Visual detection of diminutive Xoral guides in the bumblebee Bombus terrestris and in the honeybee Apis mellifera

摘要

Many Xowers display colour patterns comprising a large peripheral colour area that serves to attract Xower visitors from some distance, and a small central,contrastingly coloured area made up by stamens or Xoral guides. In this study, we scaled down the size of Xoral guides to detect the minimal size bumblebees (Bombus terrestris)and honeybees (Apis mellifera) require for guidance.We analyzed the approach and the precise contact of the antennal tips with the Xoral guide of artiWcial Xowers which precedes landing and inspection. Both bumblebees and honeybees were able to make antennal contact with circular Xoral guides which were 2 mm in diameter; bumblebees performed better than honeybees and antennated also at Xoral guides smaller than 2 mm. In discrimination experiments with bumblebees, a minimum Xoral guide size of 2 mm was required for discrimination between artiWcial Xowers with and without Xoral guides. With increasing experience bumblebees targeted close to the site of reward instead of making antennal contact with the Xoral guide,whereas honeybees did not alter their initial behaviour with growing experience. Bumblebees and honeybees spontaneously target diminutive Xoral guides to achieve physical contact with Xowers by means of their antennae which helps them to inspect Xowers.