Science & Environment

Warming world harming insects' reproduction, says study

Fruit fly (Image: Science Photo Library) Image copyright SPL
Image caption Short-term exposure to a rise in temperature can cause long-term damage to insects' ability to reproduce

A warming world harms insects' ability to reproduce, which could have long-term consequences, scientists warn.

UK researchers also found that insects in northern latitudes were more vulnerable than their southern-dwelling cousins.

The team added that many insects were unable to move great distances while they are juveniles. Therefore, they are at risk from a warming climate.

The findings have been published in the Journal of Evolutionary Biology.

"You get an extreme heat weather event that [the insect] cannot escape from because they are juveniles, so they can't move as much," explained co-author Rhonda Snook from the University of Sheffield, UK.

"They live through it because it does not kill them, but then they have the subsequent problem of reproducing."

Lasting damage

Dr Snook said the insects in the team's experiments were exposed to a temperature increase of 5.5C (9.9F) for 10 days, which was enough to cause permanent damage to the insects' ability to reproduce.

She said the team was interested in studying the effect of temperature rises in organisms that were unable to move away from their immediate environment.

"Lots of insects in their juvenile stage can't move very far because they are larvae or because they are small nymphs - they are smaller and they do not have wings so they are not as mobile so they're stuck where they are."

Dr Snook told BBC News that the team carried out the experiments on fruit flies but she expected the results to be replicated in many other insects.

"I think that this is going to be a very common effect, a very common phenomenon across insects."

The team examined the effect of increased ambient temperature rise on two populations of fruit flies: one from Spain and another from Sweden.

"We showed that the one that evolved in a colder temperature (Swedish fruit flies) was less resistant to these extreme weather events than the southern (Spanish) population. That wasn't known before.

Dr Snook explained that the Spanish flies had evolved where the predominant selection pressure was likely to have been heat.

"If your predominant selection pressure in the north is cold then you're going to be selected to be able to respond really well to that," she added.

"And the idea here is that you can't do both very well."

While global average temperatures are not projected to increase by 5.0C or more, climate modellers have suggested that extreme weather events, such as heat-waves and droughts, are set to become more frequent. In these events, localised temperatures are set to meet the conditions in which insects' ability to reproduce will be harmed.

Dr Snook suggested that any change in insect populations could result in changes in ecosystems, but to what extent would require further research.

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