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Sugar-fermenting yeast as an organic source of carbon dioxide to attract the malaria mosquito Anopheles gambiae.

Smallegange RC, Schmied WH, van Roey KJ, Verhulst NO, Spitzen J, Mukabana WR, Takken W - Malar. J. (2010)

Bottom Line: Carbon dioxide (CO2) plays an important role in the host-seeking process of opportunistic, zoophilic and anthropophilic mosquito species and is, therefore, commonly added to mosquito sampling tools.The laboratory and semi-field data were analysed by a χ2-test, the field data by GLM.In addition, CO2 concentrations produced by yeast-sugar solutions were measured over time.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Entomology, Wageningen University, P,O, Box 8031, 6700 EH, Wageningen, The Netherlands. renate.smallegange@wur.nl

ABSTRACT

Background: Carbon dioxide (CO2) plays an important role in the host-seeking process of opportunistic, zoophilic and anthropophilic mosquito species and is, therefore, commonly added to mosquito sampling tools. The African malaria vector Anopheles gambiae sensu stricto is attracted to human volatiles augmented by CO2. This study investigated whether CO2, usually supplied from gas cylinders acquired from commercial industry, could be replaced by CO2 derived from fermenting yeast (yeast-produced CO2).

Methods: Trapping experiments were conducted in the laboratory, semi-field and field, with An. gambiae s.s. as the target species. MM-X traps were baited with volatiles produced by mixtures of yeast, sugar and water, prepared in 1.5, 5 or 25 L bottles. Catches were compared with traps baited with industrial CO2. The additional effect of human odours was also examined. In the laboratory and semi-field facility dual-choice experiments were conducted. The effect of traps baited with yeast-produced CO2 on the number of mosquitoes entering an African house was studied in the MalariaSphere. Carbon dioxide baited traps, placed outside human dwellings, were also tested in an African village setting. The laboratory and semi-field data were analysed by a χ2-test, the field data by GLM. In addition, CO2 concentrations produced by yeast-sugar solutions were measured over time.

Results: Traps baited with yeast-produced CO2 caught significantly more mosquitoes than unbaited traps (up to 34 h post mixing the ingredients) and also significantly more than traps baited with industrial CO2, both in the laboratory and semi-field. Adding yeast-produced CO2 to traps baited with human odour significantly increased trap catches. In the MalariaSphere, outdoor traps baited with yeast-produced or industrial CO2 + human odour reduced house entry of mosquitoes with a human host sleeping under a bed net indoors. Anopheles gambiae s.s. was not caught during the field trials. However, traps baited with yeast-produced CO2 caught similar numbers of Anopheles arabiensis as traps baited with industrial CO2. Addition of human odour increased trap catches.

Conclusions: Yeast-produced CO2 can effectively replace industrial CO2 for sampling of An. gambiae s.s.. This will significantly reduce costs and allow sustainable mass-application of odour-baited devices for mosquito sampling in remote areas.

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Pictures showing the different setups used to apply the yeast-sugar solutions and to measure the CO2 production. A. Two 1.5 L bottles; B. One 25 L container; C. Two 5 L bottles; D. CO2 production measurement.
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Figure 1: Pictures showing the different setups used to apply the yeast-sugar solutions and to measure the CO2 production. A. Two 1.5 L bottles; B. One 25 L container; C. Two 5 L bottles; D. CO2 production measurement.

Mentions: Yeast-produced carbon dioxide was produced by mixing dry yeast (Dr. Oetker, The Netherlands, used in the laboratory experiments carried out in Wageningen or Angel Yeast Co. Ltd., China, used in the semi-field and field experiments in Kenya), sugar (Van Gilse Kristalsuiker, Suiker Unie, The Netherlands, in the laboratory experiments or Sony Sugar, South Nyanza sugar Co. Ltd., Kenya, in the (semi-)field experiments) and tap water [16] in two plastic bottles of 1.5 L or 5 L, connected with each other by silicon tubing, or one plastic container of 25 L. Mixing took place 1-1½ h before mosquitoes were released, at ambient temperature, until the dry yeast was dissolved. No additional stirring or mixing took place during the experiments. A 0.5 L respectively 1 L bottle was put in between the 1.5 L respectively 5 L bottles with the mixtures and the MM-X trap to prevent foam produced by the mixtures entering the trap (Figure 1A-C). Holes were drilled into the original screw caps of the bottles and into the side of the small bottles; silicon tubing (Ø 7 mm; Rubber B.V., The Netherlands) fitted through these holes to connect the bottles. The smaller bottle was connected to the MM-X trap using the original MM-X tubing (micron filter and orifice removed) and the Luer connection at the underside of the trap's top lid. The connections were sealed by Teflon tape and held under water to check for leakage. Several combinations of bottle size and amount of yeast, sugar and water were used. The carbon dioxide output was estimated by measuring the volume of water displaced from a submerged measuring cylinder (Table 1). For this purpose, the tubing that was attached to the MM-X traps during the mosquito trapping experiments was now led into a measuring cylinder which was held in a bucket of water (Figure 1D).


