Present susceptibility status of rat flea Xenopsylla cheopis (Siphonaptera: Pulicidae), vector of plague against organochlorine, organophosphate and synthetic pyrethroids 1. The Nilgiris District, Tamil Nadu, India.

The susceptibility status of Xenopsylla cheopis, the efficient vector of human plague in India was assessed in erstwhile plague endemic areas of Nilgiris district, Tamil Nadu following standard WHO techniques. The studies revealed the development of resistance in rat fleas to DDT--4.0%, Malathion--5.0%, Deltamethrin--0.05% and tolerance to Permethrin--0.75% in all the four blocks of Nilgiris hill district. Development of resistance may be due to the extensive use of insecticides in tea plantations and agricultural sectors where the domestic/peri-domestic rodents find their natural habitats and intermingle with each other.