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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

Study design. a, b Within each semi-field compartment, a human volunteer sat between the two MLBs at a distance of 5 m from each. The volunteer exposed his lower legs to the mosquito bites and was provided with a protective net to avoid mosquito bites elsewhere on the body, a torch to catch the mosquito in the darkness, a mouth aspirator to collect the mosquito and four paper cups for mosquito collection during the 4 h of the experiment. c Schematic of the study design. The two compartments in the SFS are located side by side. Fifteen mosquitoes were released from each of four cages (total of 60 mosquitoes) located behind the MLBs. Four plastic strings connected the chair to the cages to allow the volunteer to open the cages remotely. Each night, either treatment or control were dispersed by the two MLBs in each semi-field compartment.
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Fig3: Study design. a, b Within each semi-field compartment, a human volunteer sat between the two MLBs at a distance of 5 m from each. The volunteer exposed his lower legs to the mosquito bites and was provided with a protective net to avoid mosquito bites elsewhere on the body, a torch to catch the mosquito in the darkness, a mouth aspirator to collect the mosquito and four paper cups for mosquito collection during the 4 h of the experiment. c Schematic of the study design. The two compartments in the SFS are located side by side. Fifteen mosquitoes were released from each of four cages (total of 60 mosquitoes) located behind the MLBs. Four plastic strings connected the chair to the cages to allow the volunteer to open the cages remotely. Each night, either treatment or control were dispersed by the two MLBs in each semi-field compartment.

Mentions: A fully randomized, cross-over design was used, with either treatment (transfluthrin-impregnated polyester strips) or control (ethanol-soaked polyester strips) assigned to one of the two SFS compartments. Two MLBs were used in each SFS compartment to create a protective ‘bubble effect’ around the human volunteers [37], who sat in the middle area, 5 m equidistant from each of the MLBs, which were located 10 m apart. Fifteen mosquitoes were released from each of four cages located 3 m behind and laterally from the MLBs (60 mosquitoes, total) (Figure 3).Figure 3


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)

Study design. a, b Within each semi-field compartment, a human volunteer sat between the two MLBs at a distance of 5 m from each. The volunteer exposed his lower legs to the mosquito bites and was provided with a protective net to avoid mosquito bites elsewhere on the body, a torch to catch the mosquito in the darkness, a mouth aspirator to collect the mosquito and four paper cups for mosquito collection during the 4 h of the experiment. c Schematic of the study design. The two compartments in the SFS are located side by side. Fifteen mosquitoes were released from each of four cages (total of 60 mosquitoes) located behind the MLBs. Four plastic strings connected the chair to the cages to allow the volunteer to open the cages remotely. Each night, either treatment or control were dispersed by the two MLBs in each semi-field compartment.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Study design. a, b Within each semi-field compartment, a human volunteer sat between the two MLBs at a distance of 5 m from each. The volunteer exposed his lower legs to the mosquito bites and was provided with a protective net to avoid mosquito bites elsewhere on the body, a torch to catch the mosquito in the darkness, a mouth aspirator to collect the mosquito and four paper cups for mosquito collection during the 4 h of the experiment. c Schematic of the study design. The two compartments in the SFS are located side by side. Fifteen mosquitoes were released from each of four cages (total of 60 mosquitoes) located behind the MLBs. Four plastic strings connected the chair to the cages to allow the volunteer to open the cages remotely. Each night, either treatment or control were dispersed by the two MLBs in each semi-field compartment.
Mentions: A fully randomized, cross-over design was used, with either treatment (transfluthrin-impregnated polyester strips) or control (ethanol-soaked polyester strips) assigned to one of the two SFS compartments. Two MLBs were used in each SFS compartment to create a protective ‘bubble effect’ around the human volunteers [37], who sat in the middle area, 5 m equidistant from each of the MLBs, which were located 10 m apart. Fifteen mosquitoes were released from each of four cages located 3 m behind and laterally from the MLBs (60 mosquitoes, total) (Figure 3).Figure 3

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