A mutation enabling insects to withstand chemical attacks has been discovered in the genome of the common bed bug (Cimex lectularius).
Following World War II, insecticides like DDT effectively controlled these pests. However, bed bugs have resurfaced since the millennium, displaying resistance to potent toxins.
Research from Virginia Polytechnic Institute and State University reveals the reason behind this resistance. Samples were collected from 134 unique populations of C. lectularius across 22 US states and 4 Canadian provinces between 2008 and 2022.
Genetic screening identified a point mutation causing an amino acid substitution in nervous system chemical pathways. "When we went back and screened multiple individuals from the two populations, every one of them had the mutations," says Booth.
This mutation, known as the A302S Rdl gene mutation, is associated with resistance to dieldrin in cockroaches and other insects. Dieldrin, an insecticide developed in the 1940s, shares a similar composition with fipronil, a current insecticide used against fleas and roaches.
German cockroaches with the Rdl gene mutation developed resistance to both dieldrin and fipronil. Researchers found the same applies to bed bugs, but the timing of this development remains unclear.
"We don't know if that mutation is novel and it popped up after that, or in that time frame, or whether it was occurring in populations 100 years ago," Booth says. Bed bugs had ample exposure to cyclodienes like dieldrin before their discontinuation in the 1990s.
Fipronil continues to be used in anti-flea treatments for pets. By sequencing the genes of the common bed bug, researchers aim to understand this evolutionary timeline through further analysis of specimens from various locations and time periods.