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Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems.

Martin NJ, Smith PA, Achee NL, DeLong GT - PLoS ONE (2013)

Bottom Line: Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI.The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3) (n = 17; SD = 0.45) and 1.42 µg/m(3) (n = 30; SD = 0.96).The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency.

View Article: PubMed Central - PubMed

Affiliation: Viral and Rickettsial Diseases Department, U. S. Naval Medical Research Center, Silver Spring, Maryland, United States of America ; Preventive Medicine and Biometrics Department, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America.

ABSTRACT

Background: Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR). Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI) in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions.

Methodology/principal findings: A thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT) in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3) (n = 17; SD = 0.45) and 1.42 µg/m(3) (n = 30; SD = 0.96).

Conclusions/significance: The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h) SR concentrations in small volume (<100 L) samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.

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Related in: MedlinePlus

A schematic diagram of the three chamber system used to study mosquito behavior.Each chamber was 30.5 cm×30.5 cm×30.5 cm (28.4 L) with a 10 cm hole cut into a removable acrylic lid. A: lab air supply (5 L/min) measured with a rotameter, B: metal treatment chamber, C: acrylic mosquito introduction chamber, D: metal control chamber, E: closable funnels opened during exposures studies to allow mosquitoes, air flow, and airborne chemical to move between the chambers, F: vacuum exhaust (10 L/min).
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pone-0071884-g001: A schematic diagram of the three chamber system used to study mosquito behavior.Each chamber was 30.5 cm×30.5 cm×30.5 cm (28.4 L) with a 10 cm hole cut into a removable acrylic lid. A: lab air supply (5 L/min) measured with a rotameter, B: metal treatment chamber, C: acrylic mosquito introduction chamber, D: metal control chamber, E: closable funnels opened during exposures studies to allow mosquitoes, air flow, and airborne chemical to move between the chambers, F: vacuum exhaust (10 L/min).

Mentions: A three-chamber mosquito behavior assay system was used for laboratory evaluations (Fig. 1) [21]. The three chambers represented: treatment (containing DDT-treated textile); central (point of mosquito introduction); and control (containing DDT-free fabric). Each chamber was a 28.4 L cube with a 10 cm hole cut into a removable clear acrylic lid. The treatment and control chambers were constructed from metal with acrylic lids and were fitted with beveled funnels that allow passage of mosquitoes originating from the central chamber during tests. The central chamber was made entirely of clear acrylic.


Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems.

Martin NJ, Smith PA, Achee NL, DeLong GT - PLoS ONE (2013)

A schematic diagram of the three chamber system used to study mosquito behavior.Each chamber was 30.5 cm×30.5 cm×30.5 cm (28.4 L) with a 10 cm hole cut into a removable acrylic lid. A: lab air supply (5 L/min) measured with a rotameter, B: metal treatment chamber, C: acrylic mosquito introduction chamber, D: metal control chamber, E: closable funnels opened during exposures studies to allow mosquitoes, air flow, and airborne chemical to move between the chambers, F: vacuum exhaust (10 L/min).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756037&req=5

pone-0071884-g001: A schematic diagram of the three chamber system used to study mosquito behavior.Each chamber was 30.5 cm×30.5 cm×30.5 cm (28.4 L) with a 10 cm hole cut into a removable acrylic lid. A: lab air supply (5 L/min) measured with a rotameter, B: metal treatment chamber, C: acrylic mosquito introduction chamber, D: metal control chamber, E: closable funnels opened during exposures studies to allow mosquitoes, air flow, and airborne chemical to move between the chambers, F: vacuum exhaust (10 L/min).
Mentions: A three-chamber mosquito behavior assay system was used for laboratory evaluations (Fig. 1) [21]. The three chambers represented: treatment (containing DDT-treated textile); central (point of mosquito introduction); and control (containing DDT-free fabric). Each chamber was a 28.4 L cube with a 10 cm hole cut into a removable clear acrylic lid. The treatment and control chambers were constructed from metal with acrylic lids and were fitted with beveled funnels that allow passage of mosquitoes originating from the central chamber during tests. The central chamber was made entirely of clear acrylic.

Bottom Line: Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI.The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3) (n = 17; SD = 0.45) and 1.42 µg/m(3) (n = 30; SD = 0.96).The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency.

View Article: PubMed Central - PubMed

Affiliation: Viral and Rickettsial Diseases Department, U. S. Naval Medical Research Center, Silver Spring, Maryland, United States of America ; Preventive Medicine and Biometrics Department, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America.

ABSTRACT

Background: Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR). Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI) in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions.

Methodology/principal findings: A thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS) method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT) in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3) (n = 17; SD = 0.45) and 1.42 µg/m(3) (n = 30; SD = 0.96).

Conclusions/significance: The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h) SR concentrations in small volume (<100 L) samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.

Show MeSH
Related in: MedlinePlus