APIS Volume 19, Number 1, January 2001
In this issue
- Biological Control in Beekeeping:
- Hive Beetle Hints:
- Citrus Canker in Florida: The Eradication Effort
- Pi Chi Omega Honey Bee Project:
- Roger A. Morse Lecture and Study Fund:
- February Bee Workshops:
BIOLOGICAL CONTROL IN BEEKEEPING:
Most organisms have natural enemies. The use of parasites/parasitoids, predators and diseases is a time-honored way to help control pest populations, be they insects, weeds, mammals or others. This is called biological control <http://ipmwww.ncsu.edu/biocontrol/biocontrol.html>. For example, the ancient Chinese moved ant nests into orchards to protect their citrus trees. Perhaps the most famous example of biological control is purposeful introduction into California of the vedalia beetle from Australia in 1889 to control cottony cushion scale, which was introduced from the same country a few years before <http://www.ifas.ufl.edu/~insect/fruit/cottony_cushion_scale.htm>. "Cottony cushion scale was causing infestations so severe in California citrus groves that growers were pulling out their trees and burning them. Orchard values were plummeting. Yet, by the fall of 1889, the pest was completely controlled in the areas of introduction. The vedalia beetle literally saved the California citrus industry, and since the California success, it has been exported to many other parts of the world, often with equally successful results <http://www.nysaes.cornell.edu/ent/biocontrol/predators/rodolia_cardinalis.html>".
Because they have been relatively inexpensive and effective, the beekeeping industry has used pesticides to control many insects and mites that are associated with honey bees. As these chemicals have undergone more and more scrutiny, however, many have fallen by the wayside while others are also at risk of losing their label. As a consequence, biological control is becoming more important as a possible alternative and can be an important way to help beekeepers get off the "pesticide treadmill <http://www.ourplanet.com/txtversn/84/dinham.htm>."
The wax moth is a large problem in many areas, especially in hot climates in empty supers that are stored for any period <http://bluehen.ags.udel.edu/deces/beekeeping/wax%20moth.htm>. Traditionally, several chemicals have been used to fumigate empty supers. These include ethylene dibromide (EDB), which now has no label and so cannot be employed; paradichlorobenzene (PDB), still labeled; aluminum phosphide, labeled in some states; and carbon dioxide (CO2). Only the latter can be used on comb that contains honey, but it is dangerous, difficult to handle, and costly. Freezing can also protect comb honey (five degrees F for 24 hours will kill all stages of wax moth). Some beekeepers use cold rooms to store empty supers. The chemical of choice for fumigation at present continues to be PDB <http://pmep.cce.cornell.edu/profiles/rodent/pdb/>, but there remains concern that this material may be targeted for elimination by regulatory authorities.
A few years back, a biological control was found for wax moth. This was a specific strain of bacteria called Bacillus thuringiensis that proved deadly to wax moth larvae. The formulated product called Certan® was effective against moth larvae when applied as a spray on combs, but because of little demand for the product at the time, it was discontinued. Other strains of B. thuringiensis, often just called Bt, are available for other lepidopteran pests, but are less effective on wax moths <http://helios.bto.ed.ac.uk/bto/microbes/bt.htm>. I received the following from David Eyre in Canada <admin@beeworks.com>: "I am pleased to report that Certan is alive and well and capable as always in the fight against wax moth. Available from The Bee Works, 5 Edith Drive, R R # 2, Orillia. Ontario. L3V 6H2. Canada., Phone:- 705 326 7171,Fax:- 705 325 3461 <http://www.beeworks.com/>. Although good news, be aware that this is a Canadian company and the material is not registered in the United States as far as I can tell, and so cannot be legally used. Always check to ensure chemicals can be legally used and they have an appropriate label before purchasing them.
Another biological control against wax moth is a tiny parasitic wasp called Trichogramma. Franz Bollhalder has written an article published in Bee Biz(No. 11, Spring 2000, p. 14) on this topic <http://www.beekeeping.com/bee-biz/index.htm>. According to Mr. Bollhalder, five batches of Trichogramma were released at three-week intervals in 12 comb stores owned by Swiss beekeepers from the beginning of June to the end of August. Cardboard discs were used to deliver the wasps’ ready-to-hatch eggs. In seven of the comb stores, wax moths were controlled to the extent that no damage occurred in spite of massive infestation pressures found in most testing areas. Two important points for this to be successful include installing close-fitting doors on comb storage facilities and checking newly stored combs for wax moth infestation. Compelling reasons to use Trichogramma include its ease of application, lack of residue problems and no need for a label.
