Earth May Harbor 20 Million Insect Species, Study Suggests

There may be more insect species on Earth than has been estimated by scientists up to now.

A recent research, which was recently published in the Proceedings of the National Academy of Sciences (PNAS), suggests that the planet might be inhabited by 14.2 million to 20.3 million insects, a number three times higher than the widely accepted number of about 6 million species. The research shows just how much of the biological diversity on our planet is yet to be studied and emphasizes the need for further research on insects’ diversity while their populations are rapidly declining all over the world.

Mass survey in Costa Rica

In order to estimate the number of insect species, scientists conducted one of the biggest surveys of insect biodiversity in Área de Conservación Guanacaste, which is a 169,000 hectares protected area in the north-western part of Costa Rica. This area has a variety of different ecosystems, such as dry forests, rainforests and cloud forests.

Scaling up to a world total

In order to come up with an estimate of insects in the world, the researchers considered the number of tree species in the Costa Rican forest and compared it with the world total of tree species. Trees were selected for the task since they are habitats for a multitude of insect species. This was how they came up with the best estimate of 20.3 million insects in the world. Other alternative calculations based on mammals, amphibians, and moths yielded estimates of between 14.2 million and 20.3 million insects. “The world total of insect richness derived from our preferred upscaling reference group, trees, is 20.3 million,” the researchers said.

Majority of insect species have yet to be identified

Although insects are the largest animal group on Earth, only an estimated 1.2 million insect species have been identified so far. Based on the new study findings, it would appear the vast majority of insect species still await discovery. Furthermore, scientists consider these findings to be on the conservative side since the insect survey did not include those species dwelling deep within forest canopies and elsewhere.

Why it matters

This new research contradicts the previous scientific belief that Earth had about 6 million insect species. This research comes against a backdrop of reports of declining numbers of insects in the environment due to loss of habitat, climate change, pesticides, and other human-induced factors. The scientists explain that knowing what kind of insects there are in the world is important to understand their ecosystems and develop conservation plans. As scientists continue to explore the biodiversity of the planet Earth, it becomes apparent that many insect species are yet to be discovered by humans—and many before it’s too late.