Endrin resistance in the pine mouse.

Wild pine mice with a history of treatment with endrin exhibited a 12-fold greater tolerance to the pesticide than did mice having no history of endrin treatment. A genetic basis for the resistance would be expected, in view of the fact that the resistant mice had been exposed to endrin for 11 years. However, sublethal dosages conferred a degree of resistance on both mouse populations; this indicates the possibility of an inducible resistance.