Global warming is cutting fertility

Heat waves damage the sperm of insects to make them almost sterile, a new study on the effects of climate change on insects found.

According to researchers, this could have the same effect on humans: infertility is increasing and global warming contributes to a planet where it is increasingly difficult to procreate. The question concerns above all the males. The study, published in Nature Communications, was carried out by the English University of East Anglia where a research team investigated the possible damage from global warming on the beetle Tribolium castaneum, a widespread insect worldwide known for the problems it creates to cereal crops. The idea behind the experiment was to understand the potential damage of heat waves on reproductive capacity.

Scientists created this laboratory, where heat conditions of five or seven degrees higher than an optimal thermal value have been simulated, thus finding a reduced fertility in male insects. Damage that could be transmitted to the progeny of the beetles and that add to the set of factors that - according to international scientists - in recent years are leading to a real «ecological armageddon» in which we have already lost 75% of flying insects in the last 30 years.

The exact causes that lead to the loss of species and balance in ecosystems are still under study. «We do not know if our research explains the widely recognized collapse of the biodiversity and the abundance of insects, but the limits of the ability to reproduce beetles will certainly not help» said Matt Gage of the University of East Anglia, who led the study.

In the analysis, the researchers found that a five-day heat wave in the lab reduced sperm production by three quarters of male beetles, while females were not directly affected. «Our research shows that heat waves halve male reproductivity, and it was surprising how consistent the effect was» added Kirs Sales, co-author of the study. According to scientists, the same effects could be found in mammals, as well as in humans.

«We have shown in this paper that the sperm function is a particularly sensitive feature when the environment warms up. Because sperm function is essential for population reproduction and viability, these findings could provide an explanation of why biodiversity is suffering from climate change», continued Gage.

Among the data collected it also appears that the offspring generated by the "overheated" beetles live on average a decidedly shorter life. The insects generated, among other things, result to produce less offspring. «It is believed that beetles make up a quarter of biodiversity, so these results are very important for understanding how species react to climate change» researchers said. Through the new study, they hope to indicate models that predict the vulnerability of species and to help inform the world about the need for immediate and shared actions against global warming.