With over 3,500 species of cockroaches existing all over the globe, these resilient creatures can be found in our homes, cupboards, and everywhere you don't want to see them.
Now, a new study has found proof that they are becoming even more resilient than we thought. According to researchers from Purdue University, German cockroaches - the most common species worldwide - are no longer dying as fast as they used regardless of how much insecticide you use on them.
These cockroaches, found exclusively in human environments, are becoming resilient to almost all kinds of insecticides according to the study published in the journal Scientific Reports.
The scientists found that cockroaches, which live only about 100 days, have evolved and can now develop the resistance to insecticides. The study also shows that this resistance can even be passed down from one generation to another.
Here is how these scientists came to this conclusion
Over the course of six months, these researchers tried three different insecticides on three different cockroach colonies in order to test their resistance. They used the store-bought insecticides in three different ways.
First by using all three insecticides on one colony, one at a time. Next, they used a mixture of the insecticides on another colony before hitting the last colony with just one chemical that the roaches had a low resistance to.
The researchers found that most of the cockroach colonies simply refused to die regardless of how the treatment was used. The population size simply refused to go down no matter what the scientists did. Instead, their resistance levels actually increased in most cases which suggest that cockroaches are quickly evolving resistance to insecticides.
Abamectin gel bait was the only chemical insecticide that could actually kill a portion of a cockroach colony. However, this only happened if the roaches had a low level of resistance. The researches are going to do more genetic testing to figure out why.
"Overall, the unexpectedly poor performance of a majority of treatments in the field study suggested significant levels of starting resistance and/or selection for higher-level resistance in 4–6 months," the scientists conclude.