The Comeback Bugs

After World War Two, pesticides helped eradicate bedbugs in most of the developed world.

But those pesky bugs made a comeback more than two decades ago and some populations have become more resistant to conventional pesticides.

Now, scientists at Japan’s Hiroshima University recently discovered the genetic factors that can possibly explain why.

In a new study, a research team unveiled the most complete genomes yet of both insecticide-resistant and non-resistant bed bugs, shedding light on the mutations that have enabled the pests’ global resurgence over the past two decades.

“We identified a large number of genes likely involved in insecticide resistance, many of which have not been previously reported as being associated with resistance in bedbugs,” said Kouhei Toga, first author of the study, in a statement.

Toga and his team used long-read sequencing – a cutting-edge method that pieces together longer DNA fragments with fewer errors – to compare genomes from bed bugs collected six decades apart.

The non-resistant strain came from Nagasaki in 1955, while the resistant strain originated in a Hiroshima hotel in 2010. Their findings showed a nearly 20,000-fold resistance to pyrethroids – a widely used pesticide – in the modern bugs.

To understand this toxic resilience, the researchers identified 729 mutated transcripts – RNA molecules that help turn DNA into proteins – linked to resistance.

Many of these were related to DNA damage repair, cell cycle regulation, insulin metabolism, and lysosome functions, which highlight the complex molecular pathways that fortify these pests against chemical attacks, noted Gizmodo.

Bed bugs’ resistance arsenal includes mechanisms like metabolic detoxification and structural changes to their outer layers, making them hard to kill. The study also confirmed known resistance mutations while uncovering new ones that could guide better pest control strategies.

“Genome editing of these genes could provide valuable insights into the evolution and mechanisms of insecticide resistance,” Toga explained.

With infestations on the rise, the study may help combat bed bugs more effectively and prevent another scare, such as the Paris outbreak ahead of the 2024 Summer Olympics in the French capital.