Virulence of Varroa destructor in Colonies of Honey Bee Apis mellifera

Although Var r o a mite infestation of honeybee is widespread throughout the world, data about the level of infestation in the bees of our area are inadequate.Var r o a mite infestation was first detected in Iraq in the mid-1980s.A large investigation was carried out to determine Var r o a infestation level in the apiaries of Duhok Province, Northern Iraq.Otherwise, this study aimed to clarify the parasitic effect of the mite Varroa destructor on the mandibular and hypopharyngeal glands of Apis mellifera.A total of 1000 samples of adult workers of different ages from more than 20 separated apiaries were collected from August to the end of October 2013.Caped brood, drone and worker brood, from five apiaries were examined.A total of 450 newly emerged workers from three separated apiaries of the same area were collected during the late summer 2013.Effects of Var r o a infestation on mandibular glands and hypopharyngeal glands of newly emerged workers of honeybees were investigated.High level of the infestation was found in all apiaries of Dohuk region and may act as a risk factor to the bee health.Results showed significant differences in the size of hypopharyngeal gland acini of newly emerged workers infested with one to three mites compared to noninfested newly emerged workers, while only newly emerged workers infested with three mites showed significant differences in the size of mandibular glands as compared to noninfested newly emerged workers.Management strategies of the mid-and late summer treatment are necessary to keep the mite population at low levels before and during the period when the winter bees emerge.Considerable numbers of Var r o a mites can be controlled inside bee colonies without chemicals by removal of drone pupae or sometimes if necessary removing generations of worker pupae before emergence as adults.Using movable screened bottom boards in the opposite side of the hive entrance for the observation and counting naturally felled down Var r o a mites were very beneficial in this area during hot summer periods.