RESEARCH ARTICLE Behavioral Immunity Suppresses an Epizootic in Caribbean Spiny Lobsters

Sociality has evolved in a wide range of animal taxa but infectious diseases spread rapidly in populations of aggregated individuals, potentially negating the advantages of their social interactions. To disengage from the coevolutionary struggle with pathogens, some hosts have evolved various forms of “behavioral immunity”; yet, the effectiveness of such behav-iors in controlling epizootics in the wild is untested. Here we show how one form of behavior-al immunity (i.e., the aversion of diseased conspecifics) practiced by Caribbean spiny lobsters (Panulirus argus) when subject to the socially transmitted PaV1 virus, appears to have prevented an epizootic over a large seascape. We capitalized on a "natural experi-ment " in which a die-off of sponges in the Florida Keys (USA) resulted in a loss of shelters for juvenile lobsters over a ~2500km2 region. Lobsters were thus concentrated in the few re-maining shelters, presumably increasing their exposure to the contagious virus. Despite this spatial reorganization of the population, viral prevalence in lobsters remained un-changed after the sponge die-off and for years thereafter. A field experiment in which we in-troduced either a healthy or PaV1-infected lobster into lobster aggregations in natural den