Persistence of mulitple identical parasitoid species in a single-host, spatial simulation

We explore the problem of persistence of multiple obligate parasitoids on a single host in a discrete time, spatially explicit system. In general, the parasitoids experienced extinction until one species remained well before the 50 000-generation time limit, but the rate varied according to the parameters of the system. Smaller arenas had a greater chance of extinction. Artificially increasing interspecific competition produced rapid extinction, while decreasing competition increased persistence to the maximum time limit of the simulation. Increasing the parasitoid search efficiency or decreasing dispersal of the parasitoids relative to the host produced less longevity as did increasing host reproduction, while increasing the rate of “patch extinction” reduced the variation among the times to extinction, but did not change the time to the first extinction. Finally, increasing noise in the search parameter first reduced longevity, but then it rapidly increased near the point where the noise reached an amplitude similar to the parameter itself, where coexistence of the four parasitoids was achieved.