CIS 538 rev. Part 6

Other Considerations

Chalkbrood disease, bee predators and parasites can cause such high mortality that virtually all nesting materials must be phased out (removed from the bees environment permanently or temporarily in order to sanitize them) every year in the spring whether or not the bees are incubated. Different plans for phasing out nest materials are discussed below.

Advantages:

1. This management technique eliminates the greatest number of leafcutting bee enemies.
2. This practice is necessary to help control chalkbrood. The disease has been reduced to low levels where annual phase out of all nesting materials is practiced.
3. The vast majority of the diseased cadavers and chalkbrood spores are isolated from the bees in the phase out process. Some phased out nesting material can be sterilized and recycled.

Disadvantages:

1. Phasing out 100 percent of the bees into new nesting material tends to increase bee loss from drift.
2. There is an additional cost for new nest materials for the first 2 years and until the old nesting material can be cleaned, sterilized and recycled.
3. The cost of phase out houses and/or traps necessary to implement a full phase out program may significantly increase initial layout costs.
4. An increase in time and labor are necessary to carry out this program.

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The partial phase out is accomplished each year through excluder traps designed to catch parasites and nest-destroying insects.

Advantages:

1. Proper management will permit bees that have not been phased out to begin emerging in your field shelters 3 to 7 days earlier than bees that will emerge through the phase out traps.
2. These working bees will attract the late arrivals to the new nesting materials provided and reduces losses from drift.
3. After this routine, from 50 to 90 percent or more of the common leafcutting bee enemies could be eliminated at the beginning of each growing season.

Disadvantages:

1. Chalkbrood disease may not be significantly reduced.
2. Replacement with new nest materials could be expensive.
3. An increase in time and labor is required to carry out this program.
4. A carryover of bee enemies will occur.

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Large portable phase out house can be placed in the field next to domiciles with new or reconditioned nesting material.

1. Low cost because a minimum number of phase out houses are utilized.
2. This operation tends to minimize drift of pollinators.
3. The number of bees released at any station can be controlled.
4. When enough bees have exited the trap and accepted the new domicile, the phase out house can be moved to another domicile in the field.

1. Cost of large, portable units.
2. All the bees are in one unit; therefore, all bees could be lost in a catastrophe such as wind or fire.
3. Large phase out houses situated away from farm dwellings are more subject to theft.

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Advantages:

1. Lower cost because a minimum number of phase out houses is necessary.
2. The number of bees released at any station can be controlled.
3. Existing buildings may be used close to farm dwelling lowering costs and the risk of theft.

Disadvantages:

1. Drift loss is greater than in portable phase out houses because bees must reorient themselves to a new surrounding when the domiciles are moved to a "working" field location.
2. The size may not be optimal for small fields.

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Advantages:

1. Less drift of bees than with other phase out houses.

Disadvantages:

1. More phase out houses are necessary, possibly increasing costs.

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Advantages:

1. Under today's disease conditions, there are no advantages to not phasing out 100% every year.

Disadvantages:

1. Bee enemies can rapidly reduce the number of bees available for pollination.
2. Buying replacement bees to maintain or meet future pollination needs may be the most costly route a seed grower can take compared to the alternative of using good management practices to supply a major portion of his own bee requirements.
3. Chalkbrood disease may increase to very high levels and provide a ready source of spores to infect purchased replacement bees.

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Advantages:

1. Low cost per unit for construction.
2. Biological stress on the bee may be reduced because of less competition for food and nesting sites; may favor lower chalkbrood incidence.
3. More easily moved.

Disadvantages:

1. Small shelters increase tendency of bees to drift, leaving some shelters relatively empty and others crowded.

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Advantages:

1. Bees work better and drift less in large, well populated shelters.
2. Bees from this size range of field shelter can pollinate up to 20 or more acres.
3. Inspection and care for a few large shelters is easier than for many small ones.

Disadvantages:

1. High cost per unit for building large, well constructed shelters.
2. Bees are concentrated, so large numbers could be lost to pesticides, drift, fire, etc.
3. Parasites, predators or nest destroyers from just a few bee nests can infest the whole station.
4. Chalkbrood disease may be spread more easily because of increased stress and the closeness of a large number of bees.

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Advantages:

1. Stations can be put in the field where they are needed and then moved when the bloom is set.
2. Stations can be moved so they don't interfere with cultural practices.
3. Stations can be moved to avoid direct insecticide application
4. Bees can be phased out in a central location.
5. Fewer bees may be "stretched" to cover a large area more efficiently.

Disadvantages:

1. Bees become disoriented and tend to drift when stations are moved.
2. The cost and upkeep of the unit is higher.
3. Each move kills some developing larvae and eggs.

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There are a number of commercially produced nesting units available on the market. Their composition and design affect many things from nesting desirability to disease levels.

