Iranian non-responding contact method German cockroach permethrin resistance strains resulting from field pressure pyrethroid spraying

The present study investigated the probable responsible reasons for non-response the B. germanica to permethrin only in World Health Organization glass jar method after insecticide spraying control failure with pyrethroid insecticide groups in Islamic Republic of Iran. Eleven German cockroach strains were collected from field populations of nine infested kitchen student dormitories and two infested hospitals after insecticide spraying control failure with pyrethroid insecticide groups in Iran. The current study, in World Health Organization glass jar and knock down methods conducted on newly emerged adult males. All feral strains, with various levels of resistance to pyrethroids, in World Health Organization glass jar method at 400 min (6 h) time exposures, was not observed mortality, while the susceptible strain was observed 100% mortality in 25 min time exposures. Susceptible strain at LT50 after assessing on mortality data from the replicates by probit analysis in World Health Organization glass jar method was 15.3 min. In this study, all feral strains in World Health Organization glass jar method after 400 min (6 h) time exposures, was not observed mortality, that showed these strains very high-level resistance to permethrin. In the knock down method, the resistance ratios were 3.6 to 26.1-folds compare with the susceptible reference strain. In a comparison, among this study and previous studies resistance ratios of 8.6 to 17.7-folds for permethrin in topical application, indicated that German cockroach have had under pressure spraying. German cockroach have had in vicinity to pyrethroid insecticides especially permethrin in these locations in long period for non-responding to permethrin insecticide only in World Health Organization glass jar method, and the field evident confirm this subject.