The causes of the rapid recent declines are the continuing destruction or damage of habitats caused by agricultural intensification and land abandonment, draining wetlands, overgrazing by livestock, and the use of fertilisers and pesticides including neonicotinoids. The fragmentation of pollinator-friendly habitat greatly increases the risk of local extinctions.
Global heating is also revealed to be a major threat: 52% of all endangered butterflies in Europe are imperilled by the climate crisis – approximately twice as many as a decade ago.
throws_lemy in biodiversity
Number of wild bee species at risk of extinction in Europe doubles in 10 years
https://www.theguardian.com/environment/2025/oct/11/number-of-wild-bee-species-at-risk-of-extinction-in-europe-doubles-in-10-yearsarchived for posterity
So there is really one main cause.