Huge drop in insect populations
Climate change, intensive agriculture major factors : study
Tourists visit Mount Nuolja, where scientists and researchers were investigating the impact on climate change in many aspects of the Arctic in Sweden on August 26, 2021.
A warming world and intensive agriculture are causing insect populations to plummet by nearly half compared to areas less affected by temperature rises and industrial farming, researchers said Wednesday.
The researchers measured both insect abundance and number of species in areas across the world and compared that to insects in more pristine habitats.
The study published in Nature found that the double whammy of global warming and shrinking habitats has not just hit population numbers, but also provoked a 27 percent drop in the diversity of species.
“The reductions are greatest in the tropics,” lead author Charlie Outhwaite, a macroecologist at University College London’s Centre for Biodiversity and Environmental Research, told AFP.
But less data from tropical regions, which are richest in biodiversity, means the global decline in insects is likely worse than the study’s headline figures suggest, she said.
The calculations may also be too conservative because areas used to benchmark change – while the most pristine on the planet – have already been degraded to some extent by human activity.
While in line with earlier estimates of insect decline, the new findings are based on different methodologies.
Covering 18,000 species from beetles to butterflies to bees, the study drew from 750,000 data points collected from 1992 to 2012 at 6,000 locations.
“Previous studies have been carried out at the small scale on a limited number of species or species groups,” Outhwaite said.
The consequences of insect decline are significant.
Some three-quarters of 115 top global food crops depend on animal pollination, including cocoa, coffee, almonds and cherries.
Some insects are also crucial for pest control – especially of other bugs. Ladybugs, praying mantises, ground beetles, wasps and spiders all play crucial roles in keeping pests in check, from aphids and fleas to cutworms and caterpillars.
Insects are also crucial for decomposing waste and nutrient cycling.
The study is the first to look at the combined impact of rising temperatures and industrial agriculture, including the widespread use of insecticides.
“We often only consider one driver of change, such as land use, whereas in reality a lot of drivers will be impacting the same space,” Outhwaite said.
The interaction between these drivers, the study shows, is worse than if they had acted independently.
Even without climate change, converting a tropical forest into agricultural land leads to drier hotter areas due to the removal of vegetation that provides shade and retains moisture in the air and soil.
