Heterokairy as an anti-predator strategy for parasitic species

Heterokairy refers to plasticity in the timing of onset of developmental events at the level of an individual. When two developmental stages do not share the same ecological niche, referred to as 'ontogenetic niches', the control of the niche shift through a change in developmental timing can be advantageous for the individual (e.g., when mortality risk is different in the two niches). Heterokairy can arise either from plasticity in developmental rate (ontogenetic shift) or by a purely behavioral decision (behavioral shift). Parasitic species living inside of their hosts often inherit the predators of their hosts. To cope with the predation risk on their hosts, parasites and parasitoids show either host-manipulation abilities or either host-leaving strategies. Nevertheless, leaving the host should be associated with developmental costs, since the parasitic individuals are usually unable to parasitize another host. This process is thus related to the classical tradeoff between size and developmental time. Recent studies provided examples of behavioral heterokairy in invertebrates. The goal of this publication is to review and discuss recent results on developmental plasticity in parasitic species in an evolutionary perspective.