Bed bug feeding methods for laboratory maintenance

3 adult bed bugsBed bugs (Cimex lectularius & Cimex hemipterus) are nocturnal feeding insects that feed solely on blood from sleeping humans or other warm blooded animals. While bed bugs were a known pest to humans from the time of the Greek and Roman empires, since the 1950s their numbers had been in decline due to the widespread use of insecticides such as DTT (dichlorodipenyltrichloroethane)1, 2. However in the early 2000s a resurgence of bed bugs began in major cities worldwide.

The rapid spread of bed bugs is suggested to be caused by several factors including increased international travel which can result in the insects/eggs being transported in luggage and clothing, resistance to pesticides and lack of knowledge regarding their control3. Due to the revival of bed bugs it has become important to rear and study these insects in the laboratory. Bed bugs reared in a laboratory can be maintained using live host animals (such as chickens, rabbits, pigeons or even human volunteers4) or artificial feeding techniques (water bath or petri dish methods).

Live host method
Bed Bug Feeding Live HostThe most effective method of feeding laboratory reared bed bugs colonies in terms of cost and reliability is the use of a human volunteer. The bed bugs are held in an insect container with a fine mesh lid. The container is usually held up to the arm or leg of the volunteer, with the mesh lid touching the skin. While this method is the most cost efficient and the threat of bed bug mortality from blood leakage is eliminated, it provides an uncomfortable experience for the host during and post feeding because in the vast majority of cases an allergic reaction consisting of the formation of itchy papules occurs in response to the bed bug saliva2.

The use of live animal hosts such as chickens, pigeons, rabbits and mice offers another reliable feeding method. The skin of the animal is plucked or shaven of all feathers and hair6, the animals are then anaesthetised and the bed bugs strapped onto their exposed skin. The bed bugs can feed from an insect container through a fine mesh. Higher fecundity was reported when Cimex lectularius were fed on rabbits in comparison to humans, chickens and pigeons4. Araujo et al.6 investigated the influence of coagulation on feeding efficiency and the results revealed that the feeding process was more efficient on anticoagulant-treated pigeons than untreated pigeons. The ratio of weight gain/ingestion rate was more than threefold higher for the bed bug group fed on anticoagulant-treated pigeons6.

Water bath feeding method
clip image004There are two main artificial feeding methods in use today. The first, known as the "water bath method" was developed by Montes et al.7 and involves specialized glassware, a circulating water bath and a plastic membrane - Parafilm ‘M’. The bottom of the glassware is covered with stretched parafilm ‘M’ plastic that acts as a membrane. The blood is inserted into the membrane and kept at 37-40°C using a warm water bath and pump that circulates the water through the feeders7. Filter paper strips are placed inside the insect container to allow the bed bugs to reach the mesh lid, which is in contact with the membrane containing the blood. Perhaps the most widely used method; this removes the need for live hosts and is very effective when carried out correctly. Some disadvantages of the water bath method are the requirement for custom made glassware that can be expensive, and the potential for bed bug death due to the leaking of blood that can occur when the parafilm weakens from the heat of the water bath. 

Petri dish feeding method
clip image006The second artificial feeding method that was subsequently developed involves petri dishes, a heating plate/mat and a plastic membrane - Parafilm ‘M’. A small amount of blood is placed into the lid of a pertri dish, which is then covered with stretched parafilm ‘M’ plastic. The bottom of the petri dish is used to push down the parafilm so that it is in contact with the blood. A hotplate is used to keep the temperature of the blood at 37°C and the insect containers are placed upside down on the parafilm so that the bed bugs can feed through the mesh lid. The petri dish method shares some disadvantages with the water bath method, such as expensive heating equipment and the leaking of blood. The advantages of this method include its quick setup, use of disposable petri dishes and a reduced risk of damage caused by leaking blood, although this is still a threat4.

Conclusion
While the use of a human host for bed bug feeding provides the most cost efficient and simple method of rearing bed bugs, it is not ideal for maintaining bed bugs in the laboratory. Laboratories may have hundreds or even thousands of bed bugs in multiple jars to feed, which would be both time consuming and very uncomfortable for any human volunteer. The use of a live animal host is effective but costly, and the setup is complex and time consuming. The water bath and petri dish method provide the most attractive alternatives to using live hosts, as multiple jars can be fed at the same time, the setup and cleanup is relatively easy and the discomfort of a live host is eliminated. Artificial feeding methods allow for the use of blood from many different sources that would be impossible to achieve with a live host, such as horses and sheep. All the above methods have been used successfully for many years in bed bug laboratories.

Figure 1: Feeding of bed bugs using a human volunteer(Goddard 2009)5.
Figure 2: The water bath method of feeding bed bugs (Montes et al. 2002)7.
Figure 3: The petri dish method of feeding bed bugs (Chin-Heady et al. 2013)4.

 

References:

  1. Davies TGE, Field LM, Williamson MS. 2012. The re-emergence of the bed bug as a nuisance pest: implications of resistance to the pyrethroid insecticides. Medical and Veterinary Entomology 26(3):241-254.
  2. Kolb A, Needham GR, Neyman KM, High WA. 2009. Bedbugs. Dermatologic Therapy 22(4):347-352.
  3. Williams K, Willis MS. 2012. Bedbugs in the 21st Century: The Reemergence of an Old Foe. LabMedicine 43(5):141-148.
  4. Chin-Heady E, DeMark JJ, Nolting S, Bennett G, Saltzmann K, Hamm RL. 2013. A quantitative analysis of a modified feeding method for rearing Cimex lectularius (Hemiptera: Cimicidae) in the laboratory. Pest Management Science 69(10): 1115-1120.
  5. Goddard J. 2009. Multiple Feeding by the Common Bed Bug, Cimex lectularis, without Sensitization. Midsouth Entomologist.
  6. Araujo RN, Costa FS, Gontijo NF, Goncalves TCM, Pereira MH. 2009. The feeding process of Cimex lectularius (Linnaeus 1758) and Cimex hemipterus (Fabricius 1803) on different bloodmeal sources. Journal of Insect Physiology 55(12):1151-1157.
  7. Montes C, Cuadrillero C, Vilella D. 2002. Maintenance of a laboratory colony of Cimex lectularius (Hemiptera : Cimicidae) using an artificial feeding technique. Journal of Medical Entomology 39(4):675-679.

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