“The Fourth Individual in a Colony of Honey Bees”
Bee Culture (September 2006) Vol. 134 (9): 17-19.
Malcolm T. Sanford
On my visit to
“After suffering the importation of mites through illegal smuggling, and unwanted genetics, pests and disease through other actions, American are understandably concerned about allowing the importation of ANY foreign bee imports. All the bad consequences of foreign imports have already happened, but none of the potential benefits have ever been realized. We are sure that the legal importation of our MALKA queens would represent the other side of the equation. Among the lines of bees that we work with we breed a very productive, but little known, hybrid cross between Caucasian queens and Italian drones which are known as **Caucasit**.”2
Subsequent to visiting Mr. Braunstein’s
While discussing queen producing techniques and other issues about beekeeping in general, Martín asked me the simple question, “How many individuals are in a honey bee colony.” The stock answer I gave was something every beginner is taught: “Three of course: drone, worker and queen.” There are four Martín countered his eye twinkling. When he saw my initial confusion (he had caught the “professor” off guard), he continued that any discussion of a honey bee colony must now include the ever-present Varroa mite.
Later as I thought in depth about this, I could see Martin’s point more and more clearly. But what first popped into my head was the “12th Man” in an American football game. Here’s information from the Wikipedia “open encyclopedia” about that subject.
“The 12th Man is a tradition at Texas A&M University regarding its football team. The Texas A&M student body acts as the "12th Man" for the football team and stands throughout the entire game, ready to help the team should the need arise (now through the use of "yells" led by Yell Leaders, in an effort to pump the team up). The term has been trademarked by Texas A&M (U.S. Reg. No. 1948306). In January 2006, A&M filed suit against the Seattle Seahawks to protect the trademark. In May 2006, Texas A&M and the Seattle Seahawks settled the dispute out of court. In the agreement, Texas A&M will allow the Seahawks to continue using the phrase ‘12th Man’ provided the NFL franchise acknowledges that the trademark on the slogan belongs to the school.
“The effects of the ‘12th Man’ vary widely, but can be put in two categories. The first is simply psychological, the effect of showing the home team that they are appreciated, and showing the away team that they are somewhat unwelcome. The second seems far more important, and it directly relates to the deafening effects of a loud crowd.”3
Immediately apparent is that the 12th Man is always present in a game, especially one with high stakes, and the other side must take this into consideration. And often this provides enough “home advantage,” which is in fact just that little extra teams need in order to win.
That the Varroa mite provides an apt analogy as the 4th individual in a bee colony, just as does the 12th Man in a football game, might be a stretch for some. But this is not the case when one takes into consideration what I have seen as a prevailing attitude among the beekeeping industry, that the mite is transitory, and can be looked at as something that can be eliminated (eradicated) at will through use of management and/or chemical treatments.
Looking deeper into the subject other thoughts come into focus. The mite is not a run-of-the-mill parasite, for the honey bee has little answer to its depredations it seems, just like any team has for the other side’s 12th Man in a football game. The mite is locked into the honey bee life cycle in ways we still don’t fully understand. It is obligated to the honey bee, and thus cannot live isolated from the bee for much time. A résumé of the mite’s biology found in the book Mites of the Honey Bee4 reveals that the Varroa mite’s life history is made up of two separate phases, both intimately connected to the life cycle of its honey bee host..
The phoretic or “carrying” phase is characterized by female mites hitching rides on honey bees as they fly among and enter different colonies. Male mites die after bees emerge from a mite-infested cell, but mated, mature females are extremely well suited for life on adult honey bees. They are flattened and often can be found hidden between the armored plates (sclerites) of the honey bee abdomen. The thin membrane between armored segments found in the honey bee is pierced by the mite’s specialized knife-like mouth part, which then gives it access to the bee’s blood (haemolymph). The mites’ carapace is also hardened just like that of the bees to reduce water loss from the body, and they have specialized claws to grasp the many hairs found on a honey bee. There is evidence that the chemical makeup (cuticular hydrocarbon profile) of the Varroa mite skin is very similar to the honey bee’s, such that the bees may not be able to distinguish themselves from the mites, making it more difficult to find and dislodge them during routine grooming. Finally, the mite can survive a long time on adults while brood is absent, biding its time until reproduction becomes possible.
Varroa mites are distributed via phoresis through three behavioral mechanisms shown by honey bee colonies. Those weakened through starvation or predation, which provoke robbing, are a prime source of mites for otherwise healthy, strong hives. Not only are robber bees themselves infested, but workers abandoning weak colonies are prime sources of Varroa mites.
