Q Nest usurpation
I recently stumbled across a honey bee behavior/characteristic that helps explain some unusual occurrences I have encountered in my apiary. The term for this behavior is usurpation, and more specifically usurpation swarms.
The term, as I am sure you are aware, refers to the ability and intention of a bee swarm to invade and capture an existing colony. The existing queen is killed or removed from the colony and the invading queen takes over her duties. Initially it was thought that only Africanized honey bees (AHB) utilized the usurpation behavior, but it appears that European honey bees (EHB) also usurp other bee colonies.
I live in Southern California and unfortunately the AHB has colonized this region. Because of this, the beekeeper’s challenge has been to minimize normal swarming and to prevent colonies that have swarmed from requeening themselves. Now with usurpation on the table, the beekeeper’s strategy for dealing with the influence of the AHB has been compounded.
I know that Dr. Wyatt A. Mangum has studied and written on usurpation. Do you know of any other investigations that have been or that are currently being conducted on the subject? Do you have any guidance or recommendations how beekeepers in general and specifically urban beekeepers can mitigate the usurpation behavior?
Usurpation has been a subject of interest to me since I first heard about it when I moved to Florida in 2006. At the time, Africanized honey bees were the hot beekeeping topic in the state. Beekeepers were concerned about them. The general public was concerned about them. My phone rang nonstop and my email inbox was full of questions about AHBs. As you know, AHBs are remarkably good at becoming the dominant honey bee in any area into which they move. They have a number of remarkable behavioral traits that tilt the scale in their favor over that of European-derived honey bees. Nest usurpation is one of these traits.
As you correctly describe, nest usurpation happens when a swarm of bees with its queen takes over an existing colony of bees. I will give the example from the perspective of a managed hive. An invading swarm may land on the outside of a managed hive. The swarm will form a tight cluster around its own queen. The swarm then migrates into the hive and begins to integrate with the colony contained in it. Somewhere in the process, the managed colony’s queen is lost, likely being killed by the invading swarm. After that, the invading swarm slowly releases their queen, almost as if they are introducing her into the colony they invaded. The net result is that your colony was taken over, queen and all, by another colony. This can be bad in the case of AHBs. You could be managing European-derived honey bees one day, only to be managing African-derived ones the next. A lot has been written about nest usurpation in the context of AHBs, but I am sure this trait is present in all subspecies of western honey bees, probably just at significantly reduced rates.
This all seems very problematic and should cause us to watch our colonies closely. However, though I know nest usurpation is possible, I do not have reason to believe that it happens with high frequency. A former graduate student (Dr. Ashley Mortensen) in my laboratory looked at the frequency of nest usurpation of managed European-derived honey bee colonies in Florida. She monitored for the behavior in 288 colonies managed in an area with a high density of feral AHB colonies. To cut to the chase, we never saw one example of nest usurpation occurring in our hives. You can read more about what we did and our results here: http://dx.doi.org/10.1007/s00040-014-0383-1.
I certainly do not want to minimize the occurrence of this behavior. I do believe it happens and can play a role in the change in behavior of a colony. After all, you had one colony headed by a certain queen, only to have a new queen with many of her worker offspring accompanying her. Frankly, I do not worry much about the role this plays in AHB impacts on managed colonies.
With that background, I believe the main way that AHBs take over our colonies has more to do with mating behavior than nest usurpation. Per some data I have collected in the past, the average queen does not survive longer than about a year in the typical managed colony. Thus, your colonies are requeening at least once per year. Given you live in an area where AHBs are present, the virgin queens your colonies produce are mating with drones available from colonies in the area. Many of these drones are from AHB colonies. This has a much greater impact on your colonies becoming Africanized than does usurpation.
The good news is that I would remedy both problems (mating behavior and usurpation) the same way. I would clip and mark all my queens. I mark them to make them easier to find. I clip them because wings do not grow back. When I find a clipped queen in my hive, I know she is the one I put there. If I ever find an unclipped queen in my hive, I know that I have a new queen (regardless if she is a new virgin my bees produced or if she came in with an invading swarm) and I need to watch the colony’s behavior closely. If they become defensive, I requeen it with a queen I purchase, or have on hand, from a queen breeder who produces certified European-derived queens. The key is queen management. You need to know who your queen is and where she originated. Clipping queens is the best way to monitor this.
Q To insulate or not
As a builder, I know R factors on insulating a home or a chicken coop. So insulating bee hives for winter is a personal preference. A -20°F in winter is not uncommon for this part of Colorado. I am also experimenting with polystyrene hives and had less bearding this summer and my first winter in use. I do understand that many factors have a major bearing on the survival of the bees during a winter. I would like to know if there were any studies on insulating bee hives for winter and what the results were? Was the honey consumed more or less? Did it help survival rate? Any pros or cons?
I must admit, I have only ever managed colonies in warm climates. I have pretty limited experience trying to overwinter colonies in cold climates like what you mention. In an attempt to answer your questions, I tried to find research studies related to what you were asking. Just FYI, the best way to do this (in my opinion) is to use Google Scholar. Google Scholar is a search engine, run by Google, that searches scholarly journals for articles related to your search terms. You can find Google Scholar using Google (i.e., do Google search for “Google Scholar”). I used Google Scholar to search for “insulating honey bee hives” and then “insulating honey bee hives in winter” and I found only a few articles related to this topic. It seems that much of the research has been done in warmer climates, with quite a few of them being done in Egypt and some Middle Eastern countries. I did not really find an article that tested hive insulation in more temperate winters. [Request to the faithful readers of this column: Please email me at email@example.com if you are aware of any studies on this topic. Thanks!]
Back to your questions: It is very common for beekeepers managing bees in cooler climates to insulate their hives. Many of them do it by wrapping their colonies. The eXtension bee health site includes step-by-step instructions for wrapping a hive at https://bee-health.extension.org/wrapping-a-colony-for-a-northern-winter/. I think there are a few keys to improving colony survival during winters in colder climates. First, make sure all diseases/pests are under control months before winter arrives. Colonies invest in the production of winter bees in the months leading up to winter. Thus, you want the colonies as healthy as possible at this time. Second, you want to make sure that the colony has stored adequate amounts of honey. Stored honey is really key to successfully overwintering colonies. Honey is the fuel bees burn to generate heat to survive winter. My guess (and this is just a guess given I did not find any studies about this) is that bees overwintering in well-insulated colonies would consume less honey to maintain the cluster temperature. Third, colonies need to have adequate ventilation. A lot of moisture can build up in the hive as bees consume honey for heating purposes. You want this moisture to be able to escape the hive. Some beekeepers make small holes or notches in the uppermost super or lid to allow moisture to escape. Fourth, many websites on this topic note that insulation is important, but do not link to research to support what level or type of insulation is necessary and what level of benefit you receive. Nevertheless, it is a common practice and should be considered if overwintering in colder climates. I will circle the wagons next month and try to add more details to my answer should the readers point out some sources of information on this topic, information that I might have missed.
Q Bt control of small hive beetles
Do you know if Certan has been used to control small hive beetle larvae? It’s used to control wax moth larvae so I was wondering if it would work for small hive beetle larvae too.
To my knowledge, Certan has never been used successfully against small hive beetles. Certan is a product that contains Bacillus thuringiensis, or Bt, bacteria that live in soil and produce proteins that are toxic to various insects. Certan has been used to control wax moths in stored combs. Colleagues of mine tested multiple Bt strains against small hive beetles and failed to control the beetles using any of the test strains. You can read more about their work here: https://link.springer.com/article/10.1007/s10340-006-0141-x. I would say that we cannot rule out the possibility that …