Biotic Potential

It can be defined as the capacity of an organism/ parasite for biological success as measured by its fecundity and fertility.
It is a general observation that organisms / animals that have adopted the parasitic way of life possess greater biotic potentials (hyper reprodctivity). These parasites produce large number of offsprings to infect next host. Of these large number of offsprings most of them perish, but enough survive to maintain the species. Various types of parasites have evolved various methods of mass reproduction overcome the tremendous odds which come in the way to complete the life cycle.
In the case of parasitic protozoa, very little work has been done in actually measuring their rates of reproduction, but having a great potential of reproduction either by simple binary fission (e.g. flagellates) or by both asexual and sexual processes (e.g. all apicomplexon and ciliates). We do know that one mature eight nucleated cyst of Entamoeba coli gives rise to eight metacystic trophozoites.
The trematodes are hermaphrodites i.e. one individual parasite having both male and female reproductive organs. Some of them have self-fertilization while other having cross fertilization while other has still other ways. In all digenetic trematodes a single egg develop into large number of offsprings.
Most tapeworms undergo a type of continuous budding called strobilization in which segments are formed near the scolex. The continuous chain of buds called prognostics. Each mature segment has sets of male or female reproductive organs. Most other parasitic cestodes produce large number of eggs and each egg can produce further one adult.
In case of nematodes, male and female worms produce male and female gametes. A female gamete (ovum) is fertilized by a male gamete (sperm) to give rise a zygote. It matures to become an egg. For example a single female of A. lumbricoides, common intestinal parasite of man, capable of producing 200,000 eggs daily and has a total capacity of 27,000,000 eggs in her uterus. Similarly, a single female of Enterobius vermicularis, (human pinworm) is capable to produce 4672-16888 eggs during its life span. Like human worms, Haemonchus contortus (stomach worms), Ascaris suum (largest intestinal worm of pig), Toxocara canis, ascarid worms of dog produces many thousands of eggs daily, while Trichostrongylus of sheep. Goat, cattle, produce only a few hundred eggs daily by single female. In case of Arthropodes the biotic potential rate of these is extremely great. There are more insects on the earth than any other group of animals. Fo example Lucilia serricata or Ixodes ricinus produces very high number of eggs while Glossina sp. produce relatively few off-springs.

In conclusion, we can say that because of such great biotic potential, parasites are able to maintain themselves despite the tremendous odds against them because of the hit or miss processes necessary during the completion of their life-cycles. Indirectly, the fecundity of parasites is manifested by the magnitude of parasite infection that exists despite of the mortality rate.