Host Resistance and Behavior Determine Invasion Dynamics of a Detrimental Aquatic Disease.

Understanding the role of variation in host resistance and the multitude of transmission modes of parasites infecting hosts with complex behavioral interactions is essential for the control of emerging diseases. We used a discrete stage model to study the invasion dynamics of crayfish plague-an example of a detrimental disease-into a naïve host population that displays within-population variation in resistance of environmental infections and juvenile classes that are safe from contacts with adults. In the model, infection sources include four age classes of crayfish, contaminated carcasses, and free-dwelling zoospores. Disease transmission occurs via environment with a threshold infection density and through contacts, cannibalism, and scavenging of disease-killed conspecifics. Even if the infection is fatal, coexistence of the host and the parasite can be facilitated by variance of resistance and survival of the hiding juveniles. The model can be applied in the control of emerging diseases especially in crayfish-like organisms.