Effect of external contact with diethylstilbestrol on the reproduction of female Levant voles

When strips of filter paper impregnated with a suspension of diethylstilbestrol (DES) in soybean oil are placed in the cage of a female Levant vole, they have the same effect as injection or ingestion of DES (i.e., perforation of the vagina, interruption of pregnancy, and cessation of reproduction). However, as distinct from the relatively brief effect of ingested or injected DES, the effect of these impregnated paper strips lasts 1.5-2 months, or longer. This makes it feasible to use the contact method of chemosterilization for the suppression of vole reproduction in the field.