Evolution of parasitoid host preference and performance in response to
an invasive host acting as evolutionary trap
Abstract
The invasion of a novel host species can create a mismatch in host
choice and offspring survival (performance) when native parasitoids
attempt to exploit the invasive host without being able to circumvent
its resistance mechanisms. Invasive hosts can therefore act as
evolutionary trap reducing parasitoids’ fitness and this may eventually
lead to their extinction. Yet, escape from the trap can occur when
parasitoids evolve behavioural avoidance or a physiological strategy
compatible with the trap host, resulting in either host-range expansion
or a complete host-shift. We developed an individual based model to
investigate which conditions promote parasitoids to evolve behavioural
preference that matches their performance, including host-trap
avoidance, and which conditions lead to adaptations to the unsuitable
hosts. One important aspect of these conditions was reduced host
survival during incompatible interaction, where a failed attempt by a
parasitoid resulted in host killing. This non-reproductive host
mortality had a strong influence on the likelihood of establishment of
novel host-parasitoid relationship. Killing unsuitable hosts can
constrain adaptation under conditions which in fact promoted adaptation
when parasitoids would leave the trap host unharmed and survive
parasitoid attack. Moreover, our model revealed that host-search
efficiency and genetic variation in host-preference play a key role in
the likelihood that parasitoids will include the suboptimal host in
their host range, or will evolve behavioural avoidance resulting in
specialization and host-range conservation, respectively. Hence,
invasive species might change the evolutionarily trajectory of native
parasitoid species, which is important for predicting biocontrol ability
of native parasitoids towards novel hosts.