Evaluation of cupric sulphate as an acaricide against Varroa jacobsoni O.
Georges Guiraud, Myriam Nectoux, Jean-Francois Andrei, Michel Bounias And Dragutin Popesković
Field trials on hives showed that cupric sulphate mixed at 0.25-1 g/l with sucrose syrup yielded significant control (>70% mortality) of the parasitic mite, Varroa jacobsoni, in low or moderately infested areas, in spring-, autumn- and winter-feeding treatments. Pure sucrose may also exhibit a light effect (15-29% mortality). Syrups are freely ingested up to 0.35 g/l and the uptake decreases at 0.5-1 g/l, with no uptake observed at higher concentrations. Only slight bee mortality (<0.1%) is observed at 1 g/l (low volumes) or at 0.5 g/l (large volumes). Copper residues in honey never significantly increased from natural levels, following total uptakes of up to 3g per hive, within 1 to 7 months delay.