He and his colleagues collected adult and larval midges during field study tours to Antarctica in early 2005 and 2006. They gathered insects from penguin colonies, where the midges feed on algae and waste material.
Penguins live along the Antarctic coast, where the average summertime temperature is around 36°F (2°C). In laboratory experiments, the researchers exposed the larvae and adults to 39.2°F (4°C) and to 68°F (20°C). They wanted to see if the larval and adult midges showed any resilience against the higher temperature.
Adult Antarctic midges usually live only a week or two in the field and, in the laboratory, the adults lived for five to six days at the lower temperature. But adult midges exposed to the higher temperature died in less than a day.
However, the larval midges lived up to four days at the higher temperature ?four times longer than the adults.
"The adults were considerably less heat-tolerant than the larvae," Denlinger said. "The larval midges continuously express heat-shock proteins and are therefore prepared to respond to the normal kinds of challenges that they face in the harsh Antarctic environment. But the adults produce these proteins only when directly confronted with an environmental challenge.
"Clearly there is some kind of developmental switch that happens between the larval stage and adulthood," he added. "We're just not sure what that is."
He said that the next step is to study larval midges during the long Antarctic winter. While temperature may not play a large role during this time, as the larvae are encased in ice for months, many insects respond to seasonal changes in day length, which regulate their development. Understanding what happens to larvae during this time
Source:Ohio State University