Effect of pollen traps on the relapse of chronic bee paralysis virus in honeybee (Apis mellifera) colonies

Abstract

Pollen traps are used by beekeepers to collect pollen harvested by honeybees. Here, we set up an experiment to evaluate whether pollen traps are a risk factor involved in the development of the chronic bee paralysis, a viral honeybee disease affecting adult bees and transmitted by contact. After a recent episode of chronic bee paralysis in an apiary, pollen traps were installed on three hives while two hives without pollen traps were used as control. During the experiment, the chronic bee paralysis virus (CBPV) loads in foragers from the control hives remained lower than 108 equivalent copies of CBPV genome per bee but were higher than 1010 equivalent copies of CBPV genome per bee in the many symptomatic bees and in the hundreds of dead bees found in front of trap hives. Clinical signs of the disease persisted for 3 weeks at the entrance of the trap hives. These signs disappeared after the pollen traps were removed, accompanied by a decrease in the viral loads in foragers. Despite the small number of colonies examined, the results of this study suggest the impact of pollen traps on the relapse of chronic paralysis outbreaks in colonies infected by CBPV.