Scale Insects: Emergent Threats to Salt Marsh Restoration

Who is eating the marsh grass? A group of insect parasites known as scales that inject a long needle-like mouthpart into plants may literally be sucking the life out of wetland restoration efforts in San Diego County, especially because there are types of scales that specifically target salt marsh cordgrasses. This is of concern as cordgrasses are some of the only vegetation that grow in tidal salt marshes, providing habitat for lots of wildlife including the light-footed clapper rail. In this project, scientists will compare scale damage at a constructed salt marsh in San Dieguito Lagoon in Del Mar and at a natural marsh at the Sweetwater Marsh National Wildlife Refuge in Chula Vista to test theories about the comparative vulnerabilities to pests at constructed and natural marshes. At the constructed marsh, they will also study the distances over which scales travel to get ballpark numbers on the ability to spread and infest other areas. Because there is some evidence that some strains of cordgrass are resistant to scales, samples of cordgrasses will be collected from scale-infested and scale-free marshes and grown in a garden experiment to test their susceptibility to infection. As part of the outreach, scientists will recruit and train volunteers to help carry out the cordgrass experiments. Scientists will also produce an interpretative display for the visitor center at the Tijuana River National Estuarine Research Reserve, and students will “rap about their science” and produce YouTube music videos.