A new study finds that habitat loss from climate change and large-scale agriculture are combining to reduce global insect populations, with each problem making the other worse.
While insects can bother people at times, they are also important in pollinating plants for people to feed on, making the soil more fertile and include beautiful butterflies and fireflies. Scientists have observed a dramatic decline in both the total number and diversity of insect species, a process called slow death by 1,000 reductions. Those reductions include pesticides and light pollution.
Large single-crop agriculture that leaves less habitat and foliar food for bugs and higher temperatures from climate change are major problems for insects, but a new study in the journal Nature Wednesday looked at more than 750,000 samples of 18,000 different species of insects. Aadhar says that it is not just those two dangers acting on their own. It is how habitat loss and climate change interact that really destroys bug populations.
In about half of the cases where insect numbers were reduced, the researchers found that climate change and habitat loss from agriculture were exacerbating each other. In more than a quarter of cases of biodiversity loss, that is, fewer species, the same dynamic was at work.
“We know insects are at risk. Now we’re getting a great deal of control over what threatens them and how much,” said study author Charlotte Othwaite, an ecologist at the University College of London.
“In this case, habitat loss and climate change could often be worse than if they were acting on their own, as one can make the other’s impact worse and vice versa,” Outheit said. “If we’re only seeing these things individually we’re missing part of the picture.”
For example, monoculture agriculture often reduces tree shading, making it warmer in a given location. On top of that comes climate change, she said. Then insects that need relief from the heat or move north for cooler climates can run into problems with a lack of proper habitat from large farms.
This is especially a problem in countries like Indonesia and Brazil, where forests are being cleared and temperatures are warming more than in other parts of the world, Outhwaite said.
It’s tough on insects like the pesky midge.
“Cocoa is mainly pollinated by midges and people don’t like midges. You know they are annoying ones that bite you, they annoy you at picnics,” Outhite said. “But if you like chocolate you should appreciate it because without them we would have very little cocoa.”
The same can be said of bees, which are facing a tough time with climate change and warming from single-crop farming, Outheit said.
According to the US Department of Agriculture, insect pollinators are responsible for about a third of the human diet. And 2 in 5 species of invertebrate pollinators, such as bees and butterflies, are on the verge of extinction, said a 2016 UN Science report.
What makes this study important is that it is the first to link together climate change and industrial agriculture to harm insects, said University of Connecticut entomologist David Wagner, who was not part of the study. Because the study used many different specimens and species and looked around the world, that gives more credibility to its findings, Wagner said.