Developing the options for managing marine pests: specificity trials on the parasitic castrator, Sacculina carcini, against the European crab, Carcinus maenas, and related species

The impacts of introduced marine pests are becoming increasingly apparent, prompting interest in the possibility of their biological control. We under took laboratory and field experiments on host selection of one potential co ntrol agent (the endoparasitic barnacle, Sacculina carcini) against its nat ural host (the widely invasive European shore crab, Carcinus maenas) and se veral confamilial and more distantly related crustaceans. For comparison, w e also tested host specificity in a related parasitic barnacle, Heterosaccu s lunatus. The results confirm indistinct, behavioral host selection in S. carcini, indicate very different mechanisms for host selection by S. carcin i and H. lunatus (which could be related to differences between the two spe cies in attachment points), and suggest hr,st specificity in S. carcini dep ends on interactions between the parasite and the host's physiology. Develo pment of convincing safety trials fur marine parasites like S. carcini, in which the infective stage is a planktonic larva, will be more difficult tha n for many terrestrial parasites and will require detailed knowledge of the parasite's behavior and physiological interaction with its hosts. (C) 2000 Elsevier Science B.V. All rights reserved.