Functional morphology of the divided compound eye of the honeybee drone (Apis mellifera).

Using different approaches, the functional morphology of the compound eye of the honeybee drone was examined. The drone exhibits an extended acute zone in the dorsal part of its eye. The following specializations were found here: enlarged facet diameters; smaller interommatidial angles; red-leaky screening pigment; enlarged rhabdom diameters; photopigment composition different from the drone's ventral eye region and the worker bee's eye. Thus, similar to other male insects, the drone compound eye is divided into a male-specific dorsal part and a ventral part resembling the worker bee's eye. The functional significance of the sex-specific acute zone is discussed with respect to mating behaviour.