$1 MILLION QUESTION: HOW DO INSECTS WEATHER ENVIRONMENTAL STRESS?
COLUMBUS, Ohio – Two Ohio entomologists have received two grants totaling $1.1 million from the National Science Foundation to study how insects can survive extremely cold weather and other harsh environmental conditions.
One of the grants will help the researchers learn how an Antarctic midge – a wingless, mosquito-sized insect – can live for more than 300 days a year encased in ice, and also how it withstands inevitable environmental stressors once the ice melts. They'll use the other grant to study rapid cold hardening – a survival mechanism by which insects swiftly acclimate to extremely low temperatures.
"Insects produce specific proteins in order to survive severe stress," said David Denlinger, a professor of entomology at Ohio State and a grant co-recipient. "These proteins seem to help an insect endure times of extreme heat and cold, and also dehydration and even desiccation."
Denlinger shares the award with Richard Lee, a professor of zoology at Miami University of Ohio.
Antarctica's largest insect, Belgica antarctica, is frozen in ice for nearly 11 months of the year. Life improves only slightly for the midge during Antarctica's summer season, when the ice melts and the insect thaws out. Then it often faces environmental challenges, such as high levels of nitrogen runoff from penguin rookeries and seal wallows, as well as severe dehydration and even completely drying out. But somehow, it survives.
The researchers will study so-called heat-shock proteins, which insects and other animals produce for protection against exceedingly high temperatures.
"Even our bodies make these kinds of proteins when we have a fever," Denlinger said. "Interestingly, insects produce these very same stress proteins during times of low temperature as well as during exposure to high nutrient levels, dehydration and desiccation."
Denlinger and Lee want to learn how the proteins help protect insects from these environmental challenges. The researchers will head to Antarctica this December, where they will collect midges to bring back to Ohio to study.
They'll use the other grant to study rapid cold hardening in flesh flies, an insect that lives in more temperate climes but still must deal with the hardship of cold winter weather.
"Rapid cold hardening allows insects to continuously fine-tune their physiological function and performance to match even modest temperature changes," Denlinger said. "We're looking for the physiological basis for this kind of rapid response."
Again, the researchers will investigate the function of heat-shock proteins. Flesh flies turn on these proteins when they enter diapause – a hibernation-like state many insects enter in cold weather.
"Any time this insect enters diapause, it turns on these stress proteins and keeps them on the entire time it's dormant," Denlinger said.
The researchers will knock out the genes that produce heat-shock proteins to see how the genes' absence affects the duration of diapause, as well as the insects' tolerance to cold temperatures.
"We hope to gain a more comprehensive understanding of the integrated physiological events that enhance low temperature survival and also allow insects to adjust their physiological performance to match daily changes in environmental temperatures," Denlinger said.