APIS Volume 17, Number 8, August 1999

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 · 10 Nov 2023

In this issue

• More On Open Mesh Floors For Varroa Control
• Worker Protection Standard; Not Mandatory, But Cannot Be Ignored
• Update on Africanized Honey Bees (AHB) in South Texas: Where Will The Population Go?

MORE ON OPEN MESH FLOORS FOR VARROA CONTROL:

I discussed the possible use of mesh floors for controlling Varroa in the December 1998 <http://www.ifas.ufl.edu/~mts/apishtm/apis98/apdec98.htm#6> and June 1999 <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apjun99.htm#4> issuesof APIS. Further evidence for this technique is revealed in an article sent to me by Ken Hoare <bees@kenlia.enta.net> via electronic mail. "Observations on the Overwintering of Honeybee Colonies in Hives with Open and Solid Floorboards" was originally published by Helmut Horn in A.D.I.Z., November 1987, and subsequently translated from the original German by A. E. McArthur for the British journal Bee Craft in July 1990.

Mr. Hoare says specific plans for the floors can be found in the book Varroa Mesh Floors, edited by P.A.M., and available from Northern Bee Books, United Kingdom <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apjul99.htm#3>. Construction is very simple. A sturdy wood frame of hive dimensions with a wire mesh (8 wires to the inch) replaces the standard solid bottom board. This arrangement allows debris and mites to fall out of the hive and prevents invasion of other organisms. An entrance above the mesh floor is needed to allow bees to enter the colony. Because the mesh allows increased hive ventilation, only a small bee entrance is needed, which reduces robbing tendencies. No debris can collect on the floor, thus fewer wax moth larvae are provided hiding places. Unless one has Alaskan winters, Mr. Hoare says not to worry about using these floors during the colder weather. He suggests a minimum 2" of good-quality insulation between cover board and roof during the winter will reduce condensation in colder climates. Finally, Mr. Hoare says that a temporary Varroa screen to monitor mite levels is easily placed below the mesh should it be necessary.

Mr. Helmut Horn begins his article with the observation that the behavior of a honey bee colony during the over-wintering phase is critical for its development the following spring. This is influenced by a variety of factors, including providing suitable apiary locations, early feed (especially nucleus stocks), abundant stores (honey and pollen), protection against mice and other predators, and sufficient ventilation. The latter can be greatly influenced by designing specialized bottom boards. As Mr. Horn says: "Even today in beekeeping circles the opinion is often expressed that the over wintering behavior of a honeybee colony is largely dependent on the insulation against cold during the winter period." He concludes this deeply rooted beekeeper habit to insulate their colonies against the cold during the dormant period will not be broken easily. Hive flight openings are also reduced because of this philosophy, often compromising sufficient air supply to the colony. The dangers of poor ventilation are less during the cold winter months because the bees are tightly clustered and, due to a minimum of physical activity, have only a low requirement for oxygen. Serious problems may occur in spring at the time of the first cleansing flights, however, when dead bees, even with a low mortality rate, can disrupt ventilation by restricting the size of the entrance. The observation that colonies with poor ventilation during the summer nectar flow exhibit aberrant behavior compared to colonies that have adequate ventilation have caused Mr. Horn to substitute the solid floor boards of a number of experimental colonies with wire mesh. He quickly saw the flight behavior of the bees changed after a few hours. While colonies with solid floorboards were strenuously engaged in ventilating the hive by fanning, those which had been fitted with wire mesh floors were foraging normally.

Mr. Horn’s study employed two groups of six colonies, each equipped with open and closed floors, and was conducted over five years. The results show: 1) Colonies in hives having open wire mesh floors ceased brood rearing in autumn earlier than those having solid floors; and 2) colonies in hives with mesh floors began brood rearing later in spring than those with solid floors. These conditions correlated with fewer winter losses in colonies with open floors than with solid floors. The first two conditions, according to Mr. Horn, result in future winter bees having to nurse only a small amount of brood, incurring less stress and living longer. Early fall brood-rearing shut down prevents the colony from having to feed larvae well into late autumn, which can lead to shorter-lived bees next spring.

