Risk assessment of veterinary treatments in bee brood and adult honey bees

Abstract

Amitraz and tau-fluvalinate are veterinary treatments administered for the control of Varroa destructor in honey bee colonies. These treatments can generate harmful residues for bees. This field study addresses the issue under two scenarios: 1) administration according to the posology and 2) placing contaminated wax containing the treatments. Tau-fluvalinate (Apistan®) residues were detected in larval stages from 25.34 to 84.72 ng g−1 in scenario 1 and from 29.63 to 173.97 ng g−1 in scenario 2. In addition, it was detected in bee bread in scenario 2 from 55.72 to 573.79 ng g−1. In scenario 1, DMPF + DMF (amitraz metabolites) were found from 37.09 to 171.58 ng g−1 (Amicel®) and from 36.74 to 42.64 ng g−1 (Apivar®) in bee bread. In honey, DMPF + DMF ranged from 19.96 to 145.30 ng g−1 (Amicel®) and from 32.20 to 78.43 ng g−1 from (Apivar®). With these treatments, a significant reduction in the population of Varroa mites (mean ± s.d.) was observed between 95.15 ± 2.56% and 98.29 ± 1.97%. There were significant positive correlations between Amicel®, the population of adult bees and the population of brood during evaluation 2 showing a higher effectiveness. According to both RQ (Risk Quotient) and SRA (Standard Risk Approach) values for adult bees and larvae, there is no risk when considering exposure by contact or by ingestion of bee bread or honey. In scenario 2, there is no risk for most of the larval stages, except in two bee hives treated with tau-fluvalinate, where the SRA values were 1.73 and 1.29%, indicating a moderate risk due to acute oral exposure.