The Ixodes scapularis tick, which causes Lyme disease in North America, is more resistant to environmental conditions, such as extreme temperatures, than previously thought, scientists report.
Research to date has suggested that even when extreme temperatures – extreme cold or hot – last for a short time, they easily eliminate ticks. However, the latest observations by scientists from Washington State University (USA) in collaboration with researchers from the Cary Institute of Ecosystem show that only tick larvae are affected. On the other hand, these arachnids in the nymphal or adult stage are very little affected by extreme temperatures in the environment. An article on this topic appeared in the journal “Ecological Monographs”.
Resistant to extreme temperatures
The studies were conducted on ticks of the species Ixodes scapularisthat carry, among others, the spirochetes that cause Lyme disease in North America (in Europe, it is a different species of tick). The works were located in three military bases located along the eastern coast of the USA. More than 9,000 ticks were placed in soil samples and monitored for three years for their development and survival in different climatic conditions, both in terms of temperature and humidity. It turned out that extreme temperatures and humidity deficiencies (drought) shortened the survival of tick larvae by almost half, but not adults or nymphs. In the case of later stages of tick development, depletion of energy reserves was important for mortality. “We expected to see that in the very dry season, all ticks may be at higher risk of extinction.” However, the hot and dry conditions only affected the larvae. Short temperature had an even smaller effect. Somehow the ticks lurked and were able to survive, said lead author Jesse Brunner of the paper.
In the stage, the larvae are most sensitive to external conditions
According to scientists, the latest research indicates that the tick population is increasing I. scapularis is less constrained by extreme environmental conditions than previously thought. However, the effect of temperature on larval survival may slow down the growth of these arachnid populations, especially in drought conditions. Experts believe that studying the impact of environmental conditions, including climatic conditions, on the survival of various stages of tick development, as well as on their transformation into subsequent stages, can help to better cope with the spread of these arachnids, and with them dangerous vector diseases, that they transmit, including Lyme disease. The study shows, for example, that it is worth focusing on the impact on tick larvae, because at this stage they are most sensitive to external conditions. This is important because with climate change ticks began to appear in habitats where they were absent before.
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