Fuente: PubMed "apis mellifera" Vet Res Commun. 2026 Jul 29;50(5):490. doi: 10.1007/s11259-026-11440-9.ABSTRACTVarroa destructor is one of the most important threats to Apis mellifera in warm climates, where extended brood-rearing cycles facilitate exponential growth of the parasite. In attempts to control this mite, Spanish legislation (RD 608/2006) currently mandates one annual treatment in autumn, although this strategy often fails to prevent the parasite from compromising colony health. Here, the mite reduction and safety of supplementing this mandatory treatment (amitraz in slow-release strips, Apitraz®) of A. m. iberiensis colonies in Guadalajara (Spain) with a spring application of slow-release oxalic acid (Calistrip®: Biox) was evaluated. Accordingly, the size of the mite population and colony vigour were compared in colonies that received "Conventional" treatment (autumn amitraz only) or "Combined" treatment (spring OA and autumn amitraz). Spring OA treatment produced a 96.7% reduction in the Varroa population relative to the 173.2% increase in the conventional group, decreasing the mite load to 10.3 mites/colony. By late summer, the colonies that received the combined treatment exhibited significantly greater vigour, with 42.2% more adult bees (approximately 20,200 vs. 14,200, p < 0.05). Moreover, these colonies entered autumn with a 25-fold lower mite load, optimizing the final reduction in the mite population (98.7%) and achieving a minimal residual load (1.4 vs. 63.1 mites, p < 0.01). No adverse effects were observed with this combined treatment, confirming the safety of this regime. Consequently, we conclude that a spring intervention with OA helps preserve the health of bee colonies, boosting their overwintering potential in temperate regions while mitigating selective pressure for resistance to synthetic acaricides.PMID:42525312 | DOI:10.1007/s11259-026-11440-9