Evaluation of the resistance level of different strains of german cockroach, Blattella germanica (L.), to deltamethrin, propoxur and pirimiphos- methyl insecticides in tehran, 2000

The phenomena of inducing resistance to insecticides by Blat/ella germanica L. is considered as one of the most important constrains of control measures for this household pest worldwide. A lot of research studies have been conducted on the resistance management of B. germanica(L.) to different insecticides.The present investigation was conducted to evaluate the resistant ratios of two strains of B. germanica(L.) at Fatemyyeh Dormitory of Tehran University and Imam- Khomeini Hospital to three insecticides of pirimiphos-methyl, deltamethrin and propoxur. The resistance ratio of the two strains at LD50 level were compared with a known susceptible strain. The least resistance ratio i.e. negative cross-resistance (0.848), was observed with pirimiphos-methyl applied to the strain at Fatemyyeh Dormitory and the highest resistance ratio (7.123) was observed with deltamethrin applied to the strain at Imam-Khomeini Hospital. The resistance ratio of the strains at Imam-Komeini Hospital and Fatemyyeh Dormitory to propoxur was 1.748 and 1.696 respectively.