Drifting honey bees, those that may visit a number of colonies, also spread mites. This particularly involves drones, which are universally accepted into colonies, and can enter a large number during their lifetimes.
Finally, swarming although of minor importance, certainly contributes to the distribution of mites. This behavior also coincides with peak populations of honey bees and brood, and, therefore, results in more mites.
The reproductive phase of mites also shows how tightly they are interwoven into the fabric of honey bee colonies. Not only are certain cells more attractive to female mites, but also the ages of the larvae and workers involved. Mites prefer drone brood, which allows them a longer time for reproduction because of the increased post capping time than found in workers, and also are attracted to younger workers (nurses) over older adults (foragers). The latter behavior means that mites will have a better chance of encountering a brood cell with a suitable occupant. Once a female mite enters a cell, it hides itself in the brood food and has specialized structures (peretrimes) that allow it to breathe while encased in a liquid environment.
Evidence suggests the timing of the mite’s first feeding is critical if the female is to reproduce. Because the entire reproductive process must take place within a certain time frame (and this is dictated by the bee’s developmental cycle), observers have concluded that Varroa has greatly compressed its early developmental stages, actually eliminating a normal “6-legged larval stage” found in most other mites. Proteins from the bee’s haemolymph also show up unaltered in mite eggs, a phenomenon known to occur only in a few other parasitic arthropods.
Mites establish feeding sites by pushing aside bee legs. Defecation areas are also developed, which provide places for “resting” in between feeding, and also are used during copulation. Mite young (protonymphs) require maternal care in order to survive, suggesting that Varroa in fact shows some evidence of prenatal care and, thus, a basic sociality similar to its host. The mite has not yet adapted fully to its new host, however, for population development occurs at a similar rate in both drone and worker cells, and in different races of Apis mellifera. It appears the mite could greatly increase its reproductive rate, for example, by decreasing by two the number of eggs laid in A. mellifera drone cells and decreasing by one the number laid in worker cells.
basic biology, the honey bee colony’s health is directly related to predation
(existence) of Varroa mites in several ways,
including challenges from other organisms.
What has become a mantra for bee inspectors and others is that one must
control Varroa BEFORE any other disease management
strategy can possibly hope to be effective.
This particularly includes the newest problem facing more and more
colonies and beekeepers in the
Management of mite populations, therefore, becomes paramount in honey bee management. This of course has transformed beekeeping around the globe. Techniques and tips written in the older literature that worked for what seemed time memoriam must now be modified based on the presence of Varroa. One that comes to mind is population manipulation for mite control besides that for buildup and swarming.
And let’s not forget the transformation of the beekeeper from someone with a revulsion for of all pesticide use to an avid practitioner. The insertion of chemicals inside a living beehive and the potential management problems this practice creates in an effort to eradicate or remove Varroa has had a mixed history. Yes, mites have been killed and their population reduced, but at what cost? Potential contamination of the world’s beeswax supply and possible effect on honey quality because of this practice continues to concern everyone involved with the beekeeping industry. This is especially important because the mites have shown themselves extremely adaptable by exhibiting high rates of developing pesticide tolerance and/or resistance, meaning not only increased dosages are needed, by also more toxic compounds are required.
The full results of what either hard or soft chemicals do inside a beehive are still out. It seems increasingly important that what are known as “sub-lethal” effects (those not actively killing bees, but impacting colonies in some way that cannot be readily detected) of pesticide treatment should be analyzed more rigorously. Given what we know about beeswax as a sink for many pesticides and their carriers, and the exquisite pheromonal balance of a honey bee colony, it seems reasonable to suggest that continued application of chemicals, whether hard (Apistan® or CheckMite+®) or soft (essential oils and organic acids), must be having some kind of effect on overall honey bee productivity. It is known, for example, that even minor manipulation of colonies can affect resultant honey production.
The use of chemicals, therefore, in an effort to remove Varroa from a colony is a philosophy that many have counseled, often with limited success, must be changed in a fundamental way. Thus, a shift in thinking is in order from ridding colonies of mites to living with them, the essence of what many now call integrated pest management or IPM. If others such as Martín. Braunstein would insist that the 4th individual in a bee colony, like the 12th Man in a football game, is here to stay, and each and every bee colony and beekeeper must contend with this fact from now on, the desired effect might be achieved.