title: Clustering of host-seeking activity of Anopheles gambiae mosquitoes at the top surface of a human-baited bed net.
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.
  
  
  CONCLUSIONS
  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.
authors.forename: Amy
authors.initials: A
authors.lastname: Lynd
authors.forename: Philip J
authors.initials: PJ
authors.lastname: McCall
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology; D008954:Models, Biological; D011722:Pyrethrins / Q000494:pharmacology; D013037:Spatial Behavior / Q000187:drug effects / Q000502:physiology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins
references.citation: PLoS Negl Trop Dis. 2011 Aug;5(8):e1226
references.pmid: 21829734
references.citation: Malar J. 2005 May 26;4:25
references.pmid: 15918909
references.citation: Trends Parasitol. 2011 Apr;27(4):143-8
references.pmid: 21256083
references.citation: Bull Entomol Res. 2003 Dec;93(6):491-8
references.pmid: 14704095
references.citation: Int J Epidemiol. 2013 Feb;42(1):235-47
references.pmid: 23396849
references.citation: Malar J. 2010 Jan 19;9:21
references.pmid: 20085631
references.citation: PLoS Med. 2007 Jul;4(7):e229
references.pmid: 17608562
references.citation: Trans R Soc Trop Med Hyg. 2010 Dec;104(12):758-65
references.pmid: 20956008
references.citation: Trends Parasitol. 2011 Feb;27(2):91-8
references.pmid: 20843745
references.citation: Nature. 2012 May 15;485(7398):293
references.pmid: 22596131
references.citation: Malar J. 2013 Feb 07;12:56
references.pmid: 23388506
references.citation: Med Vet Entomol. 2001 Mar;15(1):105-12
references.pmid: 11297094
references.citation: Med Vet Entomol. 2011 Sep;25(3):247-55
references.pmid: 21108650
references.citation: Emerg Infect Dis. 2012 Sep;18(9):1508-11
references.pmid: 22932478
references.citation: Emerg Infect Dis. 2012 Jul;18(7):1101-6
references.pmid: 22709930
references.citation: Cochrane Database Syst Rev. 2004;(2):CD000363
references.pmid: 15106149
references.citation: PLoS One. 2012;7(9):e44986
references.pmid: 23028724
references.citation: Experientia. 1995 Jan 15;51(1):80-4
references.pmid: 7843335
references.citation: PLoS Med. 2011 Jan 25;8(1):e1000401
references.pmid: 21311587
references.citation: Malar J. 2004 Jan 29;3(1):1
references.pmid: 14748930
references.citation: Emerg Infect Dis. 2008 Nov;14(11):1707-14
references.pmid: 18976553
references.citation: J Am Mosq Control Assoc. 1994 Jun;10(2 Pt 2):258-65
references.pmid: 8965077