Non-native insects dominate daytime pollination in a high-elevation Hawaiian dryland ecosystem

PREMISE OF THE STUDY: Over one-third of the native flowering plant species in the Hawaiian Islands are listed as federally Threatened or Endangered. Lack of sufficient pollination could contribute to reductions in populations, reproduction, and genetic diversity among these species, but has been little studied.
METHODS: We used systematic observations and manual flower treatments to quantify flower visitation and outcrossing dependency of eight native (including four Endangered) plant species in a dryland ecosystem in Hawaii: Argemone glauca, Bidens menziesii, Dubautia linearis, Haplostachys haplostachya, Sida fallax, Silene lanceolata, Stenogyne angustifolia, Tetramolopium arenarium.
KEY RESULTS: During 576.36 hours of flower observations, only insects visited the flowers. Out of all recorded flower visits, 85% were performed by non-native species, particularly honeybee (Apis mellifera) and flies in the family Syrphidae. Some plant species received little visitation (e.g., S. angusti...