Are the millions of undescribed and extinct insect species on Earth threatened with extinction?

In a new study, Griffith ecologists have found that the millions of insects that remain undiscovered and unnamed by scientists are likely more vulnerable to extinction than named species.

Emeritus Professors Nigel Stork and Roger Kitching from Griffith's Centre for Planetary Health and Food Security worked with international researchers on a study of insect species and their prevalence in the wet tropics of Australia.

The study, “What can an analysis of Australian rainforest bark beetles suggest about the millions of insect species that have disappeared from Earth?” was published in Conservation and diversity of insects.

In the wet tropics of Australia, Professor Stork and his co-authors found that of the 107 bark beetle species identified, 58 were not described by science.

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

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

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

“Given that only 1 million of these species have been named and described so far in the last 240 years of Linnaean taxonomy, the puzzling question is: Where are the other 4 million species that have not yet been found and named?”

“What do they look like, how likely are they to be discovered and described, and are they more vulnerable to extinction? Our studies reveal that they are smaller, rarer and harder to find, as well as more vulnerable to extinction.”

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

To increase species description rates and prevent most species from disappearing before they are 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 to be more affected by human-induced environmental changes,” Professor Kitching said.

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