With just 1.2% of the world's one million described insect species assessed for extinction risk, biodiversity assessment and conservation measures remain severely constrained. Sufficiently extensive datasets and new statistical methods could enhance the reach of extinction risk classification.
Invertebrates, including insects, are poorly represented on the International Union for Conservation of Nature's (IUCN) Red List . The Red List, the world's most comprehensive information source on global conservation status, is dominated by better-known vertebrates, such as mammals and birds. Researchers find the situation alarming, as the Red List steers conservation measures and priorities.
A study by the universities of Helsinki and Stockholm, the Swedish University of Agricultural Sciences (SLU), as well as the Swedish Museum of Natural History, examined ways to extend the reach of classification of conservation status to invertebrates. To do so, the researchers used one of the world's most extensive arthropod datasets, encompassing over 33,000 species.
They found that attempts to classify rare insect species with traditional methods involve a major risk of misclassification: detecting even a severe species decline is challenging.
"Insects are difficult to observe, and most are also rare. As a result, only limited data have been gathered for most insect species, making it difficult to determine whether their populations are secure or at risk of decline. This makes existing conservation status assesment methods poorly suited to them," notes Professor Tomas Roslin of the University of Helsinki's Faculty of Biological and Environmental Sciences.
Roslin explains that unless analysis methods are updated, even the most ambitious observation projects enable extinction assessment for only a fraction of all species.
The researchers suggest three alternative ways to improve classification with new statistical methods. Although the data available for each rare species are limited, analyses can be strengthened by combining data across species. In addition, assessments may be conducted at the level of similar species instead of individually. A third option is to target extinction risk assessment to species communities and habitats.
"The statistical methods of community ecology have made tremendous strides in the past 10-15 years, providing new opportunities to assess extinction risks as well. The consequences have been especially pronounced for insects, with the majority lacking any extinction risk assessment," says Professor Jarno Vanhatalo of the University of Helsinki's Faculty of Biological and Environmental Sciences and Faculty of Science.
Insects play an important role, as they pollinate plants, recycle nutrients and feed other groups of organisms. They are also the world's most abundant and diverse animals, constituting 75 to 90% of all known animal species. The number of unknown species is much greater: about 80% of insect species remain undescribed.
Original article
Goodsell, R.M., Tack, A.J.M., Ronquist, F., van Dijk, L.J.A., Iwaszkiewicz-Eggebrecht, E., Miraldo, A., Roslin, T. and Vanhatalo, J. (2025), Moving towards better risk assessment for invertebrate conservation. Ecography, 2025: e07819. https://doi.org/10.1002/ecog.07819
Invertebrates
Invertebrates are animals that have no spine or backbone inside their body. They account for about 97% of the world's known animal species.
Arthropods
Arthropods are a subgroup of invertebrates, characterised by segmented bodies, jointed limbs and chitinous exoskeletons. They include not only insects, but also arachnids, crustaceans and centipedes.
Insects
Insects are the largest subgroup of arthropods. Their distinguishing features include a three-part body and six legs. Most also have wings. In terms of species numbers, insects are the world's largest animal group, comprising an estimated one to five million species. Most of these remain undescribed.
