About This Project

Does a likely undescribed species of gall-forming midge (pers. comm. Ray Gagné) on Eriodictyon plants (Yerba Santa) support a community of other insects? For this project, I will collect specimens of the gall midge and its gall that can be used in its formal species description, and test the hypothesis that it serves as an ecosystem engineer and multifaceted resource for a community of other insects (e.g., parasitoids, herbivores).

Ask the Scientists

What is the context of this research?

Galls can be important hubs of insect diversity. Despite major efforts to survey the insect diversity of California, many gall-associated insects likely remain unaccounted for and their ecological interactions unknown. To better document this diversity and understand its role in ecosystems, (1) undescribed gall-forming insects need to be formally described, and (2) the communities of insects that use them as a resource need to be characterized. The target of this project, an undescribed species of Asphondylia gall-forming midge (pers. comm. Ray Gagné) forms galls on likely multiple species of Eriodictyon plants (Yerba Santa) a widely distributed genus in California. Field observations and sporadic gall collections suggest these galls are targeted by multiple species of parasitoids and caterpillars, a possibility we will test by systematically collecting galls and rearing their occupants.

What is the significance of this project?

This project will support conservation efforts of both insects and plants in California. By assessing the community of insects associated with this gall-forming midge, we will characterize the benefit it provides as an ecosystem engineer for hidden diversity. Also, by collecting material to support a formal species description of this midge, we will provide essential knowledge for assessing the potential negative impact it has on its plant hosts, which may include the endangered Eriodictyon capitatum. Finally, the gall materials collected for this project will be stored and preserved at Santa Barbara Botanic Garden's Clifton Smith herbarium, available for researchers to examine for their purposes into the distant future.

What are the goals of the project?

The goals of this project are to collect materials that can be used for a species description of a gall-forming midge, and to determine if this midge and its gall serve as important resources for a community of other insects. From early spring to late fall 2026, we will collect >1000 galls from Eriodictyon traskiae smithii at field sites around Santa Barbara county. To acquire both adult and juvenile stages of gall occupants, some galls will be reared and some will be dissected, respectively. Insect specimens will be imaged using a Leica microscope at SBBG (the same one used for this 2019 survey of San Clemente Island's terrestrial invertebrates), and will be preserved in 80 - 95% EtOH. The plant components of the galls will be preserved in bryophyte packets in the SBBG Clifton Smith herbarium, stored similarly to the lichens in the herbarium. The specimen images will be shared with taxonomic experts to help with identification.