Evolution of parasitoid host preference and performance in response to an invasive host acting as evolutionary trap

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. The model was inspired by solitary
endo-parasitoids attacking larval host stages. One important aspect of
these conditions was reduced host survival during incompatible
interaction, where a failed parasitization attempt by a parasitoid
resulted not only in death of her offspring but also in host killing. This
non-reproductive host mortality had a strong influence on the likelihood
of establishment of novel host-parasitoid relationship, in some cases
constraining adaptation to the trap host species. 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.