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Clustering of host-seeking activity of Anopheles gambiae mosquitoes at the top surface of a human-baited bed net.

Lynd A, McCall PJ - Malar. J. (2013)

Bottom Line: To confirm sticky-net reliability, the experiment was repeated using a pitched sticky-net (tilted sides converging at apex, i.e., neither horizontal nor vertical).Capture rates at horizontal and vertical surfaces were not significantly different and the sticky-net was not repellent.The results provide support for the two-in-one bed net design for managing pyrethroid-resistant vector populations.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Knowledge of the interactions between mosquitoes and humans, and how vector control interventions affect them, is sparse. A study exploring host-seeking behaviour at a human-occupied bed net, a key event in such interactions, is reported here.

Methods: Host-seeking female Anopheles gambiae activity was studied using a human-baited 'sticky-net' (a bed net without insecticide, coated with non-setting adhesive) to trap mosquitoes. The numbers and distribution of mosquitoes captured on each surface of the bed net were recorded and analysed using non-parametric statistical methods and random effects regression analysis. To confirm sticky-net reliability, the experiment was repeated using a pitched sticky-net (tilted sides converging at apex, i.e., neither horizontal nor vertical). The capture efficiency of horizontal and vertical sticky surfaces were compared, and the potential repellency of the adhesive was investigated.

Results: In a semi-field experiment, more mosquitoes were caught on the top (74-87%) than on the sides of the net (p < 0.001). In laboratory experiments, more mosquitoes were caught on the top than on the sides in human-baited tests (p < 0.001), significantly different to unbaited controls (p < 0.001) where most mosquitoes were on the sides (p = 0.047). In both experiments, approximately 70% of mosquitoes captured on the top surface were clustered within a 90 × 90 cm (or lesser) area directly above the head and chest (p < 0.001). In pitched net tests, similar clustering occurred over the sleeper's head and chest in baited tests only (p < 0.001). Capture rates at horizontal and vertical surfaces were not significantly different and the sticky-net was not repellent.

Conclusion: This study demonstrated that An. gambiae activity occurs predominantly within a limited area of the top surface of bed nets. The results provide support for the two-in-one bed net design for managing pyrethroid-resistant vector populations. Further exploration of vector behaviour at the bed net interface could contribute to additional improvements in insecticide-treated bed net design or the development of novel vector control tools.

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Related in: MedlinePlus

Results from semi-field tests with a human-baited sticky-net. The percentage of An. gambiae caught on each surface of the net (expressed as a percentage of total mosquitoes caught by the net) for all three experiments. The difference between the numbers on the top net surface and the other sides was significant in all three experiments (χ2 =101.5, 104.7, 268.0 in trials 1, 2 and 3 respectively; p < 0.001).
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Figure 3: Results from semi-field tests with a human-baited sticky-net. The percentage of An. gambiae caught on each surface of the net (expressed as a percentage of total mosquitoes caught by the net) for all three experiments. The difference between the numbers on the top net surface and the other sides was significant in all three experiments (χ2 =101.5, 104.7, 268.0 in trials 1, 2 and 3 respectively; p < 0.001).

Mentions: In three trials, 81% of all An. gambiae released were caught by the sticky-net. A significantly higher proportion of mosquitoes were caught on the top surface of the net after adjustment for area (74, 76, 87%, respectively in each trial) than on the sides (χ2 =101.5, 104.7, 268.0, respectively; p < 0.001) (Figure 3). Examination of the exact location of each mosquito captured on the top surface of the net (Figure 4) showed that nearly 70% of the mosquitoes caught on this surface were within a 90 × 90 cm area over the head and chest, a distribution pattern that was highly significant (χ2 = 119.1, 99.3, 164.5 for each experiment respectively; p < 0.001).


Clustering of host-seeking activity of Anopheles gambiae mosquitoes at the top surface of a human-baited bed net.

Lynd A, McCall PJ - Malar. J. (2013)

Results from semi-field tests with a human-baited sticky-net. The percentage of An. gambiae caught on each surface of the net (expressed as a percentage of total mosquitoes caught by the net) for all three experiments. The difference between the numbers on the top net surface and the other sides was significant in all three experiments (χ2 =101.5, 104.7, 268.0 in trials 1, 2 and 3 respectively; p < 0.001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3733746&req=5

Figure 3: Results from semi-field tests with a human-baited sticky-net. The percentage of An. gambiae caught on each surface of the net (expressed as a percentage of total mosquitoes caught by the net) for all three experiments. The difference between the numbers on the top net surface and the other sides was significant in all three experiments (χ2 =101.5, 104.7, 268.0 in trials 1, 2 and 3 respectively; p < 0.001).
Mentions: In three trials, 81% of all An. gambiae released were caught by the sticky-net. A significantly higher proportion of mosquitoes were caught on the top surface of the net after adjustment for area (74, 76, 87%, respectively in each trial) than on the sides (χ2 =101.5, 104.7, 268.0, respectively; p < 0.001) (Figure 3). Examination of the exact location of each mosquito captured on the top surface of the net (Figure 4) showed that nearly 70% of the mosquitoes caught on this surface were within a 90 × 90 cm area over the head and chest, a distribution pattern that was highly significant (χ2 = 119.1, 99.3, 164.5 for each experiment respectively; p < 0.001).

Bottom Line: To confirm sticky-net reliability, the experiment was repeated using a pitched sticky-net (tilted sides converging at apex, i.e., neither horizontal nor vertical).Capture rates at horizontal and vertical surfaces were not significantly different and the sticky-net was not repellent.The results provide support for the two-in-one bed net design for managing pyrethroid-resistant vector populations.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: Knowledge of the interactions between mosquitoes and humans, and how vector control interventions affect them, is sparse. A study exploring host-seeking behaviour at a human-occupied bed net, a key event in such interactions, is reported here.

Methods: Host-seeking female Anopheles gambiae activity was studied using a human-baited 'sticky-net' (a bed net without insecticide, coated with non-setting adhesive) to trap mosquitoes. The numbers and distribution of mosquitoes captured on each surface of the bed net were recorded and analysed using non-parametric statistical methods and random effects regression analysis. To confirm sticky-net reliability, the experiment was repeated using a pitched sticky-net (tilted sides converging at apex, i.e., neither horizontal nor vertical). The capture efficiency of horizontal and vertical sticky surfaces were compared, and the potential repellency of the adhesive was investigated.

Results: In a semi-field experiment, more mosquitoes were caught on the top (74-87%) than on the sides of the net (p < 0.001). In laboratory experiments, more mosquitoes were caught on the top than on the sides in human-baited tests (p < 0.001), significantly different to unbaited controls (p < 0.001) where most mosquitoes were on the sides (p = 0.047). In both experiments, approximately 70% of mosquitoes captured on the top surface were clustered within a 90 × 90 cm (or lesser) area directly above the head and chest (p < 0.001). In pitched net tests, similar clustering occurred over the sleeper's head and chest in baited tests only (p < 0.001). Capture rates at horizontal and vertical surfaces were not significantly different and the sticky-net was not repellent.

Conclusion: This study demonstrated that An. gambiae activity occurs predominantly within a limited area of the top surface of bed nets. The results provide support for the two-in-one bed net design for managing pyrethroid-resistant vector populations. Further exploration of vector behaviour at the bed net interface could contribute to additional improvements in insecticide-treated bed net design or the development of novel vector control tools.

Show MeSH
Related in: MedlinePlus