Infective prey leads to a partial role reversal in a predator-prey interaction

An infective prey has the potential to infect, kill and consume its predator. Such a prey-predator relationship fundamentally differs from the classical Lotka-Volterra predator-prey premise because the prey can directly profit from the predator as a growth resource. Here we present a population dynamics model of partial role reversal in the predator-prey interaction. We parametrize the model to represent the predator-prey interaction of sea cucumber Apostichopus japonicus and bacterium Vibrio splendidus. We observe that two major factors stabilize the predator-prey interaction. First, the partial role reversal in the predator-prey community stabilizes the predator-prey interaction. Second, if the predator is a generalist and follows the type I functional response in attacking the prey, the predator-prey interaction is stable. We also analysed the conditions for species extinction. The extinction of the prey, V. splendidus, may occur when its growth rate is low, or in the absence of infectivity. The extinction of the predator, A. japonicus, may follow if either the infectivity of the prey is high or a moderately infective prey is abundant. We conclude that partial role reversal is an underestimated subject in predator-prey studies.