Patterns in Varroa destructor depend on bee host abundance, availability of natural resources, and climate in Mediterranean apiaries

Publisher： John Wiley & Sons Inc

E-ISSN： 1365-2311|41|5|542-553

ISSN： 0307-6946

Source： ECOLOGICAL ENTOMOLOGY, Vol.41, Iss.5, 2016-10, pp. : 542-553

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Abstract

1. Varroa destructor Linnaeus (Acari: Varroidae) is one of the greatest threats to apiculture. This study examines the role of host density, natural resource availability for bees, the management and climate in driving spatial and annual variability in the abundance of Varroa, and the occurrence of colony losses, recorded in apiaries across a Mediterranean island over a 2‐year period, using a hierarchical generalised linear model framework.

2. The seasonal abundance of Varroa showed a bimodal pattern with two peaks, the first one being in spring and larger than the second one located in summer/autumn. In contrast, bee colony losses were mainly concentrated in autumn/winter.

3. The abundance patterns of Varroa were best explained by models combining host, climate, and resource availability. A key novel finding was that low availability of natural flowering resources leads to high levels of infestation of Varroa, highlighting the importance of preserving natural resources around apiaries for the maintenance of pollination services in the landscape. Varroa abundance was also found to increase as bee density increased, probably as a result of the greater brood availability. Moreover, Varroa abundance increased as temperatures decrease and decreases as relative humidity increases, which is consistent with previous studies. Anti‐varroa treatments were only found to impact Varroa levels in the second 6 months of the year. Organic treatments outperformed synthetic treatments.

4. Empirical research on optimal seasonal timing and combinations of treatments, as well as impacts of climate and resource availability on natural dynamics of bees and Varroa in different climate zones, is urgently required.