Killing cockroaches with insecticides only makes them stronger, US study says

Commercial insecticides are becoming less effective, and what is the required extermination method? . Diatomaceous earth, crushed from sedimentary rock, can dehydrate and kill insects. (PHOTOGRAPH BY HELIN LOIK-TOMSON, GETTY IMAGES)

Many people are annoyed by the nasty cockroach infestation. It turns out there's a good reason why cockroaches are so difficult to get rid of. Research is accumulating that suggests that some German cockroaches (Blattella germanica) have developed resistance (tolerance) to insecticides. [Video] Defending against parasitic wasps that turn cockroaches into zombies by kicking For example, according to a paper published in the academic journal "Journal of Economic Entomology" in December 2021, German cockroaches collected from housing complexes in California, USA, often Some survived the five pesticides used. German cockroaches are associated with at least 11 allergens and can spread bacteria such as salmonella. The results are concerning because of their implications for human health, said Zhouyang Lee, lead author of the paper and professor of urban entomology at the University of California, Riverside. In addition, the stress caused by cockroach infestations puts your mental health at risk. Although other cockroaches can also invade homes, German cockroaches are by far the most problematic, Li said. There are different theories as to whether the German cockroach originated in Africa or Southeast Asia, but in any case, these hardy cockroaches spread around the world as cargo was transported abroad, and are now the most common cockroach in the world. (In the 1770s, Swedish naturalist Carl von Linnaeus named Blattella germanica after receiving a sample of the insect in the mail from Germany). More than 4,500 species of cockroaches have been identified worldwide, but "only German cockroaches have been confirmed to develop resistance to insecticides," Lee says. This is an example of how humans have encouraged the evolution of insect pests.

The more pesticides you use, the more cockroaches get stronger

Lee's team explored how German cockroaches in four cities in southern California reacted to gel baits. to see if they would respond to Gel baits are the most commonly used commercial pesticides in the United States for pest control. First, hundreds of cockroaches were collected from public housing complexes in Los Angeles, San Diego, Vista, and San Jose. Most were collected using vacuum cleaners and some using traps. For economic reasons, residents in the surveyed areas are more likely to use commercial pesticides than to hire commercial pesticides, Lee said. However, this tendency creates a vicious cycle. As pesticide use increases, resistant cockroaches have a greater chance of surviving and reproducing, creating generations of even more resistant cockroaches. Lee calls this vicious circle the "neverending story of pesticide resistance." The research team brought the captured cockroaches back to the laboratory and conducted an experiment in which they were exposed to each of the six insecticidal ingredients. As a control group, dozens of laboratory-reared German cockroaches that had never been exposed to the insecticide were also exposed to the same insecticidal composition. The cockroaches in the control group died as soon as they were exposed to the insecticidal ingredients. However, cockroaches caught in homes had low to moderate mortality for five of the six species. The insecticidal component abamectin exhibited a strong insecticidal effect. However, another study published in the scientific journal "Scientific Reports" in 2019 confirmed that cockroaches with high resistance to abamectin were born in just two generations or one year. Xiaohan Dennis Lee, a co-author of this paper and a Ph.D. "In other words, many resistant cockroaches have (genetic) mutations in the target site, so they are not easily affected by insecticidal ingredients." Sometimes. In addition to headaches, dizziness and nausea, the pesticide residues that are "spreading" U.S. homes can also increase your risk of developing cancer, according to the U.S. Environmental Protection Agency (EPA). No.