Biological assay methods for mosquito repellents

Area of Science:

• Entomology
• Toxicology
• Environmental Science

Background:

• Existing literature details three main biological assay procedures for repellents: ASTM E951-94, ASTM E939-94, and WHO/CTD/WHOPES/IC/96.1.
• A draft guideline from the U.S. Environmental Protection Agency (USEPA) OPPTS 810.3700 also exists for product performance testing.

Purpose of the Study:

• To identify and discuss the critical factors influencing the accuracy and precision of repellent bioassays.
• To highlight the importance of understanding these variables for efficient selection of new repellent compounds.

Main Methods:

• Review of established repellent bioassay procedures (ASTM, WHO, USEPA).
• Analysis of abiotic factors (light, temperature, humidity, dose, time, cage parameters) affecting mosquito responses.
• Analysis of biotic variables (larval nutrition, adult carbohydrate availability, female age/parity, innate attraction/repellency) in bioassays.

Main Results:

• Repellent bioassay outcomes are significantly affected by skin interactions (absorption, penetration, modification) and environmental factors.
• Mosquito biology, including nutrition, age, and innate behavior, introduces variability into repellent testing.
• Geographic location and mosquito activity cycles are critical for field testing efficacy.

Conclusions:

• Knowledge of variations in abiotic and biotic factors is essential for improving repellent bioassay precision and accuracy.
• Understanding these variables enables more efficient selection of promising repellent compounds for further toxicological and field evaluation.