Bedbugs Resurgence Due to Evolution, Climate Change? Insects Are Becoming Resistant to Pesticide

Bedbugs have been making a resurgence in Paris. However, it was learned that the insects' presence is not limited to the City of Love as it has growing activity worldwide, and pesticides reportedly no longer kill them.

Bedbugs Resurgence

Recent social media posts show bedbugs, tiny insects around the size of an apple pip that feed on human blood, covering the subway seats in Paris. According to entomologist Clive Boase, who has 30 years of expertise as a pest-control consultant, the psychological effects are typically more severe, as the current hysteria implies.

Leeches, mosquitoes, and other parasites are annoying, but they shouldn't take up residence in your house. Travelers who carry bugs home from vacations risk causing an infestation that may be exceedingly challenging to control. According to Boase, bedbugs frequently cause people to enter this non-coping phase.

The narrative is another cautionary tale about globalization, climate change, and evolutionary biology rather than one about poor hygiene and filthy trains. Warm towns make for good bedbug habitats. Cheap travel aids in their dissemination. Additionally, the effectiveness of the chemical pesticides used to kill them is waning after decades of extensive use.

Worldwide, bedbug infestations are on the rise. Similar to Paris now, New York had a panic a decade ago. According to statistics from Switzerland's Pest Advisory Service, which manages one of the few long-term insect datasets, Zurich experienced roughly 20 bedbug-related complaints each year in the ten years leading up to 2005.

After ten years, they had quadrupled. Numbers decreased during the COVID-19 lockdowns but have recently returned to growth.

"There won't be a city without bedbugs," Boase said.

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Why Pesticides No Longer Work Against Bedbugs

Insects were nearly eliminated after the Second World War thanks to the advent and widespread usage of insecticides like DDT. However, that chemical attack put enormous evolutionary pressure on the insects to evolve poison resistance. Modern bedbugs are practically immune to all insecticides, much as bacteria have developed resistance to many of the medications originally used to kill them.

A diminishing supply of chemicals to use as a weapon against them has contributed to this developing resistance. Most locations now see DDT and other fumigants like hydrogen cyanide and sulfur dioxide as too dangerous to employ. The active chemicals in many commercially available pesticide sprays are pyrethroids, which are safer but lose effectiveness with time.

Exterminators are switching to alternative strategies. The white silicate powder known as diatomaceous earth can destroy the bugs by desiccating them. Sprays made of polymers can capture them, and some oils can close the pores through which the insects breathe. The insects die at temperatures over roughly 45°C as well. Therefore, some pest-control companies offer to roast entire rooms or heat-treat damaged furniture in enclosed tents. However, these procedures are pricey.

New insecticides could likely be developed against which the bugs have no resistance. Per Boase, the market is not large enough to support much business research. Additionally, since bedbugs do not carry diseases, they aren't on the priority list of public health organizations.