Biodiversity is declining worldwide due to human intervention and climate change. Counteracting this would require accurate information about the animals that populate the planet. But apparently too little attention is paid to the most species-rich and important animal groups. Researchers have discovered that just 20 insect families make up half of the species diversity of all flying insects. The most species-rich are the inconspicuous and little-studied gall midges.
According to estimates, only 20 percent of all animal species have been discovered so far. The remaining 80 percent are considered dark taxa. But when it comes to discovering new species and studying familiar ones, science seems to focus on individual "favorites" rather than those animals that contribute most to the world's biodiversity. For example, in the information portal on global biodiversity, two-thirds of the data sets relate to birds, even though these make up only 0.2 percent of all species.
Census of Flying Insects
Researchers led by Amrita Srivathsan from the Leibniz Institute for Evolutionary and Biodiversity Research in Berlin have now turned their attention to a prominent group of animals that has been neglected so far: insects. "It is crucial to learn more about insects, as all insects together make up many times the biomass and species diversity of all vertebrates. They are essential for survival,” explains co-author Rudolf Meier from the Museum für Naturkunde Berlin. To find out which families of flying insects are particularly species-rich, the team collected samples from five biogeographic regions, eight countries and numerous habitats.
The insects were caught by the researchers via so-called malaise traps. These are tent-like constructions made of fine nets, in which flying insects get lost and are finally guided into a container with ethanol. The high-proof alcohol kills and preserves them. In this way, Srivathsan and her colleagues caught a total of over 225,000 flying insects at the various sites. Using modern gene sequencing, they were able to read the "DNA barcodes" of more than 25,000 species from 458 families. The team then identified which of these families make up the most species-rich groups of flying insects.
Most important insect families hardly explored
The result: Just 20 insect families are responsible for 50 percent of the global species diversity of flying insects. Ten of these families belong to the order Diptera, which includes mosquitoes and flies, among others. "This is really remarkable considering that the samples were collected across different climate zones and habitat types, including tropical rainforests, montane forests, savannas, mangroves and swamps, but also temperate-zone grasslands," the scientists report. They explain the global dominance of the top 20 by their high adaptability, which opens up different niches for each habitat.
But although the 20 most species-rich insect families are immensely important for the world's ecosystems, this is not reflected in the scientific interest in them. "We found that the more a family contributed to insect communities around the world, the more neglected it became," Srivathsan and her colleagues said. As a prime example, they cite the species-rich family of gall midges, which, despite their global dominance, has so far received little taxonomic attention. The research team is therefore pushing for research into the 20 most diverse insect families to be given top global priority. This is the only way to develop really effective measures against the loss of biodiversity.
Source: Museum of Natural History, Leibniz Institute for Evolutionary and Biodiversity Research; Specialist article: Nature Ecology & Evolution, doi: 10.1038/s41559-023-02066-0