Persistence, Seasonal Dynamics, and Regional Differentiation of the Parasitic Mite Tropilaelaps mercedesae in Apis mellifera L. Colonies Under Non-Endemic Climatic Conditions.

Tropilaelaps mercedesae is an emerging parasite of Apis mellifera L. that is expanding beyond its traditional tropical range, yet its ecology in temperate regions remains poorly understood. This study investigated the establishment, seasonal infestation dynamics, morphometric variation, and virus carriage of T. mercedesae populations in three climatically contrasting regions of temperate Eurasia: Sochi and Makhachkala (Russia) and Zhetisay (Kazakhstan). Honey bee colonies were monitored throughout the annual cycle to assess infestation in relation to brood availability and seasonal climatic conditions. Morphometric variation was evaluated using six diagnostic body measurements, and virus carriage was determined by reverse-transcription polymerase chain reaction for seven major honey bee viruses. Infestation patterns of T. mercedesae differed among regions but consistently followed seasonal brood availability. Morphometric analysis revealed geographic differentiation among mite populations, with canonical discriminant analysis correctly classifying 70.9% of specimens. Four viruses were detected in the mites, with deformed wing virus present in all regions and the greatest virus diversity observed in Makhachkala. Together, these results indicate that T. mercedesae can establish persistent populations across a broader climatic range than previously recognized. They also provide important information for surveillance, risk assessment, and the development of management strategies for this emerging honey bee parasite.