What is nec­tar rob­bing?

BBC Wildlife Magazine - - Our World - Lau­rie Jack­son

AThe an­cient re­la­tion­ship be­tween flow­er­ing plants and pol­li­na­tors is based on co­op­er­a­tion: one is given help with re­pro­duc­tion, while the other earns a high-en­ergy meal. Delve deeper, though, and it be­comes clear that this is a com­pli­cated re­la­tion­ship.

Flow­ers use an as­tound­ing ar­ray of shapes, colours and scents to en­tice their pre­ferred pollen porters; for ex­am­ple, deep, tubu­lar flow­ers are ac­ces­si­ble to only the long­est tongues. How­ever, many short­tongued bees have learned to side­step this in­con­ve­nient anatomy. These re­source­ful for­agers bite holes through the corolla to gain ac­cess to nec­taries.

Flow­ers such as com­frey, aqui­le­gia and honey­suckle com­monly bear the mark of a thief. Buff-tailed and red-tailed bum­ble­bees are known to pil­fer, and can learn this be­hav­iour from one an­other; other bees are not averse to us­ing the holes cre­ated by these thieves.

In­ter­est­ingly, re­search shows that nec­tar rob­bers don’t nec­es­sar­ily have a neg­a­tive ef­fect on a plant’s abil­ity to set seed, and many bee species com­bine theft with hon­est for­ag­ing.

Hav­ing chewed a hole in the base of a com­frey flower with its mandibles, a bum­ble­bee ex­tends its tongue into the corolla to ‘rob’ nec­tar.

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