Projecting the impacts of climate change on habitat distribution of Varroa destructor in Ethiopia using MaxEnt ecological modeling

Globally, Varroa destructor has been identified as a major drivers of honeybee colony losses. Climate change may worsen its effects by creating conducive conditions for its reproduction, although our understanding of their interaction remains limited. This study hypothesizes that climate change alters the suitable habitat for V. destructor in Ethiopia. It investigated its habitat distributions under current and future climate change scenarios (ssp126, ssp245, and ssp585) using the Maximum Entropy Model (MaxEnt) across the study area (1.16 million Km²), based on 62 occurrence points and 22 predictor variables (19 climatic, 2 topographic and 1 agroecological). Habitats were classified into five categories using natural breaks: unsuitable (<0.10), low suitability (0.10-0.28), moderate suitability (0.28-0.48), high suitability (0.48-0.69), and very high suitability (>0.69). The average AUC and TSS values were 0.908 and 0.7, respectively, indicating excellent model performance and strong agreement between observations and predictions. Under current climatic conditions, approximately 46.4 % of Ethiopia's land mass (538,046.35 km²) is classified as having low to very high suitability for V. destructor. The most significant factors influencing its distribution are annual temperature (43.2 %), agroecology (14.7 %), precipitation of the driest quarter (12.1 %) and annual precipitation (10.2 %). The annual temperature favorable for V. destructor incidence ranges from 5 °C to 16.5 °C, with a notable decline in incidence as temperatures increase to 30 °C. This aligns with the predicted high concentration of suitable habitats in the cool-humid and sub-humid agroecological zones. However, suitable habitats are expected to decline under future climatic conditions. Under ssp585, suitable habitat for V. destructor is projected to decline by 13.72 % by the 2030s and by 31.66 % by the 2090s. Overall, under current and future climate conditions, suitable habitats are concentrated in the cool-humid and sub-humid agroecological zones. Therefore, research and management interventions should target these areas to contain the mite's spread and impact.