Are Bed Bugs Becoming Immune To Pesticides?

Bed bugs, arguably the most intimate blood-sucking roommate of humankind, are becoming resistant to pesticides. Gene mutation is occurring in bed bugs, thus safeguarding them against the cannonade of pesticides that humans use to eliminate them. Recent research in this area highlights how the present-day “chemical weapons” used to decimate bed bug infestations are becoming increasingly ineffective. In fact, a survey conducted by the University of Kentucky found that 68% of pest-control professionals find bed bugs to be the most difficult pest to control.

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The Rise of Bed Bug Infestations

In the past 20 years, there has been an undeniable rise in bed bug infestations across the US—perhaps due to the flourishing travel and tourism industry. Once these pesky insects enter a new region, they expand their reach rapidly! As the infestation grows, measures to eliminate these bed bugs become increasingly challenging, as pest control is not only expensive, but also time consuming! Additionally, the results aren’t guaranteed! Given their paper-thin bodies, bed bugs can easily squeeze into cracks between wall crevices and furniture, which makes the effective spraying of insecticides even more difficult.

Cimex lectularius

Bed bug infestation. (Photo Credit : Wikimedia Commons)

Research by the University of Kentucky

One research effort to study the effect of present-day pesticides on bed bugs was conducted by a team of researchers from the University of Kentucky. They first sequenced the genes found in 21 pesticide-resistant bed bug populations residing in a nearby infested area. After meticulous study, they discovered that 14 of the 21 collected genes had variations associated with pesticide resistance. A different population of bed bugs carried a different combination of gene variations.

Bed bug, Cimex lectularius

Oblique-dorsal view of a bed bug ingesting blood from a human arm. (Photo Credit : Piotr Naskrecki/Wikimedia Commons)

Research also identified that all the genes were active (gave rise to specific proteins) primarily in the outer shell of the insect’s fingernail-like cuticle, called an exoskeleton, rather than in the digestive tract, which is where most bed bug populations develop mechanisms to neutralize the deadly pesticide spray. Researchers observed that their outer shell (exoskeleton) is exposed to the sprayed pesticides, and accounts for the majority of the area on which the pesticide is sprinkled. However, it has now become genetically equipped to fend off the poisonous effect of pesticides. Their exoskeleton has become like a suit of armor composed of protective genes.

This research also identified two of the mechanisms that helped bed bugs in their fight against pesticides. The first one involves the metabolic enzyme cytochrome p450, which helps the insects minimize the effect of the toxins. A gene variant that provides pesticide resistance enables the bed bugs to produce large quantities of the p450 enzyme. The other mechanism relies on a protein found on the surface of nerve cells. There’s an ion channel that tells the cell when to fire. The insecticides and pesticides available on the market today target this particular ion channel. They cause the bed bugs’ nervous system to break down, killing the insect quickly. However, pesticide-resistant bed bug populations have been found to carry a mutation in the ion channel that prevents the pesticide from affecting their nervous system.

Structure of lanosterol 14 α demethylase (CYP51)

Cytochrome p450. (Photo Credit : Chem183Student/Wikimedia Commons)

The researchers suspect that the bed bug proteins decelerate pesticide penetration and detoxify the chemicals (pesticides/insecticides). Moreover, the multiple resistance mechanisms in place imply that these tiny pests have outsmarted us and our conventional pesticide use. Thus, infiltrating the pest infestation with our current chemical repertoire is not all that useful and can actually have more of a toxic effect on the inhabiting humans than the pests!

Research by Purdue University

In another study by Purdue University on pesticide-resistant bed bugs, researchers gathered 10 different bed bug populations from diverse regions of New Jersey, Ohio, Indiana, Virginia, Washington etc. They exposed the insects to two popular pesticide chemicals—bifenthrin and chlorfenapyr. They exposed the bed bugs to these chemicals for seven days. Bifenthrin is a pyrethroid that typically attacks the nervous systems of insects. Chlorfenapyr, on the other hand, is a chemical that attacks the mitochondria of cells. To put it simply, mitochondria are the energy-producing elements inside a cell. Generally, professional pest-control experts used chlorfenapyr, while non-professional users normally use bifenthrin, which is available over-the-counter in the form of insecticide sprays and aerosols.

The researchers discovered that nearly half of the samples they observed had reduced susceptibility to bifenthrin, and nearly one-third of bed bug population sample was even less susceptible to the stronger chemical, chlorfenapyr.

Researchers pointed out that these chemicals do work against bed bugs, but only on some bed bug populations. So, their utility in pest management cannot be completely ruled out. In order to keep these tools from losing their effectiveness further, it is essential that they are used sparingly. The best way to use them is to alternate with other non-chemical methods. Sufferers of repeated infestations have a better chance of getting rid of all their bed bugs—including those that have developed a resistance—if they combine these chemical strategies with alternative solutions like heat, steam or silica gel!

References:

  1. University of Kentucky
  2. Purdue University
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About the Author:

Hussain Kanchwala is an Electronic Engineer from University of Mumbai. He is a tech aficionado who loves to explicate on wide range of subjects from applied and interdisciplinary sciences like Engineering, Technology, FinTech, Pharmacy, Psychology and Economics.

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