Are Earth’s missing millions of undescribed insect species prone to extinction? 

In two new research papers, Griffith ecologists have highlighted the millions of insects that remain undiscovered and unnamed by scientists were likely to be more vulnerable to extinction than named species.

In journals Current Biology and Insect Conservation and Diversity, Professors Emeriti Nigel Stork and Roger Kitching from Griffith’s Centre for Planetary Health and Food Security worked with international researchers on two studies that looked at insect species and prevalence in Australia and Borneo respectively as case study sites.

In Borneo, the teams collected rove beetles in an area of tropical forest. Of the 252 different species of beetle that were recorded, 76% were new to science and not previously named.

Dr Mike Boyle, from the University of Hong Kong and lead author, compared samples from unlogged forest and logged forest and showed that the unknown species were more likely to have disappeared than known species in logged forest.

In the Wet Tropics of Australia, Professor Stork and co-authors found that among the 107 species of bark beetles identified, 58 were undescribed by science.

As hypothesised, the undescribed species were significantly smaller, less abundant and less widespread than described species, making them harder to find and more extinction-prone than named species.

“In recent years estimates of how many species of insects there might be on Earth have varied from 100 million or more to as low as 2 million,” Professor Stork said.

“A consensus figure of 5 million species published by myself is now frequently used, supported by four different methods of calculating global species richness.

“Since only 1 million of these species have been named and described so far in the past 240 years of Linnaean taxonomy, the puzzling question is: where are the other 4 million species that have yet to be found and named?

“What are they like, what is the likelihood of their discovery and description, and are they more vulnerable to extinction? Our studies reveal that they are smaller, rarer and more difficult to find as well as being more extinction prone.”

Professor Nigel Stork

Only 20% of the estimated 5 million species of insects on Earth are named and yet insects are poorly represented in protected area assessments, and insect declines are of concern globally.

To increase species description rates and to avoid most species becoming extinct before being named, Professors Stork and Kitching are calling on taxonomists to use new character systems provided by DNA methods and advances in the rapidly developing field of artificial intelligence.

“The unknown components of tropical insect biodiversity are likely more impacted by human-induced environmental change,” Professor Kitching said.

“If these patterns are widespread, how accurate will assessments of insect declines in the tropics be?”

The studies have been published in Current Biology and Insect Conservation and Diversity.

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