Efficacy of organophosphate formulations against the German cockroach, Blattella germanica, collected from several restaurants in two multitenant buildings in Tokyo

摘要

Lethality and repellency of emulsifiable concentrates (EC) or microencapsulated concentrates (MC) of fenitrothion, diazinon, propetamphos and chlor-pyrifos-methyl were examined with12 separate colonies of the German cockroach, Blattella germanica. Field colony individuals were collected from 5 different restaurants situated on the 7th floor of a building in Koto-ku, and 7 restaurants located on the 5th floor of another building in Meguro-ku, Tokyo, Japan. Adult male progeny of each colony were released into a container with insecticide-treated harborage surfaces. All colonies, except for the one from the Italian restaurant in Koto-ku, showed low levels of susceptibility to fenitrothion EC and MC, diazinon EC and MC, chlorpyrifos-methyl EC and propetamphos EC. However, the levels of lethality against colonies varied even though they originated from the same floor of a building. The poor efficacy of the test insecticides was probably a result of long-term use of these compounds in this area of building. Various susceptibilities among colonies indicate that the German cockroach does not frequently hybridize between restaurants even located on the same floor of a building. Propetamphos MC was the most effective against all exposed colonies, followed by fenitrothion MC and diazinon MC. Changes in behavior toward insecticides and insecticide resistance in the EC formulations may cause low mortalities in cockroaches. The test colonies showed two different types of low susceptibilities, one due to high aversion to the test formulations and another due to insecticide resistance.