The environmental harms of high-intensity agriculture present a challenge as we try to keep up with food demands.
Scientists have long been warning of a mass extinction of insects owing to climate change, habitat loss and the extensive use of pesticides. In fact, according to a new study, in many of the worst-affected areas the numbers of insects have already halved as a result of intensive agriculture and climate change.
In the study published in the journal Nature a team of researchers at University College London explains that numerous groups of insects are losing out worlwide to the double whammy of rising temperatures and the expansion of intensive agriculture.
“Many insects appear to be very vulnerable to human pressures, which is concerning as climate change worsens and agricultural areas continue to expand,” says Charlie Outhwaite, a scientist at the university’s Centre for Biodiversity & Environment Research.
The scientists behind the study analyzed a large dataset of insect abundance and species richness from areas across the globe, including some 750,000 records for nearly 20,000 insect species. They then compared insect biodiversity in different areas based on two variables: how intensive agriculture has been in any given area and how much warming the local climate has undergone.
They found that in areas subject to high-intensity agriculture and marked warming, the number of insects is 49% lower on average than in most natural habitats with no recorded climate warming. The number of different species was also 29% lower in affected areas.
Tropical areas have seen the biggest declines in insect biodiversity as a result of intensive land use and climate change, the researchers have discovered.
Needless to say, this is bad news for the environment and ecosystems in affected areas.
“Losing insect populations could be harmful not only to the natural environment, where insects often play key roles in local ecosystems, but it could also harm human health and food security, particularly with losses of pollinators,” Outhwaite explains.
“Our findings may only represent the tip of the iceberg as there is limited evidence in some areas, particularly in the tropics which we found have quite high reductions in insect biodiversity in the most impacted areas,” he adds.
Somewhat encouragingly, in areas of low-intensity agriculture and with natural habitats situated nearby insects manage to do better despite substantially warming temperatures. In areas where three-quarters of the land is covered by natural habitat, insect populations has declined only by 7%, compared to a decrease of 63% in comparable areas where only a quarter of the land area has natural habitat cover.
“Many insects rely on plants for shade on hot days, so a loss of natural habitats could leave them more vulnerable to a warming climate,” the scientists note.
Less encouragingly, the effects of people on insect populations may be even greater than their results suggest because this study did not take into account other factors such as manmade water and air pollution.
“The environmental harms of high-intensity agriculture present a tricky challenge as we try to keep up with food demands of a growing population,” observes Tim Newbold, a scientist at UCL’s Centre for Biodiversity and Environment Research.
“We have previously found that insect pollinators are particularly vulnerable to agricultural expansion, as they appear to be more than 70% less abundant in high-intensity croplands compared to wild sites. Careful management of agricultural areas, such as preserving natural habitats near farmland, may help to ensure that vital insects can still thrive,” Newbold stresses.