An insect apocalypse is on the way with insect populations having plummeted, especially in places like Europe, according to experts, who have been warning about mass extinctions of arthropods for years.
Then again, maybe it isn’t happening. Or at least not in the United States.
The oft-heralded mass extinction of insects has been exaggerated as the creepy-crawlies aren’t dying off on a massive scale, according to Bill Snyder, a professor of agroecology at the University of Georgia.
Snyder has reached this conclusion with his colleagues from the U.S. Department of Agriculture and other research institutions after analyzing more than 5,300 data points for insects and other arthropods collected at monitoring sites between four and 36 years across 68 natural and managed areas.
What they found was that insects at some sites did show fluctuations in their abundance and diversity, but at many other sites their numbers have remained unchanged. “This lack of overall increase or decline was consistent across arthropod feeding groups, and was similar for heavily disturbed versus relatively natural sites,” explain the scientists, who published their findings in a new study.
“The apparent robustness of US arthropod populations is reassuring,” the scientist explain. “Yet, this result does not diminish the need for continued monitoring and could mask subtler changes in species composition that nonetheless endanger insect-provided ecosystem services.”
Snyder says he set out to investigate whether a so-called insect apocalypse was in progress after seeing a swarm of bugs at his home in the state of Georgia. “I noticed the lights outside were full of insects, as many as I remember as a kid,” he recalled. “People have this notion [that] there seems [to be] fewer insects, but what is the evidence?”
So with some colleagues he began analyzing publicly available data on arthropod populations gathered around the United States over the years and decades: grasshoppers on a prairie in Kansas; ground arthropods on a grassland in New Mexico; mosquito larvae at a site in Maryland; macroinvertebrates and crayfish in a lake in Wisconsin; crab burrows in Georgia coastal ecosystems; ticks in a forest in Massachusetts; caterpillars at a location in New Hampshire; arthropods in Arizona; and stream insects in the Arctic in Alaska.
The experts wanted to see overall trends while factoring in such variables as insecticide use, light pollution and rate of urban development. “No matter what factor we looked at, nothing could explain the trends in a satisfactory way,” explains Michael Crossley, a postdoctoral researcher in entomology who worked on the study.
“We just took all the data and, when you look, there are as many things going up as going down,” Crossley says. “Even when we broke it out in functional groups there wasn’t really a clear story like predators are decreasing or herbivores are increasing.”
However, that does not necessarily mean that everything is hunky-dory. Although, overall, arthropod populations appear to be robust in the U.S., insects are facing a variety of threats in many areas, not least excessive pesticide use and habitat loss.
Previous studies in Europe, which has a higher population density than the United States, have found that the continent’s insects have been experiencing dramatic declines in their numbers. Key pollinators such as honey bees and bumblebees have been especially hard hit with experts warning that unless conservation efforts are stepped up, the days of these insects may well be numbered.
Yet targeted polices and practices can help arthropods to recover across most of their natural ranges, Snyder points out.
“It’s not the worst thing in the world to take a deep breath,” he says. “There’s been a lot of environmental policies and changes [in recent years]. A lot of the insecticides used in agriculture now are narrow-acting. Some of those effects look like they may be working.”
