A study of the genetic code of bed bugs reveals that these human blood feeders are adaptive and hardy
An international study involving Rothamsted Research, allows scientists for the first time to read the genetic make-up of bed bugs, and begin to understand genes linked to the insect’s adaptive biology and behaviour.
Much like how our eyes scan a sequence of letters to read and understand a sentence of English, scientists have, for the first time, sequenced and annotated the genetic code of the common bed bug (Cimex lectularius). This has allowed them to read the bed bug genetic make-up and make big steps in understanding the genes which are linked to evolutionary adaptations in the insect’s biology and behaviour. The research, which was carried out by a group of over 80 scientists based across the world, is today, 2 February 2016, published in Nature Communications.
Bed bugs, the very thought of which makes a person shudder and scratch, were nearly eradicated after World War II in most economically and politically stable countries. In the past 20 years however, there has been a recovery in their population across much of the world.
The research involved the rearing of bed bugs to extract DNA from their cuticle, which is what forms the outer protective skeleton of the insect. This was followed by sequencing, automated annotation, and manual analyses of the bed bug genetic code or, what the scientists call, the genome. The research provides a full annotation of the genes which makeup the bed bug genome.
In collaboration with colleagues of the consortium, Rothamsted Research scientist, Dr Jing-Jiang Zhou, who is strategically funded by the BBSRC, identified the collection of genes that are linked to the bed bug’s sense of smell (olfaction) and sense of taste (gustation). Commenting on his contribution to the research, Dr Zhou, said: “Sense of smell and taste are critical to how bed bugs find mates to reproduce, locate their human hosts to feed, and navigate through the dark environment of a bed. To do all of this, bed bugs use smell (olfaction) and taste (gustation) receptors, and smell (odorant) binding proteins.
The collection of what are called chemosensory genes – in other words genes which response to chemical stimuli – was substantially reduced in the bed bug compared to insects which feed on plants. It is however, similar to the trend noted in the genome sequences of other blood-feeding insects.”
Other areas of the bed bug genome research included the identification of the genes which are linked to how bed bugs mate, feed, form mutually dependent relationships with bacterial organisms, and become resistant to pesticides.
Commenting on the work, leading author, Dr Joshua Benoit, from the University of Cincinnati said: “Given that bed bugs are associated with humans in the built environment, are active at night and have no wings to fly we expected a collection of genes which were linked to controlling the ways in which this parasite locates and accepts its host, and ingests and digests blood. And also a range of genes linked to how bed bugs have, over time, become resistance to pesticide.”
The research has uncovered underlying characteristics surrounding fundamental questions such as why bed bugs feed only off blood, and how they can survive an entire year without a meal.
Dr Benoit said: “If someone’s home is infested and that person leaves the premises for a few weeks in the hope that the bed bugs will go away, that isn’t going to happen. The bed bugs will be hungry and waiting for when the ‘host’ gets back home”.
The outer protective cuticle of bed bugs plays a significant role in their resistance to pesticides. It’s believed that resistance is a result of changes in the expression of cuticle proteins. The researchers identified 273 genes that encode common cuticle proteins, all of which have been associated with pesticide resistance in various other insects.
Dr Zhou concluded: “Almost certainly humans and bed bugs will remain closely associated for the foreseeable future.
As the only British scientist in this study, I am very proud to have contributed to the work. It provides us the genetic resources to study molecular mechanisms of bed bug olfaction and chemosensory specialisation through comparative genomic studies. And is a platform for future research to ask questions such as: what has triggered the current bed bug resurgence and do bed bugs originate from one or multiple sources?”
Tags: genetics human health Rothamsted Research press release