Biological Control of Parasites

As a rule, all species of animals are regulated by other living organisms (antagonists) which are not under manipulation by man but they are naturally occurring in our surrounding environment. The process called natural biological control when man attempts to use naturally occurring antagonists to lower a pest population which would cause losses to plant or animals. Biological control is an ecological method designed by man for lower a pest or parasite population to keep these populations at a non harmful level. In practice, applied biological control has no direct application to internal animal parasites especially in their parasitic stages which may be indirectly regulated by intermediate, paratenic or transport vectors even free living larval stages. Many organisms such as viruses, bacteria, turbellarians, earthworms, tardigrades, fungi, spiders, ants, insects, rodents, birds, and other living things are found to contribute significantly toward limiting parasite populations such as arthropods, protozoans and helminthes of domesticated animals. Numerous pathogens and predator of parasites (arthropods) have been known for decades, but few biocontrol programs have been developed. Parasites are controlled almost exclusively by chemical acaricides. The development of resistance to acaricides and their harmful to the environment necessitate alternative control strategies such as habitat modification, use of pheromones and hormones, improvement of host resistance and biological control. Research on the potential use of pathogens, parasitoids, or predators for the biological control of animal parasites lags for behind for plant pests. Among the discouraging remarks are statements that natural enemies are not efficient for biological control, because the population of parasites is so large and that there is little potential for biological control (Cole., 1965). Because the fecundities of predators appear to be below the level required to respond to the explosive increase in example tick numbers which follow certain types of weather such statements may explain partly the longtime neglect of this field and similar arguments were also expressed during the first steps of plant pest biocontrol.