关键词: 德国小蠊, 抗药性, 药膜法, 半数击倒时间

Abstract:

Objective To determine the current resistance of the Blattella germanica (L.) to commonly used pesticides in Tianjin, and provide evidence for better cockroaches control. Methods The residual film method recommended by WHO was applied to measure the median knockdown time (KT₅₀) for B. germanica. Batches of B. germanica were exposed to five insecticide residues (dichlorovos, acephate, propoxur, betacypermethrin and permethrin) in glass jars to determine their knockdown resistance levels. Resistance ratios were calculated as RR₅₀＝KT₅₀ of the test strain/KT₅₀ of the susceptible strains. Results The KT₅₀ for field-collected B. germanica in Nankai, Jinnan, Hexi, Tanggu, Dongli, Xiqing and Beichen were 6.15, 6.49, 8.37, 8.22, 7.84, 9.29 and 12.40 min to dichlorovos, 74.28, 65.36, 29.52, 30.23, 30.67, 58.64 and 33.08 min to acephate, and 24.97, 40.63, 27.17, 24.43, 40.73, 42.44 and 40.91 min to propoxur, respectively. The RR₅₀ values for B. germanica of dichlorovos, acephate and propoxur were below 3. The KT₅₀ to betacypermethrin for field populations in Nankai, Tanggu and Xiqing were 32.61, 36.50 and 51.00 min respectively, with the RR₅₀ ranging from 6.48 to 10.71 times. The values for Jinnan, Hexi, Dongli and Beichen were all greater than 120.00 min, with the RR₅₀ greater than 20. The KT₅₀ to permethrin for field populations in Nankai, Jinnan, Hexi, Dongli and Beichen were all above 120.00 min, with the RR₅₀ greater than 20. However, the KT₅₀ value for Xiqing strains was 26.96 min, with the RR₅₀ lower than 5, and the value for Tanggu population was 14.10 min, with the RR₅₀ lower than 3. Conclusion B. germanica control in Tianjin requires reduced administration of betacypermethrin and permethrin along with increased carbamates such as propoxur and organophosphorus pesticides such as dichlorovos and acephate.

Key words: Blattella germanica, Insecticide resistance, Residual film method, Median knockdown time