Parasitic Mite Syndrome (PMS)

Varroa mites feeding on unsealed brood.

Varroa mites feeding on unsealed brood.

PMS or Parasitic Mite Syndrome is a condition that causes a honey bee colony to deteriorate and eventually dwindle away and die. There has not yet been a pathogen detected which causes the brood symptoms that appear with this syndrome. However there are always varroa mites present with this syndrome. The brood symptoms look similar to other diseases but the larvae don’t rope. Colonies with PMS will show symptoms of white larvae that are chewed or pecked down by workers. Larvae may appear sunken to the side of the cell and may show symptoms of white with some debris at the posterior end. Pupa will be chewed down/removed or the pupa face chewed part of the way down as seen in the photo. Most of the symptoms shown are from hygienic bees trying to remove varroa mite infested cells and or larvae/pupa from cells. There is sometimes color to the larvae and this is attributed to age, decomposition or secondary bacteria.

When you start to see pupa with their face chewed down(multipule cells), this is a sign that your mite levels are starting to climb.

When you start to see pupa with their face chewed down(multipule cells), this is a sign that your mite levels are starting to climb.

Symptoms:
• Spotty brood pattern, varroa mites present on adult bees.
• Mites can often be seen crawling across sealed brood.
• Mites can also be found in open brood cells (usually chewed down larvae, refer to images)
• Lack of adult population (time-dependent).
• Large colonies are aggravated by high varroa mite levels and often show increased aggressiveness, lack of eggs and developing larvae (due to unfit conditions for raising brood), supercedure cells are often present, crawling bees near hive entrance or bees with DWV (Deformed wing virus).
• No odor present until the chewed down larvae start to change color and decay.

Note the spotty brood pattern.  The mite infestation is so bad that the bees start to chew down pupa/larvae and stop brood production.  You may also notice supercedure cells.

Note the spotty brood pattern. The mite infestation is so bad that the bees start to chew down pupa/larvae and stop brood production. You may also notice supercedure cells.

Here is an image of PMS.

Here is an image of PMS.

Chewed down pupa, larvae and a varroa mite hiding in the bottom of a cell.

Chewed down pupa, larvae and a varroa mite hiding in the bottom of a cell.

PMS symptoms.
PMS and  Deformed Wing Virus(DWV).

PMS and Deformed Wing Virus(DWV).

This is what PMS looks like once the population of the colony has dwindled.  You will not see many mites present at this stage of PMS; there will also be very little open brood present in the colony.  The population will be small and you may see multiple supercedure cells. At this stage PMS looks very similar to European Foulbrood except the larvae are different ages and there is no uniformity when it comes to open brood symptoms.

This is what PMS looks like once the population of the colony has dwindled. You will not see many mites present at this stage of PMS; there will also be very little open brood present in the colony. The population will be small and you may see multiple supercedure cells.
At this stage PMS looks very similar to European Foulbrood except the larvae are different ages and there is no uniformity when it comes to open brood symptoms.

Click here EFB Blog to see images of EFB.

You will often find Supercedure cells in colonies with high mite infestations.  You will also see supercedure cells with other disease like EFB.

You will often find Supercedure cells in colonies with high mite infestations. You will also see supercedure cells with other disease like EFB.

High mite infestation in brood.

High mite infestation in brood.

Treatments:
Keep varroa mite levels low. Monitor varroa mite levels or treat at least twice a year for varroa mites.

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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