Field trials reveal the complexities of deploying and evaluating the impacts of yeast-baited ovitraps on Aedes mosquito densities in Trinidad, West Indies

Lester D James,David W Severson,Ethan Romero-Severson,Molly Duman-Scheel,Naresh Nandram,Nikhella Winter,Rachel Shui Feng,Azad Mohammed,Akilah T M Stewart

doi:10.1038/s41598-022-07910-0

Abstract

The use of lure-and-kill, large-volume ovitraps to control Aedes aegypti and Aedes albopictus populations has shown promise across multiple designs that target gravid females (adulticidal) or larvae post-oviposition (larvicidal). Here we report on a pilot trial to deploy 10 L yeast-baited ovitraps at select sites in Curepe, Trinidad, West Indies during July to December, 2019. Oviposition rates among ovitraps placed in three Treatment sites were compared to a limited number of traps placed in three Control areas (no Aedes management performed), and three Vector areas (subjected to standard Ministry of Health, Insect Vector Control efforts). Our goal was to gain baseline information on efforts to saturate the Treatment sites with ovitraps within 20–25 m of each other and compare oviposition rates at these sites with background oviposition rates in Control and Vector Areas. Although yeast-baited ovitraps were highly attractive to gravid Aedes females, a primary limitation encountered within the Treatment sites was the inability to gain access to residential compounds for trap placement, primarily due to residents being absent during the day. This severely limited our intent to saturate these areas with ovitraps, indicating that future studies must include plans to account for these inaccessible zones during trap placement.

Highlights

The use of lure-and-kill, large-volume ovitraps to control Aedes aegypti and Aedes albopictus populations has shown promise across multiple designs that target gravid females or larvae post-oviposition
Yeastbaited ovitraps were highly attractive to gravid Aedes females, a primary limitation encountered within the Treatment sites was the inability to gain access to residential compounds for trap placement, primarily due to residents being absent during the day
Our goal was to obtain information on household access for ovitrap placement, general attractiveness of inactive yeast-baited ovitraps to gravid Aedes females when placed in a natural urban environment, and numbers of eggs laid in individual traps throughout the typical breeding season

Summary

Introduction

The use of lure-and-kill, large-volume ovitraps to control Aedes aegypti and Aedes albopictus populations has shown promise across multiple designs that target gravid females (adulticidal) or larvae post-oviposition (larvicidal). Yeastbaited ovitraps were highly attractive to gravid Aedes females, a primary limitation encountered within the Treatment sites was the inability to gain access to residential compounds for trap placement, primarily due to residents being absent during the day. This severely limited our intent to saturate these areas with ovitraps, indicating that future studies must include plans to account for these inaccessible zones during trap placement. Of these arboviruses has historically depended on efforts directed at controlling the mosquito vectors, most often by breeding site reduction and insecticide a pplications[9]. Gravid Aedes females actively seek to oviposit in man-made containers in and around human dwellings[13,14], with a majority of mosquito breeding often seen in neighborhoods with low and medium socioeconomic levels[15]

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Conclusion