Bedbugs (Cimex lectularius) were in the news in recent months for epidemic outbreaks in across the United States. A brand new study shows WHY they are even harder to kill than ever. Researchers at the Ohio State University sequenced the bedbug transcriptome, which means they isolated all the DNA that was being used by the bugs (there’s lots of “junk” in most genomes that is not transcribed, or used) and figured out the sequence of the nucleotides (the building blocks of the double helix). This has only recently become possible to do as quickly and cheaply as they did – and we’re still probably talking in the tens of thousands of dollars at least!
The researchers found a number of genes that detoxify pesticides being used frequently – much more frequently than a colony of bedbugs isolated since the 1970’s. This means the bedbugs have probably evolved higher pesticide resistance, which is why our usual pesticides aren’t getting rid of them easily anymore. Yikes!
Host-parasite interactions is the fancy ecologist word for what people and bedbugs are doing: they live on sucking human blood, we humans don’t like that, we try to kill or avoid them, and they try to get around our defenses. A LOT of research has been done both on the “arms race” of these systems (for example, we develop new pesticides and they develop new resistance) and to the ecological population dynamics on shorter time scales.
Some pairs of hosts and parasitoids have numbers that go in cycles, like spruce trees and budworms that attack them: the parasitoid feeds up on the hosts, killing them off, until the host population crashes. Since the parasitoids cannot find the hosts as well, their population declines, too. Then the hosts build up and it keeps going. Other pairs of species have surprisingly stable numbers, like the California red scale and a parasitoid introduced to control it. How these interactions function partly depends on the spatial scales of each species. Bedbugs seem to be good at dispersing with people traveling, and people are probably not going to decrease our population densities (move out of the cities) any time soon.
So are they here to stay? Given human ingenuity and our history of pesticide research, I bet we’ll come up with a defense. But sooner or later, the bed bugs will overcome that, too.