The ability to feed after treatment with insecticides significantly increases the bedbugs’ chances of survival. This is the conclusion of a study published by the Entomological Society of America, which raises the need to consider this fact in laboratory tests to assess the effectiveness of insecticides used against this pest.
Like other bloodsucking insects, blood sucking is an essential physiological process for the survival of bed bugs (Cimex lectularius), which feed exclusively on blood. During the development of the nymph, a blood meal is necessary for her to move on to the later stage, while the production of eggs and sperm requires regular meals.
Furthermore, a recent blood ingestion also appears to have a stimulating effect on bed bug detoxification enzymes, enhancing the insects’ ability to overcome insecticidal stress.
A study carried out at Rutgers University, in New Jersey (USA), analyzes this phenomenon, to determine the effects that the ingestion of blood after exposure to different classes of insecticides has on the mortality of bedbugs.
The results show that the impact is important, as post-treatment feeding significantly reduces or delays bedbug mortality, giving them the opportunity to reproduce, with differences depending on the insecticide treatment used.
According to tests, ingestion of blood significantly reduced mortality in bed bugs treated with deltamethrin spray, essential oil mixture spray (Bed Bug Fix) and diatomaceous earth powder. Similarly, the mean survival time of bed bugs exposed to a chlorfenapyr spray and an essential oil blend spray (Ecoraider) increased but did not affect final mortality.
First instars hatched from eggs treated with chlorfenapyr liquid spray had reduced intakes compared to nymphs hatched from untreated eggs. However, those who hatched from treated eggs and were able to eat had lower mortality and longer survival times than those who did not ingest blood. None of the insecticides tested had a significant effect on the amount of blood consumed or the percentage of ingestions.
The study authors conclude that food availability following insecticide exposure has a significant effect on bed bug mortality by stimulating detoxification enzymes responsible for insecticide resistance.
And, based on this conclusion, they state that protocols for testing the effectiveness of insecticide products should consider offering a blood meal to bed bugs treated in laboratory tests, within 1 to 3 days following treatment.
Otherwise, data on the effectiveness of the product collected in laboratory tests, carried out without taking this factor into account, may not be indicative of the effectiveness of the product in a situation in the real environment, in which the bed bug can access a guest after treatment of the stay.
Source: Narinderpal Singh et al: Post-treatment feeding affects bed bug mortality (Hemiptera: Cimicidae) exposed to insecticides, Journal of Economic Entomology,