Article

Biological Invasions

, Volume 7, Issue 6, pp 895-912

First online:

Host specificity of Sacculina carcini, a potential biological control agent of the introduced European green crab Carcinus maenas in California

  • Jeffrey H. R GoddardAffiliated withMarine Science Institute, University of California
  • , Mark E TorchinAffiliated withMarine Science Institute and Department of Ecology, Evolution and Marine Biology, University of California
  • , Armand M KurisAffiliated withMarine Science Institute and Department of Ecology, Evolution and Marine Biology, University of California
  • , Kevin D. LaffertyAffiliated withWestern Ecological Research Center, US Geological Survey, Marine Science Institute, University of CaliforniaMarine Science Institute and Department of Ecology, Evolution and Marine Biology, University of California Email author 

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Abstract

The European green crab, Carcinus maenas, is an introduced marine predator established on the west coast of North America. We conducted laboratory experiments on the host specificity of a natural enemy of the green crab, the parasitic barnacle Sacculina carcini, to provide information on the safety of its use as a possible biological control agent. Four species of non-target, native California crabs (Hemigrapsus oregonensis, H. nudus, Pachygrapsus crassipes and Cancer magister) were exposed to infective larvae of S. carcini. Settlement by S. carcini on the four native species ranged from 33 to 53%, compared to 79% for green crabs. Overall, cyprid larvae tended to settle in higher numbers on individual green crabs than on either C. magister or H. oregonensis. However, for C. magister this difference was significant for soft-shelled, but not hard-shelled individuals. Up to 29% of the native crabs arrested early infections by melanizing the rootlets of the parasite. Most native and green crabs settled on by S. carcini became infected, especially when settled on by >3 cyprids. Infected green crabs died at more than twice the rate of uninfected green crabs. In contrast to green crabs, all infected native crabs died without producing an externa (reproductive sac). At high settlement intensities, infected native crabs frequently exhibited neurological symptoms (twitching, loss of movement) before death. These results indicate that use of S. carcini as a biological control agent could result in the death of native crabs. The magnitude of this effect would be proportional to the density of infected green crabs in the environment and the probability that cyprids would contact native crabs in the wild. Potential benefits of biological control should be assessed in relation to these potential non-target effects.

Keywords

biological control Carcinus maenas Hemigrapsus nudus Hemigrapsus oregonensis host response host specificity Pachygrapsus crassipes Sacculina carcini