DIAGNOSIS OF ACUTE PARALYSIS - APPLICATION TO EPIDEMIC HONEYBEE DISEASES IN FRANCE DURING 1990

Varroa jacobsoni is the vector of acute paralysis virus (APV). Its injection into the hemolymph by the acarian mite induces particular symptoms in brood and bees. These symptoms can be mistaken for those of foulbrood, sacbrood or acarian disease. At first, the diagnosis of APV was determined by gel immunodiffusion (IDG): the virus was isolated from larvae infected by APV and inoculated into healthy bees maintained at 35-degrees-C and with 50% of hygrometry. Two or three days later, the virus was isolated from dead bees and purified, and then an immune serum prepared in rabbit and used for IDG diagnosis. In 1990, the diagnosis of APV, chronic paralysis (CPV) and sacbrood (SVB) was made in all samples sent to the laboratory. In 78 samples, APV was found only 6 times, twice associated with European foulbrood. On the other hand, an increase in American foulbrood, European foulbrood and sacbrood was found. The decrease in prophylaxis of brood diseases to the exclusive detriment of varroatosis treatment, and the widespread use of pesticides against Varroa jacobsoni are probable explanations for this increase. At the foraging bee level, the chronic paralysis virus diagnosed in a large number of hives partly explains the depopulation. The synergistic effect between pesticides and meteorological conditions should also be taken into consideration.