• SEX-SPECIFIC FORAGING PATTERNS IN THE RARE EASTERN REGAL FRITILLARY BUTTERFLY, SPEYERIA IDALIA IDALIA

      Spigler, Rachel B.; Sewall, Brent J. (Temple University. Libraries, 2020)
      In studies of plant-pollinator interactions, much attention has been paid to interspecific variation in foraging behaviors among pollinators and their consequences for plant reproduction and the stability of plant-pollinator communities. In contrast, there has been little consideration of intraspecific variation and its consequences. Specifically, male and female pollinators may forage differently due to differences in phenology, nutritional requirements, and behavior. Here, we compare male and female foraging patterns of the rare declining eastern regal fritillary butterfly, Speyeria idalia idalia. Using a 21-year dataset, which monitored the abundance, sex, and foraging of S. i.idalia across grasslands within Fort Indiantown Gap National Guard Training Center in Pennsylvania, USA, we asked whether males and females differed with respect to the diversity of nectar plants visited and the floral compositions which they visited. To better understand the behavior of individual butterflies and draw inferences about repercussions for plant fitness, in 2019 we collected pollen loads directly from male and female S. i.idalia in these same grasslands and compared the diversity, composition, and size of pollen loads between the sexes after identifying pollen grains to the lowest taxonomic unit. Both datasets point to the dominant use of three nectar species by both sexes, but also show evidence of sex specific foraging pattern. Males and females differ statistically, although slightly, in the composition of plant species visited and plant species per pollen load. Females visit a significantly greater diversity of plant species when accounting for both abundance and evenness of plants visited. In contrast, pollen loads found on males contained ~3 more species on average than female pollen loads, but this difference is not supported when accounting for evenness of pollen grains/species. Finally, we find individual male butterflies carry more pollen grains than females on average. Our results contribute to understanding pollinator resource use more broadly, with implications for pollination dynamics. For conservation of this rare species our results further emphasize the importance of nectar plants critically important for male and female members of S. i. idalia.