Host-feeding preference of the mosquito, Culex quinquefasciatus, in Yucatan State, Mexico.

Abstract

Studies were conducted to determine the host-feeding preference of Culex quinquefasciatus Say (Diptera: Culicidae) in relation to the availability of human and domestic animals in the city of Merida, Yucatan State, Mexico. Mosquitoes were collected in the backyards of houses using resting wooden boxes. Collections were made five times per week from January to December 2005. DNA was extracted from engorged females and tested by PCR using universal avian- and mammalian-specific primers. DNA extracted from avian-derived blood was further analyzed by PCR using primers that differentiate among the birds of three avian orders: Passeriformes, Columbiformes and Galliformes. PCR products obtained from mammalian-derived blood were subjected to restriction enzyme digestion to differentiate between human-, dog-, cat-, pig-, and horse-derived blood meals. Overall, 82% of engorged mosquitoes had fed on birds, and 18% had fed on mammals. The most frequent vertebrate hosts were Galliformes (47.1%), Passeriformes (23.8%), Columbiformes (11.2%) birds, and dogs (8.8%). The overall human blood index was 6.7%. The overall forage ratio for humans was 0.1, indicating that humans were not a preferred host for Cx. quinquefasciatus in Merida.

Full text

Page 1

Journal of Insect Science: Vol. 10 | Article 32
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 1
Host-feeding preference of the mosquito, Culex
quinquefasciatus, in Yucatan State, Mexico
Julian E. Garcia-Rejon 1a, Bradley J. Blitvich2b, Jose A. Farfan-Ale 1c, Maria A. Loroño-Pino
1d, Wilberth A. Chi Chim 1e, Luis F. Flores-Flores 1f, Elsy Rosado-Paredes1g, Carlos Baak-
Baak 1h, Jose Perez-Mutul 3i, Victor Suarez-Solis4j, Ildefonso Fernandez-Salas5k, and Barry
J. Beaty 6l
1 Laboratorio De Arbovirología, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma
de Yucatán, Ave. Itzáes No. 490 x 59, Centro Mérida, Yucatán, México. 97000.
2 Department of Veterinary Microbiology and Preventive Medicine, Iowa State University. 2116 Veterinary Medicine
Building. Ames, Iowa, USA 50011-1250
3 Departamento de Neurociencias, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad
Autónoma de Yucatán, Ave. Itzáes No. 490 x 59, Centro Mérida, Yucatán, México. 97000.
4 Unidad Interinstitucional de Investigación Clínica y Epidemiológica. Facultad de Medicina, Universidad Autónoma
de Yucatán Av. Itzáes No. 498 x 59-A Centro Mérida, Yucatán, México. 97000.
5 Laboratorio de Entomología Médica, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, Ap.
Postal 109-F, San Nicolás de los Garza, Nuevo León, México.
6Arthropod-borne and Infectious Disease Laboratory, Department of Microbiology, Immunology and Pathology,
College of Veterinary Medicine and Biomedical Science, Colorado State University, 3185 Rampart Road, Fort
Collins, Colorado, USA. 80523-1692.
Abstract
Studies were conducted to determine the host-feeding preference of Culex quinquefasciatus Say
(Diptera: Culicidae) in relation to the availability of human and domestic animals in the city of
Merida, Yucatan State, Mexico. Mosquitoes were collected in the backyards of houses using
resting wooden boxes. Collections were made five times per week from January to December
2005. DNA was extracted from engorged females and tested by PCR using universal avian- and
mammalian-specific primers. DNA extracted from avian-derived blood was further analyzed by
PCR using primers that differentiate among the birds of three avian orders: Passeriformes,
Columbiformes and Galliformes. PCR products obtained from mammalian-derived blood were
subjected to restriction enzyme digestion to differentiate between human-, dog-, cat-, pig-, and
horse-derived blood meals. Overall, 82% of engorged mosquitoes had fed on birds, and 18% had
fed on mammals. The most frequent vertebrate hosts were Galliformes (47.1%), Passeriformes
(23.8%), Columbiformes (11.2%) birds, and dogs (8.8%). The overall human blood index was
6.7%. The overall forage ratio for humans was 0.1, indicating that humans were not a preferred
host for Cx. quinquefasciatus in Merida.

