Surveillance of Varroa destructor in Honey Bees: A One Health Approach and Epidemiological Modelling

Introduction
Varroa destructor is one of the major drivers of honey bee colony decline worldwide. Beyond its direct parasitic effects, this mite facilitates the transmission of viral pathogens, particularly Deformed Wing Virus, resulting in increased colony mortality and reduced productivity. Within a One Health framework, honey bee health is closely linked to biodiversity conservation, crop pollination, and food security.

Methods
A descriptive observational study was conducted on 120 honey bee colonies distributed across three ecological zones: intensive agricultural areas (n=45), peri-urban areas (n=35), and semi-natural areas (n=40). Infestation levels of Varroa destructor were assessed from March to September 2025 using natural mite fall counts and alcohol wash methods on standardized samples of 300 bees per colony. Environmental variables including temperature, relative humidity, vegetation cover, apiary density, and proximity to pesticide-treated crops were recorded. Multivariate statistical analysis was performed to identify risk factors associated with high infestation rates.

Results
The overall mean infestation rate was 5.6 ± 1.9%. Colonies located in intensive agricultural areas showed significantly higher infestation levels (7.1%) compared with peri-urban (5.3%) and semi-natural areas (3.8%). Clinical signs suggestive of viral infection were observed in 42% of heavily infested colonies. Colonies exceeding an infestation threshold of 6% demonstrated an average 28% reduction in adult bee population and increased risk of autumn weakening. Moderate temperatures (22–28°C) and high brood density were significantly associated with accelerated parasite population growth.

Conclusions
Integrating parasitological and environmental data improves early surveillance of Varroa destructor and facilitates identification of high-risk colonies. This integrated approach provides a strategic tool for sustainable pollinator protection within a One Health perspective.