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

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.

Comparison of Trapping Efficacy of Locally Modified Gravid Aedes Trap and Autocidal Gravid Ovitrap for the Monitoring and Surveillance of Aedes aegypti Mosquitoes in Tanzania

“…However due to conveniences yeast was selected for further evaluation. This is evident in other studies that have shown the effectiveness of yeast baited traps and ovitraps at luring different mosquito species including Aedes [17,18,45]. While yeast was not as attractive as fermented grass, it was far simpler to use as bakers yeast is cheap, standardised and is widely available.…”

“…Lethal ovitraps (gravid traps) such as Gravid Aedes Trap (GAT) and Autocidal Gravid Ovitrap (AGO) are among the most widely used traps for sampling Aedes mosquitoes and primarily designed to capture gravid mosquitoes [15]. These are passive traps that use water and organic materials to attract mosquitoes seeking a place for oviposition [16][17][18]. Mosquitoes are captured by either a sticky surface, oil, or insecticide lined inside the GAT [12] or an adhesive sticky board in AGO traps [19].…”

Comparison of the Trapping Efficacy of Locally Modified Gravid Aedes Trap and Autocidal Gravid Ovitrap for the Monitoring and Surveillance of Aedes aegypti Mosquitoes in Tanzania

“…However, due to convenience, yeast was selected for further evaluation. This is evident in other studies that have shown the effectiveness of yeast-baited traps and ovitraps at luring different mosquito species including Aedes [17,18,45]. While yeast was not as attractive as fermented grass, it was far simpler to use as baker's yeast is cheap, standardized, and widely available.…”

“…Lethal ovitraps (gravid traps) such as Gravid Aedes Trap (GAT) and Autocidal Gravid Ovitrap (AGO) are among the most widely used traps for sampling Aedes mosquitoes and are primarily designed to capture gravid mosquitoes [ 15 ]. These are passive traps that use water and organic materials to attract mosquitoes seeking a place for oviposition [ 16 , 17 , 18 ]. Mosquitoes are captured by either a sticky surface, oil, or insecticide lined inside the GAT [ 12 ] or an adhesive sticky board in AGO traps [ 19 ].…”

Evaluation of superabsorbent polymer (SAP) in oviposition traps used in the integrated control of Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) (Diptera:Culicidae)

“…Traps called ovitraps were used for egg collection in the field, which consist of a black plastic material (10.5 cm in diameter and 15 cm in height) with removable pressed wooden paddles filled with 495 mL of tap water, and 1 mL of beer yeast solution (0.04%) was added to increase attractiveness and stimulate egg deposition by females 20 , 35 - 36 .…”