Hi all

I was wondering when the term “virulent” was first attached to varroa mites. The earliest clear reference (1983) I could find places the term in scare quotes. They write



> In the case of V. jacobsoni it seems unlikely that a ‘virulent’ strain has arisen simultaneously in two different areas and a possible link between the origin of the two outbreaks should be sought.



Griffiths, D. A., Gray, J., Pegazzano, F., & Cavalloro, R. (1983, June). Varroa—The acarologists' view. In Varroa jacobsoni Oud. affecting honey bees: Present status and needs. Proceedings, EC Experts' Group Meeting, Wageningen (pp. 79-83).



The term was picked up by Morse and all, and expounded upon in 1984:



> This article examines the evidence about the virulence of Varroa in tropical, subtropical and temperate parts of South America. All of the Varroa there are apparently descended from a population introduced into Paraguay in 1971 in an influx of bees from Japan. Yet the effect on beekeeping has varied greatly in the different parts of the continent.



> While we observed that Varroa infestations are less damaging in tropical than in temperate areas of South America, German investigators have noted a high rate of infestation in warm (but temperate) regions of the Rhine Valley, and a lower rate in colonies at a higher altitude.



> It is not yet known why the mite populations remain lower in tropical climates, but Ritter and De Jong found that in tropical Brazil a much larger percentage (40--75%) of female mites entered brood cells without reproducing than in the German Federal Republic and Turkey (about 20%). And among those mites leaving offspring, the average reproductive success per female was found to be lower in Brazil.



> The finding that Varroasis is not invariably a terminal disease for honeybee colonies, at least in the South American tropics, will be especially encouraging to beekeepers in many developing countries.



de Jong, D., Gonçalves, L. S., & Morse, R. A. (1984). Dependence on climate of the virulence of Varroa jacobsoni. Bee World, 65(3), 117-121.



Obviously, this “virulence" is reproductive behavior on the part of female mites. Mites that are more successful at reproducing will multiply much more quickly in the colonies. The association between varroa and viruses was first noted by Bailey, in 1982



> By contrast, much acute paralysis virus has been detected in dead bees sent to Rothamsted from Moscow, USSR, where it was associated with Varroa jacobsoni and with the mortality of many bees in the field. Only when the virus is injected does it quickly multiply and kill bees, so it may be transmitted by V. jacobsoni when the mite pierces the body wall of adult bees to feed.



> Two further important points issuing from the discussions in this paper are the inadvisability of (1) transporting bees from one country to another, since this risks the spread of exotic and potentially dangerous pathogens that are difficult to detect, and (2) keeping many more colonies than can support themselves on the natural forage available. The second point is difficult to assess, but it is of fundamental importance to the long-term economy of beekeeping. Beekeepers may be tempted to keep too many colonies after an unusually good season. They can often profitably harvest honey after an exceptional nectar flow in their area, although their colonies are far too numerous to support themselves under average conditions. The total harvest may well be greater than that obtained with colonies able to forage more effectively. But if the colonies are to be maintained for long, they must be supplied with much sucrose syrup after poor or indifferent seasons. The imprudence of this practice has long been appreciated by the more perceptive beekeepers but it can easily be ignored, especially when the price of sugar is low relative to that of honey. In such circumstances endemic infections will increase, especially by those viruses and other pathogens that are transmitted only when live bees come into close contact, as discussed above. Varroa jacobsoni also may well be of this kind, because it multiplies more rapidly than usual in infested colonies when these become unusually numerous in a locality.



Of course, this final paragraph falls on deaf ears



P







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