A too-early commencement of brood in spring causes a reactivation of the winter bee food gland and forces an increase in muscular activity to maintain the necessary brood nest temperature. This forces the colony to forage early, and especially if unfavorable weather conditions prevail, and leads generally to premature heavy forager loss. The colonies virtually fly themselves "bald," Mr. H. Horn concludes, resulting in colonies that have large areas of brood and only a few old bees. These conditions become most important in temperate climates, Mr. Horn says, when regular cold spells can occur after long warm periods. Due to weaknesses in the colony from premature brood rearing, the endemic disease parasite Nosema apis can easily gain the upper hand. Other disease vectors may also cause serious damage. The wire mesh floor guarantees a constant exchange of air, and heat build up due to direct sunlight on the hive wall is unlikely to result in premature brood production. Brood rearing only begins in earnest when the weather begins to be warm for lengthy periods. Thanks to the enormous laying capacity of the queen bee and a large number of over-wintered bees, the "brood deficit" relative to colonies in hives with solid floors, Mr. Horn says, is rapidly compensated for and, after a very short time, even exceeded. Because of this, colonies are able to exploit early nectar flows in an optimal manner.

Over wintering colonies in hives with open floors, according to Mr. Horn, when compared to those on solid floors, offers another positive advantage. Due to the constant exchange of air only moderate condensation occurs. Thus, fungal formation on the outside of combs does not occur as happens in colonies over wintering in hives with solid floors. . Although temperate zones are emphasized in Mr. Horn’s paper, those in more tropical areas may also benefit from ideas presented here. Ventilation is important to retard undesirable growth of microorganisms in warm, moist environments as well.

Beekeeping using hives with open floors is advantageous during summer, Mr. H. Horn says. The wire mesh floor replaces a moving screen on the hive front. During migratory beekeeping, a sufficient air exchange is guaranteed and there is no need for additional ventilation. The fact that the colonies having wire floors cease brood rearing earlier in autumn offers new possibilities in the treatment against Varroa. Mr. Horn’s experiments have shown a complete halt to brood rearing can be caused by continuously feeding concentrated sugar syrup in autumn. This results in less brood that is parasitized by Varroa throughout the winter.

Similar positive effects are offered by the open floor in the spring according to Mr. H. Horn. Delayed spring brood rearing results in loss of fewer winter bees, and colonies often have better pollen resources at their disposal later in the season. By exploiting this natural pollen income, the beekeeper can better induce an artificial nectar flow by feeding sugar syrup, encouraging early drone rearing. Because of the greater attraction of drone brood for Varroa and the simultaneously low availability of worker brood, a large number of mites can be trapped in drone comb and removed from the colony very early in the season. A good strategy to maximize this is to insert drawn drone comb into the brood nest the previous autumn.

The use of the wire mesh floor during winter has one disadvantage Mr. H. Horn says. Food consumption is 10-15 percent higher. The reason for this is increased heat loss through the open floor. Despite the increase in food consumption and a higher metabolic rate, however, Mr. H. Horn’s colonies on hives with wire floors have suffered no adverse effects. Significantly, they also over wintered more successfully than colonies with solid floors. The reason for this, he says, probably lies in the different brood rearing patterns during the winter period, when colonies on solid floors may raise brood even during the dormant period or much later into the season, while colonies on open wire floors enjoy an extended brood-free period.

Although the focus of mesh-floor use is mite control for many beekeepers, Mr. H. Horn’s paper is important because it also emphasizes additional aspects of colony manipulation that can be implemented as part of an integrated pest management approach to Varroa control in conjunction with other best management practices. His results appear to corroborate many of the beneficial findings for modified bottom boards, slatted racks, and pollen traps as reported by other investigators in the July 1999 APIS <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apjun99.htm#4>. All of these fit nicely into an overall management philosophy that beekeepers might wish to modify for their own use depending on geographic location.

