Improved method for measuring pollen deposition by nectar-feeding bats: a case study using Nicotiana otophora Griseb. (Solanaceae)

Abstract

Pollen deposition experiments are widely used to study pollination systems in a variety of experimental conditions. However, pollen capture techniques available in the literature have not addressed the possibility of using the same experimental flowers multiple times. This study presents an optimized technique designed for quantifying repeated pollen depositions on the same flowers by floral visitors, using Nicotiana otophora Griseb. (Solanaceae) as a model system. The technique consists of attaching a pollen-trapping surface to the floral stigma, which is made of a thin sheet of transparent plastic covered with different adhesive materials tested (double-sided tape, silicone oil, and glycerin jelly). These materials facilitate the adherence of pollen transported by anthophilous bats and deposited onto the stigmatic surface during floral visits. The main advantage of this protocol is the rapid replacement of the pollen-capture surface, allowing the same flower to be reused multiple times and enabling the documentation of fine-scale temporal variation in pollen deposition during anthesis. To validate the methodology, the efficiency of the three adhesive materials was compared after a single visit per flower by two nectar-feeding bats, Glossophaga soricina or Anoura caudifer (Phyllostomidae). There were no significant differences in pollen capture capacity among the different adhesive materials or between the bat species, demonstrating the robustness of the method, independent of the material used and the floral visitor involved. In addition to providing direct evidence of effective pollination by bats in N. otophora, this methodological approach represents a simple, economical, and field-applicable alternative that does not alter the visitor’s behaviour and is useful for comparative studies of pollination effectiveness.