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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 and mortality of Anopheles gambiae s.s. mosquitoes after exposure to transfluthrin-impregnated strips of different ages using the closed cylinder method. a Kaplan–Meier survival estimates of An. gambiaes.s. knock-down test during 15 min for strips of different age. Gray areas show the estimated 95% CI. b Assessment of 24-h An. gambiae s.s. mortality caused by the polyester strips of different ages after exposure to the knock-down test. Graph showing mean and 95% CI.
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Fig6: Knock-down and mortality of Anopheles gambiae s.s. mosquitoes after exposure to transfluthrin-impregnated strips of different ages using the closed cylinder method. a Kaplan–Meier survival estimates of An. gambiaes.s. knock-down test during 15 min for strips of different age. Gray areas show the estimated 95% CI. b Assessment of 24-h An. gambiae s.s. mortality caused by the polyester strips of different ages after exposure to the knock-down test. Graph showing mean and 95% CI.

Mentions: Transfluthrin-impregnated strips continued to knock-down mosquitoes up to 3 weeks after being impregnated (Figure 6a), although the time for knock-down of 50% of the mosquitoes (KD50)—as estimated from a Kaplan–Meier survival curve fitted to the data—increased with the age of the strips (Table 3). Twenty-four hours after being impregnated, the KD50 of the strips was 2 min (IQR 1–2 min). The KD50 increased to 7 min (IQR 5–10 min) 3 weeks after the impregnation.Figure 6


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 and mortality of Anopheles gambiae s.s. mosquitoes after exposure to transfluthrin-impregnated strips of different ages using the closed cylinder method. a Kaplan–Meier survival estimates of An. gambiaes.s. knock-down test during 15 min for strips of different age. Gray areas show the estimated 95% CI. b Assessment of 24-h An. gambiae s.s. mortality caused by the polyester strips of different ages after exposure to the knock-down test. Graph showing mean and 95% CI.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig6: Knock-down and mortality of Anopheles gambiae s.s. mosquitoes after exposure to transfluthrin-impregnated strips of different ages using the closed cylinder method. a Kaplan–Meier survival estimates of An. gambiaes.s. knock-down test during 15 min for strips of different age. Gray areas show the estimated 95% CI. b Assessment of 24-h An. gambiae s.s. mortality caused by the polyester strips of different ages after exposure to the knock-down test. Graph showing mean and 95% CI.
Mentions: Transfluthrin-impregnated strips continued to knock-down mosquitoes up to 3 weeks after being impregnated (Figure 6a), although the time for knock-down of 50% of the mosquitoes (KD50)—as estimated from a Kaplan–Meier survival curve fitted to the data—increased with the age of the strips (Table 3). Twenty-four hours after being impregnated, the KD50 of the strips was 2 min (IQR 1–2 min). The KD50 increased to 7 min (IQR 5–10 min) 3 weeks after the impregnation.Figure 6

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