Study shows fall in insect population by nearly a quarter
Ankita Mukhopadhyay
April 24, 2020
While the population of terrestrial insects declined significantly, freshwater insects reported a rise thanks to cleanups of lakes and rivers. Scientists attributed the fall in numbers on land to habitat destruction.
A study by two German universities has unearthed a startling fact about insects – about 24% of them have been lost over a course of 30 years. Touted as the 'largest study' of insect change to date across 1676 sites in the world, the study particularly reported a decline in the population of land-dwelling insects.
Insects like grasshoppers, ants and butterflies – land-dwelling insects – recorded a nearly 1% drop in population per year. Scientist Dr Roel van Klink said this indicated a decline of 50% over 75 years.
The decline in terrestrial insect population was attributed to the destruction of insects' natural habitats following urbanization.
Insects disappear quietly
The US and Germany recorded particularly steep declines in insect population. In the US Midwest, insect population fell by 4% a year, as insects lost their food and habitat.
Vital species we can't afford to lose
Every species on Earth plays an important role. But when it comes to sustaining life on our planet, some are more important than others. On World Wildlife Day, DW takes a look at some of those we can't afford to lose.
Image: Alex Wild/University of Texas at Austin
1. Bees
It's no secret that bees are vital — in fact, they were even declared the most important species on Earth by the Royal Geographical Society. As the world's foremost pollinators, they play a major role in the life cycle of many plant species and help maintain healthy ecosystems. They are also responsible for pollinating many of the crops we eat.
Image: Alex Wild/University of Texas at Austin
2. Ants
We might consider them a pest at times, but ants are another common insect we should never take for granted. They can be found on every continent except Antarctica and fulfill a variety of roles, from circulating nutrients in the soil, to dispersing seeds and eating other insects. Scientists are currently studying the possible impact of climate change on ant colonies around the world.
Image: CC BY-SA 2.0/Geoff Gallice
3. Fungi
Neither plant nor animal, microbe or protozoa, fungi are sometimes described as the "fifth kingdom of life on Earth." They can be found in the water, in the soil and in the air. They essentially act as the world's natural nutrient recyclers and some species can even absorb harmful metals like mercury and digest polyurethane plastics.
Image: picture-alliance/blickwinkel/McPhoto
4. Phytoplankton
It's hard to understate just how important these micro-organisms are to life on Earth. For one thing, they produce more than 50 percent of the planet's atmospheric oxygen — without them, the amount of free oxygen in the atmosphere would be much lower, making for a very uncomfortable environment. They are also the foundation of the food chain in marine ecosystems.
Image: picture-alliance/dpa/P.Degginger
5. Bats
What do bananas, baobab trees and tequila have in common? They all depend on bats for pollination and insect regulation. All over the world, different species of bats fill a vital ecological niche to ensure certain crops continue to thrive. A healthy population of bats can save millions of dollars worth of pesticides and they are an important sign of a robust ecosystem.
Image: picture-alliance/Bildagentur-online/Weber
6. Earthworms
The humble earthworm is so important to Earth's biosphere that it is sometimes referred to as an "ecosystem engineer." They lead busy lives aerating and enriching the soil and recycling organic material — and, of course, occupying an indispensable place in the food chain. Despite their status as a stalwart of many ecosystems, certain species are under threat from such things as land clearance.
Image: picture alliance/blickwinkel/J. Fieber
7. Primates
As our closest living biological relatives, primates offer a great deal of insight into human biology. They are also a keystone species in many tropical forests, serving as "gardeners" by dispersing seeds and creating places where new plants can grow. In order for such forests to survive and thrive, we need to ensure the survival of the primates who inhabit them.
Image: DW
8. Coral
Often called the rainforests of the sea, coral reefs fill a diverse range of roles, from serving as a foundation for intricate food webs, to protecting coastlines. Researchers also estimate coral reefs support as much as a quarter of all marine life, making them one of the most diverse ecosystems on Earth. The loss of coral reefs would imply the loss of countless marine species.
Image: picture-alliance/AAP/James Cook University
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"The decline across insect orders on land is jaw dropping. Ongoing decline on land at this rate will be catastrophic for ecological systems and for humans. Insects are pollinators, natural enemies of pests, decomposers and besides that, are critical to functioning of all Earth's ecosystems", Nick Haddad, a butterfly expert at Michigan State University told the Associated Press.
All hope isn't lost
However, all hope isn't lost for insects. The study revealed that freshwater insects recorded an average annual increase over just over 1% in their population, or a 38% increase over 30 years.
Northern Europe, Western US and Russia were the biggest gainers in freshwater insect population. Scientists attributed the positive movement to the cleaning up of polluted lakes and rivers.
"Insect populations are like logs of wood that are pushed under water. They want to come up, while we keep pushing them further down. But we can reduce the pressure so they can rise again. The freshwater insects have shown us this is possible," said Dr. Roel van Klink, a scientist at the German Center for Integrative Biodiversity Research at Leipzig University.
