Conditions for the Potential Northward Expansion of Ranges of the Main Vectors of Lyme Disease and Tick-Borne Encephalitis (Based on the Example of the Magadan Region and Norway)

Introduction: Climatic conditions determine the spread of the main vectors of ixodid tick-borne borreliosis and tickborne encephalitis in Eurasia.
Objective: : To assess the conditions of possible changes in the boundaries of the ranges of the main vectors of Lyme disease and tick-borne encephalitis based on the examples of the Magadan Region and the west coast of Norway.
Materials and methods: Feasibility of forming populations of the main vectors of ixodid tick-borne borreliosis (tick-borne encephalitis) is determined by the calendar date of the meeting of individuals with the host, which ultimately determines whether the egg-laying and nourished ticks manage to get the necessary amount of heat to complete development. In this context, an analytical and theoretical study was undertaken to establish the potential of emergence of independent vector populations in two regions. The analysis was carried out in Microsoft Word 10 by comparing different ten-day variants of the tick feeding time frames and indicators of the soil surface heat supply (allowing or not allowing thermal constant gains) during the warm period, when the average monthly temperature does not fall below the threshold value for the development of these phases (+10 °C).
Results: Currently, the emergence of independent populations of the taiga tick in the Magadan Region is unlikely due to the impossibility of obtaining required values of thermal constants for the completion of embryogenesis in a certain time span. The emergence of independent populations of forest mites on the west coast of Norway is related to the possibility of gaining thermal constants of development by overwintering ovipositors in the required period of time.
Conclusion: Given the values of the thermal constants of development of the main vectors of Lyme disease and tickborne encephalitis, it seems possible to propose a science-based forecast of the northward expansion of their range due to expected climate change.

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