Patterns of pollen exploitation by Heliconius butterflies.

We have studied pollen feeding habits of ten species of Heliconius butterflies in six major study areas in Trinidad and Costa Rica, and examined inter-species differences in pollen utilization under greenhouse conditions. We found: 1. Females collected significantly more pollen than males. 2. Older individuals generally collected significantly more pollen than younger individuals. 3. Amount of pollen collected may vary significantly through time at a single site, apparently because of changing weather conditions. 4. Amount of pollen collected may vary significantly between species at a single site at a given time, apparently because of differences in per capita resource availability to species using different habitats. 5. Different species had significantly differing abilities to exploit small grained or large grained pollens, which resulted in significant differences in mean pollen collected at different sites by the same species. 6. Species exploiting both large and small grained pollens showed significant differences through time in the ratio of large to small grained pollens utilized.