In the 15 years Chitra Bhan Khatri has been keeping bees in west Nepal, he never had trouble providing food for his insects — until last year, when unseasonally heavy rain left his honeybees hungry.

Five days of torrential rainfall in Dang district in October sent temperatures plummeting, killing the bright yellow blooms of the mustard plants Khatri grows to provide nectar and pollen for his 300 colonies of European honeybees.

Then, when he took his bees to graze on nectar from chiuri (butter) trees in a nearby forest, the rain had knocked all the flowers off their branches, he said.