Over 40 percent of insect species face extinction: study
Lewis Sanders IV
February 11, 2019
From butterflies to bees, nearly half of all insect species are threatened with extinction "over the next few decades." Scientists have warned of the devastating impact it could have on the future of humankind.
It's a wondrous spectacle: Each year countless monarch butterflies migrate thousands of miles south. The insect relies on its remarkable sense of direction — but numerous impacts are putting the insects off-track.
Image: picture-alliance/dpa/R. Loznak
One-of-a-kind
The monarch butterfly is a migrating marvel: It's the only insect that every year travels for two months and up to 5,000 kilometers (3,100 miles), from Canada and the United States to Mexico, where it spends the winter. There, the monarch butterfly roosts in the pine and fir forests in the Sierra Madre mountains west of Mexico City, which protect the insects, and help keep them from freezing.
Image: picture-alliance/dpa/R. Loznak
Mysterious insect
Not just the distance is amazing — also the butterflies' sense of direction fascinates scientists and experts. The monarch butterfly divides its migration over three generations, meaning no single butterfly lives long enough to make the roundtrip back to the US and Canada. And still, year in and year out, they seem to know exactly where they are heading.
Image: Reuters/C. Jasso
A perfect cycle
The butterfly synchronizes its lifecycle with milkweeds by laying its eggs on the plant in the US. In fall, when the milkweeds start to die, a young generation of monarch butterflies leave for Mexico. As soon as the first milkweeds appear in spring, the monarch butterfly returns to begin the cycle anew. There's evidence that they possess a genetically coded instinct for which direction to fly.
Image: imago/INSADCO
Agricultural pest
Milkweed is considered a pest in farming — industrial agricultural practices including monculture cropping and intensive pesticide use has decreased the plant that monarchs rely upon. It's one of the factors linked to monarch butterflies' decline.
Image: Reuters
Magnetic Compass
The baby butterflies that set off on the migration have never been to Mexico and therefore can't know the route. But still, the monarchs always find their way back to the Mexican reserve, where they wait out the winter. Studies in 2014 and 2016 suggest the sun offers orientation. In addition, the insects possess an inner magnetic compass corresponding to the Earth's magnetic field.
Image: picture-alliance/dpa/F. Poelking
Hard to count
Despite monarch butterflies being perfectly equipped to take on the vast distance each year, their numbers are decreasing nonetheless. It is hard to count individual butterflies, though, so experts came up with a specific method of assessing how many butterflies have migrated back to Mexico: They look at the area of forest the monarch butterfly covers.
Image: picture-alliance/dpa/F. Pölking
Declining numbers
And this area has declined dramatically. Since the winter of 1996-1997 it has shrunk, from about 44 acres (18 hectares) to 6 acres (2.5 hectares) in the winter of 2017. The reasons for this are diverse, among them more intense storms and busy hurricane seasons. Such extreme weather disturbs the insects' migration route and uproots trees, which the butterflies rely on in order to survive.
Image: picture-alliance/dpa/R. Blackwell
Competing with avocados
Other reasons for the butterflies' decline include illegal logging and land use changes. Monarch butterflies migrate to pine and fir forests that thrive at about the same altitude as prime avocado-growing land. In February 2018, Mexican police shut down an illegal avocado plantation that had been set up in the Monarch butterfly's overwintering grounds.
Image: Fotolia/fredredhat
No trees, no butterflies
On the positive side, Mexican officials claim to have nearly eliminated illegal logging in butterfly refuge zones. Fighting such deforestation is key, because the spectacular migration of thousands of Monarch butterflies can only continue if there are enough trees for the monarch butterfly to find shelter in.
Image: LUIS ACOSTA/AFP/Getty Images
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'Threatened worldwide'
Researchers said:
"Biodiversity of insects is threatened worldwide."
"Our work reveals dramatic rates of decline that may lead to the extinction of 40 percent of the world's inspect species over the next few decades."
"Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species."
The researchers, whose work was published in the leading international journal in the discipline of conservation science, Biological Conservation, pointed to several factors, including habitat loss, pollution, pesticides and biological factors, such as pathogens. They also cited climate change, saying "it is particularly important in tropical regions."
"Failure to do so will jeopardize food security by posing imminent threats to the global economy, nutrition and diet diversity, and the biodiversity of ecosystems," said the Chicago Council on Global Affairs in a report. "But our success in doing so will ensure our ability to feed a growing population for generations to come."
According to the researchers led by Francisco Sanchez-Bayo of the University of Sydney and Kris A.G. Wyckhuy of the University of Queensland, there are several steps that can be taken to mediate losses and reverse the trend.
"A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide," the researchers said.
Humans have been using medicinal plants for thousands of years. They even play an important role in modern medicine. Here are just a few that are still used to ward off illnesses and treat symptoms.
Image: picture alliance/blickwinkel/H. Duty
Bitter bark
Quinine is known for creating that bitter taste in tonic water but it is also on the World Health Organization's list of essential medicines. It's long been used to treat malaria - though it is no longer recommended as a first-line treatment by the WHO - and was first isolated from the bark of the cinchona tree in the early 1800s.
Image: picture alliance/blickwinkel/A. Jagel
Fragrant remedies
The bell-shaped flowers of the yellow cowslip (primula veris) are certainly charming. But this plant is more than just a pretty face. Native to most of Europe and western Asia, it is used as a herbal remedy against asthma and bronchitis.
Image: picture alliance/blickwinkel/H. Duty
Wake me up
Guarana, a climbing plant native to the Amazon basin is very common in Brazil where it is enjoyed as a drink. The plant's small red berries contain caffeine and have become a popular energy supplement. It's also used for stomach complaints.
Image: CC by A C Moraes
Miracle worker
The bark of the African cherry (Prunus africana) is something of a miracle worker. Traditional healers in Kenya use it to treat a host of ailments, including malaria, stomach pain and kidney problems. But it is most treasured for its use in prostate cancer treatments.
Image: DW/H. Fischer
Combating yawns
Ginseng is one of the most popular herbal remedies in the world and the plant's roots have long been used in Asia and North America to treat various complaints. Often taken as a tea, the Asian variety - which is considered to be more of a stimulant than its American counterpart - is used to boost the immune system and fight fatigue.
Image: CC-BY-SA-Lohrie
Jack of all trades
Vetiver is an extremely versatile grass. Native to India, it's been used to control erosion, in the production of essential oil, to make bags and mats, as an animal feed and in traditional medicine. The grass has antiseptic properties and is used in creams and soaps to treat acne and sores. Its anti-inflammatory properties have also seen it used in the treatment of gout and arthritis.
Image: picture-alliance/dpa/P.Goetgheluck
Dandelion improvements
The lowly dandelion is full of vitamins and minerals and it's often used as a diuretic to eliminate unwanted fluid in a person's body. Initial research also suggests it might improve digestion as well as gall bladder and liver function.