Every year, the number of insects that fly, crawl, or burrow in some parts of the planet drops by a percentage point or two. This means that areas of severe decline could lose up to a third of all insects in two decades.
That is the bad news that scientists are revealing today in Proceedings of the National Academy of Sciences (PNAS). Dozens of insect experts have contributed to a number of reports in the magazine about how insects are doing, good or bad, around the world.
The good news – if there is good news to be found – is that not all insects lose weight that quickly. Some even bloom. Most importantly, researchers say, there is hope that our planet, with its abundant and diverse creatures, will keep going.
The insect world, estimated to be up to 10 million species, suffers from more than one problem. The threats range from deforestation, climate change and invasive species to industrialized agriculture and light pollution. (Read More: Where Did All The Insects Go To?)
“Death by a thousand cuts,” says David Wagner, an entomologist at the University of Connecticut who contributed to the new report.
Resilient insect populations are vital for a variety of reasons, from helping the global food supply to producing backyard flowers through pollination. While most of us would prefer not to encounter many of the smallest creatures on the planet, their role in our lives cannot be overstated. The need to make saving insects a priority cannot become a priority either, according to scientists.
“Insects, like any piece of the natural world, are losing weight,” said Matthew Forister, an insect ecologist at the University of Nevada, Reno, who also contributed to the report. “But it is clear that insects have an opportunity to recover. It’s dark, but it’s not too late. “
Beyond the exaggeration
Reports of the global decline in insects are not new. In recent years, a growing body of research and news has drawn attention to the problem in very different terms – explanations from insect Armageddon on the one hand, to reporting challenging notions of an impending apocalypse for six-legged people on the other.
Wagner says he and other researchers who contributed to the new report want to go beyond the exaggeration by analyzing as much research as possible on the current global status of insects.
“This is a much more rampant, careful, and critical assessment,” he says, than some of the previous reports that highlighted extreme losses in specific regions and extrapolated around the world.
A checkered white butterfly (Pontia protodice) feeds on verbena in Texas.
Photo by Rolf Nussbaumer, Nature Picture Library
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Are insects declining alarmingly? Yes, he says. Is it more complex than the impending global collapse? Also yes.
Forister, who studies butterflies in the western United States, points out two species that represent very different situations.
Commonly found in southern parts of the United States, Mexico, and Central America, the gulf mother-of-pearl butterfly is now blooming in California because people there cultivate its host, the passion vine, a popular ornamental plant.
In contrast, the great marble butterfly, which lives on invasive mustard plants, was widespread until its population crashed, likely a victim of the triple impact of climate change, habitat loss, and pesticides.
Forister’s study specifically focuses on how climate change affects butterflies. Species struggle with forest fires, drought, and extreme weather events, and while previous theories have suggested that butterflies could simply move up or down mountain slopes in mountainous areas to take advantage of better conditions, at least this does not seem to be the case for all species.
Other species, including the famous monarch butterfly, performed better than expected in the summers of 2011 to 2015, when warmer conditions gave them more time to reproduce. But that has not stopped the ongoing decline of monarchs in the west. (Learn why western monarchs were denied protection of endangered species.)
How we can help
Amid devastating statistics, Forister and Wagner say there is hope.
Germany pledged almost $ 120 million for insect conservation, monitoring and research in 2019. Costa Rica advocated international organizations spending $ 100 million on the inventory and sequencing of pieces of DNA for “every multicellular creature in the country for a decade,” which will be particularly important for the myriad of unknown tropical insects, Wagner writes in the introductory article by Report.
Citizen scientists are stepping up to expand the knowledge base. An app, iNaturalist, where users upload images for identification and categorization, is becoming one of the greatest sources of insect viewing.
Solutions to overarching problems like climate change require laws and new guidelines, but individuals can make a difference to insects in their backyards, neighborhoods and communities, say Wagner and Forister. (Read about how bumblebees become extinct in a time of climate chaos.)
One way is to reduce the use of pesticides and herbicides on lawns. Better still, consider converting part of your lawn into a natural area. Insect habitat could increase by more than four million acres in the U.S. if every home, school, and park were to convert 10 percent of its lawns, writes entomologist Akito Y. Kawahara of the University of Florida at Gainesville in the PNAS report . Grow native plants and limit outdoor lighting, which attracts and often kills nocturnal insects.
It’s even easier to expose hives in gardens and bare earth for bee nests in the fall, says Lusha Tronstad, an invertebrate zoologist at the Wyoming Natural Diversity Database who studies the decline of the western bumblebee and was not involved in the report. Do not rake leaves before winter.
“People can be a little lazy, and that benefits insects,” she says. (Here are nine ways to help bees and other pollinators in the home.)
Tronstad also notes that the fate of a species can quickly change for better or for worse. The western bumblebee has declined 93 percent in just over two decades.
The endangered blue Karner butterfly named by the novelist and entomologist Vladimir Nabokov has now responded well to restoration efforts, says Wagner. The little butterfly has long suffered from fire fighting, residential and business development in its sandy habitat from the edges of the Great Lakes to New England. Efforts to plant and nurture lupins – which adults and larvae need – and other habitat improvement projects are helping.
Are small, personal changes like reducing the use of pesticides on your lawn preventing the worst effects of climate change? No, says Forister. But it will make a difference in your local insect populations, and those differences add up.