Varroa Disease in Honey Bees*

The International Symposium on Varroa Disease was organized by the Central Board of Apiculture of the Ministry of Agriculture and Food Industry of the Bulgarian People’s Republic following the initiative of the International Federation of Beekeepers’ Associations – APIMONDIA. It was attended by approximately 30 apiculturists and beekeepers of Bulgaria, Romania, USSR, and Yugoslavia. In Bulgaria, Varroa disease had widely spread of late. Many of the localities with apiaries infested by Varroa disease are in the zone of the Bulgarian border with Greece, Romania, Turkey and Yugoslavia. The Romanian experts reported that no such mite has been found to exist in their country. In Yugoslavia, no investigation has been made in this respect. No literature exists either in Greece or Turkey reporting existence of the parasite there. In 1975 and 1976, Varroa disease was found in Argentina and Uruguay. There is a possibility of this disease to also exist in the northern region of Africa. According to Bulgarian experts, Varroa jacobsoni was identified in Bulgaria in 1964-1965 or a little later. Most often, the bee and drone larvae on the lower part of combs are invaded by Varroa jacobsoni. In autumn, all brood is infested. This mass invasion of larvae and pupae causes their death. The death of unsealed brood reminds of the foulbrood infestation. When the invasion is strong, which usually occurs in autumn, bees would leave the hive, or, in December, the whole colony would die. This usually happens three or four years after the parasite has infested the colony, when the infestation rate exceeds 30%. The supply of great quantities of sugar syrup in autumn, the mixed invasions and infections, as well as other unfavourable factors foster the fast development of Varroa disease. Two biological characteristics specific to the parasite makes its control difficult: (1) it concomitantly infests the brood and adult bees, and (2) it multiplies very fast, twice and a half faster than the cycle of bees’ development. In Bulgaria, Varroa disease is controlled by imported drugs such as chlorbenzol, Folbex, Milbex, Amilix, as well as phenothiazine, moth balls, etc. The most efficient and promising seems to be “Varroatin”, (phenothiazine + paraformaldehyde), under the form of tablets, produced in Bulgaria. Each package containing 120 tablets includes special wicks; 1-3 tables – according to the strength of the colony, and wicks are introduced, fumigating, in the hive. In Bulgaria, the control of Varroa disease and of other bee diseases is made by the veterinary service in co-operation with the public control teams, beekeepers, agricultural experts, etc., who are paid for their inspection of each colony. All beekeepers’ associations existing in Bulgaria make up the Central Council of Apiculture under the Ministry of Agriculture and Food Industry (Prof. S. NEDYALKOV). Prof. YURUKOV, Deputy Minister of Agriculture, is the Chairman of the Council. At the Symposium, Dr. N. ZAKHARIEV, Chairman of the regional Council of Apiculture, read a report on the activity of the Council of Apiculture in Pleven county, dwelling on the stages of development of the disease. In the first stage, the number of parasites in the colony is small, with no real infestation possibilities. In the second stage, their number increases, the colony becomes weak because of the death of bees, and is robbed by stronger colonies. Both in the first and second stages, healing is possible whether “Varroatin” is used. In the third stage, the infestation is strong, 6-8 mites existing on each bee; now bees would leave the colony. Dr. N. DIMITROV reported about the control of Varroa disease in Plovdiv county. In that region, 35,000 colonies exist, 10,000 belonging to the apicultural farm, the rest being handled by amateur beekeepers. The major methods of control of Varroa disease include: study by experts of the biology of the parasite, and the methods of controlling Varroa disease; minute inspections, and registration of all bee colonies; assessment of the stage of infestation, and quarantine measures; sanctioning of the beekeepers who did not supply the drug in due time; drafting of special directions for the use of Varroatin and phenothiazine, and talks in this respect with beekeepers. Special groups for the control of Varroa disease were instituted, following which the invasion is now minimum. In the new directions for use of Varroatin, before introducing the fumigating tablets, it is recommended to smoke the colony – through the hive entrance –, so that bees should fill their sacks with honey. Tablets are then introduced. The hive entrance is closed for 20-30 minutes, with a wet cloth or paper. Into a weak colony (3-4 frames with bees) a tablet is introduced; into a medium strength colony (4-7 frames) – two tablets; and into a strong colony (7-10 frames) – three tablets. Treatment is made twice, both in spring and summer, and 4 times in autumn, every three days. The parasites fall and die in 2-3 days (Dr. D. IANEV).