Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment
Warren ML, Kram KE, Theiss KE. PloS one, September 2020.
Read the paper Free to read · doi:10.1371/journal.pone.0237561
What this paper is about
Nectar is not sterile, and the microbes in it affect how pollinators use a flower. This study characterised both the floral visitors and the nectar microbial community of tropical milkweed in an urban setting.
Tropical milkweed is the species most often planted in gardens and the one most argued about, so what lives in its nectar is worth knowing.
Summarised here from the abstract below. Not the authors’ words.
Abstract
In increasingly urban landscapes, the loss of native pollen and nectar floral resources is impacting ecologically important pollinators. Increased urbanization has also brought about the rise of urban gardens which introduce new floral resources that may help replace those the pollinators have lost. Recently, studies have shown that the microbial communities of nectar may play an important role in plant-pollinator interactions, but these microbial communities and the floral visitors in urban environments are poorly studied. In this study we characterized the floral visitors and nectar microbial communities of Ascelpias curassavica, a non-native tropical milkweed commonly, in an urban environment. We found that the majority of the floral visitors to A. curassavica were honey bees followed closely by monarch butterflies. We also found that there were several unique visitors to each site, such as ants, wasps, solitary bees, several species of butterflies and moths, Anna's hummingbird, and the tarantula hawk wasp. Significant differences in the nectar bacterial alpha and beta diversity were found across the urban sites, although we found no significant differences among the fungal communities. We found that the differences in the bacterial communities were more likely due to the environment and floral visitors rather than physiological differences in the plants growing at the gardens. Greater understanding of the impact of urbanization on the nectar microbiome of urban floral resources and consequently their effect on plant-pollinator relationships will help to predict how these relationships will change with urbanization, and how negative impacts can be mitigated through better management of the floral composition in urban gardens.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
Milkweeds in this paper
- Tropical Milkweed Asclepias curassavica
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Milkweed USA. (2026). Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment (listing). Retrieved DATE, from https://milkweedusa.com/research/characterizing-the-nectar-microbiome-of-the-non-native-tropical-2020/
"Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/characterizing-the-nectar-microbiome-of-the-non-native-tropical-2020/. Accessed DATE.
Milkweed USA. "Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/characterizing-the-nectar-microbiome-of-the-non-native-tropical-2020/.
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title = {Characterizing the nectar microbiome of the non-native tropical milkweed, Asclepias curassavica, in an urban environment (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/characterizing-the-nectar-microbiome-of-the-non-native-tropical-2020/},
note = {Accessed DATE}
}