Why is pollen in Camellia oleifera inedible to honeybees?

This Commentary examines a recent study that addressed a long-standing controversy: Is the lethal effect of Tea-oil Camellia on honeybee larvae due to nectar or pollen toxicity? Flowers of Camellia oleifera are adapting to bird pollination, evolving 'anti-bee' traits such as theasaponin-containing pollen, which is toxic to bee larvae.