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Scientists predict mass insect extinctions happening soon

Nick Wigham, February 12, 2019 7:00PM news.com.au

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A close up of a praying mantis. Picture: Nathan Edwards media_cameraA close up of a praying mantis. Picture: Nathan Edwards

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More than a third of the world’s insects are threatened with extinction in the next few decades, with the main causes intensive* farming, pesticides* and climate change.

And insect populations are declining eight times faster than mammals, birds and reptiles, according to the first major review of scientific insect research.

But populations of some species, such as cockroaches and houseflies, are likely to boom.

Researchers Dr Francisco Sánchez-Bayo from the University of Sydney, NSW, and Kris Wyckhuys from the University of Queensland studied 73 reports from the past 13 years on the topic of insect population decline. The results are published in the journal Biological Conservation.

Dragonflies are one of the groups of insects found to be most in trouble. This one was photographed in Darwin, NT. media_cameraDragonflies are one of the groups of insects found to be most in trouble. This one was photographed in Darwin, NT.

“Our work reveals dramatic* rates of decline that may lead to the extinction of 40 per cent of the world’s insect species over the next few decades,” the researchers wrote.

They found evidence for decline in all insect groups reviewed, but said it was most dramatic for butterflies and moths, native bees, beetles and aquatic insects such as dragonflies.

“From our compilation* of published scientific reports, we estimate the current proportion of insect species in decline (41 per cent) to be twice as high as that of vertebrates*, and the pace of local species extinction (10 per cent) eight times higher, confirming previous findings,” they wrote.

A hive of Australian native bees. media_cameraA hive of Australian native bees.

Insects are important to the Earth’s ecosystems* and humans depend on them. They keep pests under control, feed on dead animals and plants, pollinate crops, improve soil health and provide food for many other animals.

The researchers set out to identify the causes of the drop in insect populations.

The main cause, they found, was habitat loss due to intensive agriculture and urbanisation*.

They also pointed to the use of pollutants, mainly synthetic* pesticides and fertilisers, as well as the impact of invasive* species and climate change.

“Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades,” the report said.

Caterpillars may annoy us when they eat leaves in the vegetable garden, but they turn into moths and butterflies and are an important part of Earth’s ecosystems. media_cameraCaterpillars may annoy us when they eat leaves in the vegetable garden, but they turn into moths and butterflies and are an important part of Earth’s ecosystems.

The research also found that some insects — such as cockroaches and houseflies — could and would make the most of the decline or extinction of other species.

“Concurrently*, the abundance* of a small number of species is increasing; these are all adaptable*, generalist* species that are occupying the vacant niches* left by the ones declining.”

VIDEO: Try making your own paper mantis insect

GLOSSARY

  • intensive: trying to get the most out of something
  • pesticides: chemicals that kill pests, such as insects
  • dramatic: striking
  • compilation: collection
  • vertebrates: animals with backbones
  • ecosystems: communities of living things
  • urbanisation: processing of land becoming towns and cities
  • synthetic: made by humans
  • concurrently: happening at the same time
  • abundance: lot of something
  • adaptable: can change with changing conditions
  • generalist: good at lots of different things
  • niches: a particular job

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QUICK QUIZ

  1. What proportion of insect species could become extinct in the next few decades?
  2. How does insect species’ decline compare to that of vertebrates?
  3. Why are insects important?
  4. What types of pollutants are mentioned?
  5. Name two insect species that could benefit from other insect species’ decline.

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. A world without butterflies
The most dramatic decline of insects was in the groups listed below. Write all the possible consequences you can think of if these insects were to disappear from our ecosystem for good:

BUTTERFLIES AND MOTHS

NATIVE BEES

BEETLES

DRAGONFLIES

Time: allow 20 minutes to complete this activity
Curriculum Links: English, Science, Critical and Creative thinking

2. Extension
The article states that “unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades”. What ways can you think of to change our food production to save the declining insect species? What do we as consumers of food need to do to support this?

Time: allow 15 minutes to complete this activity
Curriculum Links: English, Science, Critical and Creative thinking

VCOP ACTIVITY
After reading the article, with a partner, highlight as many wow words or ambitious pieces of vocabulary that you can find in yellow. Discuss the meanings of these words and see if you can use them orally in another sentence.

HAVE YOUR SAY: What are your favourite insects? What job do they do? What could put this species at risk of extinction?
No one-word answers. Use full sentences to explain your thinking.

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