CBRF Projects 2000

Adony Melathopoulos¹,

Bill Ruzicka², and

John Gates³

1.     Agriculture & Agri-Food Canada, Beaverlodge,AB

2.     Bill’s Honey Farm, Kelowna, BC,

3.     Ministry of Agriculture and Food, Vernon, BC

Fungi are a major source of disease among the mites of the world. The fungus Hirsutella thompsoni was among the first to demonstrate the ability to kill mites. Preliminary work suggested the fungus kills Varroa in the laboratory. Field experiments were conducted in 2000 to determine the dose and formulation required to kill Varroa in bee colonies. Colonies treated with H. thompsoni were evaluated in southern British Columbia and were compared to colonies treated with Apistan or colonies left untreated. Population growth through the summer for colonies treated with H. thompsoni was not significantly different from that observed in colonies left untreated, however growth was higher than in colonies treated with Apistan. The fungus, however did not negatively influence the production of honey or bee populations. The results suggest continued improvement in the formulation and application technology of H. thompsoni is required before the fungus can be used to control Varroa in colonies.

The full report of this project was published in Hivelights Vol 13 #4, December 2001

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K.E. MacKenzie¹,

R.E.L. Rogers²,

J.P. Parkman³,

J.A. Skinner³,

R.S. Daniels⁴ and

D. Nelson⁵

1.     Agriculture and Agri-Food Canada, Kentville, NS;

2.     Wildwood Labs, Kentville, NS;

3.     University of Tennessee, Knoxville, TN;

4.     Trail, BC; and

5.     Agriculture and Agri-Food Can., Beaverlodge,AB.

Formic acid is an alternate treatment to fluvalinate for the control of Varroa mite.  Yet, formic acid is a hazardous material that should be handled with great care.  A membrane-permeation device for formic acid has been developed.  Field trials in 1999 found that although formic acid vapors are released throughout the 28-day test period in honey bee colonies, the release rate reached only 5 g per day, somewhat less than is desired.  Thus, further investigations of alternate packaging were carried out. 

A texturized bladder was designed in the hopes of increasing permeation through a larger surface area.  Problems in manufacturing meant that this approach was abandoned and instead larger non-textured bladders were produced.  In addition, a laboratory comparison of liquid versus gel formulation found that the gel showed enhanced permeation.  Larger bladders charged with formic acid gel were used for field trials during the fall of 2000. 

Field trials were carried out in three locations in 2000: Beaverlodge, Alberta; Kentville, Nova Scotia and Knoxville, Tennessee.  Varroa mites were present in low numbers at both Canadian sites while populations have been present in Tennessee for many years.  Thus, both release rates and mite drop were monitored at all three sites.  In Alberta, an Apistan treatment was compared to the permeation device.  However, little comment can be made about bladder performance at the two Canadian sites because of low mite numbers there.  In Tennessee, Apicure, Apicure 2X and Apilife VAR  treatments were compared to the bladder method.  Preliminary data analyses find the bladder to provide less Varroa control than the other methods.  Formic acid permeation from the bladders under different temperature regimes is currently being examined.

The effect of formic acid treatment on residues in honey has received insufficient attention.  We examined three techniques to assay for formic acid residues in honey: acid-base titration, spectrophotometry and ion-chromatography, for such an analysis.  The latter, ion chromatography, was determined to be the technique of choice.  Residue analyses of honey from a worst-case scenario formic acid trial run in Tennessee found mean residues levels to be 616 ppm. I.e. approximately 6 times the naturally occurring level in honey. This compares favorably to the World Health Organization allowable daily intake of 0-3 mg/kg body weight/day. 

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Mark Winston

Department of Biological Sciences, Simon Fraser University, Burnaby, BC

The objective of our CBRF-funded project was to determine if Integrated Pest Management methods could be used to reduce the frequency and amount of synthetic chemical pesticide use in bee colonies. We compared standard Apistan treatments to Apistan/Thymol and a full IPM system using hygienic queens, screened bottom boards, and thymol. After one year, all treatments produced the same amounts of honey and showed no differences in brood or adult populations. While the Apistan treatment had fewer mites, the mite levels in the other treatments were below an economically important threshold. If these results continue in the next year's research, they will indicate that pesticide reduction is biologically feasible, economically sound, and environmentally desirable.

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