Large-Volume Gravid Traps Enhance Collection of Culex Vectors.

Area of Science:

• Medical Entomology
• Vector-Borne Disease Surveillance
• Insect Ecology

Background:

• Routine vector surveillance relies on effective gravid mosquito traps.
• Existing Centers for Disease Control and Prevention (CDC) gravid traps have limitations in collection volume.
• Optimizing gravid trap design is crucial for accurate mosquito population assessment.

Purpose of the Study:

• To compare the efficacy of large-volume gravid traps against the standard small-volume CDC gravid trap.
• To identify key design features influencing gravid mosquito collection rates.
• To evaluate the impact of infusion volume and container characteristics on trap performance.

Main Methods:

• Multiple large-volume (≥35 L) gravid trap designs were tested against the small-volume (6 L) CDC gravid trap.
• Collections of gravid mosquitoes, primarily Culex species, were compared over three years and across seasons.
• Trap performance was analyzed based on infusion volume, container size/type, and trap placement.

Main Results:

• Large-volume gravid traps collected significantly more gravid Culex mosquitoes (average 6.6-fold increase) compared to CDC traps.
• Collection efficacy varied seasonally, with spring showing the largest differences (8- to 56-fold increases with large traps).
• Infusion container size and volume were critical factors, influencing trap-to-infusion surface distance.

Conclusions:

• Large-volume gravid traps offer superior performance for collecting gravid mosquitoes, enhancing surveillance capabilities.
• Trap design, particularly infusion volume and container specifications, significantly impacts collection efficiency.
• A 100 L infusion in a 121 L container was most effective, with a 35 L option also showing promise.