Scientists have warned of ‘insect apocalypse’ in recent years, noting a sharp decline in specific regions – especially in Europe. A new study suggests these warnings may have been exaggerated and not representative of what is happening to insects on a larger scale.
University of Georgia agronomy professor Bill Snyder sought to find out if the so-called “insect apocalypse” actually happened, and if so, it began. Some scientists say that maybe in just 30 years all insects will be extinct, so this is a really important and timely question for agriculture and conservation.
Snyder and a team of researchers from UGA, Hendrix College and the US Department of Agriculture used more than 5,300 data points on insects and other arthropods – collected over four to 36 years at the sites. Surveillance represents 68 natural and regulated areas – to seek evidence of a reduction across the United States.
Some groups and sites show an increase or decrease in abundance and diversity, but many remain unchanged, creating true richness, and a tendency toward biodiversity that is generally indistinguishable. This overall increase or decrease deficit was consistent among the arthropod feeding groups, and was similar for sites that were significantly disturbed compared to relatively natural sites. These results have recently been published in Natural ecosystems and evolution.
Observe the locality
The idea for the study started last year with a cross-country trip by Snyder from Washington state to his new home in Georgia.
“I had the same observation that a lot of people have. We were driving across the country – you don’t see a lot of insects on your car or windshield.”
When he got back to his home in Bishop, Georgia, it all seemed like a different story.
“I noticed the lights outside were full of insects, as much as I remember when I was a kid,” he said. “People have this notion – it seems [there are] less insects – but what is the evidence? “
There is some alarming evidence that European honey bees are at issue, but Snyder is curious whether insects everywhere are in decline. “We depend on insects for a lot of things,” he said. “If the insect disappears, it will be really, really bad. It could be the end of human existence.”
He was discussing the topic with a biologist and another friend, Matthew Moran at Hendrix University, and they recalled the Science Foundation’s Network of Long Term Ecological Research (LTER) sites. The nation of the United States, was established in 1980 and includes a network of 25 monitoring sites across each of the country’s major ecological regions.
NSF’s LTER data are publicly available, but have not previously been compiled into a single data set to verify evidence of large-scale density change and biodiversity over time to date. .
The arthropod data sampled by the team included grasshoppers at Konza Prairie in Kansas; terrestrial arthropods in the Sevilleta desert / grassland in New Mexico; mosquito larvae in Baltimore, Maryland; invertebrates and crayfish in the North temperate North Lake in Wisconsin; aphids in the Midwestern United States; crab caves in the Georgia coastal ecosystem; mites in the Harvard Forest in Massachusetts; moths at Hubbard Brook in New Hampshire; arthropods in Phoenix, Arizona; and a line of insects in the Arctic in Alaska.
The team compared the samples with human footprint index data, which included multiple factors like insecticide, light pollution, and the built environment to see if there are any overall trends.
Michael Crossley, postdoctoral fellow in entomology and lead author of the study, said: “Whatever we consider, nothing can adequately explain trends. worth. “We’re just taking all the data, and when you look, there’s a lot of things going up that are going down. Even when we share it in functional groups, there’s not yet a dynamic story. predators are decreasing or herbivores are on the rise. “
“This is an implication for conservation and one for scientists, who are calling for more data due to lack of sampling in certain areas or certain insect species. We are already leveraging the muscles. This assembly uses this multitude of “unused data”. Crossley, an agricultural entomologist, who uses geospatial and molecular tools, explains to understand the ecology and evolution of pests and improve management outcomes. “There have to be more datasets that we don’t even know. We want to keep looking for a better idea of what’s going on.”
Good news and bad news
To answer Snyder’s big question, “Is there an overall drop?” No, according to research. “But we’re not going to ignore minor changes,” Snyder said. “It is worth it to distinguish between the two.”
The specific insects that we rely on for critical ecosystem services like pollination, natural pest control, and decomposition are still clearly declining in North America, the authors note.
According to Snyder, in Europe, where studies detect a significant decline in insects, could have a larger, more permanent impact on insects than the US, where the population density is lower. .
“Deep breathing isn’t the worst thing in the world,” Snyder suggested. “There have been a lot of policy and environmental changes. A lot of the insecticides used in agriculture today have limited effects. Some of those effects seem to be working. use. “
When it comes to conservation, there’s always room for people to get involved and do their part.
“It’s hard to know when you’re a single host if you’re having influence when you plant more flowers in your garden,” he says. “Maybe some of the things we’re doing are starting to have a beneficial effect. This could be a hopeful message that the things people are doing to protect bees, butterflies and other insects are doing.” really effective. ”
The insect apocalypse? Not too fast, at least in North America
Michael S. Crossley et al., No decline in insect diversity and abundance on US Long Term Ecological Research sites, Natural Ecology & Evolution (2020). DOI: 10.1038 / s41559-020-1269-4
Provided by University of Georgia
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