Influence of virus abundances in donor colonies and nurse hives on queens of Apis mellifera during the rearing process

Abstract

Background: Honeybees are one of the three most important animals for mankind. In order to be safe and increase
number of bee colonies for pollination, the breeding of queens is necessary. For several decades, bees were selected
on economic and behavioral aspects. With the appearance of the neozootic mite Varroa destructor beekeepers were
forced to adapt their methods. Varroa destructor can act as a vector for many different bee pathogenic viruses and by
this potentiates its devastating impact.
Aim: Methods of rearing queens were not evaluated since the mites’ appearance. Besides scientific approaches, viruses
received too little attention in regard to the rearing process of honeybee queens. Herein, we present a detailed analysis
of virus abundances [Aparavirus, acute bee paralysis virus (ABPV); Triatovirus, black queen cell virus (BQCV); Cripavirus, chronic bee paralysis virus (CBPV); and Iflaviruses, deformed wings virus (DWV), Sacbrood virus (SBV), VDV-1] in breeding hives, donating first instar larvae, hives that are nursing these larvae until the pupa stage, and on queens of Apis mellifera in a breeding apiary.
Methods: Nurse and donor colonies of the queen-rearing process were sampled in the year 2020 and analyzed by RT
qPCR. Virus quantifications were correlated with queen mortalities and seasonal effects.
Results: Virus detections increased in reared queens, however, the elevated virus titers did not increase the mortality
of the queens until their exclosure. Moreover, we observed a lower interrelation between virus abundance in queens
and their original donor colonies, than between nurse hives and their nursed queens.
Conclusion: The bee pathogenic viruses ABPV, BQCV, CBPV, DWV, SBV, and VDV-1 do not influence the mortality of bee queens during the rearing process. Whether respective virus loads result in sublethal or long-term effects remains to be elucidated