Findings could help the development of effective strategies to reduce tick populations.

A new study led by Washington State University has revealed that blacklegged ticks (Ixodes scapulars) are capable of surviving extreme cold and heat, contrary to previous research.

The research shows that only larval ticks are unable to survive periods of hot or cold conditions. Nymph and adult ticks are unaffected by extremes in weather, only dying when they run out of energy.

A hard-bodied species, the blacklegged tick is found in eastern and northern Midwest areas of the United States as well as southeastern Canada. It is a carrier of pathogens that are responsible for a number of diseases including Lyme disease, which is the most common vector-borne illness in North America. 

Jesse Brunner, lead author of the study said: “We thought we would see some evidence that if there was like a very dry period, all the ticks might be at a greater risk of dying.

“However, just the larvae were impacted by heat and dry conditions. Cold weather had even less of an impact. Somehow, they hunker down and survive great.” 

For the study, researchers placed more than 9,000 ticks in soil core enclosures located at three military bases across the east coast of the United States. Their development and survival was monitored over a three-year period to provide data on the ticks’ response to climatic conditions.

Results indicated that although tick mortality is unaffected by extreme weather conditions, it does make them use up energy supplies faster. The researchers say that this means that the hotter weather could shorten the window of opportunity for ticks to find a host.

The lifespan of tick larvae was particularly affected by frequent periods of hot and dry weather, reducing their median survival time by half.

The researchers say that the results highlight the importance of targeting interventions during the larvae stage when ticks are at their most vulnerable. They hope to develop effective strategies, such as vaccinating host species to resist ticks which will help reduce tick populations and mitigate the risk of disease transmission. 

Mr Brunner said: “The ultimate goal is to develop a comprehensive framework that can predict and effectively manage tick populations. 

“This could in turn lead to improved public health outcomes.”

The study has been published in Ecological Monographs.