Hotter weather could spur crop-eating bugs

HUNGRY FOR MORE::If the planet’s temperature rises by 1.5°C, wheat and rice losses from insects would rise by a third as insects’ metabolisms speed up, researchers said


Sat, Sep 01, 2018 - Page 7

A warmer world likely means more and hungrier insects chomping on crops and less food on dinner plates, a new study suggests.

Insects consume about 10 percent of the globe’s food, but that figure would increase to 15 to 20 percent by the end of the century if climate change is not stopped, said study lead author Curtis Deutsch, a University of Washington climate scientist.

The study looked at the damage bugs like the European corn borer and the Asiatic rice borer could do as temperatures rise.

It found that many of them would increase in number at key times for crops. The hotter weather would also speed up their metabolism so they would eat more, the researchers reported in Thursday’s journal Science.

Their predictions are based on computer simulations.

“There’s going to be a lot of crop loss, so there won’t be as much grain on the table,” said study co-author Scott Merrill, an ecology professor at the University of Vermont.

The researchers calculate additional losses of 48 million tonnes in wheat, rice and corn from hungry bugs if the temperature rises another 1.5°C from now.

The study estimates that in that warmer scenario, US corn, wheat and rice losses from insects would jump by a third.

Bug damage to Russia’s rice crop would jump sixfold, and nine countries — North Korea, Mongolia, Finland, Kyrgyzstan, Georgia, Bhutan, Armenia, the UK and Denmark — would see at least a doubling of wheat loss from bugs.

If there are no drastic cuts in emissions from coal, oil and gas, the world would reach that 1.5°C mark and extra insect loss in about 2050 — give or take a decade or so, Deutsch said.

“In the history of agriculture, one of the most important themes is the continuing struggle between farmers and insects,” said Chris Field, director of the Woods Institute for the Environment at Stanford University, who was not part of the study. “Based on this study, climate change tilts the balance in the insects’ favor.”

The Russian wheat aphid is a good example because “the populations are absolutely insane ... they are born pregnant,” Merrill said. “If you increase the temperature a couple degrees you can see the population growing much faster.”

The researchers said that richer countries might be able to reduce projected losses with insecticides and other pest-fighting techniques.

The study comes as insect experts across the globe worry about declining numbers of flying insects, especially pollinators, such as bees.

However, while many insects might be declining for a variety of reasons, those associated with agriculture crops — especially invasive species — seem to be doing better, said the University of Delaware’s Doug Tallamy, who was not part of the study.

University of Illinois entomologist May Berenbaum, said the study was distinctive.

“Problem insects are expanding their ranges with climate warming,” she said in an e-mail.

Another study in the journal looked at how the world’s vegetation changed since the last ice age and applied that concept to current warming.

The study logged massive changes to Earth’s landscape around the globe over more than 14,000 years from the last glacier period.

The same magnitude of warming — more than 4°C — is projected to occur with human-caused climate change, but could be in only 100 years or so, said study coauthor Jonathan Overpeck, a University of Michigan climate scientist.

“It really paints a picture that is a lot more dire,” Overpeck said, calling it “vegetation chaos.”