Effects of Genetic Origin of Honeybees and Climate on Prevalence and Infestation Levels of Varroa

SIMPLE SUMMARY: Varroa is a parasite of honeybees and is one of the main problems that beekeeping faces worldwide: it affects honey production and is involved in colony losses reported in some parts of the world. The objective of this study was to assess the effect of honeybee genetic origin, climate type and the interactions between these two variables on the prevalence and infestation levels of Varroa in a large population of 1134 colonies. The morphotype, haplotype and climate type of each colony were determined. The results indicate that the climate has an effect on the prevalence and infestation levels of Varroa: both were higher in the temperate sub-humid climate than in the semi-warm climate and the warm sub-humid climate. The morphotype has no effect: there were no differences between Africanized, European and Hybrid honeybees for the prevalence and infestations levels of Varroa. The haplotype has an effect on prevalence but not on infestation levels, and the African haplotype has a higher prevalence than the European haplotype, but no differences were found between the two haplotypes for infestation levels of Varroa. Correlations between Varroa infestation levels and mean annual temperature, mean annual precipitation, winter precipitation and the Lang index were found. ABSTRACT: The objective of this study was to evaluate the effect of honeybee genetic origin, climate type and the interactions between these variables on the prevalence and infestation levels of Varroa in a large population of honeybee colonies (n = 1134). For each colony, the morphotype, haplotype and climate type were determined. No differences between the Africanized, European and Hybrid morphotypes were found for the prevalence and infestation levels of Varroa (p > 0.05). Differences between honeybee haplotypes were found for the prevalence of Varroa (p < 0.05), and the prevalence was higher in the African haplotype than in the European haplotype. No differences between honeybee haplotypes were found for the infestation levels of Varroa (p > 0.05). Differences were found between climate type for the prevalence and infestation levels of Varroa (p < 0.05): the temperate sub-humid climate had a higher prevalence and higher infestation levels than the semi-warm climate and the warm sub-humid climate. Correlations between the infestation levels of Varroa and mean annual temperature, mean annual precipitation, winter precipitation and Lang index were found.