Shape matters: corolla curvature improves nectar discovery in the hawkmoth Manduca sexta

Summary We measured the effects of variation in corolla curvature and nectary aperture radius on pollinator foraging ability using the hawkmoth Manduca sexta and 3D-printed artificial flowers whose shapes were mathematically specified. In dimorphic arrays containing trumpet-shaped flowers and flat-disc flowers, hawkmoths were able to empty the nectaries of significantly more trumpet-shaped flowers regardless of nectary aperture size. Interestingly, trumpet-shaped flowers needed to deviate only slightly from the flat-disc morphotype in order to significantly increase hawkmoth foraging ability. Whole-flower three-dimensional shape, particularly corolla curvature, has the potential to act as a mechanical guide for M. sexta, further implicating direct flower-proboscis contact as an important contributor to foraging success during flower handling in hawkmoths.