Heat waves powered by climate change make insects infertile, new study suggests

Heat waves seem to sterilize male insects, a discovery that has serious consequences in a world of rising temperatures and mass extinction.

A new study found that heat waves reduced sperm production in beetles by three-quarters and halved the amount of offspring they could produce.

With huge drops of insects that have already been recorded by scientists from Germany to Puerto Rico, the findings are once again a huge source of concern for scientists.

Heat waves such as those that hit a lot of the northern hemisphere this summer seem to rise and become more intense as the average temperature on Earth rises.

The scientists suggested that their findings could even have consequences for people, as previous work has shown that heat shock has the power to cause infertility in mammals.

"We know that biodiversity suffers from climate change, but the specific causes and sensitivities are difficult to identify," said Professor Matt Gage of the University of East Anglia, who led the research.

"We have shown in this work that the sperm function is a particularly sensitive property when the environment is warmed up, and in a model system that represents an enormous amount of global biodiversity."

Beetles such as the red flower beetle used in the study represent a staggering quarter of all biodiversity on earth, with about 400,000 species so far.

In the study of the team, which was published in the journal Nature CommunicationsBeetles were exposed to simulated heat waves 5-7 ° C for five days over optimal conditions.

They then followed this work with experiments to assess the damage to reproductive success and sperm function, as well as long-term effects on offspring.

After the initial exposure had reduced the chances of reproducing, a second heat wave made them virtually sterile – producing only 1% of the offspring produced under normal conditions.

"Insects in nature are likely to experience multiple heat wave events, which could pose a problem to population productivity if male reproduction can not adapt or recover," said Kirs Sales, a PhD student who led the study.

To make matters worse, the effects of heat stress seem to cross generations. The descendants of heat-wave shocked fathers lived a shorter life, and the sons produced fewer offspring from their own country.

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Recent studies have shown that in some areas up to 75 percent fewer insects have fallen, an effect that is linked to everything from overuse of pesticides to destruction of habitats.

With insects playing a vital role in supporting global biodiversity and pollinating plants, scientists have warned that their loss will cause "ecological armageddon".

"Because the sperm function is essential for the reproduction and viability of the population, these findings can explain why biodiversity suffers from climate change," Professor Gage said.

"Heat waves are particularly damaging extreme weather conditions. It is known that local extinctions occur when temperature changes become too intense.

"We wanted to know why this happens and an answer could be related to sperm."

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