The life cycle and effectiveness of insecticides against the bed bugs of Thailand.

The purpose of this study was to determine the life cycle and effectiveness of insecticides against bed bugs in Thailand. Bed bugs from dwelling places in Chon Buri and Chiang Mai provinces were determined to be Cimex hemipterus and Cimex lectularius, respectively. Both bed bug species were reared by feeding on rabbit blood at 2-day intervals in laboratory conditions at 28-32 degrees C with 75% relative humidity. The duration from egg to adult stages took 39.9 +/- 7.0 and 36.9 +/- 8.2 days in C. hemipterus and C. lectularius, respectively. The insecticides, propetamphos 20% CS, pirimiphos-methyl 50% EC, bifenthrin 25% WP and alpha-cypermethrin 5% SC, were tested against adult C. lectularius using a Potter spray tower. The concentrations at which 50% of bed bugs were either dead or moribund (ED50) for propetamphos and pirimiphos-methyl were 6.67 and 14.93 mg/m2 for the active ingredients on day 3 and the ED50 for bifenthrin and alpha-cypermethrin were 1,767.76 and 353.55 mg/m2, respectively. The results reveal C. lectularius in Thailand has a tendency to develop pyrethroid resistance.