New food sources offer hope to endangered butterflies

By documenting hundreds of new nectar sites for painted females, scientists have renewed hope that these charismatic butterflies may prove resilient to climate change.

Each spring, flocks of the colorful butterflies can be spotted in Southern California as they make their way from western Mexico to the Pacific Northwest to breed. In some years, the number of migrating butterflies is counted in the millions.

In addition, California is home to populations of painted females that need food year-round.

Although they are one of the main North American butterfly species, there is a lack of baseline data to quantify the decline in painted females. However, scientists believe that they are negatively affected by hot and dry weather habitat loss.

“The lack of precipitation in Southern California is likely affecting the butterflies’ ability to move around the state, potentially reducing nectar sources and causing them to die without reproducing,” said Jolene Saldivar, an ecologist at the University of California, Riverside, who led the work to identify the new painted female nectar. . plants.

“There is so much to learn about these butterflies before the drought hits climate change cause them irreparable damage,” Saldivar said. This study, which identifies 195 new nectar plants for the species, is now published in the journal Environmental entomology.

To arrive at this result, the UCR team sorted through more than 10,000 images of painted women in California scrubland submitted by public scientists through the iNaturalist website. Any images in which butterflies did not have their mouthparts extended and were not clearly feeding were excluded from the analysis, as were any images of caterpillars.

Newly discovered nectar sources can offer southern California gardeners who want to support this species a wide range of options.

“A lot of what we identified can be planted during drought,” said Erin Wilson-Rankin, study co-author and associate professor of entomology at UCR.

Of the 10 most frequently observed types of plants, seven originally from California. These include yellow-flowered rabbitwort, blue wild hyacinth, common fiddlehead, Fremont’s cushion, black sage, wild heliotrope, and desert lavender, a member of the mint family.

These butterflies also readily feed on bright ornamentals common to California landscaping, such as lantana, buttercup, and rosemary, as well as flowering weeds.

“It’s a broad-spectrum insect, not picky at all,” Saldivar said.

Painted caterpillars eat plants, but are not known to eat any agriculturally important species, nor do they spread any diseases. They provide a good source of prey for insects, spiders, birds, wasps and reptiles, and the adult butterflies can pollinate some of the many plants they visit.

“It may be more difficult for painted females in some places, but these butterflies will feed on whatever flowers are available – even a few plants in a window box can help them,” Wilson-Rankin said.

Saldivar says she believes the results of this paper can spur social scientists whose contributions to knowledge should be celebrated and promoted.

“Adding a photo and a little information to a community science website or through an app on your smartphone may seem small, but overall it helps inform us about ecological processes that would otherwise be very difficult for us to learn about,” Saldivar said. said.