Researchers Unveil Factors that Make Bed Bugs Extraordinarily Resistant to Insecticide Elimination
By the 1960s, extensive pesticide use had almost eliminated bed bug populations. However, in the last two decades, these bloodsuckers have made a nasty comeback. Recently, scientists have pinpointed genetic factors contributing to this unwanted comeback.
A group of scientists led by Hidemasa Bono from Hiroshima University has analyzed the most complete genome of an insecticide-resistant bed bug to date and compared it to an insecticide-susceptible (non-resistant) bed bug genome. Their findings, published in the journal Insects in September, offer unparalleled insights into the genetic alterations leading to insecticide resistance in bed bugs, potentially informing future pest control approaches.
Bed bugs can be real nuisances despite not transmitting diseases to humans. Bed bug bites can cause itching, sleep loss, anxiety, and, occasionally, allergic reactions, according to the Centers for Disease Control and Prevention (CDC). Incessant itching may also lead to secondary skin infections.
"We identified numerous genes associated with insecticide resistance, many of which haven't been linked to bedbug resistance before," said Kouhei Toga, the first author of the study, in a university statement.
The researchers in Japan obtained non-resistant genome sequences from descendants of wild bed bugs caught six decades ago in Nagasaki and resistant genomes from descendants of bed bugs discovered in a Hiroshima hotel in 2010. With a "groundbreaking" method called long-read sequencing, which enabled the sequencing of longer DNA segments with fewer gaps, they subseqently mapped both genomes virtually error-free, the team reported in the statement.
They then compared the two genomes and identified hundreds of mutations associated with insecticide resistance in the resistant strain. Moreover, they found the hotel bed bug genome to be 19,859 times more resistant to pyrethroids, a common synthetic pesticide, than the non-resistant genome, according to the study.
"We successfully sequenced the genome of insecticide-resistant bed bugs, which showed 20,000-fold greater resistance compared to susceptible bed bugs," said Toga. "By comparing the amino acid sequences between the susceptible and resistant bed bugs, we identified 729 transcripts with resistance-specific mutations," he continued, "transcripts" being RNA molecules that decode DNA instructions into proteins. The researchers' results corroborated resistance mutations discovered in previous studies while also uncovering new ones.
"These transcripts included genes related to DNA damage response, cell cycle regulation, insulin metabolism, and lysosome functions. This implies that these molecular pathways may contribute to the development of pyrethroid resistance in bed bugs," Toga explained. Lysosomes are organelles containing digestive enzymes found in many animal cells.
By pinpointing these mutations, the study ultimately offers new genetic resources for monitoring, understanding, and addressing insecticide resistance in wild populations as well as those that have already invaded our homes. Nothing like another Paris 2023 bed bug scare is desired.
The discovery of these genetic mutations in insecticide-resistant bed bugs could lead to the development of more effective pest control strategies in the future. Furthermore, ongoing advancements in technology and science could potentially help us uncover new methods to combat resistance in various pest species, contributing significantly to global health.
