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Tunnel Test for Mosquito Repellents
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Tunnel Test for Insecticide treated Material
The tunnel test for mosquito repellents has been a widely used test to determine the efficacy of insecticide-treated materials based on mosquito mortality and blood-feeding success. This test helps in the development of effective repellents thus, indirectly, helping to combat mosquito-borne diseases.
Mosquitoes are vectors for pathogens causing serious diseases like malaria, dengue and Zika. Therefore, effective vector control strategies are essential for reducing the spread of such diseases. Insecticide-treated materials such as bed nets and wall paints, have proven to be effective barriers. However, their efficacy must be evaluated and the tunnel test allows manufacturers to assess their efficacy under controlled laboratory conditions. By mimicking real-world scenarios, the tunnel test for mosquito repellents provides valuable insights into how these materials can prevent mosquito bites and ultimately reduce the transmission of vector-borne diseases.
Test species and scope of products
The tunnel test for mosquito repellents is conducted against female Anopheles, Aedes and Culex mosquitoes and the products tested include insecticide-treated materials such as bed nets and wall paints.
Conditions Required to Perform Tunnel Test for mosquito repellents
- Non-blood-fed mosquitoes (aged 5–8 days) are required for the tunnel test.
- A suitable bait (such as a guinea pig or rabbit) is required to attract the mosquitoes for biting.
- The test must be conducted under controlled conditions, including specified temperature, exposure time and humidity levels.
Tunnel Test Procedure
- The assay is conducted in a 60-cm (25 cm x 25 cm square section) glass tunnel.
- A 25 cm square cage, covered with polyester netting, is attached at both ends of the tunnel.
- A bait (e.g., mouse) is placed in a small section of the tunnel to attract mosquitoes.
- A treated test sample is placed in a disposable cardboard frame at one-third of the tunnel’s length.
- Nine 1-cm holes are made in the netting sample to allow mosquitoes access to the bait.
- At the opposite end of the tunnel, 50–100 mosquitoes are released towards the treated netting to see if they pass through to reach the bait.
- The mosquitoes from each section of the tunnel are collected and counted separately after 15 hours of exposure.
- An aspirator is used to collect the live mosquitoes, and the dead mosquitoes are removed from the bait chamber with the help of forceps.
- The live mosquitoes are transferred into plastic cups containing 10% sucrose solution and their mortality rate is recorded after 24 hours.
Test Validity Criteria:
Control Mortality: Mortality in the control group should not exceed 10% after 24 hours. If it exceeds this, the test is invalid and must be repeated. For extended holding times, control mortality should not exceed 20%.
Blood Feeding in Control: The blood-feeding success in the control group must exceed 50%. If it falls below this threshold, the test is invalid and should be repeated.
Precautionary Measures to Undertake while Testing
- Test conditions like temperature, humidity and lighting should be closely monitored and controlled.
- Testing personnel should wear protective equipment during testing to avoid accidental bites or sample contamination.
- Non-blood-fed, healthy mosquitoes must be used for the test. Mosquitoes must be handled with care to avoid any injury or stress, which can lead to variations in results.
- Animals used as baits must be handled ethically and humanely according to the approved guidelines.
- Strictly follow the exposure times to ensure consistency in results.
- Proper disposal of hazardous materials and dead mosquitoes must be followed according to the lab regulations for safety and environmental concerns.
Importance of the Tunnel Test for mosquito repellents
The tunnel test provides a controlled yet realistic assessment of the effectiveness of insecticide-treated materials against mosquitoes. The test is thus important to manufacturers to meet the required performance standards of the products. Additionally, testing ensures that repellent-treated materials inhibit the transmission of diseases like malaria and dengue by mosquitoes, thus contributing to public health.
Benefits of the Tunnel Test
- Regulatory compliance
The testing of mosquito repellents through the tunnel test method aids a manufacturer in identifying and confirming whether their insecticidal products meet national and international regulatory requirements.
- Market competitiveness
Products that pass the tunnel test for mosquito repellents may be presented as scientifically validated effective products. This provides a competitive edge to the manufacturer in a crowded market.
- Product refinement and development
Manufacturers obtain many valuable insights through the tunnel test to refine and develop their products.
- Consumer trust and safety
The tunnel test ensures that a product intended to protect against mosquito bites is safe and of the highest efficacy, hence instilling confidence in the product by its consumers.
Related test methods
At Microbe Investigations Switzerland, the following standard test methods are also available to test repellent efficacy:
- Arm-in-cage test
- Room test/Modified Room Test
- Olfactometer test
- Chamber Test/Peet-Grady Chamber Test
- WHO cone test
At MIS, we offer a comprehensive range of entomology testing services for insecticide-treated lotions, creams, sprays and fabrics. Our well-equipped lab and expert entomologists ensure high-quality assessments and analyses. For more information on the tunnel test, consult our specialists.
FAQs
A tunnel test is a laboratory assay used to measure the mortality (death) and blood-feeding success of host-seeking mosquitoes on an insecticide-treated material.
The most commonly tested species are Anopheles, Aedes and Culex species.
A tunnel test is applicable for insecticide-treated nets (ITNs) and paint materials.
It takes 3-4 weeks to complete the Tunnel test.
In the tunnel test for mosquito repellents, mosquitoes are exposed to a repellent-treated material placed in a controlled tunnel environment. Mosquitoes are usually released in one section, with a bait at the opposite end. Mortality and blood-feeding success are measured.
The key parameters measured during the tunnel test are the mortality rate of mosquitoes, the blood-feeding success rate, the repellency rate and the duration of repellency.
The tunnel test method is particularly suitable for insecticide-treated materials, such as bed nets, fabrics, curtains and wall coverings.
No, the tunnel test relies mostly on host-seeking adults since the test needs to establish the efficiency of repellents or insecticides against mosquitoes that usually bite and transmit diseases.
Multiple trials are carried out to ensure the reliability of the results. Generally, at least three independent trials should be carried out in controlled conditions to account for the variability in mosquito behavior and ensure statistical significance.
The repellency rate of mosquitoes is determined based on the percentage of mosquitoes deterred from passing through the treated material. This is done by comparing the number of mosquitoes that attempt to reach the bait in the treated and untreated sections of the tunnel.
In lab-controlled tunnel tests, the environment is highly uniform, and factors like temperature, humidity and exposure time are carefully controlled, while field tests provide insights into real-world performance.
The duration of repellent efficacy can be tested by conducting the test at different time intervals after treating the material with the repellent. The repellency and mortality rates over time can be measured to determine the duration of efficacy.
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