Vertebrate Pest Conference Proceedings collection


Date of this Version

February 1982


Alpha-chlorohydrin (EPIBLOC) introduces a new form of rodenticide - the toxicant-sterilant. EPIBLOC, as a pest control product registered and used in some countries, changes the concept of chemosterilants from theoretical to practical. The active ingredient also acts as an acute toxicant in the control of rodents. It is effective on both sexes and all age groups. Alpha-chlorohydrin is rapidly absorbed and metabolized; therefore, it is neither a secondary toxicant nor a cumulative toxicant. Another unique biological characteristic of this compound is its species specificity with regards to male sterility. First, only sexually mature males are rendered sterile through the development of lesions in the epididymis, and second, male sterility is restricted to rodent species. Adult males of some mammalian species become temporarily infertile when treated with nonlethal doses of alphachlorohydrin. These males regain their fertility shortly after the end of treatment. Males from seven rodent species are known to develop permanent sterility. Of all the species tested Rattus norvegicus has been subjected to the most research. The single oral dose which produces temporary infertility in this species is 15-20 mg/kg of body weight; the dose that produces permanent sterility is 90-100 mg; and the LD50 is 150-160 mg. Field tests with EPIBLOC on a variety of rodent pests have provided a body of practical information. Namely: (i) effective as a toxicant-sterilant with a single administration of bait; (ii) reduction in the rodent population due to death ranges from 70-95%; (iii) the reproductive rebound phenomenon commonly observed after baiting with toxicants is prevented due to the sterilant property; (iv) 80-95% of surviving adult males are sterile and act as a deterrent to repopulation; and (v) the species specificity for sterility, the metabolic activity and the biodegradable characteristics allow it to be used under many environmental conditions.