Mystery of long-legged bees solved by scientists

SCIENTISTS have discovered why a South African bee species have grown extraordinarily long legs.

Research at Stellenbosch University has found that oil-collecting Rediviva bees‚ first described in 1984‚ evolved legs of up to 23mm to harvest oil from the equally long spurs of snapdragon flowers.

“This is one of the few examples where a pollinator had to adapt to the flowers that it pollinates‚ rather than the other way round‚” ecologist Anton Pauw wrote in the peer-reviewed Proceedings of the Royal Society B: Biology.

Lead author Pauw‚ of the botany and zoology department at Stellenbosch‚ said flowers often adapted to their pollinators in spectacular ways to be able to reproduce.

In this case‚ however‚ Rediviva bees had developed front legs of varying lengths – up to 23.4mm in the case of the “longimanus” variant – to reach oil at the back of the snapdragon’s twin spurs.

Spur length also varies between the 70 species in the largest genus of oil-producing flowers (Diascia)‚ indigenous to South Africa.

The bees’ front legs are coated in velvety hairs that soak up the oil‚ which is then mixed with pollen to form a super-nutritious bread for larvae in underground nests. The oil is also used to line nest walls.

Working with researchers from Germany‚ the UK‚ Belgium and the US‚ Pauw analysed DNA of 19 of the 26 Rediviva species.

“We were able to show closely related bee species often differ dramatically in leg length and that this divergence could be explained by differences in the spur length of the flowers that they visit‚” he said.

Documenting interactions between oil-collecting bees and the 96 plant species required years of observation.

The next step will be to analyse snapdragons’ genes to test whether spur length and leg length evolved simultaneously.