1. Habitat Loss and Fragmentation
Urban expansion and agriculture reduce meadows, hedgerows, and woodlands—critical pollinator habitats. This decreases native plant diversity and abundance, impacting nectar, pollen, and nesting sites. Specialist species decline, while generalists dominate, changing ecosystems.
2. Pesticides and Chemical Exposure
Synthetic insecticides, especially neonicotinoids, accumulate in nectar and pollen, disrupting bees’ memory, navigation, and foraging—even at low levels. Wild pollinators are especially vulnerable, as pesticide testing often overlooks non-honeybee species.
3. Invasive Species
Non-native plants and animals can outcompete native species, disrupting local pollinator networks. Some invasives attract pollinators away from native plants. Introduced pollinators and agricultural imports can spread pests and diseases to native species.
4. Disease and Parasites
Viruses, fungi, and mites (e.g., Varroa destructor) threaten both managed and wild pollinators. Pathogen spread is accelerated by global trade and the movement of bees, leading to colony collapse and reduced pollination services.
5. Air Pollution
Pollutants like ozone and nitrogen oxides disrupt chemical signals that guide pollinators to flowers, reducing foraging efficiency and disrupting plant-pollinator interactions.
6. Climate Change
Shifting temperatures and weather patterns create mismatches between flowering times and pollinator activity. This reduces food availability and can weaken colonies, compounding habitat loss and disease impacts.
7. Nutritional Stress
Pollinators rely on diverse floral resources. Monocultures and urban development limit this, causing malnutrition and reduced immunity. For social bees, this can reduce reproduction and increase mortality.