeepers vital information in a timely manner which may influence their treatment decisions.

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