Research Group 1: Evolutionary Ecology

 Blood-sucking bugs as a gentle method for blood-collection in warm-blooded animals

Christian C. Voigt

Blood samples are routinely used for many diagnostic purposes. However, the collection of blood samples is often stressful for the focus animal. Stress may alter the blood parameter under study and therefore invasive blood sampling may confound an experimental design. In addition, it may not be possible to collect blood from some animal, owing to their minute or inaccessible veins that may be hidden under a thick epithel. Some focus animals routinely have to be immobilized for blood collection, which puts the animal at risk to suffer from the trauma of handling and anaesthesia. 

Recently, a new and less invasive method has been suggested: The use of starved blood-sucking bugs, e.g. Dipetalogaster maximus (see Fig. 1), Triatoma infestans or Rhodnius prolixus (Reduviidae; Triatominae; Heteroptera).

Fig. 1: Blood-sucking bug before (A) and after a blood meal (B) (source: Voigt et al. 2006 J Wildl Dis).

For collecting blood, bugs are usually released in the vicinity of the focus animal. Mostly wingless larval instars are used that neither fly nor move fast. Triatomine bugs find their victim following gradients of temperature and carbon dioxide. After stinging the focus animal, the bugs ingest blood for 2 to 30 minutes (mean 15 minutes). After a given time or after the bug has finished its blood meal the bugs can be picked up from the focus animals. Then the ingested blood is taken from the bug by puncturing the bug’s crop with a conventional needle and syringe. Most bugs survive this procedure. However, we do not recommend to use bugs more than once to avoid cross-contamination of focus animals with pathogens.

As parasites blood-sucking bugs are especially well adapted to the quick ingestion of large amounts of blood. The advantages of this method are:

-         blood-sucking bugs can potentially ingest large amounts of blood (up to 4 ml),

-         different larval instars can be used for different blood volumes.

-         Blood-sucking bugs don’t cause hematomas,

-         they heparinize blood,

-         the stinging proboscis is 30times smaller than a conventional needle (Fig. 2).

-         Blood-sucking bugs are not thoroughly attached to their victims like (Zecken),

-         they don’t cause massive after-bleeding like leaches.

Fig. 2: Conventional needle and bug proboscis seen under an electron microscope picture. Pictures A and B and pictures C and D were taken with the same magnification. The whole needle is pierced into the skin (A), whereas the bug only pierces the tip of the proboscis as seen in D into the skin (source: Voigt et al. 2006 J Wildl Dis).

Since blood-sucking bugs may alter the blood parameters of interest owing to dilution or ingestion validation studies have to be performed before bugs can routinely be used in an experiment. Successful validation studies have already been performed for the following blood parameters:

-         Isotopic washout rate in blood during doubly-labeled water experiments (Voigt et al. 2003 J exp. Zool, Voigt et al. 2005 Comp Biochem Physiol. A)

-         Steroid hormones (Voigt et al. 2004 Gen Comp Endocrin)

-         Antibodies (RHD Voigt et al. 2006 J Wildl Dis; rabies virus: Voss et al. in prep.)

Blood-sucking bugs have already been used in the following focus animals:

Mammals:

-         Rodents: Mice, gerbils, mole rats

-        Primates

-         Lagomorphs: Wild and domestic rabbits (Voigt et al. 2004, 2006), European brown hare

-        Carnivores: Domestic cat

-         Chiroptera: Various Bat species (Voigt et al. 2003, 2005)

Birds:

-         Common Terns (Becker et al. 2006 J Orn)

-         Stonechats

-         Quails

-         Domestic chicken

We have developed several application that facilitate the collection of blood with triatomine bugs. All application are under patent of the Institute for Zoo and Wildlife Research. For more information please write Dr. Christian Voigt at voigt@izw-berlin.de.