Study proves cockroaches growing immune to pesticides

Treatments were made monthly throughout the 6-month study after the researchers calculated the present population assessments of cockroaches present in the area.

By ZACHARY KEYSER
cockroach 224.88 (photo credit: Courtesy)
cockroach 224.88
(photo credit: Courtesy)
Not only could cockroaches theoretically be able to survive a nuclear Holocaust, a study performed by Purdue University, published in the Journal of Scientific Reports, now shows that a German species of the insect (Blattella germanica L.) is now immune to most pesticides and chemicals intended to kill them.
The new study claims that these cockroaches start to build an immunity to pesticides that they come into contact with, and that the immunity to the new chemicals or poisons can be developed in as quickly as one generation - therefore what affected the parent no longer will affect the offspring.
“We didn’t have a clue that something like that could happen this fast,” co-author of the study Michael Scharf said. “Cockroaches developing resistance to multiple classes of insecticides at once will make controlling these pests almost impossible with chemicals alone.”
"Proposed strategies for managing resistance in B. germanica include rotating between different products or using mixture products with multiple modes of action, rather than using single active ingredient (AI) products with single modes of action," the study explained. "Our study represented a seminal effort to assess trans-generational impacts of different resistance management strategies on resistance evolution in B. germanica."
To account for movement of these insects from one apartment to another, all the apartments within a building were studied under the same control, whether initially infested or not, and received the same treatments - clustering these buildings together to gain a control over the study.
Treatments were made monthly throughout the 6-month study after the researchers calculated the initial population assessments of cockroaches present in the area.
Though the research team experienced what were believed to be wide range control failures over the study actually formulated into a hypothesis that these cockroaches are evolving with physiological resistance to the chemicals being used, each time, each generation - instead of reaching their original intended conclusion, which was to determine what pesticide is most effective in defeating these insects.
"In these [assessments], percent survivorship as presented is indicative of the proportion of resistant individuals present in a population," the study wrote, as well as alluding to the fact many of these survivors could be offspring of other treated cockroaches born within the month.
Given this discovery, the researchers included a formal suggestion that the rotation of chemicals used for treatment is the best way to keep populations of cockroaches from thriving.
"Based on the above results showing extensive product failures in the field and concurrent evolution of resistance to [pesticides], we next sought to investigate resistance to the same [chemicals] as used in field studies," the study said, which allowed them to come to the conclusion that, "survivorship was generally elevated in choice [pesticides] for all field-selected strains regardless of [the chemical used]."
"Regardless of resistance intervention strategy, resistance levels increased to almost all [pesticides] tested in this study, with the rotation strategy seeming to produce the lowest selection intensity."
In short, make sure you change up the chemicals you are using to kill these adorable, always invited, little insects.


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