ALTERING THE BALANCE OF NATURE:

• Well adapted parasites exist in a balanced relationship with their hosts.
• This minimizes the chances of becoming extinct.
• Therefore, it is likely that more than one parasite will be required in any given control situation.

There are a number of instances in the literature where the population cycling of a parsite in relation to its host has been monitored, in which the parasite appears to consistenly only parasitize a portion of the population.

A possible explanation for this phenomena is that over millions of years, balanced relationships have evolved in nature.

Scientists studying natural systems may find it difficult to perturb this balance in favor of increased parasitism.

A host specific organism runs the risk of becoming extinct if it kills off all of its hosts.

This has at times been cited as a reason why "natural" biological control will never be practical for nematodes.

Although it may not be feasible to effect control with a single organism, combinations of organisms could be developed or organisms utilized in combination with cultural controls which might provide control comparable to chemical nematicides.

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