Based on the analysis of biological symbiotic relationship, the mechanism of facultative parasitic behavior is
incorporated into the particle swarm optimization(PSO) to propose a two-population PSO model called particle swarm
optimization based on parasitic behavior(PSOPB), which consists of the host and the parasite population. In this model,
the two populations exchange particles according to individual’s fitness value sorted in a certain number of iterations. The
parasitic population gets the particles with good fitness, whereas the particles with poor fitness belong to the host. In order
to embody the rule of survival of the fittest in biological evolution, the particles with poor fitness in the host population are
removed and replaced by the re-initialization of the particles in order to maintain constant population size. The experiment
results of some benchmarks show the effectiveness of PSOPB.