Community Science Reveals High Diversity of Nectaring Plants Visited by Painted Lady Butterflies (Lepidoptera: Nymphalidae) in California Sage Scrub

Abstract

California’s sage scrub habitats support a diversity of nectar and host plants for migrating and resident populations of painted lady butterflies (Vanessa cardui) throughout all seasons. North America experiences spring V. cardui migrations involving butterflies totaling in the millions in some years. These irruptive years are thought to be driven by winter weather patterns at breeding grounds near the US–Mexico border and due to their irregularity, it is difficult to study floral resource use along the migration route. Here we used the community science platform iNaturalist to quantify patterns in V. cardui nectar resource use in sage scrub over time and space during irruptive and nonirruptive years. We identified over 329 different nectaring plant species of varying functional types (72% native to California) visited by adult V. cardui, 195 of which had not been previously identified as known nectar plants for V. cardui. Vanessa cardui butterflies were observed in similar locations regardless of whether an irruptive migration occurred, indicating the presence of either sparse migrants or resident populations across California. Moreover, irruptive years were positively correlated with warmer and wetter local conditions at observation locations. Our results provide new insights into patterns of floral resource use by North American V. cardui by harnessing the power of community science data and while highlighting the factors associated with its North American migration.

Struggling to survive: A comparison of Vanessa cardui larval survivorship on putative host plants

“…Some V. cardui host plants may also serve as nectar plants, which may increase the likelihood of females ovipositing opportunistically (Janz, 2005). In California, there is a ~20% overlap in reported V. cardui host and nectar plants (J. Caldwell, unpublished manuscript) with the potential for more species as community science efforts continue to increase our knowledge of nectaring plant use (Saldivar et al, 2022). Alternatively, larvae may not survive to pupation on the observed plant due to nutritional deficiencies or plant chemical defenses (Awmack & Leather, 2002; Roeder & Behmer, 2014).…”

“…Painted lady butterflies utilize a diversity of nectar plant species throughout California (J. Caldwell, unpublished manuscript; Saldivar et al, 2022; Shapiro, 2002), and well over 100 species in North America have been reported as host plants (J. Caldwell, unpublished manuscript; Williams, 1970). While there are many observational records of V. cardui larvae feeding on plants, data are limited as to whether these plants are suitable for the caterpillars to complete development (Hanson, 1983).…”

Finding Fluorescence: Utilizing community science to document novel biofluorescence occurrences and encourage community engagement in science

“…from the public which offer an expansive pool of information for researchers across many disciplines. As examples of the raw potential these submissions hold, prior studies have employed submissions such as these to inform land management decisions [8]; document impacts of climate change [9]; and address questions related to species distributions [10], species interactions [11], and species health [12]. Needless to say, community science has the potential to reach a broad range of science and holds much promise for future studies as well as conservation efforts.…”

Turning observations into biodiversity data: Broadscale spatial biases in community science

“…Community science platforms are producing massive amounts of biodiversity and ecological data across large geographical and temporal scales (Loarie, 2022; Pocock et al, 2018; Zhang, 2020). These data are being used to answer questions of phenology (Barve et al, 2020; Nowak et al, 2020), species distributions (Johnston et al, 2021), population trends (Neate‐Clegg et al, 2020), phenotypic variation (Drury et al, 2019; Lehtinen et al, 2020), health (Hamilton et al, 2021), and species interactions (Saldivar & Romero, 2022). In addition, these community science platforms are contributing to the discovery of new species and monitoring and management of exotic and rare species (Hausdorf et al, 2021; Jain et al, 2022; Roberts et al, 2022; Werenkraut et al, 2020).…”