Advantages:

1. They are readily accepted by bees as nesting sites.
2. Potential damage from wasp parasites such as Monodontomerus is greatly reduced.
3. Standard 4-foot bee boards are convenient to install in field shelters, to store overwinter and to sell on the open market.
4. Insect enemies can enter only through the open end of the nest hole.
5. Wood is a good insulator and readily absorbs and holds moisture from leaves used in cell construction, thereby maintaining a more stable microenvironment.
6. Wood may be easily marked for identification with paint or a hot branding iron.

Disadvantages:

1.  Initial and replacement costs are high.
2. Storage bulk is much greater than the other nesting material.
3. Transportation weight is much higher than for other nesting material.
4. Boards with a single entrance hole are difficult to sample and evaluate for bee development, survival and chalkbrood disease.
5. Effective chalkbrood suppression requires full phase out every year in addition to heat sterilization of boards.
6. Bees killed by chalkbrood fungus are a serious source of contamination of emerging adult bees that have to chew through spore laden cadavers in adjacent cells in order to exit.

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1. These have all the advantages listed for wood bee boards.
2. This type of board can be sterilized and reused by removing the back and punching out cells containing bee larvae instead of waiting until after phase out in the spring.
3. Once cells are "punched out," treatment for chalkbrood is easier by dipping cells and heat treating the boards.

1. Initially, these boards are quite expensive and may be hard to find. Reuse lowers long-term costs.
2. The bulk of boards stored overwinter equals that of standard wood bee boards.
3. Transportation and handling weight are equal to standard wood boards.
4. Parasitism may be equal or higher than standard bee boards.
5. Pollen balls may be higher than polystyrene bee boards.
6. The punching-out process may kill some overwintering bee larvae.
7. The punching-out process may help spread chalkbrood disease.
8. Punched-out bee cells (loose cells) require special handling and care in storage over winter and during incubation in the spring (see University of Idaho CIS 588, Managing Leafcutting Bees with the Loose Cell Method).
9. Loose cells are more susceptible to rodent damage during winter storage.

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1. Bees readily accept these nesting sites.
2. The boards absorb moisture and provide the same insulation quality as standard bee boards.
3. They can be taken apart to remove bee cells then sterilized and reused.
4. Loose cell management techniques apply.

Disadvantages:

1. The initial cost for material is high.
2. Board sections tend to warp and crack, making the bees vulnerable to nest destroyers and wasp parasites such as Monodontomerus.
3. Sealing backs of holes to prevent access by parasites and nest destroyers is difficult.
4. Weight approximates standard bee boards.
5. Potential parasitism by Sapyga is equal to wood boards.

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Advantages:

1. Insulation quality is superior to all other nest materials.
2. Because they are standardized, they can be taken apart to remove bee cells and then reused to lower costs.
3. Handling weight is less than standard bee boards.
4. Loose cell management techniques apply.
5. Relatively easy to disinfect.

Disadvantages:

1. The backs of nest holes cannot be readily sealed to exclude parasites and predators.
2. The initial cost is high, but reuse lowers long-term cost.
3. Leaf moisture dissipates slowly, often resulting in mould development and bee mortality.
4. Improperly assembled laminates tend to leave cracks that allow chalcid wasp parasites and nest destroyers to enter more readily.
5. These nesting materials are more susceptible to rodent and bird damage.

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Advantages:

1. Insulation quality is superior to all other nest materials.
2. Handling weight is less than standard bee boards.
3. Relatively easy to disinfect.

1. Same as those for laminated, molded sheets of styrofoam or polystyrene and disadvantages 4, 5 and 6 under solid boards given above under Section I.

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Advantages:

1. They are lightweight and less bulky.
2. The initial cost is low.
3. Cell removal is easy, and labor costs are minimal.

Disadvantages:

1. Bees will often drift if wood boards or some other more acceptable nesting material is close by.
2. There is a potential for greater parasite and nest-destroying problems.
3. Nests distort and fall apart if they get wet.
4. Cells are more susceptible to predation by sparrows, magpies, woodpeckers and other insectivorous birds and rodents.

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Advantages:

1. Holes in which bees have previously nested are especially attractive to female leafcutting bees as good nesting sites.
2. Services for punching out cells from bee boards with removable backs and for cleaning out the holes of excluded, drilled bee boards are commercially available. Most of these boards, when cleaned and heat sanitized, are superior nesting materials and cost less than new boards.
3. All bee cells are usually extracted from laminated boards and molded styrofoam sheets each fall. These nesting materials can easily be sanitized for chalkbrood control before they are reused.

