title: Nightly biting cycles of malaria vectors in a heterogeneous transmission area of eastern Amazonian Brazil.
abstract: BACKGROUND
  The biting cycle of anopheline mosquitoes is an important component in the transmission of malaria. Inter- and intraspecific biting patterns of anophelines have been investigated using the number of mosquitoes caught over time to compare general tendencies in host-seeking activity and cumulative catch. In this study, all-night biting catch data from 32 consecutive months of collections in three riverine villages were used to compare biting cycles of the five most abundant vector species using common statistics to quantify variability and deviations of nightly catches from a normal distribution.
  
  
  METHODS
  Three communities were selected for study. All-night human landing catches of mosquitoes were made each month in the peridomestic environment of four houses (sites) for nine consecutive days from April 2003 to November 2005. Host-seeking activities of the five most abundant species that were previously captured infected with Plasmodium falciparum, Plasmodium malariae or Plasmodium vivax, were analysed and compared by measuring the amount of variation in numbers biting per unit time (co-efficient of variation, V), the degree to which the numbers of individuals per unit time were asymmetrical (skewness = g1) and the relative peakedness or flatness of the distribution (kurtosis = g2). To analyse variation in V, g1, and g2 within species and villages, we used mixed model nested ANOVAs (PROC GLM in SAS) with independent variables (sources of variation): year, month (year), night (year X month) and collection site (year X month).
  
  
  RESULTS
  The biting cycles of the most abundant species, Anopheles darlingi, had the least pronounced biting peaks, the lowest mean V values, and typically non-significant departures from normality in g1 and g2. By contrast, the species with the most sharply defined crepuscular biting peaks, Anopheles marajoara, Anopheles nuneztovari and Anopheles triannulatus, showed high to moderate mean V values and, most commonly, significantly positive skewness (g1) and kurtosis (g2) moments. Anopheles intermedius was usually, but not always, crepuscular in host seeking, and showed moderate mean V values and typically positive skewness and kurtosis. Among sites within villages, significant differences in frequencies of departures from normality (g1 and g2) were detected for An. marajoara and An. darlingi, suggesting that local environments, such as host availability, may affect the shape of biting pattern curves of these two species.
  
  
  CONCLUSIONS
  Analyses of co-efficients of variation, skewness and kurtosis facilitated quantitative comparisons of host-seeking activity patterns that differ among species, sites, villages, and dates. The variable and heterogeneous nightly host-seeking behaviours of the five exophilic vector species contribute to the maintenance of stable malaria transmission in these Amazonian villages. The abundances of An. darlingi and An. marajoara, their propensities to seek hosts throughout the night, and their ability to adapt host-seeking behaviour to local environments, contribute to their impact as the most important of these vector species.
authors.affiliation: Florida Medical Entomology Laboratory, University of Florida/IFAS, Vero Beach, Florida, USA. rhzimmer@hotmail.com.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Zimmerman
authors.forename: L Philip
authors.initials: LP
authors.lastname: Lounibos
authors.forename: Naoya
authors.initials: N
authors.lastname: Nishimura
authors.forename: Allan K R
authors.initials: AK
authors.lastname: Galardo
authors.forename: Clicia D
authors.initials: CD
authors.lastname: Galardo
authors.forename: Mercia E
authors.initials: ME
authors.lastname: Arruda
mesh_terms: D000818:Animals; D000852:Anopheles / Q000145:classification / Q000502:physiology*; D001938:Brazil; D005247:Feeding Behavior; D005843:Geography; D006801:Humans; D008288:Malaria / Q000635:transmission; D012621:Seasons; D013997:Time Factors
references.citation: Rev Saude Publica. 2002 Feb;36(1):75-80
references.pmid: 11887233
references.citation: Rev Saude Publica. 1997 Feb;31(1):9-14
references.pmid: 9430921
references.citation: Am J Trop Med Hyg. 1972 Sep;21(5):634-9
references.pmid: 5074686
references.citation: Am J Trop Med Hyg. 2012 Apr;86(4):649-55
references.pmid: 22492150
references.citation: Rev Panam Salud Publica. 1997 Jul;2(1):18-25
references.pmid: 9309945
references.citation: Bull World Health Organ. 1956;15(3-5):461-71
references.pmid: 13404433
references.citation: Med Vet Entomol. 2009 Dec;23(4):335-49
references.pmid: 19941599
references.citation: Mem Inst Oswaldo Cruz. 1996 Jul-Aug;91(4):391-8
references.pmid: 9070397
references.citation: Am J Trop Med Hyg. 2007 Mar;76(3):461-9
references.pmid: 17360868
references.citation: Mem Inst Oswaldo Cruz. 1992;87 Suppl 3:371-83
references.pmid: 1343717
references.citation: J Am Mosq Control Assoc. 1987 Sep;3(3):433-41
references.pmid: 3504928
references.citation: Mem Inst Oswaldo Cruz. 2007 Jun;102(3):303-11
references.pmid: 17568935
references.citation: Rev Saude Publica. 1987 Aug;21(4):291-304
references.pmid: 3445112
references.citation: Am J Trop Med Hyg. 1972 Sep;21(5):755-63
references.pmid: 4561523
references.citation: J Med Entomol. 2006 Sep;43(5):947-56
references.pmid: 17017232
references.citation: Am J Trop Med Hyg. 2002 Jan;66(1):18-22
references.pmid: 12135261
references.citation: Bull World Health Organ. 1968;38(2):239-53
references.pmid: 5302300
references.citation: Acta Trop. 2012 Mar;121(3):281-91
references.pmid: 22015425
references.citation: Med Vet Entomol. 1992 Oct;6(4):325-34
references.pmid: 1463897