David VanderDussen (NOD Apiary Products) has prepared a Summary of “Take Home Messages” on Mite Control, Nosema, and an IPM Strategy for Canada. The article, written for Hivelights and reproduced on the CHC website, gives an overview of presentations made at the Colony Health Symposium at the Canadian Honey Council AGM (January 2008).

Here’s a quick “summary of the summary” —
For details, please see David VanderDussen’s article at http://www.honeycouncil.ca/users/folder.asp?FolderID=6171.

Dennis vanEngelsdorp:
Update on CCD in America

“The current situation in the US is in flux, but there are reports of up to 90% colony losses in CA in colonies staged for 2008 almond pollination, occurring over a 2-week period,” Dennis vanEngelsdorp reported. “No single factor explains CCD, and multi-factor analysis has been initiated to see which factors in combination may cause collapse.”

He noted that residues of the active ingredients in Apistan® and Checkmite+® (i.e., fluvalinate and coumaphos respectively) can build up in both wax and pollen within the hive, reaching levels where the pollen becomes toxic to bees.

Richard Rogers:
Opportunities for Improving Honey Bee Health

Resistance to Apistan® and Checkmite+® are now widespread, Richard Rogers reported. He identified Varroa control as the key management issue for beekeepers. “Queens have been found emerging with varroa from their cells and with Deformed-Wing Virus.”

Dr. Albert Robertson:
Saskatraz Breeding Project

Dr. Robertson discussed the Saskatraz project, aimed at breeding “productive, gentle honey bees with tolerance to mites and brood diseases” identified by natural selection and monitored for honey production, Varroa levels, and other factors.

One particularly interesting point: “It was concluded that severe varroa infestations can cause CCD symptoms and experiments are under way to test whether severe mite stress can trigger pathogenic virus expression.” The breeding program continues.

Dr. Robert Currie:
Varroa Mite Resistance & Tolerance in Selected Honey Bees – “Environmental Impact”

Dr. Currie discussed mite loads and the thresholds that beekeepers should strive to stay under, as well as the winter activity of Varroa mites and Varroa tolerance indicators for those involved in breeding programs. He emphasized the need for beekeepers to “stay on top of monitoring their mite infestation levels and apply a registered treatment of formic acid (or some other acaricide) early in fall to make sure early or late fall thresholds are not exceeded.”

Dr. Ernesto Guzman:
Alternative Treatment for Varroa Mite Control

Dr. Guzman talked about the process leading to focusing on three methods of applying thymol that will be further assessed this year. He reported the results of thymol test already conducted, and indicated that temperature is a significant factor.

Dr. Stephen Pernal:
Nosema

In Dr. Pernal’s session, following a detailed discussion of both Nosema apis and Nosema ceranae, a question was raised about the effective time frame for FumagilinB after the bees take it up and store it in the hive, when fed as recommended.

Answer: “Based on older work, it is clear that if fumagillin is fed at prescribed doses, any medicated feed stored in the comb retains some activity until the spring…. The activity is no doubt lower than in the fall, but it reinforces the fact that the reason the treatment works is that bees continue to consume the medicated feed throughout the winter.”

Treatments for nosema control being tested at Beaverlodge Research Farm included “various dosages and application techniques” of fumagillin, thymol, albendazole and VitaGold. Of these, fumagillin was most effective in trials.

See:
• Summary of Take Home Messages- CHC — AGM January 2008 — For Mite Control, Nosema, and an IPM Strategy for Canada
  Canadian Honey Council
  2008 Symposium Theme: Colony Health
  David VanderDussen, NOD Apiary Products, Ontario