Fruit flies’ ability to change genes could help climate-change research: study

Fruit flies adjust to a sudden drop in temperature by drastically changing their genes and metabolism so they can keep on buzzing around a fruit bowl, says an international study led by a Canadian researcher.

Environmental physiologist Heath MacMillan at York University in Toronto led the study involving scientists from Canada, Switzerland and Japan.

He said researchers raised fruit flies from eggs through to their maggot stages at a room temperature of 21 C, and when they were adults half the flies were transferred to a 6 C space.

When the difference between the two groups was measured six days later, researchers were fascinated at the extent to which the flies had adapted to the cold.

They adjusted to the so-called chill coma by changing about a third of their 15,000 genes, as well as half their metabolites or chemicals, MacMillan said.

“What was surprising was the magnitude, how big of a change it was.”

The finding is important because understanding insects’ temperature tolerance is a crucial step in protecting and controlling insects worldwide, he said.

MacMillan said the study, published Thursday in the journal Scientific Reports, could some day help scientists unravel the effects of climate change on insects, which represent more than 75 per cent of all animal species.

The flies that are a general nuisance to fruit lovers are often used for research because they develop from eggs to adult flies in about a week.

MacMillan said scientists are developing new ways to understand how the fruit flies’ genes interact with each other and function to help them survive at low temperatures.

Most insects are cold-blooded and don’t generate body heat internally the same way as humans but rather track it in the environment, he said.

When they’re lazing about in a fruit bowl sitting on a counter at 23 C for example, fruit flies adjust their temperature accordingly, the same way they match the temperature in a fridge if the bowl is transferred there, by going into a chill coma, MacMillan said.

They aren’t dead even if they look like they are while in the fridge because of their ability to adjust to the temperature change, he said.

The flies must respond to temperature changes in all seasons and don’t cease existing in the winter.

“They go somewhere else. They deal with those winter temperatures and those winter conditions every year,” MacMillan said. “And winter is changing an enormous amount with climate change.”

Understanding how insects respond to temperature could help scientists apply that knowledge to how climate change will affect where animals live, MacMillan said.

“For us in Canada, one of the things that is a risk with climate change is that a lot of pest species that exist for crops or medical tests and tend to live further in the south may be working their way further north.”

Many insects have already responded to climate change, he noted, including butterflies and honey bees, which are moving north in some parts of the world.