October 20, 2011
Bed Bugs Biting Back!
(Ivanhoe Newswire) -- You may not be going to bed alone. After years of winning the war against bed bugs, they're back! Not only have they returned, but they're stronger and insecticide resistant. New research from a team at Virginia Tech has discovered some of the genetic mechanisms for the bugs´ resistance to two of the most popular insecticides used to control them.
Bed bugs, largely absent in the U.S. since the 1950s, have returned with a vengeance in all 50 states during the last few decades. Previously, a class of insecticides, known as pyrethoids, was successful in controlling the pests. Unfortunately, the new bugs have developed a resistance to them.
The discoveries will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs. It also provides molecular markers for surveillance.
"Different bed bug populations within the U.S. and throughout the world may differ in their levels of resistance and resistance strategies, so there is the need for continuous surveillance," lead author Zach Adelman, associate professor of entomology with the Vector-Borne Disease Research Group at Virginia Tech was quoted as saying.
Two populations of bed bugs were studied. The first, a resistant population from Richmond, Va., collected in 2008. The second had been collected in 1973 from Ft. Dix, NJ, and raised in a lab ever since.
Two popular insecticides, deltamethrin and beta-cyfulthrin, were used during the study. The researchers determined that it requires 5,200 times more deltamethrin or 111 times more beta-cyfulthrin to kill the Richmond bed bugs than the lab bugs during a 24-hour test.
"Deep sequencing of pyrethoid-resistant bed bugs reveals multiple mechanisms of resistance within a single population," the authors wrote.
The research team was able to identify genes that are commonly used to produce enzymes that can bind to, deactivate, and break down insecticides. In the resistant bugs, production of some of these enzymes was turned up significantly.
Mutations were also found in the sodium channel gene of the resistant bugs. This gene is the target for pyrethoid insecticides. The mutation makes the bed bug's nervous system partially resistant to the toxic effects of the insecticide.
"It is reasonable to suggest that the genes responsible for both acquired insensitivity to these neurotoxicants and their enhanced detoxification have been selected for in populations that have been subjected to long-term insecticide pressure," the authors concluded.
SOURCE: PLoS One, published online October 19, 2011