STYLE

Insects' carnal urges curbed by storms on the horizon, says new research

10/02/2013 05:41 EDT | Updated 01/23/2014 06:58 EST
LONDON, Ont. - A little rain can put a real damper on a bug's sex life, says a new study led by researchers at the University of Western Ontario.

Curious about folklore that suggests animals — even humans — physiologically sense coming storms and alter their behaviour accordingly, biologists Jeremy McNeil and Christopher Guglielmo, in conjunction with researchers at the University of Sao Paulo in Brazil, studied the mating activities of insects under changing atmospheric conditions.

They tracked sexual behaviour under stable conditions, falling air pressure and increasing air pressure of three different bugs: the curcurbit beetle, the true armyworm moth and the potato aphid.

What they found was that all three sensed a drop in air pressure signaling impending rain and chose self-preservation over sex, curbing their carnal urges.

"Decreasing atmospheric conditions means storms, so you're going to have wind and rain and everything else," McNeil said.

"Well, if you're the size of an aphid, which is a very tiny sap-sucking plant-feeder, a rain drop hitting you while you're sitting on the edge of a leaf holding on with only two of your three pairs of legs is pretty damn dangerous."

With a storm on the horizon, the male curcurbit beetles were less interested in females and made fewer courtship efforts. Basically, they cut out the foreplay.

The loss of interest is an adaptation that "reduces the probability of injury and death of insects, which makes sense if you consider that high winds and rainstorms are life-threatening for them," Jose Mauricio Simoes Bento, of the University of Sao Paulo, said in a statement.

Among moths and potato aphids, females significantly reduced their calling behaviour when the atmosphere foretold of rain, and mating activity declined.

Small wonder, McNeil said.

"If there is turbulence, and it's the male that will be seeking the stationary female, there may be some that respond by going 'Whew. Dangerous.' And therefore there will be delay and they may search the following night if it gets better."

McNeil said the next step will be to study whether, as the insects age, they might be more willing to take risks for a sexual reward.

The study is published in the latest issue of the journal "PLOS ONE."

Previous studies have shown that insects, mammals, birds, reptiles and fish all have adapted to detect imminent changes in weather.

For example, flying ants swarm and fly off just before seasonal rains begin, and birds and bees are usually in their nests when storms hit.

MORE:cpStyle