Mr. Bollhander concludes in his paper: "Six releases @ 450 to 500 Trichogramma from mid-May (calendar week 21) in 3-week intervals are sufficient for treating a comb store of maximum volume 0.8 cubic metres. The additional, sixth, release compared with the previous year extends the Trichogramma application by three weeks. This is necessary for successful use in warmer areas, where the wax moth season lasts longer <http://www.beeman.dircon.co.uk/waxmoth.htm>." More information on acquiring and managing Trichogramma can be found on the World Wide Web <http://www.cips.msu.edu/ncr125/GuideTricho.htm>.
A much tougher biological control problem is for tracheal and Varroa mites that have plagued beekeepers in the United States since the early 1980s. These critters are much more intimately associated with honey bees as they share the same nest. Tracheal mites live most of their lives inside the honey bees’ breathing tubes (tracheae) <http://members.edventures.com/custom/wr/terms/t/trachae/termbrowser.html>, which greatly protects them. Nevertheless, some fumigants like those from menthol crystals and/or formic acid appear to work at least on a limited basis, but are dependent on ambient temperature for greatest effect <http://www.ifas.ufl.edu/~mts/apishtm/threads/tracheal.htm>.
Because Varroa is found on the exterior of adult honey bees, it is more vulnerable than the tracheal mite <http://www.ifas.ufl.edu/~mts/apishtm/threads/varroa.htm>. One line of research is being conduct at the Rothamsted bee research facility of the United Kingdom’s Institute of Arable Crops Research (IACR). Fungi are the most promising natural enemies of Varroa, according to Katie Shaw (katie.shaw@bbsrc.ac.uk). "At least 13 commercial fungal products have already been developed for specific pests in horticultural and agricultural systems, consisting of spore formulations that are applied directly to the target <http://www.iacr.bbsrc.ac.uk/res/depts/entnem/research/briangrp/kshaw/tkshaw.html>."
A specific fungus has been found that makes Varroa sick, according to A. Melathopoulos, B. Ruzicka and J. Gates in Canada. Their paper, "Can You Make Varroa Sick?" appears in HiveLights (November 2000, pp. 15-16), the official organ of the Canadian Honey Council <http://www.honeycouncil.ca/>. The authors investigated the effect of introducing spores of the mite-killing fungus, Hirsutella thompsoni into bee colonies <http://www.honeycouncil.ca/chc-ccm/docs/november.pdf>. They compared the effectiveness of two formulations (spray and dust) with formic acid and Apistan®. According to the results, H. thompsoni shows considerable promise in preliminary experiments, but more needs to be done to develop a proper formulation and improved delivery method <http://www.ifas.ufl.edu/~mts/apishtm/Apis_2001/Hirsutella/BCHPA2000HIRSUTELLA/sld001.htm>.
Besides fungi, information has recently appeared on Internet discussion lists <http://bee.airoot.com/beeculture/digital/1999/column6.htm> that some beekeepers have observed lower Varroa populations in honey bee colonies with populations of pseudoscorpions <http://www.ag.ohio-state.edu/~ohioline/hyg-fact/2000/2062.html>. Although they also can prey on honey bees, the fact that these arthropods feast on mites, among other creatures found in a hive, suggests they might be a viable biological control option <http://insects.ummz.lsa.umich.edu/MES/notes/entnote16.html>. D. Caron and K. Ross in the second edition of Honey Bee Pests, Predators, and Diseases (Cornell University Press, 1990), edited by R. Morse and R. Nowogrodski indicate these arthropods have been detected in beehives from Brazil to India. In that publication, the authors conclude: "In general, the question of whether the benefits of pseudoscorpions to honey bees are outweighed by the harm they cause is unresolved." Thus, it appears that not enough is known about pseudoscorpions at this time to consider them as a viable biological control option. In addition, there may be great risk to bee colonies if these creatures are inappropriately transferred from one habitat to another. This has been called the "Nemesis Effect," and must be taken seriously when considering the introduction of any species for biological control or other reasons <http://www.ifas.ufl.edu/~mts/apishtm/apis99/apmay99.htm#2>.
