Around the world, populations of insects are declining and experts warned that they could disappear completely within a century.

A recent review of scientific studies found that almost half of the total insect species are experiencing a steep decline in population and a third are already extinct. Researchers found that the rate of decline of insects around the world is eight times faster than that of birds, reptiles, and mammals.

The disappearance of insects around the world could cause a "catastrophic collapse of nature's ecosystems," the researchers stated.

Their report appears in the publication of Biological Conservation.

Insects Are Disappearing

The biggest driver of the decline, according to the review, is habitat loss due to urbanization and agriculture. Pollution, particularly the heavy use of pesticides and fertilizers, is also a major contributor to the dwindling number of insects around the world.

Other factors such as pathogens, introduced species, and climate change are also some of the key factors that threaten insect populations.

The analysis, which looked at 73 studies that assess insect decline, found that butterflies and moths are the worst hit by the trend. The number of bees has also been seriously affected.

"If insect species losses cannot be halted, this will have catastrophic consequences for both the planet's ecosystems and for the survival of mankind," stated Francisco Sanchez-Bayo of the University of Sydney and an author of the study. "It is very rapid. In 10 years you will have a quarter less, in 50 years only half left and in 100 years you will have none."

Insects outnumber humans by a huge margin. There are 17 times more insects around the world than humans, according to another study.

Insects are necessary to all ecosystems, pollinating plants and serving as food for other animals. The disappearance of insects would cause cascading effects that will impact all life forms on the planet, including humans.

How To Save Insects

The researchers added that to save the insects and prevent the catastrophic consequences of their disappearance, humans should find a better way of food production.

"Unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades," they wrote.