Bed Bug Repellency Test

    Repellents & Attractants (No-choice test & Choice test)

No choice and choice tests are conducted to determine if pesticide product repels bed bugs.

• Barrier test  (No-choice test)

The barrier test is performed to evaluate the efficacy of repellents in creating a protective barrier that hinders bed bugs from reaching a specific area or surface.

Test procedure explained 

• Barrier test simulates a human host (heat and CO2) to attract bed bugs for testing repellents.
• Bed bugs are exposed to the test barriers (such as filter paper) treated with repellents.
• The simulation of a host (heat and CO2) in the test system is done to lure the bed bugs to cross the barrier.
• Analysis of results is based on the efficacy of the repellent barrier in preventing bed bugs from crossing it.

Volatile repellents – This test runs with 5 replicates using ten bed bugs each time with an equal number of treated samples and untreated controls. Bed bugs are exposed to the repellent vapors (sample product) to check if the repellent can keep the bed bugs away from the system mimicking the human host(e.g. carbon dioxide and heat).

Impregnated fabric – This test is performed on both treated and untreated pieces of fabric using a test system to mimic the human host (e.g. carbon dioxide and heat). The test determines if a bed bug is repelled by the impregnated fabric (bed bug repellent) or not.  

2. Harborage  test  (Choice test)

The objective of the harborage test is to evaluate the efficacy of repellent products on bed bug behavior.

Test procedure explained  

• Experiment setup consists of crystallizing dishes with treated and untreated harborages.
• A specified number of bed bugs are introduced in the middle of the crystallizing dish between the harborages. 
• The number of bed bugs in the treated and untreated harborages or outside the crystallizing dish is counted at specific time intervals.
• During the observation period, the crystallizing dishes are left open. To minimize the impact of light on bed bug behavior, lights in the room are switched off, and soft twilight from the outside is used for data recording. 
• After the observation, crystallizing dishes are closed with mesh fixed with a rubber band to prevent bed bugs from escaping, and the room is completely darkened. 
• After 24 hr,  the position of all bed bugs is counted again.
• The number of lethally affected bed bugs is determined by forceps stimulation. 
• Bed bugs are categorized as lethally affected if they show no or only uncoordinated movement, or if they can’t turn back into the ventral position from the dorsal position.

Volatile repellents – A modified version of the still-air olfactometer can be used to evaluate the efficacy of bed bug-repellent products. The still-air olfactometer device must have a source of carbon dioxide and heat to mimic a human host. The test involves looking at the mobility behavior of the bed bugs in the presence and absence of repellent in the treated area when there is a human-mimicking host. A negative control is also set up with carbon dioxide and heat (mimicking human host) without repellent.

Alternatively, a Y-tube assay can also be used to check the bed bug’s response to different scents and repellents. 

Impregnated fabric – Both untreated and treated fabric are tested together with bed bugs placed onto the top of fabric. Their response/ movement either towards or away from the treated fabric is observed and measured.

In parallel, a control test is also run with an untreated fabric.