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A study revealed that cockroaches are evolving to become nearly impossible to exterminate using insecticides.
Scientists from Purdue University in Indiana, United States, examined German cockroaches, the most common species found inside homes. These insects carry toxins that can trigger asthma and expose humans to bacteria like salmonella.
Insecticides are usually used to get rid of cockroaches, but the scientists said that German cockroaches have developed resistance to those chemicals. The scientists also noted that cockroaches are resistant not only to insecticides they have been previously exposed to but also to those that they have never encountered.
To test the cockroaches’ resistance, the scientists used three treatment methods in several apartment buildings for six months. They used three different pesticides consecutively for the first method, then a mixture of two pesticides for the next. When both methods failed, the scientists used one insecticide, which successfully reduced the cockroach population. However, this method worked only because the scientists specifically studied the cockroaches in the buildings to determine which insecticide would successfully exterminate the insects.
The scientists attribute the insecticides’ failure to cross-resistance, or the cockroaches’ ability to tolerate a poisonous substance through contact with it. When a cockroach develops cross-resistance, its offspring will inherit this trait. As a result, houses end up having an entire population of resistant cockroaches.
Despite this phenomenon, the scientists pointed out that pests like cockroaches can still be effectively removed from houses in other ways. Families can use special vacuums that can trap insects or place sticky traps around the house. The scientists also suggest making it a habit to take out trash every day.