|
Don't
let the Bed Bugs Bite:
The Regulation of Feeding Behaviour by Cimex lectularius |
 / The University of Sheffield
/ Animal &
Plant Sciences / Evolutionary
& Ecological Entomology / Bed Bugs |
| An Introduction
to the Common Bed
Bug, Cimex Lectularius
Bed bugs,
as their name implies, are bugs (members of the order Hemiptera).
They
share this order with approximately 70,000 other known species
including various shield, assassin and water bugs.
Bed bugs are placed within the Cimicidae family along with
bat and bird bugs, all of which are obligate blood feeders.
C.
lectularius is perhaps the best known
member of the Cimicidae (Figure 1. presents a
hypothetical phylogenetic tree) and is one of three species which
regularly target humans[1].
C. lectularius is
only present on the host when feeding, a trait shared with all other
Cimicidae. When not foraging or feeding bed bugs spend the
majority of their lives
inactive and hidden in refuges, typically tight crevices[2-3].
 Figure 1.
A Hypothetical Phylogenetic Tree for the Cimicidae. (From Reinhardt
&
Siva-Jothy, 2007 [5])
While
mated female C. lectularius often produce
eggs without the need to take their first adult
meal, their output of eggs is far greater when fed. Eggs
typically
hatch a week following laying and pinhead-sized nymphs emerge.
C. lectularius undergoes five nymphal
instars before incomplete metamorphosis to adult. In optimal
conditions, bed bugs can develop from egg to adult within five weeks[1].
Adult bugs
are typically 4-6mm long, although it may increase to up to 7mm
following the uptake of blood.
Reproduction Reproduction is rather unique in bed bugs.
In a process termed 'traumatic insemination', males puncture the
female's abdomen and ejaculate directly into her body[3-4].
Male
genitals have a needle-like structure, adapted to this
purpose. Females have a unique organ to deal with
injected sperm and seminal
fluids: the 'spermalege'. The spermalege is sign posted
externally by a pouch, the only site on the
abdomen that males can penetrate. While the full function of
the spermalege is currently unknown, it does serve to protect mated
females against pathogens present on the male intromittent organ[3].
Diet C. lectularius is an
obligate blood-feeder and
inserts its
piercing mouthparts into host
capillaries.
During feeding bugs rapidly ingest a remarkably large volume
of
blood. In one sitting bugs may take as much as 4.9 times
their
unfed weight, depending on their sex and developmental stage[2].
In order to contain
this meal the abdomen of the insect expands greatly (Figure 2.).
Once fully engorged
the bug removes itself from
the host and seeks a suitable refuge.
When replete C. lectularius no longer
responds to cues indicative of the presence of a host. The
nutritional status of recently fed bugs is apparent through their
altered 'sausage-like' body shape (Figure 2.).
With time, visual assessment becomes more and more
difficult
as
digestion and excretion proceeds, diminishing the volume of the
ingested meal. Once the previous meal is sufficiently
depleted,
the bug again becomes receptive to host cues and will feed.
 Figure 2. Unfed (left) and recently fed (right) adult female bed bugs, demonstrating their different shapes (not to scale) References [1] Lehane, M. (2005) The biology of blood-sucking in insects, Cambridge, Cambridge University Press [2] Schaefer, C. W. (2000) Bed bugs (Cimicidae). In Schaefer, C. W. & Panizzi, A. R. (Eds.) Heteroptera of economic importance. Boca Raton, CRC Press LLC [3] Reinhardt, K., Naylor, R. & Siva-Jothy, M. T. (2003) Reducing a cost of traumatic insemination: female bedbugs evolve a unique organ. Proceedings of the Royal Society of London. Series B: Biological Sciences, 270, 2371-2375 [4] Stutt, A. D. & Siva-Jothy, M. T. (2001) Traumatic insemination and sexual conflict in the bed bug Cimex lectularius. Proceedings of the National Academy of Sciences, 98 (10), 5683-5687 [5] Reinhardt, K. & Siva-Jothy, M. T. (2007) Biology of the bed bugs (Cimicidae). Annual Review of Entomology, 52, 351-374 |
© 2007 Kenny Wintle  |