Insect population collapse: new evidence links it to dams
Insects are the most numerous group of animals on the planet. There are an estimated 5.5 million species, 80% of which remain to be discovered. Yet insects are experiencing steep, widespread declines across the world: a “death by a thousand cuts” because of human activity.
Insects perform almost every role imaginable in an ecosystem, including pollinating crops, keeping pests under control, and acting as food for other animals. The potential consequences of their decline are so dire that it has been dubbed the “insect apocalypse”.
Following the flurry of attention this impending environmental catastrophe generated, a more complex picture has emerged – with one gap in our understanding glaringly clear. Despite tropical and subtropical regions housing an estimated 85% of Earth’s insects, what is happening in those regions is critically understudied.
Understanding insect decline requires long-term datasets, which are rare, especially from the global south. In our new study, we present one of the most comprehensive known datasets of subtropical freshwater insects, spanning 20 years. What we found were pervasive declines in insect numbers across all examined aquatic insect groups, including midges, mayflies and dragonflies.