The use of modified bottom boards in beekeeping is nothing new it seems, which adds emphasis to my musings on the "old" beekeeping literature in the July 1999 APIS <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apjul99.htm#1>. Mr. Jim Medill, for example, writes in the July 1999 American Bee Journal (Vol. 139, No. 7, pp. 499-500) letters to the editor section about a combination moving screen and bottom board originally designed by a Mr. Carl Jansen.

This is a complex apparatus, which employs a middle ventilation divider (MVD), according to Mr. Medill. He provides a complete set of plans and suggests this could be modified to catch small hive beetle larvae by providing an amount of soil below the ventilation screen to catch those that are seeking to pupate. If that technique proves to be effective, it would be yet another use for this versatile technology. In addition, Mr. Medill suggests a further wrinkle, which he learned many years ago from another beekeeper. He writes that while one is designing and implementing a new bottom, it is prudent to rotate the entrance 90 degrees so it is parallel to the frames. This provides a wider entrance, important for increased ventilation in hot weather and during heavy honey flows. He himself did this decades ago and found that this arrangement helped manipulations greatly.

WORKER PROTECTION STANDARD; NOT MANDATORY, BUT CANNOT BE IGNORED

With increased use, the bar for pesticide use has been significantly raised by beekeepers, as described in the January 1999 APIS <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apjan99.htm#1>. "The label is the law" standard has been mentioned many times in this newsletter, with a specific warning to Florida beekeepers about increased scrutiny in this area from the Florida Department of Agriculture and Consumer Services, as described in the December 1998 APIS <http://www.ifas.ufl.edu/~mts/apishtm/apis98/apdec98.htm#2>. It is important to realize, however, that label use is only part of the regulations that Florida pesticide compliance inspectors are being asked to implement. Another is whether or not operations are adhering to what is called "The Worker Protection Standard." With reference to this, I have in my possession a three-page checklist that employees of the Bureau of Compliance Monitoring of the Division of Agriculture Environmental Services carry and are asked to fill out when inspecting agricultural operations.

A description of this legislation is found in "Summary of the Worker Protection Standard for Agricultural Pesticides," by Jack L. Runyan, Agriculture Information Bulletin No. 680, Agriculture and Rural Economy Division, Economic Research Service, U.S. Department of Agriculture <http://www.usda.gov/agency/oce/oce/labor-affairs/wpssumm.txt>. "The U.S. Environmental Protection Agency (EPA) revised its 1974 Worker Protection Standard by issuing its new Worker Protection Standard (WPS) on August 21, 1992 (40 Code of Federal Regulations--40 CFR). The WPS, which became effective on October 20, 1992, expands coverage to include more employees and expands employers' requirements for training employees who handle pesticides, protecting employees from pesticide exposure, and providing emergency assistance to exposed employees. Some of the provisions of the WPS also apply to owners, operators, and members of their immediate families."

The good news is that the WPS does not specifically include livestock producers (beekeepers). It was really designed for agricultural employers who have employees performing hand labor operations in fields, forests, nurseries, and greenhouses treated with pesticides, and/or employees handling pesticides in these locations. However, according to Mr. Runyan, the WPS covers more agricultural employers than most other laws and regulations. And although many laws and regulations affecting agricultural employment exempt farming enterprises that employ small numbers of hired farm workers, the WPS has no exemptions based on the number of employees. In addition, WPS provisions are complicated and likely to affect a large number of employers and their workers. Thus, this important act should not be ignored by beekeepers actively employing pesticides in their operation.

