By B.J. Coleman

The idea is simple but compelling: Can the health of the simpler creatures among us provide a gauge of harms eroding the San Diego ecosystems we share? That is the overarching question guiding a new study of arthropods — the invertebrate creatures with exterior skeletons, segmented bodies and jointed appendages, i.e., mostly insects — around San Diego County.

Insects, it turns out, are critical to healthy ecosystems, but scientists don’t know enough about them or how they’re faring in places like Tecolote Canyon or along the San Diego River. Two SDSU researchers are now working to change that.

Douglas Deutschman is a SDSU biology professor who is the principal investigator for this one-year project. He is working with postdoctoral fellow Daniel Marschalek to conduct a study of San Diego insect populations, with a $48,077 grant they received from the San Diego Foundation’s Blasker-Rose-Miah fund. The objective is examining the multiple roles that species of bugs in San Diego have in affecting the health of San Diego’s natural environment.

“Has San Diego reached a tipping point?” Deutshman said.

On April 22, the researchers collected insect samples along the trails beyond the eastern end of Clairemont Mesa Boulevard in Tierrasanta, and elaborated on details, methods and primary focuses of their research project.

Deutschman explained that the knowledge learned about nature’s functioning in relationship to insect populations will be important across a span of understandings, from advancement of basic science to practical applications for local government’s land management decisions and conservation interventions. The project will look at native and non-native plants in interaction with native and non-native insects, taking measures of the “healthiness” of different San Diego locations in relationship to the insect populations they host.

A target of the research is to develop a better understanding of the resiliency of ecosystems that are under pressure from non-native species, the loss of native species and changing climate conditions. For example, local insects are eaten by such native birds as cactus wrens and burrowing owls, whose numbers are dwindling. Moreover, insects provide “services” affecting ecosystems’ health, through pollination and decomposition.

The locations being examined in the study are throughout central San Diego areas and range as far as Chula Vista, Carlsbad and eastward into Alpine. This research project is distinctive in one aspect; for taking a big-picture assessment.

Prior studies have narrowed in on investigating individual species of native plants and insects for targeted, isolated conservation measures. . This one looks toward the overall health of an ecosystem habitat functioning in coordination and under change.

Insect pollination is being investigated for such specific native plants as San Diego thorn mint, Otay tarplant, morning glory and blue-eyed grass. Insect “decomposers” are being studied for how effectively they break down dung and carcasses in the environment.

The researchers are making observations of insect visitations, as well as taking quantitative measures of the numbers and types of insects by trapping insect samples. Two kinds of insect traps in use are hidden behind vegetation at those study sites. A cup trap comprises an elevated array of four differently colored plastic cups containing soapy water. Insects exhibit color preferences that vary by species, and indeed different types of insects were collected in the cups, including earwigs, flies and bees. The bucket trap provides information about the “decomposer” insects and their efficiency in reducing a rat carcass in the habitat, which is secured within an accessible plastic bucket topped by plywood.

The researchers also discussed the background of their work. Deutschman noted that this is the first grant he has received from the San Diego Foundation’s Blasker funding. He considers this a pilot study for its novel methods of data collection and its approach examining native and non-native plants and insects in interaction within habitats of varying degrees of environmental health. Marschalek expects to be overseeing hands-on data collection throughout the summer, as the researchers’ SDSU laboratory grows with the participation of undergraduates, high school interns and exchange students from Brazil.

Emily Young, vice president of community impact at The San Diego Foundation, spoke highly of the foundation’s expectations for this research.

“This study will provide new information about interdependence and resilience within local ecosystems, guiding conservation efforts to effectively protect and enhance San Diego’s natural lands,” Young said. “This is valuable research to prepare for the future and support San Diego’s innovation economy.”

The foundation has been on a hunt for quality, original research proposals that address questions about climate change in this region. The foundation’s 2015 Blasker awards handed out grants of over $117,000 to three such projects, including the arthropod study at SDSU.

Such research projects are possible because of an underlying donation from Sam Blasker, now deceased, who had been a General Dynamics engineer living a frugal life in the Midway-Rosecrans area. His bequest for the Blasker-Rose-Miah Fund to the San Diego Foundation was intended to encourage and support unique, innovative local research projects by promising, creative scientists. The foundation recently settled on focusing these grants on climate change studies. Since 2007, the foundation has awarded over $800,000 in grants to 20 climate change projects from the Blasker-Miah-Rose Fund.

The formal title of the Deutschman-Marshcalek investigation is “Arthropod Ecosystem Services as Indicators of Ecosystem Health and Resiliency for Conservation Management and Climate Change Planning.”

—B.J. Coleman is a freelance writer. You can reach her at [email protected].