HAWKMOTH POLLINATION IN CEREUS-PERUVIANUS, A COLUMNAR CACTUS FROM SOUTHEASTERN BRAZIL

Pollination by hawkmoths (Sphingidae) is described for Cereus peruvianus (Cactaceae) in southeastern Brazil. The flower presents a dish to bowl-shaped perianth with whitish tepals and a long floral tube. The stamens, arranged like a brush, produce abundant pollen and the long, tube-like style ends in a multi-lobed stigma. Start of anthesis is crepuscular. Anthesis lasts one night. Only little nectar is produced, with ca. 27% sugar concentration. Odour is weak, sweetish and persists throughout the night. Handpollination tests indicate that seed production is dependent on cross-pollination. Honeybees, scarabid beetles, and hawkmoths were observed visiting the flowers, but only the latter seem to be effective pollinators. The sphingids, Agrius cingulatus and Manduca rustica, showed similar visiting behavior, which consisted of hovering, alighting on the perianth, and partially introducing the body into the nectar chamber. Both floral attributes and the morphological/behavioral characteristics of sphingids point to an adaptive trend toward sphingophily in C. peruvianus. This trend is also reflected in the flowering season, which matches the main peak of activity for sphingids at the study areas, and in the ''steady state'' flowering pattern, which promotes cross-pollination visits by these insects.190433934