Bad news: two insecticides show reduced efficacy in most common bedbug species, study finds.
Against humans, bedbugs always seem stronger. They are no longer content to devour his blood at night, taking his victim by surprise. Ruining your sleep, your bedding, sometimes even your life, is not enough. Now these pests are resisting the only weapon available to their poor pantry: the insecticide bomb.
A study published in the journal Journal of Economic Entyomology confirms what we feared: the effectiveness of these products to overcome bedbugs continues to decline. The two molecules in vogue in the United States display their powerlessness against certain species, report the researchers.
Mortality less than 75%
Thus, three populations of “bed bugs” out of ten collected in cities (Indiana, New Jersey, Ohio, Tennessee, Virginia, Washington) have a greatly reduced sensitivity to chlorfenapyr; for bifenthrin, the proportion rises to five pest populations.
To arrive at this finding, the researchers exposed these bugs to the two insecticides and calculated the mortality. When it is less than 75%, science estimates that the species has developed resistance, which was the case with both molecules.
Tenacious
The most common bedbug (Cimex lectularius) is already showing signs of resistance to deltamethrin and other pyrethroid insecticides, the researchers say. This explains the re-emergence of pests in North America, then in the United Kingdom and in Europe. According to a survey conducted among industry professionals, dubbed “Bugs Without Borders”, the bedbug is by far the most difficult insect to eradicate.
The researchers believe that the two insecticides targeted by the study should be used in combination with other methods, “in order to preserve their effectiveness in the long term”. They also raise a question, which has not yet been answered. Chlorfenapyr and bifenthrin have different modes of action; however, bed bugs are resistant to both, according to mechanisms that still elude the authors. Further work will therefore be necessary to better understand how the bedbug always ends up winning the battle.
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