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An improved autocidal gravid ovitrap for the control and surveillance of Aedes aegypti.

Mackay AJ, Amador M, Barrera R - Parasit Vectors (2013)

Bottom Line: We had developed an autocidal gravid ovitrap (AGO) as a simple, low-cost device for surveillance and control of Ae. aegypti without the use of pesticides that does not require servicing for an extended period of time.Semi-weekly collections of Ae. aegypti females in the AGO-B were significantly correlated with cumulative rainfall 8 to 28 days prior to sampling, whereas egg collections in paired conventional ovitraps were not.When vector abundance was low, the AGO-B provided greater sensitivity and precision as a surveillance device, compared with paired conventional ovitraps.

View Article: PubMed Central - HTML - PubMed

Affiliation: Entomology and Ecology Activity, Dengue Branch, Centers for Disease Control and Prevention, 1324 Calle Cañada, San Juan, Puerto Rico. amackay@illinois.edu

ABSTRACT

Background: Limited success has been achieved using traditional vector control methods to prevent the transmission of dengue viruses. Integrated control programs incorporating alternative tools, such as gravid ovitraps (lethal ovitraps and sticky ovitraps) may provide greater potential for monitoring and reducing vector populations and dengue virus transmission. We had developed an autocidal gravid ovitrap (AGO) as a simple, low-cost device for surveillance and control of Ae. aegypti without the use of pesticides that does not require servicing for an extended period of time. The purpose of our study was to improve the efficacy and efficiency of this device.

Methods: Competitive assays were performed in the laboratory and an outdoor cage to evaluate whether modifications to the structure and appearance of our original trap design (AGO-A), and the addition of an olfactory bait (hay infusion), improve trap function. The performance of a modified trap design (AGO-B) was then assessed and compared with conventional ovitraps in a series of field tests in San Juan City, Puerto Rico. Generalized linear mixed models were used to analyze adult Ae. aegypti capture data from the laboratory, outdoor cage and field experiments.

Results: Increasing the size of the trap entrance, altering the color of trap components, and increasing the volume/surface area of the aqueous bait significantly improved the performance of the AGO in the outdoor cage. In a subsequent field comparison, captures of Ae. aegypti females were 3.7 fold greater in the improved trap (AGO-B), compared with the original design (AGO-A). An infusion bait produced "in situ" significantly improved capture rates of the improved trap under both semi-natural and field conditions. Semi-weekly collections of Ae. aegypti females in the AGO-B were significantly correlated with cumulative rainfall 8 to 28 days prior to sampling, whereas egg collections in paired conventional ovitraps were not. When vector abundance was low, the AGO-B provided greater sensitivity and precision as a surveillance device, compared with paired conventional ovitraps.

Conclusions: The AGO-B can be used to efficiently attract and capture gravid Ae. aegypti females for more than 8 weeks without the need for trap maintenance.

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Related in: MedlinePlus

Major axis regression comparing collections in the AGO-B and paired ovitraps. Scatter plot of the log10 transformed mean numbers of adults collected per AGO per day (ma) and log10 transformed mean numbers of eggs collected per ovitrap pair per day (me) for each sampling date in field experiments 1 and 2. Line represents a fitted major axis regression [Log10 (me) = 1.250 + 1.306 Log10 (ma)].
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Figure 7: Major axis regression comparing collections in the AGO-B and paired ovitraps. Scatter plot of the log10 transformed mean numbers of adults collected per AGO per day (ma) and log10 transformed mean numbers of eggs collected per ovitrap pair per day (me) for each sampling date in field experiments 1 and 2. Line represents a fitted major axis regression [Log10 (me) = 1.250 + 1.306 Log10 (ma)].

Mentions: Coefficients for the Taylor Power Law regression of data collected from paired ovitraps in the third field experiment were significantly different from coefficients derived from data collected in field experiments 1 or 2, therefore these data were excluded from the pooled data sets used to calculate minimum sample size. Taylor Power Law regression models using data pooled from the first two experiments were significant for both the AGO-B (R2 = 0.755, F = 70.9, df = 1, 23, P < 0.001) and the paired ovitraps (R2 = 0.722, F = 51.8, df = 1, 23, P < 0.001). The slope and y-intercept (95% CI) for the AGO-B were 1.832 (1.382, 2.283) and −0.118 (−0.207, -0.030), respectively. The slope and y-intercept for the paired ovitraps were 1.203 (0.855, 1.552) and 1.279 (0.783, 1.775), respectively. A major axis regression of the log10 transformed mean values for the first two field experiments produced a slope of 1.306 (0.520, 2.092) and y-intercept of 1.250 (1.128, 1.372; Figure 7). Minimum sample sizes calculated using coefficients from Taylor’s Power Law regressions of the pooled data sets were similar between the two sampling methods at equivalent high vector densities, but considerably fewer AGO-Bs were sufficient to estimate abundance compared with the paired ovitraps at equivalent low vector densities (Table 5).


