Pacific Institute for the Mathematical Sciences - PIMS

Parasitoids are a specialised class of predators that use a single prey
or host for their juvenile development but unlike parasites kill the
host as a result of this development. Within this lifestyle there are
many variations in life history that can be highly specific to the
host-parasitoid species complex under consideration. For example, the
developmental stage of hosts attacked can vary from eggs through larvae
to adults: endoparasitoid eggs are ingested or injected into the host
and the parasitoid develops inside the body of the host;
ectoparasitoids develop attached to the outside and draw the nutrients
out of the host; idiobionts kill or paralyse the host at the time of
oviposition; koinobionts permit the host to continue to grow, although
development may be arrested in some cases.
In some species, solitary parasitoids, a single adult will emerge from
a host, in gregarious species more than one adult emerges - this can
range from two to several thousand depending on the species. There are
many additional complications such as superparasitism where the
offspring of more than one conspecific adult develop with a host;
multiparasitism where contraspecific offspring develop within a host
and hyperparasitism where a secondary parasitoid will develop using a
primary parasitoid of another host as its host. In heteronomous species
males and females have different develop life histories for example
developing on different host species.
In some heteronomous hyperparastiod species males are known to develop as hyperparasitoid of females of their on species.
Parasitoids are also of immense importance in natural and agricultural
ecosystems where they influence or regulate the density of many of
their hosts. Much research on parasitoids has been stimulated by their
frequent success in biological control programmes. Many parasitoid
species have been used to combat agricultural pests, with huge savings
in both financial and human terms resulting from successful programs.
The coupling of host-parasitoid dynamics (each population directly
impacts on the other) makes them ideal candidates for mathematical
modelling.
In this talk we will present some mathematical models of multi-species
host-parasitoid systems. The mathematical models will be systems of
integro-difference equations and systems of reaction-diffusion-taxis
equations. The focus of the talk will be on the spatio-temporal
dynamics of these systems and their ecological implications.

PIMS-MITACS Mathematical Biology Seminar Series 2007