World
There are around 20,000 species of bees all over the world. Many of them bees have evolved to have unique flights and floral preferences that compliment their flowers.
Bee populations of all species are declining worldwide due to colony collapse disorder where adults of the hive die suddenly.
Several factors such as insecticide and herbicide usage, global warming, climate change, and more are the reason for the decline in bee population all over the world.
There are several irreversible effects of the declining bee population. Plants dependent on bees for pollination would die off, and this would disturb the food web.
Several organisms dependent on those plants will also die. Birds that eat bees will also be affected. Many animals might lose their food sources leading to destroyed food webs.
Without bees, plants such as blueberries and cherries that are 90% pollinated by bees might not survive without human intervention. Agriculture and enrichment will be affected.