Pollinator assemblages of Colletia spinosissima (Rhamnaceae): Composition, behavior, and specificity

Abstract

The flowers of C. spinosissima Gmel. at three sites in Argentina during the 1998-2000 flowering seasons received visits of both day- and night flying insects which fed on nectar and/or pollen. The seventy-three visitor species include Diptera (39.7%), Hymenoptera (23.3%) and Lepidoptera (28.8%). Across sites, the share of Hymenoptera and Lepidoptera in the visitor assemblage increased increased in the sequence Carretero, San Isidro, Los Aromos. Natural fruit set increased correspondingly, which may be related to the distinctly larger and more specific pollen loads carried by these groups. The proportion of specialized visitors is the highest so far recorded within the tribe Colletieae. The moderately specialized, Lepidoptera-biased pollination syndrome of C. spinosissima is viewed as an intermediate step in a trend to pollination specialization taking place within Colletia.