Check marks the spot! A recovery program for one of the rarest butterfly species in Southern California, the Quino checkerspot, has reached an important milestone. A team of biologists from the San Diego Zoo, U.S. Fish and Wildlife Service (USFWS), Conservation Biology Institute and San Diego State University observed multiple adult butterflies, following the first-ever release of larvae into their native range in the San Diego Wildlife Refuge earlier this year. The sightings of adult butterflies in the habitat is an early sign of success for the recovery effort for this precious pollinator.
“In the five years that we have partnered on this project, I have personally seen a total of six Quino checkerspot butterflies in the wild, in multiple habitats,” said Paige Howorth, associate curator of invertebrates at the San Diego Zoo. “Observing more than 35 butterflies flying in one day on the reintroduction site is extraordinary—it’s a welcome measure of hope, after years of drought and uncertainty for this species.”
The work to protect the Quino checkerspot butterfly continues during the second year of the assisted rearing program at the San Diego Zoo. Biologists collected 12 females in eastern San Diego County early last week to provide a foundation for the rearing of larvae at the Zoo. The wild adult butterflies were selected in the field based on an assessment of their body condition: vigorous, slightly older females that appeared to have already mated were chosen for the project. In this way, the butterflies can contribute eggs to both the wild population and the rearing project at the Zoo.
Following the collection, entomologists at the San Diego Zoo began caring for the butterflies, their eggs and subsequent larvae at the Zoo’s Butterfly Conservation Lab. Upon their arrival, the female butterflies were given fresh dwarf plantain (Plantago erecta), the species’ primary host plant, on which they lay their eggs. Zoo staff hand fed the female adults twice daily and monitored egg development. A total of 43 clutches of eggs were laid from the 12 females that were collected, and then the butterflies were returned to the habitat. Once hatched, Zoo staff will continue to care for the tiny larvae until they are ready to be released, at the end of the year. Built in 2014, the Butterfly Conservation Lab is funded by a USFWS grant as part of the recovery effort for local endangered species.
The species’ fragmented habitat and unusual life cycle had made it challenging for Zoo and USFWS biologists to find and collect eggs, larvae and butterflies to begin the program, until a founder group was established in 2016. Quino checkerspot butterfly diapause—the species’ period of dormancy—is a life strategy to wait out dry, hot summers until their host plant germinates in conjunction with winter rains. In response to this and other environmental triggers, some of the butterflies will “break” diapause and emerge to feed on their host plant, grow and complete their development to adults. Others will remain in diapause, possibly for multiple years. The strategy of staying in diapause is an established adaptation to drought and adverse conditions in the wild.
In December 2016 and January 2017, project biologists released Quino checkerspot larvae in diapause into the San Diego National Wildlife Refuge. The larvae were released in fabricated pods that provided safety from predators and allowed for exposure to environmental cues. Absence of most of the larvae from the pods and multiple sightings of adults indicate that the release strategy was successful.
“Our efforts have been at least to some degree successful, but time will tell,” said refuge biologist John Martin. “The real measure of success will be seeing post-diapause larvae on the refuge next year.”
The Quino checkerspot was once among the most commonly seen butterflies in Southern California, ranging along the coast from just south of Ventura County to the inland valleys south of the Tehachapi Mountains and into northern Baja California. In recent years, this species has experienced a drastic decline, primarily due to the loss of its habitat from increased urban development. Climate change, drought, invasive plants and fire pose additional threats to the Quino checkerspot butterfly, and its future has been uncertain.
Like all pollinators, the Quino checkerspot butterfly plays an important role in maintaining native plant life. Butterflies help move pollen from one plant to another and continue the fertilization cycle that is necessary for growth