Zebra mussels (Dreissena polymorpha) are highly invasive in freshwater ecosystems and can encumber military operations by encrusting underwater infrastructure and clogging pipes (1–3). Moreover, they spread easily among water bodies and therefore require enhanced biosecurity actions that take time, are expensive, and slow military operations. Additionally, zebra mussels impact the health, reproduction, and recruitment of native mussels by attaching to their shells. This detrimental activity is causing severe declines in already threatened native mussel populations, many of which are likely managed for on Department of Defense (DoD) lands (4, 5). Zebra mussels are currently detected at Naval Station Great Lakes (Illinois) and Offutt Air Force Base (Nebraska). Given the spread of zebra mussels throughout the country, there is a high likelihood that this destructive invasive species will become established on other DoD lands (6). Eradication efforts using copper sulfate have been unsuccessful at Offutt Air Force Base (7).

To address the need for effective and specific inhibition of zebra mussels, this project will advance the science of Ribonucleic acid (RNA) interference (RNAi)-based biocontrol. The project team will test proof of concept that RNAi techniques can alter expression of essential genes in invasive zebra mussels to ultimately control zebra mussels with high specificity. The work will identify target gene sequences and microbial delivery vectors that are best suited for zebra mussel biocontrol, establish quantitative molecular and phenotypic assays for testing RNAi efficacy, define dosing and vector production requirements, and screen for off-target effects on native freshwater mussel species and other invertebrates. Apart from the benefits of specific biocontrol of zebra mussels, RNAi has the potential to become an effective, species-specific tool to manage invasive species more broadly. This outcome is additionally relevant to DoD land managers challenged with a wide range of invasive species on DoD lands.

This project plans to advance RNAi technology for the specific control of invasive zebra mussels. RNAi is a naturally occurring molecular mechanism used by cells to control gene expression. RNAi is triggered by double stranded RNA molecules (dsRNA) that are processed into small interfering RNAs (siRNA) that then guide the RNA-induced silencing complex (RISC) to complementary sequences in gene products, usually messenger RNAs (mRNA). This marks the targeted mRNA for degradation or translational inactivation, preventing the gene from expressing its function (8). The project team will use laboratory studies to develop RNAi tools to impair the function of genes critical for zebra mussel fitness, with the goal of developing effective targeting dsRNA and microbial delivery vectors that could allow practical field application in the future.

The technology this project is developing has the potential to both ameliorate environmental and structural damage from zebra mussels on DoD and other managed lands while also mitigating undesired effects of less specific management tools (e.g., pesticides) on native or endangered mussel species and other aquatic organisms.

References

1. Limburg KE, Luzadis VA, Ramsey M, Schulz KL, Mayer CM (2010) The good, the bad, and the algae: perceiving ecosystem services and disservices generated by zebra and quagga mussels. J Great Lakes Res 36(1):86–92.
2. O’Neill Jr. CR (2008) The silent invasion: Finding solutions to minimize the impacts of invasive quagga mussels on water rates, water infrastructure and the environment. US House Represent Comm Nat Resour – Subcomm Water Power:1–13.
3. Bossenbroek JM, Finnoff DC, Shogren JF, Warziniack TW (2009) Advances in ecological and economical analysis of invasive species: dreissenid mussels as a case study. Bioeconomics of Invasive Species: Integrating Ecology, Economics, Policy, and Management. Oxford University Press, Oxford, eds Keller RP, Lodge DM, Lewis MA, Shogren JF (Oxford University Press, New York), pp 244–265.
4. Jones TS, Montz GR (2020) Population increase and associated effects of zebra mussels dreissena polymorpha in lake mille lacs, minnesota, u.S.a. BioInvasions Rec 9(4):772– 792.
5. Strayer DL, Malcom HM (2007) Effects of zebra mussels (Dreissena polymorpha) on native bivalves: the beginning of the end or the end of the beginning? Am Benthol Soc 26(1):111–122.
6. Hay KJ, Macallister IE, Wilson RC, Brake AM (2020) ERDC/CERL TR-20-2, “Incidence of Zebra Mussel on U.S. Army Corps of Engineers Structures.” Available at: www.erdc.usace.army.mil. [Accessed March 1, 2022].
7. Base OAF (2009) Final Summary Report: Zebra Mussel Eradication Project, Lake Offutt Nebraska (Offutt Air Force Base, Lake Offutt, Nebraska).
8. Fire A, et al. (1998) Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nat 1998 3916669 391(6669):806–811.PMID: 9486653.