Until the 1950s, varroa was a parasite on Apis cerana, the Indian honey bee. On the Indian honey bee varroa is commensal and does little damage to its host. When Apis mellifera colonies of European descent were moved into the Indian honey bees range, varroa found a new host upon which it could proliferate without the checks and balances present with the Indian Honey bee. The severe parasitism that occurs when varroa infests European honey bees is not unusual for a parasite that moves to a new host. In nature, it often takes thousands of years of selection for a more commensalistic relationship or tolerance to develop. It is unlikely that resistance will provide a quick solution to the varroa problem, and for now, beekeepers must learn to detect and manage the parasite.
Varroa is an obligate parasite of honey bees. It cannot survive on bumble bees, wasps, or any
other insect. Varroa must feed on both adult bees and brood to reproduce. Like many other
parasites, varroa depends upon hormones obtained from its host to regulate internal process
such as egg development. Varroa will feed on adult bees for 4-13 days before entering brood
cells. They then seek out cells with larvae preparing to pupate and infest cells just prior to
sealing. They will feed for about 60 hours and then begin laying eggs. They will then lay one
egg every 30 hours with the first egg becoming a male and subsequent eggs females.
Immature mites are white and soft bodied. Varroa females mature in six days and become
reddish-brown and hard bodied. Mites that have not completed their development before the
adult bee emerges are not viable and die shortly after the adult bee emerges. In worker brood,
varroa can increase their population only slightly. When drone brood is present, varroa will
preferentially enter drone brood. As the drone brood cycle is longer, more varroa offspring
develop per cell, and the varroa population climbs rapidly.
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The drone brood examination method can be performed whenever drone brood is present. It is the best test to use when drone brood is present. A capping scratcher is used to remove approximately 100 mature drone pupae onto a white lid or paper. The pupae are visually examined for oval reddish-brown mites. They can often be observed moving about on the brood. When drone brood is present more than 70% of the mites in a colony can be found in drone brood cells.
The ether roll method can be performed any time. To ether roll test colonies, collect approximately 300 adult bees in a jar by raking the open jar across the surface of a comb. Force the bees to the bottom of the jar by tapping the jar on a soft surface such as the palm of your hand. Give the bees a one to two second burst of engine starter fluid (which contains ether). Replace the lid and shake and roll the jar. If present, mites can be observed sticking to the side of the jar. Because many mites are in brood cells during the summer, the number of mites detected using this method will vary greatly depending on the brood rearing status of the colony.
Midwest beekeepers should test their colonies for varroa twice a year using one of the above methods. The best times to test colonies are mid-March to May 1 and again in August.
When varroa mites are detected in the spring, colonies should be treated prior to the main
honey flow and drone rearing period. Varroa infestation levels do not increase in colonies that
are not rearing brood and increase very slowly in colonies with only worker brood.
Therefore, by going into the drone rearing period with few or no mites in the colony, they
are protected from the explosion of mites that can occur when drones are being raised. For
spring treatment place one Apistan strip for every five frames of bees and brood in the brood
nest. It is critical to successful treatment that Apistan strips be placed in contact with the
cluster of bees and brood. This is easy in the spring since the cluster is almost always in the
second hive body near the lid. Another advantage of spring treatment is that one strip will
often suffice as colony populations are at their seasonal low. Treat all colonies in an apiary at
the same time.
Fall treatment is frequently not necessary if a good spring control program was implemented. However, beekeepers should test colonies in August and treat again if warranted. Varroa infestation can increase in colonies by two routes. Existing mites can multiply or new mites can invade the colony. Spring treatment is almost always adequate to eliminate damage from mite reproduction; however, invasion pressure of mites from surrounding untreated infestations can make fall treatment necessary. Ether roll testing is the preferred method in August and can be done with bees collected from the honey supers. If six or more mites are found, remove supers as soon as possible and treat colonies with Apistan strips (one strip for every five frames of bees and brood). It is critical to treat these colonies while the queen is still laying so the colony will enter winter with a healthy adult bee population. Colonies with one to five mites detected by ether roll in August may benefit from fall treatment; however most will winter with good populations and can be treated more economically the following spring. Ether roll tests conducted in late fall when colonies have ceased rearing brood will yield more mites than similar tests conducted when brood is present. A colony yielding 10 mites on an ether roll test in November will usually winter in good condition. A colony yielding one to two mites on an August test may yield 10 or more mites in November.
There are many variables that can augment or mitigate varroa injury. In wintering bees with low levels of varroa, beekeepers should pay careful attention to other colony quality factors such as: adequate food reserves, freedom from brood diseases, freedom from nosema, sheltered wintering locations, winter cartons or other colony packing, and colonies headed by young queens.
When varroa first arrived in the United States, the standard recommendation from Europe was to treat colonies in the fall after brood rearing ceased. This approach has not been adequate in the Midwest. Varroa increases rapidly when drone brood is present, and Midwest beekeeping conditions provide four months of intensive drone brood rearing. The fall treatment approach is also expensive because three or more Apistan strips will be required to treat populous colonies.
