Two New Alternatives to the Conventional Arm-in-Cage Test for Assessing Topical Repellents

Area of Science:

• Entomology
• Public Health
• Toxicology

Background:

• European guidelines for testing insect repellent efficacy (Product Type 19) are under revision.
• Current laboratory methods, like the arm-in-cage (AIC) test, may not accurately reflect real-world repellent performance.
• Field testing is discouraged by the European Chemical Agency due to disease transmission risks.

Purpose of the Study:

• To evaluate alternative laboratory methods for assessing topical mosquito repellent efficacy.
• To identify methods that better replicate field mosquito landing rates.
• To ensure reliable and reproducible protection time data across testing facilities.

Main Methods:

• Three European laboratories participated, using Aedes albopictus mosquitoes and 30 human subjects per test.
• Phase 1 compared a conventional AIC test with a sleeved AIC test, varying exposed arm area and cage volume.
• Phase 2 utilized room-based testing as a field proxy, employing 15% N,N-diethyl-m-toluamide repellent at two doses.

Main Results:

• Alternative methods, including sleeved AIC and room-based testing, successfully recreated field-like mosquito landing rates.
• Protection times measured using the alternative methods were reproducible across the participating laboratories.
• The Kruskal-Wallis test confirmed the statistical significance of the findings.

Conclusions:

• The evaluated alternative laboratory methods show potential as replacements for the current standard AIC test.
• These methods offer a safer and more reliable way to assess topical repellent efficacy.
• Reproducibility across labs suggests these alternatives can support regulatory decision-making for insect repellents.