Who would love the thought of having creepy crawlers all over their place? It may be easy for people to kill these crawlers now, but scientists warn that these creepy crawlers might be becoming more immune to the insecticides used to kill them. They are becoming harder and harder to kill.
Researchers have found the German cockroaches have become harder to kill because, through time, they have developed a cross-resistance to the insecticides used to kill them. The result of the study was published in the journal Scientific Reports. Michael Scharf, a professor at Purdue University led the study. He got the support he needed from the US Department of Housing and Urban Development.
"There is a challenge in handling cockroaches that have never been realized before," Scharf said in a statement. "When cockroaches develop a certain type of immunity against multiple classes of insecticides will make it impossible for people to control these pests with just the chemicals alone."
Researchers also note that various insecticides work differently. Some exterminators use a mixture of these classes and they sometimes change the level of these classes too. This is the approach they put into practice to ensure that if there are roaches that are resistant to one mixture, another element in the mixture will be able to kill them.
The authors of the study put their approach to a test by observing multi-unit buildings over a six-month period. For every treatment, three different types of insecticides were used in rotation. In the third treatment, the scientists used the insecticide to which the cockroaches started resisting and used it throughout the rest of the duration of the research.
There was an observable growth in the population of cockroaches that resisted the insecticides as a result of the cross-resistance. "We would see an increase in resistance four to six times per generation," Scharf said. "We didn't know something like that could happen fast."
Researchers have noted that the female roaches that were resistant to the treatment have a three-month reproductive cycle which means they could give birth to 50 or more offspring or so. "Even if only a small portion of the cockroaches is resistance to insecticides, those roaches can gain cross-resistance, making it impossible to kill."
The study also found the prevalence of cockroach cross-resistance problem has become prevalent in urban areas, particularly in low-income families. Last year, the genome of cockroaches have been mapped to find out why they could be such tenacious survivors.
