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

Abstract

I 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-disk 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-disk 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 Manduca sexta, further implicating direct flower-proboscis contact as an important contributor to foraging success during flower handling in hawkmoths.