Climate change: Heatwaves 'halve' male insect fertility

Rodiano Bonacci
Novembre 15, 2018

Half the beetles who experienced the heatwave could produce after and a second heatwave nearly sterilized the exposed males.

New research suggests that male fertility could be threatened in the years to come by the onset of climate change. Females, however, were unaffected. "We've shown in this work that sperm function is an especially sensitive trait when the environment heats up, and in a model system representing a huge amount of global biodiversity", explains Matt Gage, the research group leader.

A rise in temperature caused by climate change could pose a significant threat to male fertility, research has shown.

"Two concerning results were the impact of successive heatwaves on males, and the impacts of heatwaves on future generations", said Sales.

'Since sperm function is essential for reproduction and population viability, these findings could provide one explanation for why biodiversity is suffering under climate change. With the insects that experienced the heatwave, fertility in male insects was reduced by three quarters, and any sperm that was produced couldn't migrate to the female insect, and ending up dying before fertilization took place.

When males were exposed to two heatwave events 10 days apart, their offspring production was less than 1 per cent of the control group, researchers said.

Climate change is affecting biodiversity around the world, but the drivers remain poorly understood.

For the goal of their study, the team studied the red flour beetle (Tribolium casteneum) to see what effect the heatwaves have on male fertility in insects. "Insects in nature are likely to experience multiple heatwave events, which could become a problem for population productivity if male reproduction cannot adapt or recover".

The research also shows that offspring sired by heatwaved dads - or their sperm - live shorter lives - by a couple of months. "A warmer atmosphere will be more volatile and hazardous, with extreme events like heat waves becoming increasingly frequent, intense and widespread", he continues.

"Our research shows that heatwaves halve male reproductive fitness, and it was surprising how consistent the effect was", Kirs Sales, a postgraduate researcher who led the research, said.

Could doctors one day issue alerts warning would-be parents to avoid conceiving during heatwaves, to avoid potential genetic damage? Local extinctions are known to occur when temperature changes become too intense.

The team hope that their findings can help inform conservation efforts.

"We'd really like to know what the mechanism of this trans-generational damage is", he said.

Attempting to find the underlying causes of male vulnerability to climate change, the researchers found that the male beetles were mating half as frequently as the control subjects.

A study published in the journal Demography this year found that "sexual behavior probably wasn't the explanatory factor" behind dips in conception during heatwaves, Gage said.

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