Disadvantages:

1. Chalkbrood will increase if boards are not sanitized or heat treated thoroughly.
2. Not all holes will be available for renesting because filled holes from which bees do not emerge will remain capped and unavailable if the boards are not redrilled.
3. The outer one or two bees will emerge from some holes leaving only a shallow hole for renesting. Females nesting in shallow holes produce a disproportionately larger number of male offspring.
4. Heat sanitation must be accomplished with great care. Nesting material must be arranged so heated air can freely pass under and through the piled nest materials. A fan is necessary to circulate the hot air.
5. Time and labor required to prepare excluded nest materials for reuse may exceed the cost of new material in some cases.

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Advantages:

1. Buying bees may be the only way to obtain sufficient pollinators to produce a crop economically.
2. Bees imported from Canada usually are free of chalkbrood.
3. Parasite and predator levels are usually lower in imported bees reared under the loose cell system.

Disadvantages:

1. Canadian bees may be more susceptible to chalkbrood when reared under Idaho conditions.
2. Certain parasites are more prevalent in Canadian bees and require special treatment or controls.
3. Bees imported from other parts of the United States have chalkbrood levels as high as Idaho bees and in some cases have not received the proper care or treatment for parasite control.
4. Cost of bees may be high if supplies are limited.

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IX. Using the loose cell system of alfalfa leafcutting bee management.

Refer to UI CIS 588, Managing Leafcutting Bees with the Loose Cell Method, for detailed instructions.

Advantages:

1. Sanitation measures for chalkbrood control are easier because the entire cell is exposed.
2. The cells take up less space in storage and incubation.
3. Determining the number of living bees is much easier by cutting or x-raying so the number of bees being placed in the field may be estimated more accurately (7,000 females per acre were considered adequate for 1,000-pound seed set, according to early estimates. Currently most growers use 10,500 - 14,000 females per acre, or 3-4 gallons of live bees. For another way to estimate bee needs in the field, see slide show 3).
4. Loose cells are more easily diagnosed for chalkbrood, pollen masses, and other mortality factors.
5. Loose cells can be more easily processed (shaken, tumbled, screened) to remove wastes, nest destroyers and predators.

Disadvantages:

1. Initial costs for nest materials and cell stripping equipment is high.
2. More time is required to manage the bees.
3. Mistakes or carelessness can result in greater or possibly total losses.

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Sanitation is one of the most cost effective means of controlling diseases of the Alfalfa Leafcutting Bee. The main objective is to remove as many disease causing spores as possible from the bee's environment.

Advantages:

1. Dipping of loose cells in hypochlorite solution aids in suppressing chalkbrood and thus reduces bee losses.

Disadvantages:

1. Cost in time and effort to dip cells is high.
2. Dipping equipment may be expensive.
3. Dipping procedures and solution concentration must be precise to avoid bee mortality.
4. Cells must be carefully handled to avoid damage during the drying process.
5. Drying conditions must be carefully controlled to avoid mortality.
6. Fumes and liquid can be irritating and can affect human health in other ways. If mixed with ammonia or acids, hypochlorite can release chlorine gas, which can be fatal.

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Special  Precautions

Because of unusually high bee board losses due to thefts, law enforcement officials have requested that these suggestions be included here as a safety guide for buyers, sellers and owners of alfalfa leafcutting bees.

1. Brand your boards (front and back), and register your brand with the sheriff.
2. If you do not have a brand, prominently identify your bee nests with permanent ink, spray paint, etc.

1. If possible, place shelters away from well-traveled roads. Use dead-end farm roads when practical.
2. Place shelters so you and your neighbors can easily observe them.
3. The chance of theft is much greater when bees are first put out in the spring and during late summer and fall. Extra precautions are needed.
4. If you are to be away or on vacation, inform your neighbors because the "neighbor-watch" program is the most effective way to curb thefts.

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When selling, give the buyer a bill-of-sale or receipt that includes:

1. The number and identifying marks of bee nesting materials.
2. The identity of buyer and seller.
3. X-ray analysis results for the bees, to document live count in case there is some question after bees are sold..

1. Seller's identity. Check driver's license and write down identifying information.
2. If the seller has a vehicle, note the make, license number and state.
3. If bees, brands or seller are questionable, ask the local sheriff's office to run a check and verify for ownership.
4. Demand a bill-of-sale that fully identifies bees and seller.
5. Get x-ray results for % live cells and mortality factors.
6. Transact the sale by check or money order, not cash.

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Further discussion of Fall and winter management 

If you have comments, corrections, or additions to the information provided in this document, contact Karen.

CIS 538 Contents:
INTRODUCTION
WINTER 
SPRING 
SUMMER 
FALL 

OTHER 
Phase out
Shelter Size and Design
Nesting Material
Buying bees and/or loose cells
Sanitation
Avoiding theft; Purchase precautions.

ABOUT THE AUTHORS

Pollination Ecology