HIVE BEETLE HINTS:
A couple of small hive beetle hints that I recently got from Mr. Laurence Cutts, Florida’s chief apiarist:
- Control of Varroa will keep beetle populations from exploding, as there are more bees to deal with the problem in the colony.
- Keep a fluorescent light on all the time shining on the honey house floor. This attracts beetle larvae, which can then be scooped up in a shovel and put in water where they quickly drown.
- Remove bottom boards from stacks of stored supers so larvae can drop out of the stacks and be attracted to the fluorescent light.
For other information on small hive beetle, consult the APIS World Wide Web site <http://www.ifas.ufl.edu/~mts/apishtm/threads/smbeetle.htm>.
CITRUS CANKER IN FLORIDA: THE ERADICATION EFFORT
According to the USDA’s Animal and Plant Health Inspection service, "Of all of the agricultural pests and diseases that threaten citrus crops, citrus canker may be one of the most devastating. Citrus canker is a highly contagious disease caused by the bacterium Xanthomonas axonopodis pathovar citri. An infestation can destroy entire crops, but the disease poses no health risk to humans or animals.
"Between 1986 and 1992, citrus canker was found at 13 locations in 4 Florida counties. Some locations involving groves consisted of a single property while others in residential areas included as many as 240 properties. An eradication program was carried out as a joint effort between the Florida Division of Plant Industry and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). The program consisted of surveys to detect infected trees, removal and destruction of infected and adjacent trees, and regulatory activities necessary to prevent the spread of the disease.
"By the time the program was completed, 580 trees were destroyed at 281 residential properties and 33,263 trees were destroyed in 5 commercial groves. The last positive tree was found in Manatee County in January 1992. Based on a 2-year period in which intensive surveys found no infected plants, eradication of citrus canker in Florida was declared in 1994. Following the declaration of eradication, relatively little survey activity has taken place in the previously infested areas <http://www.aphis.usda.gov/oa/ccanker.html>."
Unfortunately, the disease has returned to the Sunshine State. It was first detected again in the counties of Dade and Broward in 1995, Manatee in 1997, Collier in 1998, and Palm Beach, Hendry and Hillsborough in 1999 <http://doacs.state.fl.us/canker/canker-florida.pdf >. The Florida Department of Agriculture and Consumer Services (DOACS) has again embarked on an ambitious plan to eradicate the disease. Governor Bush has declared a state of emergency in affected areas and increased funding has been appropriated for the effort.
On a World Wide Web site dedicated to this problem, Agriculture Commissioner, Mr. Bob Crawford says: "The only known eradication method is cutting down and disposing of infected or exposed trees. Inspectors with our department are inspecting citrus throughout the state. You may have already been visited and found to have infected or exposed trees on your property, which have been or will be cut. I appreciate the sacrifices you are making as part of the effort to put an end to this serious problem. I am committed to trying to save the millions of backyard fruit trees throughout the state that have not yet been impacted by canker as well as our $8.5 billion commercial citrus industry <http://doacs.state.fl.us/canker/message.htm>."
A wide range of organisms and/or phenomena spreads canker. These include wind-driven rain, flooding, air currents, insects, birds, and human movement within groves over short distances. Overhead irrigation may also play a role in spreading the bacteria. Movement of infected plants, seedlings, propagative material, and fruit is the primary means of spreading the canker pathogen over larger distances. Contaminated clothing, tools, packing boxes, and other items associated with harvesting and postharvest handling of fruit are also potential sources of infection. Canker bacteria survive and multiply primarily in naturally occurring lesions <http://www.aphis.usda.gov/oa/ccanker.html>.
Questions concerning whether honey bees spread canker continue to surface. There is no scientific evidence to my knowledge that this is the case. The insects generally implicated are those that damage the plant in some form such as leaf miners <http://www.ifas.ufl.edu/~insect/CITRUS/citrus_leafminer.htm#intro>. Honey bees are benign in that sense; they also usually confine their activities to blossoms. Although the bees themselves may not contribute to canker spread, the activities of beekeepers in groves are far more suspect. Anyone working in canker areas must take great pains to disinfect people and equipment. Specific soaps for personnel, quaternary ammonium chloride solutions (for tools and equipment, including vehicles), steam, hot water and detergent are all recommended as found on the World Wide Web site <http://doacs.state.fl.us/canker/decontamination.pdf>.