An improved autocidal gravid ovitrap for the control and surveillance of Aedes aegypti.

Mackay AJ, Amador M, Barrera R - Parasit Vectors (2013)

Major axis regression comparing collections in the AGO-B and paired ovitraps. Scatter plot of the log10 transformed mean numbers of adults collected per AGO per day (ma) and log10 transformed mean numbers of eggs collected per ovitrap pair per day (me) for each sampling date in field experiments 1 and 2. Line represents a fitted major axis regression [Log10 (me) = 1.250 + 1.306 Log10 (ma)].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750875&req=5

Figure 7: Major axis regression comparing collections in the AGO-B and paired ovitraps. Scatter plot of the log10 transformed mean numbers of adults collected per AGO per day (ma) and log10 transformed mean numbers of eggs collected per ovitrap pair per day (me) for each sampling date in field experiments 1 and 2. Line represents a fitted major axis regression [Log10 (me) = 1.250 + 1.306 Log10 (ma)].
Mentions: Coefficients for the Taylor Power Law regression of data collected from paired ovitraps in the third field experiment were significantly different from coefficients derived from data collected in field experiments 1 or 2, therefore these data were excluded from the pooled data sets used to calculate minimum sample size. Taylor Power Law regression models using data pooled from the first two experiments were significant for both the AGO-B (R2 = 0.755, F = 70.9, df = 1, 23, P < 0.001) and the paired ovitraps (R2 = 0.722, F = 51.8, df = 1, 23, P < 0.001). The slope and y-intercept (95% CI) for the AGO-B were 1.832 (1.382, 2.283) and −0.118 (−0.207, -0.030), respectively. The slope and y-intercept for the paired ovitraps were 1.203 (0.855, 1.552) and 1.279 (0.783, 1.775), respectively. A major axis regression of the log10 transformed mean values for the first two field experiments produced a slope of 1.306 (0.520, 2.092) and y-intercept of 1.250 (1.128, 1.372; Figure 7). Minimum sample sizes calculated using coefficients from Taylor’s Power Law regressions of the pooled data sets were similar between the two sampling methods at equivalent high vector densities, but considerably fewer AGO-Bs were sufficient to estimate abundance compared with the paired ovitraps at equivalent low vector densities (Table 5).

Bottom Line: We had developed an autocidal gravid ovitrap (AGO) as a simple, low-cost device for surveillance and control of Ae. aegypti without the use of pesticides that does not require servicing for an extended period of time.Semi-weekly collections of Ae. aegypti females in the AGO-B were significantly correlated with cumulative rainfall 8 to 28 days prior to sampling, whereas egg collections in paired conventional ovitraps were not.When vector abundance was low, the AGO-B provided greater sensitivity and precision as a surveillance device, compared with paired conventional ovitraps.

View Article: PubMed Central - HTML - PubMed

Affiliation: Entomology and Ecology Activity, Dengue Branch, Centers for Disease Control and Prevention, 1324 Calle Cañada, San Juan, Puerto Rico. amackay@illinois.edu

ABSTRACT

Background: Limited success has been achieved using traditional vector control methods to prevent the transmission of dengue viruses. Integrated control programs incorporating alternative tools, such as gravid ovitraps (lethal ovitraps and sticky ovitraps) may provide greater potential for monitoring and reducing vector populations and dengue virus transmission. We had developed an autocidal gravid ovitrap (AGO) as a simple, low-cost device for surveillance and control of Ae. aegypti without the use of pesticides that does not require servicing for an extended period of time. The purpose of our study was to improve the efficacy and efficiency of this device.

Methods: Competitive assays were performed in the laboratory and an outdoor cage to evaluate whether modifications to the structure and appearance of our original trap design (AGO-A), and the addition of an olfactory bait (hay infusion), improve trap function. The performance of a modified trap design (AGO-B) was then assessed and compared with conventional ovitraps in a series of field tests in San Juan City, Puerto Rico. Generalized linear mixed models were used to analyze adult Ae. aegypti capture data from the laboratory, outdoor cage and field experiments.

Results: Increasing the size of the trap entrance, altering the color of trap components, and increasing the volume/surface area of the aqueous bait significantly improved the performance of the AGO in the outdoor cage. In a subsequent field comparison, captures of Ae. aegypti females were 3.7 fold greater in the improved trap (AGO-B), compared with the original design (AGO-A). An infusion bait produced "in situ" significantly improved capture rates of the improved trap under both semi-natural and field conditions. Semi-weekly collections of Ae. aegypti females in the AGO-B were significantly correlated with cumulative rainfall 8 to 28 days prior to sampling, whereas egg collections in paired conventional ovitraps were not. When vector abundance was low, the AGO-B provided greater sensitivity and precision as a surveillance device, compared with paired conventional ovitraps.

Conclusions: The AGO-B can be used to efficiently attract and capture gravid Ae. aegypti females for more than 8 weeks without the need for trap maintenance.

Show MeSH
Related in: MedlinePlus