Nematodes immune to anthelm.

Omar O. Barriga oobarrig at pop.service.ohio-state.edu
Sat Jan 25 12:00:44 EST 1997


Sorry, but I forgot something important.

	Dan Holdworth mentioned a fairly popular theory that says that susceptible 
parasites are better fit than resistant parasites (Why, otherwise, the 
susceptible population would exist in nature instead of the resistant 
population?). A common extension of this theory is to recommed to leave the 
resistant parasites alone: since they are less fit, sooner of later they 
would be replaced with the susceptible parasites again.
 	Although this sound right and may even be true in geological times, it does 
not work in the time frame of interest to the farmers. There are many examples 
that it does not work in real life but the most common might be the resistance 
of the domestic fly to the DDT. The flies became resistant in the 1950s 
and they are still resistant now, 40 years later.
		Cheers!
			Omar O. Barriga., DVM, PhD 



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