Formic acid-based treatments for control of Varroa destructor in a Mediterranean area.

Abstract Two formic acid autumnal treatments, gel packets (BeeVar formulation) and impregnated paperwick (Liebig-Dispenser), were tested in apiary to evaluate their effectiveness against Varroa destructor Anderson & Trueman and their residues in honey in a Mediterranean region (Sardinia, Italy). Both treatments were efficient in the apiary control of the varroosis, with values of percentage of mite mortality ranging between 93.6 and 100%, without statistical differences between them. The more gradual release of formic acid from the gel application allowed a longer action (2 wk for each treatment) compared with the Liebig-Dispenser (≈3 d for each treatment). The rate of daily evaporation ranged between ≈5 and 9 g/d from BeeVar and ≈26 and 35 g/d from the Liebig-Dispenser, in the first and second treatment, respectively. The total amount of formic acid administered per hive during all the treatment period was ≈200 g for either treatment. A significantly higher adult bee mortality was recorded in the Liebig-...