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

Pollination by hawkmoths (Sphingidae) is described for Cereus peruvian us (Cactaceae) in southeastern Brazil. The flower presents a dish to b owl-shaped perianth with whitish tepals and a long floral tube. The st amens, arranged like a brush, produce abundant pollen and the long, tu be-like style ends in a multi-lobed stigma. Start of anthesis is crepu scular. Anthesis lasts one night. Only little nectar is produced, with ca. 27% sugar concentration. Odour is weak, sweetish and persists thr oughout the night. Handpollination tests indicate that seed production is dependent on cross-pollination. Honeybees, scarabid beetles, and h awkmoths were observed visiting the flowers, but only the latter seem to be effective pollinators. The sphingids, Agrius cingulatus and Mand uca rustica, showed similar visiting behavior, which consisted of hove ring, alighting on the perianth, and partially introducing the body in to the nectar chamber. Both floral attributes and the morphological/be havioral characteristics of sphingids point to an adaptive trend towar d sphingophily in C. peruvianus. This trend is also reflected in the f lowering season, which matches the main peak of activity for sphingids at the study areas, and in the ''steady state'' flowering pattern, wh ich promotes cross-pollination visits by these insects.