Given the seriousness of the situation, one can expect growers to be nervous and conservative about allowing access to Florida groves this spring. Beekeepers contemplating moving to the orange this year, therefore, should plan ahead and contact grove owners well in advance to determine what the situation is with regard to canker in their area. The beekeeper armed with specific knowledge about the canker eradication program, who communicates that he or she has a good grasp of the situation, including a plan to reduce the risks involved, stands the best chance of getting access to citrus groves this coming season.
PI CHI OMEGA HONEY BEE PROJECT:
Many times we hear of pest control operators only in the context of killing honey bees. Imagine pest control specialists, however, working with insects to help feed people and give them a chance to rise above poverty. This is the basis behind Pi Chi Omega’s honey bee project. Pi Chi Omega is a National Professional Pest Control Fraternity that promotes education within the pest control community <http://www.pestweb.com/Pichi/Purpose/purpose.html>. This year the organization celebrates its 50th anniversary with a reception at Purdue University’s Entomology Hall in honor of John Osmun, the founder of the fraternity. According to the December 2000 issue of the fratenity’s newsletter, for its 50th year, the fraternity has set a goal of raising enough money for 100 donated beehives. The first year the program donated 8 colonies, the second 72 and so far in 2001, 63 hives have been committed.
The hives are donated through Heifer Project International, which provides animals (and training in their care) offering hungry families around the world a way to feed themselves and become self-reliant. <http://www.heifer.org/>. Because of Pi Chi Omega’s efforts, the United Nations offered to assist Heifer Project by providing a full-time honey bee assistant in Ghana. Pest Control Technologymagazine <http://www.pctonline.com/> is also promoting this effort as part of a supplement devoted to the fraternity’s 50th year celebration <http://www.pctonline.com/articles/article.asp?ID=1326&AdKeyword=pi+chi+omega>
One does not have to be a member of Pi Chi Omega to donate. Send checks, payable to Pi Chi Omega — Beehive Project, to the executive director, Dr. William Jackson, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403
ROGER A. MORSE LECTURE AND STUDY FUND:
In response to a great outpouring of grief and sadness at the passing of Dr. Roger A. Morse <http://www.ifas.ufl.edu/~mts/apishtm/apis_2000/apjun_2000.htm#4>, the Department of Entomology at Cornell University is inviting concerned beekeepers to carry on his work through The Roger A. Morse Apiculture Lecture and Study Fund <http://cuinfo.cornell.edu/Direct/departments/?keyword=entomology&action=Search&case_sensitive=No>. To donate, send a check made out to Cornell University (write Roger A. Morse Fund #053905 on the memo line) to The Roger A. Morse Fund, Cornell University Development Office, College of Agriculture and Life Sciences, 272 Roberts Hall, Ithaca, NY 14853.
FEBRUARY BEE WORKSHOPS:
The Clay County Cooperative Extension Service is sponsoring a short course Saturday, February 3, 2001 from 9:00 a.m. to 3:00 p.m. at the Clay Country Agriculture Center in Green Cove Springs < http://www.ifas.ufl.edu/www/extension/map/clay-county.htm>. Speakers include myself, Laurence Cutts, Jerry Latner and Dr. Alonso Suazo, who will discuss the latest findings in his research on small hive beetle. Cost is $10.00 per person; registration deadline is February 1. Make checks payable to Clay County 4-H Foundation/BeeSC and mail to P.O. Box 278, Green Cove Springs, FL 32043-0278, phone (904) 284-6355 <http://www.ifas.ufl.edu/~mts/apishtm/Apis_2001/clay_county_honeybee_short_cours.htm>.
The following Saturday the annual snowbird beekeeping meeting will be held at Archbold Biological Station. The February 10 event will be from 10:00 a.m. to 3:00 p.m. Onsite registration is $6 per person/$10 per couple, with lunch costing another $6 per person. This meeting was conceived by the late Dr. Roger A. Morse in 1997 and held every year since. The program features a tribute to Dr. Morse and an update on bee inspection and small hive beetle research in Florida. For further information, contact Paul Cappy in New York 607-749-2364 or Tomas Mozer in Florida 904-829-2911 <tommozer@hotmail.com>. For detailed information about the Archbold station, consult the World Wide Web <http://www.archbold-station.org/abs/visitorinfo/visitor.htm>.
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
©2000 M.T. Sanford "All Rights Reserved"
