APIS Volume 11, Number 5, May 1993
In this issue
- Restrictions on Beekeeping Increasing?
- Sequential Sampling for Tracheal Mites
- Focus on Varroa Research
- Quality Honey
RESTRICTIONS ON THE RISE?
Two disturbing bits of news recently came my way. As reported in the Tara Beekeepers Newsletter, south Metro Atlanta, Gwinnett County recently upheld its ordinance restricting beekeeping to agriculturally zoned areas. This happened despite attempts by Dr. Keith Delaplane of the University of Georgia and others who met with the County Planning Commission to explain why this wasn't necessarily a good idea. The Commission was given a copy of the Texas Model City Beekeeping Ordinance, and several arguments for keeping bees in urban areas were advanced, including the fact that this would limit competition from wild colonies of African bees. The decision to ignore the advice and evidence was unanimous.
I also received a call from a lawyer hired by a local planning commission in Florida to help with a case brought by a beekeeper. The beekeeper is suing for "unreasonable" restrictions which are adversely affecting his occupation. The powers that be are now enforcing an old ordinance restricting beekeeping altogether in the community, depriving the beekeeper of income. The history appears to be one where urbanites have moved into an area where the beekeeper had been operating for a long time. The lawyer wanted an expert witness who would explain to the court why such an ordinance was appropriate. He didn't find one here. But that isn't stopping him from arguing to uphold the restriction.
There will undoubtedly be more of these kinds of scenarios in the future. Beekeepers must be prepared at any moment to go before county commissions or judges and plead a case for the continuation of beekeeping in both urban and rural areas. As an aid to those who find themselves in this situation, I have published ENY 115, Good Neighbor Guidelines and Ordinances. It should be available from any County Extension Office via the Gainesville VAX or IFAS CD-ROM Disk 7. I will mail out a copy on request as well.
SEQUENTIAL SAMPLING FOR TRACHEAL MITES
As I pointed out last month, the tracheal mite problem continues to vex beekeepers. It is expensive to treat bee colonies with chemicals to control mites; such applications are not always effective and their use hinders the search for genetic resistance. For these and other reasons, chemicals should be applied only when a certain infestation level is reached. Unfortunately, a uniform procedure has yet to be developed to determine treatable levels.
Into this fray come several investigators at Pennsylvania State University. They have published a detailed bulletin (#871) entitled "A Sequential Sampling Scheme for Detecting the Presence of Tracheal Mite (Acarapis woodi) Infestations in Honey Bee (Apis mellifera L.)." This publication, according to the authors, gives information on how to classify tracheal mite infestation levels in individual colonies resulting in considerable savings in time, labor and expense. It is available free from Maryann Tomasko, Department of Entomology, Penn State University, 501 ASI Bldg., University Park, PA 16802, ph 814/865-4621.
FOCUS ON VARROA RESARCH
Volume sixteen of Experimental and Applied Acarology(No. 4), December 15 1992 is a full issue devoted to the Varroa bee mite. In an effort to distribute the latest information on the biology of this dangerous bee parasite, the editor, Dr. J. Beetsma, has compiled this special volume.
A group of Italian investigators reported how quickly colonies treated for Varroa can be reinfested. This confirms thoughts I expressed in the MarchAPIS that these mites are really a beekeeper community problem. In "Reinfestation of an Acaricide-Treated Apiary by Varroa jacobsoni Oud.," the authors detail experiments showing a small reinfestation in the spring, rising dramatically in the fall when nectar was scarce. Drone excluders did not limit mite importation into the colony and it appeared that robbing infested colonies was a prime source of mites.
The conclusions of the study are: (1) treatments should be carried out at the same time in all colonies by all beekeepers in a given area; (2) treatments should not be carried out too early, since risk of reinfestation is maximal in the end of the season; (3) products with long-lasting action could be introduced twice, thirty days at the end of summer (so unparasitized winter bees develop) and for fifteen days before bees cease activity for the winter; (4) since feral colonies are perhaps the main source of reinfestation, effective swarm control would be a useful technique to reduce reinfestation. In a caveat at the end, the authors suggest reinfestation rates should be examined in other geographic areas.
In "Lack of Allozyme Variability Among Varroa Mite Populations," A. Biasiolo, also from Italy, found that mites from different parts of the world were very similar in genetic makeup and there was little evidence that different species exist. However, the paper suggested this might be the result of introductions of the same population over the globe. Samples collected only in Europe and China were compared. Mention is made that South American mites are somewhat, though not very, different. The author also suggests the variability might be small because of the mite's closed breeding system within the bee colony.
A group of investigators from the Netherlands reported the number of mites found in worker versus drone cells. In "Differential Periods of Varroa Mite Invasion into Worker and Drone Cells of Honey Bees" the mites' apparent preference for drone brood was reconfirmed, but, the authors conclude, other mechanisms may be determining whether mites invade drone or worker cells. Mites invaded cells only when the larva covered the cell bottom and the more worker brood cells present, the higher the rate of invasion.
In "Observations on the Initiation and Stimulation of Oviposition of the Varroa mite," authors from the Netherlands found that in order to successfully lay eggs, females need access to adult bees. Neither contact with juvenile hormone nor larval food provoked egg laying.
German researchers in "Grooming Behaviour of Apis cerana,Apis mellifera and Apis dorsata and its Effect on the Parasitic Mites Varroa jacobsoni and Tropilaelaps clarea" reconfirmed conclusions from other studies that cerana worker bees have a more intensive and effective grooming response for Varroa mites. However, these researchers were unable to replicate full grooming by cerana on mellifera workers as reported in other research. In addition, the effect of the grooming by mellifera was only to remove mites, not to catch and destroy them.
