Given all the goings on, it is difficult to select any one presentation that could be considered a trendsetter at Apimondia ‘99. However, a paper by Dr. Denis Anderson, Research School of Biological Sciences, Australian National University, Canberra comes close. His presentation was entitled, “Are There Different Species of Varroa jacobsoni?” (Proceedings of the 36th Apimondia Apicultural Congress, Vancouver, Canada, pp. 59-62, September 1999). The conclusions hint that there may be an explosion of new knowledge surrounding honey bees and related organisms in the next century through DNA analysis.
Dr. Anderson provocatively suggests that Varroa jacobsoni, first discovered on the island of Java, may not in fact be the cause of all the problems that have been attributed to this organism. First evidence came from size discrepancies between mites on the original host (Apis cerana) and those found on Apis mellifera. Then it was discovered that V. jacobsoni found on Java could not reproduce on Apis mellifera brood. Studies in Brazil also revealed low mite fertility Finally and DNA analysis corroborated differences between Varroa on Java and mites parasitizing honey bees in Europe.
Subsequent studies by Dr. Anderson from 1996 to 1998 reported at Apimondia ’99 compared mitochondrial DNA (MTDNA) of Varroa jacobsoni on Java, parasitizing the original host (Apis cerana), with other species of Asiatic Varroa (V. underwoodi and V. rinderei) and other mites. This was then compared to MTDNA of reproducing mites found on Apis mellifera in 32 different countries. Other studies, Dr. Anderson contends, provided evidence that reproductive isolation occurs in the same geographic locality between mites parasitizing Apis cerana and those reproducing on Apis mellifera. Thus, only one mite species appears to exist in any one country or island, with the exception of the island of Luzon in the Philippines, which has two. The species are distinct enough, according to Dr. Anderson, that they can be divided into two broad kinds, called haplotypes.
The Korean haplotype is the most common worldwide, found in Africa, Europe, the Middle East, Asia and the Americas. It is also the damaging mite that all of us have come to call Varroa. The Japan-Thailand haplotype is less common, confirmed in Japan, Thailand and the Americas. This benign cousin (the original Varroa jacobsoni) does not reproduce on Apis mellifera. Could this be a reason why honey bees in Brazil and parts of Mexico tolerate Varroa without chemical treatment?
Dr. Anderson concludes that Varroa is really represented around the world by five separate species. Only one has spread from Apis cerana to become a serious parasite of Apis mellifera. This mite is not Varroa jacobsoni as described from Java, he says, and must be renamed, along with three new species found in the Philippine islands.
What this research means for the beekeeping community is not clear. If the Varroa now parasitizing Apis mellifera in much of the world with such tragic results is indeed renamed, this could make a good deal of scientific literature on this particular organism instantly out of date. Renaming the beast, however, will mean little to those most plagued by its depredations at the present time. It remains for applied research to take the next step and use this new information to help beekeepers better understand and control this pest in the future.
The verdict is in. The mite affecting honey bees so dramatically has now been officially renamed to Varroa destructor.
