The first recent case ofCimex hemipterus(Hemiptera: Cimicidae) withsuper-kdrmutations in the Republic of Korea

Abstract

With the increase in international travel and trade, in conjunction with the development of insecticide resistance, infestations of Cimex lectularius (L.) and Cimex hemipterus (F.) (Hemiptera: Cimicidae) have resurged globally in the last 2 decades. Recently, it was reported that C. hemipterus was also found in temperate regions, indicating the possibility of its expansion outside tropical regions. Cimex hemipterus has not been officially recorded in Korea since its initial description in 1934. Here, we report the first recent case of C. hemipterus in Korea based on morphological and molecular identification. Partial sequencing of the voltage-sensitive sodium channel gene revealed super-kdr mutations (M918I and L1014F) that are associated with pyrethroid resistance. This case report serves as a warning to intensify the bed bug surveillance system in Korea regarding the presence of C. hemipterus and to prepare effective alternative insecticides for pyrethroids.

Species identification and pyrethroid resistance genotyping of recently resurgent Cimex lectularius and Cimex hemipterus in Korea

“…Harboring both the M918I and L1014F mutations is known as super-knockdown resistance ( super-kdr ) in C. hemipterus [ 11 , 12 ]. The first case of C. hemipterus recently documented in Korea revealed the presence of these 2 super-kdr mutations, indicating the high potential of this bed bug for pyrethroid resistance [ 4 ]. Similarly, all C. lectularius samples collected after 2015 have been saturated with both resistance mutations (V419L and L925I) [ 2 ].…”

“…Following morphological identification, genomic DNA was extracted from single or multiple (2–5 individuals) adult bed bugs. As described previously, molecular identification was conducted on the mitochondrial cytochrome oxidase subunit I gene sequence [ 4 ]. The primers used in this study are listed in Supplementary Table S1 .…”

“…After bed bug species identification, species-specific genomic DNA fragments of the genomic DNA fragments of the vssc gene, flanking the kdr or super-kdr mutation sites, were PCR-amplified as previously described [ 2 , 4 ]. For C. lectularius , two separate vssc fragments, one containing the V419L mutation site in domain I S6 and the other containing the L925I and I936F mutation sites between domains II S4 and II S5, were amplified.…”

“…For C. hemipterus , however, a single vssc fragment flanking the nine mutation sites (L899V, M918I, D953G, Y/L995H, A1007S, V1010L, I1011F, L1014F V1016E, and L1017F/S) was amplified between the domain II S4 loop and domain II S6. PCR was conducted as previously described [ 2 , 4 ] using the primers listed in Supplementary Table S1 . The resulting PCR products were directly sequenced to identify the presence or absence of mutations.…”

“…Cimex lectularius has been present at low densities in Korea over the past 20 years [2,3], whereas the recurrence of C. hemipterus was first reported in 2022 [4]. C. hemipterus is mainly distributed in tropical or subtropical regions, unlike C. lectularius, primarily found in temperate zones, including Korea [5].…”