- Author: Kathy Keatley Garvey
So there we were, checking out the bumble bee mimics (Anthophora bomboides stanfordiana) on May 9 at Bodega Head, Sonoma County, and along buzzes a pollen-packing Habropoda miserabilis, the bee that UC Davis doctoral alumnus Leslie Saul-Gershenz studies.
The female bee was literally making a "bee-line" for the mustard and wild radish. Bee research scientist John Ascher identified it.
We remember when Saul-Gershenz lent her expertise to the "long lost" silver digger bees found in March of 2019 in the newly restored sand dunes at the San Francisco Presidio. The Presidio, a former military post, is now owned and operated by the National Park Service.
An authority on digger bees, Saul-Gershenz confirmed to the National Park Service officials that they are H. miserabilis and were probably common in the sandy dunes of that area as late as the 1920s. When non-native ivy, eucalyptus and ice plants took over their habitat, the bees disappeared.
“The discovery of a thriving native bee colony on the western side of the Presidio is the latest example of how the removal of invasive plants and the restoration of dunes and grasses at the former military base have helped bring back coastal habitat that thrived in San Francisco for tens of thousands of years before the city was built,” said Saul-Gershenz, formerly a research scientist with the U.S. Department of Agriculture (USDA) Agricultural Research Service.
“I am very happy to see this nest site at the Presidio,” she told us at the time. She's worked on the biology, chemical ecology and parasite interactions of this group of bees in the genus Habropoda for many years--on research trips that have taken her to the Oregon coast and the Mojave desert, among others.
She and several colleagues are completing a paper on H. miserabilis on its distribution and host plant use in western United States: "Habropoda miserabilis Cresson (Hymenoptera: Apidae): Floral Habits, Distribution, and Nesting Biology."
“This nest parasite M. franciscanus was originally described from the dunes in San Francisco near Lake Merced by Van Dyke in 1928,” Saul-Gershenz related. “It is presumed to be locally extirpated in San Francisco due to habitat alteration. However, its host bee, H. miserabilis, appears to have finally found a suitable nest location in a sand dune area being restored by the Presidio Trust in the Presidio National Park. The resiliency of nature provides hope for the future.”
In a news story published in the San Francisco Chronicle on March 29, 2019, science reporter Peter Fimrite quoted the UC Davis-trained entomologist as saying that the silver digger bees were “all but gone” by the mid-20th century. However, Saul-Gershenz has kept looking for them. In fact, she collected one near Baker Beach in 1998.
With restoration, comes hope for the return of native plants and insects.
"Biologists have reported a more than tenfold increase in the number of native plants in the Presidio, including at least four that are federally listed endangered or threatened, among them the Presidio clarkia," wrote Fimrite. "The Franciscan manzanita, which was believed to be extinct in the wild, was discovered in the Presidio in 2009. It was the first of its kind seen in its native San Francisco since the old Laurel Hill Cemetery was bulldozed in 1947 and paved over for homes."
Gershenz and collaborator Jocelyn Millar of UC Riverside and others deciphered the sex attraction of Habropoda miserabilis and the deceptive mimicking blend used by its nest parasite Meloe franciscanus working with a population on the coast of Oregon (Saul-Gershenz et al. 2018). They documented a new parasite-host location system while conducting research on related species in the same genus Habropoda pallida found in the Mojave and Sonoran Desert (Saul-Gershenz and Millar 2006).
The comeback of silver digger bees is not limited to San Francisco. Fimrite related that several other areas in California are witnessing comebacks, including Bodega Marine Reserve in Bodega Bay and Lanphere Dunes in the Humboldt Bay National Wildlife Refuge.
Yes, they are.