1.1 Million Bee Colonies Dead This Year ...

The information provided here was generated by a survey conducted by the Apiary Inspectors of America. They took the survey in January and February this year, and in the process, gathered information from 18% of the colonies in the U.S.

The survey found that about 35% of all the colonies in the U.S. died last winter. Of those that died, 71% died of natural causes, 29% from symptoms that are suspect colony collapse disorder. Doing the math that comes to at least 10% of all the bees in the U.S. last year died of Colony Collapse Disorder. I believe that is a significant number of colonies.

Unfortunately, the survey had to be conducted early on to get numbers to congress and the surveyers weren’t able to count the bees still under snow banks in the north. Now that the snow has mostly melted, the losses there have been found to be staggering, but it’s not known yet what proportion, if any, died of CCD. In any event, the losses now are estimated, by my survey this week anyway, to be, instead of 35%, closer to 44% of all the U.S. bees died last winter. Again, doing the math, that comes to 1.1 million colonies, just shy of what’s needed for almond pollination next spring. Hmmmm....

This survey, conducted by the Apiary Inspectors of America (AIA) in collaboration with the USDA-ARS Beltsville Bee Lab was done to not only count dead beehives, but to help determine the distribution of various bee parasites and pathogens. Preliminary results from this survey reveal:

1. Nosema (a gastrointestinal disease) levels tended to be higher in colonies collected from CCD-suspect apiaries

2. Average varroa mite-infestation levels over all sampled colonies were approaching critical levels (9.5 mites/100 bees), but levels did not differ between colonies in CCD-suspect and non-CCD suspect apiaries.

3. Israeli Acute Paralysis Virus (IAPV) was found in 9 of the 11 states sampled, and in 47% of all sampled colonies.

   The last of these finding begs the question, "What should beekeepers do who are or suspect their colonies are infected with IAPV?" To answer this question a review of both published and the most current data from multiple research efforts is in order.

What do we know about IAPV as of May, 2008?

1. What is IAPV's linkage to CCD?

   • As published in September 2007 (Cox-Foster et al, Science, 2007)
   • Among pathogens, IAPV is the most consistent indicator of CCD
   • Kasmir Bee Virus (KBV), Nosema apis, and Nosema ceranae are also indicators of CCD
   • Additional "stress" factors may be needed to activate IAPV
   • No cause and effect between IAPV and CCD was demonstrated

2. How many strains of IAPV exist in the US?

   • At least two strains, or "families", of IAPV are present in the United States (Journal of Virology, in Press)
   • One lineage is most prevalent in apiaries from the eastern and northwestern U.S. and probably was present before importation of Australian bees into the US in 2005.
   • The second strain is more frequent in sampled colonies from the western U.S. This strain matches more closely to several isolates sequenced to date from Australian package bees.
   • The strain of IAPV found in Israel that defined this newly described species, is distinct from those in the US and Australia.
   • Extensive variation in the genetic sequence of the virus suggests that the virus is rapidly changing in the U.S. or has been present as multiple lineages for some time.

3. What happens to IAPV infected colonies?

   • On-going research in Israel and the U.S. supports the assertion that IAPV can impact adult bee health and result in rapid mortality of infected bees.
   • Not all colonies with IAPV are in poor health
   • Some colonies that have IAPV can "clear" their infection to below detectable levels over time; this is perhaps due to resistance in these colonies to either varroa and/or viruses

4. How can IAPV be transmitted?

   • IAPV can move from uninfected to infected colonies within an apiary
   • While not demonstrated for IAPV, other bee viruses (DWV, SBV, BQCV) can be brought to colonies on forger pollen loads, suggesting an outside reservoir for some bee viruses (Singh, et al, poster at Eastern Branch ESA, 2008, from PSU)
   • IAPV has been detected in non-apis bees in the vicinity of IAPV positive colonies in 2007. (Singh, et al, poster at Eastern Branch ESA, 2008, from PSU)

5. How widespread is IAPV in the US?

   • As of Fall, 2007, IAPV was found in at least 19 states; and thus, the virus is widespread.
   • IAPV has been present in the US since at least 2002 (Chen and Evans, 2007).
   • IAPV seemed to have a more limited distribution in 2004 than at present (Cox-Foster et al 2007).

Considering all these factors, undue concern over IAPV detection is not warranted. While IAPV's role in colony losses remains a priority in ongoing research, we do know that high levels of other common bee viruses, such as KBV, DWV, and ABPV, have also been linked with certain incidences of high colony mortality or decline in worker numbers. We also know that nearly all bee colonies are infected with at least one type of virus and that all these viruses are potentially pathogenic.