title: New experimental data on use of rotenone as an acaricide for control of Varroa destructor in honey bee colonies.
abstract: Three slow release experimental rotenone formulations were tested to evaluate their effectiveness against Varroa destructor Anderson & Trueman in colonies with sealed brood and to determine whether they left residues in honey and bees wax: we evaluated cardboard strip containing 1 g rotenone and two types of polyvinyl chloride (PVC) strips containing 1 (high-dose) and 0.5 (low-dose) g of rotenone, respectively. In general, the efficacy of the treatments, expressed as percentage of mite mortality, was highly variable in all treatment groups (range, 0-96.8%). The highest effectiveness was obtained with the high-dose-PVC strips, which caused an average percentage of mortality ranging between 47 and 69% in the adult bees and sealed brood, respectively. At the end of the treatment, rotenone residues ranged between 0.03 and 0.06 and 1.5-144.0 mg/kg in honey and wax, respectively. Rotenone residues in wax were still detectable 4 mo after the treatment period, whereas no residues were found in honey. The higher residues content and persistence recorded in wax samples, was probably due to the lipophilic nature of rotenone. A reduction in the amount of adults was recorded for the group treated with high-dose-PVC strips compared with the untreated colonies. Toxicological risks connected with the use of rotenone and the low maximum level recently fixed by European legislation (0.01 mg/kg) suggest that rotenone is not a good candidate for reducing varroa populations in honey bee colonies.
authors.affiliation: Dipartimento di Protezione delle Piante, Sezione Entomologia Agraria, University of Sassari, Sassari, Italy. albsatta@uniss.it
authors.forename: Alberto
authors.initials: A
authors.lastname: Satta
authors.forename: Ignazio
authors.initials: I
authors.lastname: Floris
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Caboni
authors.forename: Paolo
authors.initials: P
authors.lastname: Cabras
authors.forename: Martin
authors.initials: M
authors.lastname: Eguaras
authors.forename: Gustavo
authors.initials: G
authors.lastname: Velis