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Modified mosquito landing boxes dispensing transfluthrin provide effective protection against Anopheles arabiensis mosquitoes under simulated outdoor conditions in a semi-field system.

Andrés M, Lorenz LM, Mbeleya E, Moore SJ - Malar. J. (2015)

Bottom Line: Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs.A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions.Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect diminished with time.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular Neurobiology, University of Göttingen, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany. martaandresm@gmail.com.

ABSTRACT

Background: Efforts to control malaria vectors have primarily focused on scaling-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying. Although highly efficient against indoor-biting and indoor-resting vectors, these interventions have lower impact on outdoor-biting mosquitoes. Innovative vector control tools are required to prevent outdoor human-mosquito contacts. In this work, the potential of spatial repellents, delivered in an active system that requires minimal user compliance, to provide personal protection against exophagic mosquitoes active in the early evening was explored.

Methods: A device previously used as an odour-baited lure and kill apparatus, the mosquito landing box (MLB), was modified to dispense the volatile synthetic pyrethroid, transfluthrin, as a spatial repellent. The MLB has an active odour-dispensing mechanism that uses a solar-powered fan and switches on at dusk to provide long duration dispensing of volatile compounds without the need for the user to remember to employ it. Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs. Transfluthrin was emanated from polyester strips, hanging inside the MLB odour-dispensing unit. A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions. The knock-down capacity of the transfluthrin-treated strips was also evaluated at different time points up to 3 weeks after being impregnated to measure duration of efficacy.

Results: The protective transfluthrin bubble provided 68.9% protection against An. arabiensis bites under these simulated outdoor conditions. Volatile transfluthrin caused low mortality among mosquitoes in the semi-field system. Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect diminished with time.

Conclusion: Modified MLBs can be used as efficient and long-lasting dispensers of volatile spatial repellents such as transfluthrin, thereby providing high levels of protection against outdoor-biting mosquitoes in the peri-domestic space. They have a potential role in combatting outdoor malaria transmission without interfering with effective indoor interventions such as LLINs.

No MeSH data available.


Related in: MedlinePlus

Knock-down test. a Polyester strips treated with transfluthrin were kept in half paper cups and hung from a thread to mimic the light and ventilation condition in the modified MLBs. b, d The polyester strips were placed at the bottom of the plastic bottle, and covered with a plastic mesh to avoid contact between the strips and the mosquitoes (c). e Both sides of the cylinder were closed using a net. f Example of an experiment with polyester strips treated with 90 mg transfluthrin. After a few minutes all mosquitoes were knocked down at the base.
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Fig4: Knock-down test. a Polyester strips treated with transfluthrin were kept in half paper cups and hung from a thread to mimic the light and ventilation condition in the modified MLBs. b, d The polyester strips were placed at the bottom of the plastic bottle, and covered with a plastic mesh to avoid contact between the strips and the mosquitoes (c). e Both sides of the cylinder were closed using a net. f Example of an experiment with polyester strips treated with 90 mg transfluthrin. After a few minutes all mosquitoes were knocked down at the base.

Mentions: Polyester strips are an efficient means of delivering volatile odours [41]. To test the longevity of transfluthrin on the substrate, a knock-down test was performed with strips that had been stored for varying number of days since impregnation. Polyester strips were collected after each experiment, kept in cut paper cups and hung in similar conditions to those in the MLBs, i.e., a space where wind could freely circulate but where the impregnated strips were partially protected from sun-light (Figure 4a).Figure 4


Modified mosquito landing boxes dispensing transfluthrin provide effective protection against Anopheles arabiensis mosquitoes under simulated outdoor conditions in a semi-field system.

Andrés M, Lorenz LM, Mbeleya E, Moore SJ - Malar. J. (2015)

Knock-down test. a Polyester strips treated with transfluthrin were kept in half paper cups and hung from a thread to mimic the light and ventilation condition in the modified MLBs. b, d The polyester strips were placed at the bottom of the plastic bottle, and covered with a plastic mesh to avoid contact between the strips and the mosquitoes (c). e Both sides of the cylinder were closed using a net. f Example of an experiment with polyester strips treated with 90 mg transfluthrin. After a few minutes all mosquitoes were knocked down at the base.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4477292&req=5

Fig4: Knock-down test. a Polyester strips treated with transfluthrin were kept in half paper cups and hung from a thread to mimic the light and ventilation condition in the modified MLBs. b, d The polyester strips were placed at the bottom of the plastic bottle, and covered with a plastic mesh to avoid contact between the strips and the mosquitoes (c). e Both sides of the cylinder were closed using a net. f Example of an experiment with polyester strips treated with 90 mg transfluthrin. After a few minutes all mosquitoes were knocked down at the base.
Mentions: Polyester strips are an efficient means of delivering volatile odours [41]. To test the longevity of transfluthrin on the substrate, a knock-down test was performed with strips that had been stored for varying number of days since impregnation. Polyester strips were collected after each experiment, kept in cut paper cups and hung in similar conditions to those in the MLBs, i.e., a space where wind could freely circulate but where the impregnated strips were partially protected from sun-light (Figure 4a).Figure 4

Bottom Line: Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs.A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions.Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect diminished with time.

View Article: PubMed Central - PubMed

Affiliation: Department of Cellular Neurobiology, University of Göttingen, Julia-Lermontowa-Weg 3, 37077, Göttingen, Germany. martaandresm@gmail.com.

ABSTRACT

Background: Efforts to control malaria vectors have primarily focused on scaling-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying. Although highly efficient against indoor-biting and indoor-resting vectors, these interventions have lower impact on outdoor-biting mosquitoes. Innovative vector control tools are required to prevent outdoor human-mosquito contacts. In this work, the potential of spatial repellents, delivered in an active system that requires minimal user compliance, to provide personal protection against exophagic mosquitoes active in the early evening was explored.

Methods: A device previously used as an odour-baited lure and kill apparatus, the mosquito landing box (MLB), was modified to dispense the volatile synthetic pyrethroid, transfluthrin, as a spatial repellent. The MLB has an active odour-dispensing mechanism that uses a solar-powered fan and switches on at dusk to provide long duration dispensing of volatile compounds without the need for the user to remember to employ it. Two MLBs were located 5 m from a human volunteer to investigate the repellent effects of a transfluthrin 'bubble' created between the MLBs. Transfluthrin was emanated from polyester strips, hanging inside the MLB odour-dispensing unit. A fully randomized cross-over design was performed in a large, semi-field, screened cage to assess the effect of the repellent against laboratory-reared Anopheles arabiensis mosquitoes under ambient outdoor conditions. The knock-down capacity of the transfluthrin-treated strips was also evaluated at different time points up to 3 weeks after being impregnated to measure duration of efficacy.

Results: The protective transfluthrin bubble provided 68.9% protection against An. arabiensis bites under these simulated outdoor conditions. Volatile transfluthrin caused low mortality among mosquitoes in the semi-field system. Transfluthrin-treated strips continued to knock down mosquitoes in laboratory tests, 3 weeks after impregnation, although this effect diminished with time.

Conclusion: Modified MLBs can be used as efficient and long-lasting dispensers of volatile spatial repellents such as transfluthrin, thereby providing high levels of protection against outdoor-biting mosquitoes in the peri-domestic space. They have a potential role in combatting outdoor malaria transmission without interfering with effective indoor interventions such as LLINs.

No MeSH data available.


Related in: MedlinePlus