The general duties of the WPS require an agricultural employer or a pesticide handler-employer to:

1. Assure that each worker and handler subject to the standard receives the required protections.
2. Assure that any pesticide subject to the standard is used in a manner consistent with the labeling of the pesticide, including the requirements in the standard.
3. Provide sufficient information and directions to each person who supervises any worker or handler to assure that each worker or handler receives the required protection. The information and directions must specify which persons are responsible for actions required to comply with the standard.
4. Require each person who supervises any worker or handler to assure compliance by the worker or handler with the provisions of this standard and to assure that the worker or handler receives the required protection.

The general duties also prohibit agricultural and handler employers from taking any retaliatory actions against workers attempting to comply with this standard, or from taking any action that prevents or discourages any worker or handler from complying or attempting to comply with the WPS.

More specific obligations require everyone applying pesticides to obey instructions printed on the pesticide container's label. With reference specifically to the Worker Protection Standard, the following apply:

1. Only appropriately trained and equipped workers allowed in area during pesticide application.
2. Workers may enter a treated area before the Restricted Entry Interval (REI) has expired only if the worker will have no contact with pesticide residue or is entering for a short term, emergency, or specifically excepted tasks.
3. Workers must be provided with protective equipment in proper working order. Workers must be notified of pesticide applications, treated areas must be posted, and/or oral warnings must be given to workers as directed by labeling.
4. Pesticide safety poster must be on display in a central location.
5. Decontamination site must be provided and maintained if workers are required to enter treated area during a Restricted Entry Interval (REI) and the ensuing 30 days.
6. Emergency assistance must be provided to any worker when there is reason to believe the worker was poisoned or injured by pesticide.

Others are part of the Pesticide Handler Protection Standard:

1. Only appropriately trained and equipped handlers allowed in area being treated.
2. Handler handling highly toxic pesticides must be monitored every two hours.
3. Handler fumigating in a greenhouse must be in continuous voice or visual contact with another handler.
4. Handler must provide information to agricultural employer prior to applying any pesticide.
5. Each handler must have pesticide safety training from a qualified trainer.
6. Each handler must understand all labeling requirements related to safety before starting handling activity.
7. Handlers must use protective clothing.
8. Handlers must be provided with a decontamination site.
9. Handlers must be provided with emergency assistance.

Again, this is a complex law with many provisions. Questions should be addressed to Mr. Dale Dubberly, 3125 Conner Blvd., Bldg. 8 L-29, Tallahassee, FL 32399-1650, tel. 850/488-8731, fax 850/488-8498.

UPDATE ON AFRICANIZED HONEY BEES (AHB) IN SOUTH TEXAS: WHERE WILL THE POPULATION GO?

Dr. Frank Eischen describes a resurgence of wild, or feral, honey bee colonies in south Texas (American Bee Journal, Vol. 139, No. 9, pp. 594-595, July 1999). Most of these are Africanized (AHB) and appear to be the result of tolerance to Varroa mite developing in these populations <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apmay99.htm#1>.

If this phenomenon continues, according to Dr. Eischen, we may well be in for an expansion of AHB, as was seen in the early 1990s when it crossed the Texas-Mexican border. There seems to be much less stopping the insect now that there has been extensive selection pressure applied by Varroa for almost a decade. A description of the possible reasons for AHB stalling in Texas was published in the July 1994 APIS <http://www.ifas.ufl.edu/~mts/apishtm/apis94/apjul94.htm#1>. Where the population goes and how fast over the next few years is only a best guess at this time, Dr. Eischen concludes, but there seems little doubt that both AHB and Varroa will be part of the beekeeping landscape for decades to come.

Sincerely,

Malcolm T. Sanford
Bldg 970, Box 110620
University of Florida
Gainesville, FL 32611-0620
Phone (352) 392-1801, Ext. 143 FAX: 352-392-0190
http://www.ifas.ufl.edu/~mts/apishtm/apis.htm
INTERNET Address: MTS@GNV.IFAS.UFL.EDU
©1999 M.T. Sanford "All Rights Reserved"