Pyrethroid resistance in cockroach populations has been a public health challenge since the 1950s. The pyrethroid resistance in the German cockroach, Blattella germanica, is primarily attributed to knockdown resistance (kdr) mutations (E434K, C764R, and L993F) in the voltage-sensitive sodium channel gene (vssc). In this study, the pyrethroid resistance state of the German cockroach in the Republic of Korea (ROK) was assessed by analyzing the frequencies of kdr mutations using one-step PCR with total RNA. The results revealed that among the 25 populations examined, 14 populations exhibited the L993F kdr mutation, while no other mutations were detected. Since other cockroach species are also commonly found in human dwellings in ROK, the vssc genes were cloned from four other species, including Blattella nipponica, Periplaneta americana, Periplaneta japonica, and Periplaneta fuliginosa. Based on the genomic DNA (gDNA) sequences obtained from the vssc cloning, primer sets were designed to amplify the vssc fragment spanning the L993F mutation for each species and used to monitor the development of pyrethroid resistance in cockroach populations in the ROK. The study will facilitate the implementation of a nationwide monitoring program to assess cockroach resistance and select suitable alternatives.

• Hyun Kyu Shin(Department of Agricultural Biotechnology, College of Agriculture and Life Science Seoul National University, Seoul 08826, Republic of Korea)
• Susie Cho(Department of Agricultural Biotechnology, College of Agriculture and Life Science Seoul National University, Seoul 08826, Republic of Korea)
• Heung Chul Kim(Force Health Protection and Preventive Medicine, Medical Department activity-Korea/65th Medical Brigade, Unit 15281, APO AP 96281-5281, USA, Current address: U Inc., Daesakwan-ro 34gil, Yongsan-gu, Seoul, 04409, Republic of Korea)
• Si Hyeock Lee(Department of Agricultural Biotechnology, College of Agriculture and Life Science Seoul National University, Seoul 08826, Republic of Korea, Research Institute for Agriculture and Life Sciences, Seoul National University, Republic of Korea)