Sugar-fermenting yeast as an organic source of carbon dioxide to attract the malaria mosquito Anopheles gambiae.

Smallegange RC, Schmied WH, van Roey KJ, Verhulst NO, Spitzen J, Mukabana WR, Takken W - Malar. J. (2010)

Pictures showing the different setups used to apply the yeast-sugar solutions and to measure the CO2 production. A. Two 1.5 L bottles; B. One 25 L container; C. Two 5 L bottles; D. CO2 production measurement.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2984570&req=5

Figure 1: Pictures showing the different setups used to apply the yeast-sugar solutions and to measure the CO2 production. A. Two 1.5 L bottles; B. One 25 L container; C. Two 5 L bottles; D. CO2 production measurement.
Mentions: Yeast-produced carbon dioxide was produced by mixing dry yeast (Dr. Oetker, The Netherlands, used in the laboratory experiments carried out in Wageningen or Angel Yeast Co. Ltd., China, used in the semi-field and field experiments in Kenya), sugar (Van Gilse Kristalsuiker, Suiker Unie, The Netherlands, in the laboratory experiments or Sony Sugar, South Nyanza sugar Co. Ltd., Kenya, in the (semi-)field experiments) and tap water [16] in two plastic bottles of 1.5 L or 5 L, connected with each other by silicon tubing, or one plastic container of 25 L. Mixing took place 1-1½ h before mosquitoes were released, at ambient temperature, until the dry yeast was dissolved. No additional stirring or mixing took place during the experiments. A 0.5 L respectively 1 L bottle was put in between the 1.5 L respectively 5 L bottles with the mixtures and the MM-X trap to prevent foam produced by the mixtures entering the trap (Figure 1A-C). Holes were drilled into the original screw caps of the bottles and into the side of the small bottles; silicon tubing (Ø 7 mm; Rubber B.V., The Netherlands) fitted through these holes to connect the bottles. The smaller bottle was connected to the MM-X trap using the original MM-X tubing (micron filter and orifice removed) and the Luer connection at the underside of the trap's top lid. The connections were sealed by Teflon tape and held under water to check for leakage. Several combinations of bottle size and amount of yeast, sugar and water were used. The carbon dioxide output was estimated by measuring the volume of water displaced from a submerged measuring cylinder (Table 1). For this purpose, the tubing that was attached to the MM-X traps during the mosquito trapping experiments was now led into a measuring cylinder which was held in a bucket of water (Figure 1D).

Bottom Line: Carbon dioxide (CO2) plays an important role in the host-seeking process of opportunistic, zoophilic and anthropophilic mosquito species and is, therefore, commonly added to mosquito sampling tools.The laboratory and semi-field data were analysed by a χ2-test, the field data by GLM.In addition, CO2 concentrations produced by yeast-sugar solutions were measured over time.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Entomology, Wageningen University, P,O, Box 8031, 6700 EH, Wageningen, The Netherlands. renate.smallegange@wur.nl

ABSTRACT

Background: Carbon dioxide (CO2) plays an important role in the host-seeking process of opportunistic, zoophilic and anthropophilic mosquito species and is, therefore, commonly added to mosquito sampling tools. The African malaria vector Anopheles gambiae sensu stricto is attracted to human volatiles augmented by CO2. This study investigated whether CO2, usually supplied from gas cylinders acquired from commercial industry, could be replaced by CO2 derived from fermenting yeast (yeast-produced CO2).

Methods: Trapping experiments were conducted in the laboratory, semi-field and field, with An. gambiae s.s. as the target species. MM-X traps were baited with volatiles produced by mixtures of yeast, sugar and water, prepared in 1.5, 5 or 25 L bottles. Catches were compared with traps baited with industrial CO2. The additional effect of human odours was also examined. In the laboratory and semi-field facility dual-choice experiments were conducted. The effect of traps baited with yeast-produced CO2 on the number of mosquitoes entering an African house was studied in the MalariaSphere. Carbon dioxide baited traps, placed outside human dwellings, were also tested in an African village setting. The laboratory and semi-field data were analysed by a χ2-test, the field data by GLM. In addition, CO2 concentrations produced by yeast-sugar solutions were measured over time.

Results: Traps baited with yeast-produced CO2 caught significantly more mosquitoes than unbaited traps (up to 34 h post mixing the ingredients) and also significantly more than traps baited with industrial CO2, both in the laboratory and semi-field. Adding yeast-produced CO2 to traps baited with human odour significantly increased trap catches. In the MalariaSphere, outdoor traps baited with yeast-produced or industrial CO2 + human odour reduced house entry of mosquitoes with a human host sleeping under a bed net indoors. Anopheles gambiae s.s. was not caught during the field trials. However, traps baited with yeast-produced CO2 caught similar numbers of Anopheles arabiensis as traps baited with industrial CO2. Addition of human odour increased trap catches.

Conclusions: Yeast-produced CO2 can effectively replace industrial CO2 for sampling of An. gambiae s.s.. This will significantly reduce costs and allow sustainable mass-application of odour-baited devices for mosquito sampling in remote areas.

Show MeSH
Related in: MedlinePlus