There is a body of evidence suggesting adult mellifera worker bees uncap and remove mite-infested larvae. Two German researchers in "The Removal Response of Apis mellifera L. Colonies to Brood in Wax and Plastic Cells After Artificial and Natural Infestation with Varroa jacobsoni Oud. and to Freeze-killed Brood," attempted to find the specific signals by which bees detect affected larvae. They were unable to do so, but did show that there was better infested larval removal from plastic comb ("Jenter"- and ANP-Comb) than from wax comb. They also compared removal of freeze-killed brood with that of Varroa infested brood and found a positive correlation, indicating that the standard test for "hygienic behavior" using freeze-killed brood could also be used to measure mite resistance.
Researchers at the University of Florida reported a comparison of honey bee and mite skins (cuticles). In "Cuticular Hydrocarbons from Varroa jacsobsoni," evidence was found that mites appear to mimic the individual bee they are on. Thus, mites found on worker pupae had the same skin makeup as the pupae; those found on adult workers and drones which are different from each other also "looked like" their hosts. The authors speculate that one reason for this is to prevent bees from detecting mites, in essence helping them become integrated into honey bee colony life.
Drones could be a key to breeding for Varroa resistance, according to German authors of "Selection of Resistance Against Varroa jacobsoni Across Caste and Sex in the Honeybee (Apis mellifera L., Hymenoptera: Apidae)." Because honey bees with a short post-capping stage (faster larval development) are partially resistant to Varroa and drones have large variation in this trait, selecting for rapidly-developing drones is possible. Using drones would also avoid some usual selection problems encountered in honey bees. Another generation of workers would not have to be reared to see if the short post capping trait actually shows up as is necessary when selecting queens.
A series of earlier research results can be seen in the August 1992 APIS.
QUALITY HONEY
Securing the best quality and quantity honey possible is the goal of every honey producer. The field is not without ideas and filled with some controversy. Major considerations have been when to remove honey from the colony and management technique to ensure the bees make the most and best sweet possible. In a recent article, "Effects of Frequency of Honey Removal and Empty Comb Space on Honey Quantity and Quality," Bee Science, Vol. 2, No. 4, pp. 187-192, a Canadian team led by Dr. Tibor Szabo examined several scenarios based on previous statements in the literature. The authors specifically examined differing views about whether frequent honey removal increases/decreases final production, the amount of honey that should be capped before removal and the concept that more empty comb space stimulates final production.
Thirty-six overwintered colonies were used in the study; 18 had one-year-old queens, the others were headed by two-year-olds. Three honey removal treatments (four, two, and one times) and three regimes of supering (adding five, ten and 11-15 supers!). In total nine treatments were replicated four times. During the honey flow, the "abandon method" was used. Supers were simply taken off and stacked on end; the bees abandoned them and no robbing was apparent. At the end of the flow, a bee blower was used. All supers were individually weighed to determine production and three combs of honey per colony were taken at random to determine quality based on diastase number and moisture content.
The results of the study indicated that frequency of honey removal and age of the queen significantly influenced production. Colonies with two honey removals produced more honey (312.6 lb) than those with either one or four removals (233.2 and 255.6 lb, respectively). Colonies with one-year-old queens yielded more honey (309.7 lb) than those headed by two-year-old queens (224.6 lb). The number of empty supers applied had little influence on honey production.
When honey was taken off four times, there was little if any of the comb capped. About half the cells were capped with two removals; all was capped with one removal. Moisture content was significantly affected by the number of supers provided and the frequency of honey removal. It was highest in colonies with five supers and four honey removals (19.0%); lowest with 12 supers and two removals (16.7%). The highest diastase numbers as expected, were for single honey removal; the lowest with four removals.
The authors conclude that too frequent honey removal decreases quality. Moisture content was acceptable with two removals, but not with four. In addition, extra comb space is needed to ripen the crop adequately. Although honey can be "artificially" dried in hot rooms, the authors contend that quality is diminished because enzyme count is low and there is an increase in hydroxymethylfurfural (HMF). The latter number is routinely considered an indication of how much honey is heated and therefore degraded.
Where moisture content is a problem in temperate and subtropical areas, the authors recommend adding more supers than normal (perhaps six to seven, for example, instead of five) and removing honey twice for maximum quality and quantity. Finally, they discuss the importance of a young queen, but are not necessarily in agreement, in spite of their results, that one-year- olds are far more productive than two-year-olds.
Two fact sheets available from this office address in detail quality, standards and moisture in honey. They are Hint for the Hive #129, Honey Judging and Standards and Hint for the Hive #130, Moisture in Honey.
APIMONDIA MEETS IN CHINA
The 33rd International Apicultural Congress is scheduled to meet in Beijing, China September 20-26, 1993. I am in receipt of the second circular which contains all the details. The theme is the honey bee and human health. For thousands of years, Chinese medicine has used various forms of natural therapies to treat diseases. It seems only natural, therefore, that apitherapy should be the focus of this meeting. If you would like more information on this conference, contact me for a registration form.
Several tours are being offered as part of the Apimondia meeting. Perhaps most relevant, however, is the chance to travel with this country's best known apitherapist, Mr. Charles Mraz. He and colleagues of the American Apitherapy Society, Inc. are planning a trip through the Citizen Ambassador Program which is scheduled to visit Chinese clinics and physicians practicing apitherapy, as well as Dr. Fang Zhu's International Conference on Apitherapy, Bee- Acupuncture and Healthcare in Nanjing. The trip is scheduled from September 19 through October 2. For details, contact Mr. Michael Rennaker, phone 509/534-0430.
Malcolm T. Sanford
Bldg 970, Box 110620
University of Florida
Gainesville, FL 32611-0620
Phone (904) 392-1801, Ext. 143 FAX: 904-392-0190
INTERNET Address: MTS@GNV.IFAS.UFL.EDU