In addition to the basic management plan, a few dos and don'ts are important in managing varroa. Do not leave Apistan strips in bee hives throughout the year. It is illegal to leave them in hives for longer than the prescribed four to six weeks. Continuous treatment provides an optimum environment for varroa to become resistant to Apistan. Apistan strips should be used once and discarded. Cull combs with large patches of drone comb from your brood nest. This has always been a good management practice for honey producing colonies. It will also reduce the growth potential for varroa in your colonies. Don't waste time visually inspecting adult bees for varroa. Most of the mites feed by piercing the flexible membrane that connects the hardened plates of the abdomen and are not readily visible. When mites are readily visible on adult bees the colonies are heavily infested and usually cannot be saved.
Colonies that collapse due to varroa infestation typically die from mid-August to
mid-October. Frequently, they will look like populous colonies in July and store a good crop
of honey. As the amount of brood rearing in the colony declines, emerging varroa mites have
nowhere to go except into the reduced cycle of brood in the late summer colony. This
relationship is illustrated in the plot of bee and mite population development at left (taken
from Dietz and Hermann 1988). Colony populations crash as entire cycles of brood are
parasitized. Unwary beekeepers find dead colonies with no bees and neighboring colonies
robbing the honey from the supers. If infested apiaries are not treated as needed, beekeepers
may find dead colonies with wax moths destroying the combs. The sudden collapse typical of
varroa is difficult to appreciate until you have experienced it.
The registration fee is $60 and includes four meals, reference notebook, and refreshments. Click here for a mail-in form.
Trainers will include: Dr. Marion Ellis, University of Nebraska Apiculture Specialist, Charles Simonds, Nebraska State Apiary Inspector, Bob Cox, Iowa State Apiarist, Gary Ross, Kansas State Apiarist, and Joli Winer and Cecil Sweeny, Mid-Con Agrimarketing. Lodging has been reserved in the Lincoln and Wahoo areas and a list of facilities and their rates will be sent to all registrants. More information will be posted on this Web page by May 1. Further details will be provided in subsequent issues of Bee Tidings.
| Bees and their Relatives | History of Beekeeping |
| Life History of a Honey Bee Colony | Bee Anatomy |
| Chemical Communication in Bees | The Dance Language of Bees |
| Pollen and Nectar Sources | Management for Honey Production |
| Honey Processing and Marketing | Wax Processing |
| Wintering Colonies | Diseases and Parasites |
| Crop Pollination | Queen Rearing |
| Africanized Honey Bees |
Anacreon
Strong overwintered colonies are best for apple pollination. Package bees and nucs have a
low proportion of foragers. Small colonies require most of their population to maintain the nest environment.
One strong colony per acre will provide adequate pollination. If package bees or nucs are used,
two to four colonies per acre may be required. One colony with 40,000 bees has more foragers
that two colonies with 20,000 bees each.
Dorothy will always be remembered for her efforts to start the Eastern Nebraska Honey Producers Association and her indefatigable energy in sharing her love of bees and beekeeping with others at the Nebraska State Fair. Together Dorothy, her husband Ed, and their son Jerry operated Bishop Apiaries. Ed preceded Dorothy in death, and Jerry will continue the family business.
Donna Waugh and her husband, Bill, worked side by side to operate Waugh Apiaries
at North Platte. Bill was a Director of the Sioux Honey Association. Both Bill
and Donna were active in the Nebraska Honey Producers Association and the
American Beekeeping Federation. Donna was preceded in death by her husband and
the family business has been sold. Both women found great joy in their work and
gave generously of their time and energies to beekeeping organizations.
"Enthusiasm, or an ardent love of its duties, is a very desirable, if not an absolute, requisite to successful apiculture. To be sure, this is a quality whose growth, with only slight opportunity, is almost sure. It only demands perseverance. The beginner, without either experience or knowledge, may meet with discouragements -- unquestionably will. Swarms will be lost, colonies will fail to winter, and the young apiarist will become nervous, which fact will be noted by the bees with great disfavor, and, if opportunity permits, will meet reproof more sharp than pleasant. Yet, with persistence, all these difficulties quickly vanish. Every contingency will be foreseen and provided against, and the myriad of little workers will become as manageable and may be fondled as safely as a pet dog or cat, and the apiarist will minister to their needs with the same fearlessness and self-possession that he does to his gentlest cow or favorite horse. Persistence, in the fact of all these discouragements which are so sure to confront inexperience, will surely triumph. In sooth, he who appreciates the beautiful and the marvelous, will soon grow to love his companions of the hive, and the labor attendant upon their care and management. Nor will this love abate until it has been kindled into enthusiasm.
True, there may be successful apiarists who are impelled by no warmth of feeling, whose superior
intelligence, system and inpromptitude, stand in lieu of, and make amends for, absence of enthusiasm.
Yet, I believe such are rare, and certainly they work at great disadvantage."
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