Page 2

Journal of Insect Science: Vol. 10 | Article 32
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 2
Keywords: Blood meal identification, flavivirus, human blood index, West Nile virus
Abbreviations: WNV, West Nile virus, HBI, human blood index, FR, forage ratio, HFI, host feeding index
Correspondence:agrejon@uady.mx,bblitvich@iastate.edu,cjafarfan@uady.mx,dmaria.lorono@gmail.com,
ewillynet_58@hotmail.com,ffflores@uady.mx,grparedes@uady.mx,hc_baak@hotmail.com,ipmutul@uady.mx,
jvsuarez@uady.mx,kifernand@fcb.uanl.mx
Received: 16 March 2008, Accepted: 27 August 2008
Copyright : This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits
unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Vol. 10, Number 32
Cite this paper as:
Garcia-Rejon JE, Blitvich BJ, Farfan-Ale JA, Loroño-Pino MA, Chi Chim WA. Flores-Flores LF, Rosado-Paredes E, Baak-
Baak C, Perez-Mutul J, Suarez-Solis V, Fernandez-Salas I, Beaty BJ.. 2010. Host-feeding preference of the mosquito,
Culex quinquefasciatus, in Yucatan State, Mexico. 12pp. Journal of Insect Science 10:32 available online:
insectsicence.org/10.32

Page 3

Journal of Insect Science: Vol. 10 | Article 32
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 3
Introduction
Knowledge of the blood-feeding preferences
of a mosquito species provides important
insight into the dynamics
transmission and allows vector control
authorities to design and implement efficient
strategies for vector control (Tempelis 1975;
Vinogradova 2000). The significance of Culex
quinquefasciatus Say (Diptera: Culicidae) in
the transmission of
(Flaviviridae: Flavivirus) (WNV) in Mexico
is poorly understood. However, it is well
documented that this species is a principal
vector of WNV in the United States (Turell et
al. 2005). Cx. quinquefasciatus has accounted
for more than half of the WNV-infected
mosquito pools reported
transmission seasons in the United States
(Hayes et al. 2005).
of virus
West Nile virus
during some
Cx. quinquefasciatus populations from the
United States feed readily on both birds and
mammals (Reisen and Reeves 1990; Reisen et
al 1990; Zinser et al. 2004). For instance, in
Tucson, Arizona, 50% of engorged Cx.
quinquefasciatus had fed on humans, 32% had
fed on birds, and 12% had fed on dogs (Zinser
et al. 2004). Cx. quinquefasciatus populations
in East Baton Rouge Parish, Louisiana fed
most frequently on dogs (69%), followed by
birds (16%) and humans (11%) (Niebylski
and Meek 1992). In Harris County, Texas,
52% of engorged Cx. quinquefasciatus had
fed exclusively on mammals, and 39% had
fed exclusively on birds; the remainder
contained mixed avian and mammalian blood
meals (Molaei et al. 2007). Dogs were the
most common (41%) vertebrate host followed
by mourning doves (18%) and cats (9%). Cx.
quinquefasciatus populations from the United
States are relatively efficient laboratory
vectors of WNV under laboratory conditions
(Goddard et al. 2002; Turell et al. 2005).
Taken together, these findings suggest that
Cx. quinquefasciatus serves both as an
important amplification and as a bridging
vector of WNV in the United States.
Serologic
widespread WNV activity in Mexico (Blitvich
et al. 2003; Estrada-Franco et al. 2003;
Farfan-Ale et al. 2004, 2006; Loroño et al
2003). The seroprevalence for WNV in horses
sampled in Yucatan State in 2002 was 1.2%
(Loroño et al. 2003). In a longitudinal study of
WNV infection in birds conducted in Yucatan
State from 2000 to 2003, the seroprevalence
for WNV was 0.06% (Farfan-Ale et al. 2004).
In a more recent study, 52% of horses
sampled in the neighboring state of Quintana
Roo in 2003 were seropositive for WNV
(Farfan-Ale et al. 2006). Several WNV
isolates have also been collected in Mexico.
One isolate was from a pool of Cx.
quinquefasciatus collected in northern Mexico
in 2003 (Elizondo-Quiroga et al. 2005); all
other WNV isolates were from sick or dead
vertebrates (Beasley et al 2004; Blitvich et al.
2004; Deardorff et al 2006; Elizondo-Quiroga
et al. 2005; Estrada-Franco et al. 2003). This
study was conducted to determine the host-
feeding preferences of Cx. quinquefasciatus in
an urban area of Yucatan State, Mexico
because WNV has been isolated from Cx.
quinquefasciatus in Mexico and serves as an
important ampiflying host and a bridging
vector of WNV in the United States.
evidence has demonstrated
Materials and Methods
Description of study sites
Mosquito collections were made in the city of
Merida (20° 58’ 12” N, 89° 37’ 12” W) in
Yucatan State, Mexico. Merida has a warm
and humid climate throughout the year with

Page 4

Journal of Insect Science: Vol. 10 | Article 32
an average annual temperature of 26oC (79oF)
and distinct seasons, rainy from May to
October and dry from November to April. The
average annual precipitation is 929 mm (766
mm in the rainy season, 163 mm in the dry
season). The average elevation in Merida is 10
meters. The population is approximately
750,000.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 4
Mosquito collections
Diurnal outdoor resting mosquitoes were
collected in the backyards of 40 houses. The
houses were located in a 36 square-mile area
of Merida. The houses were spaced evenly
apart; each was approximately 0.5 to 1 mile
from the closest study site. Mosquitoes were
collected from each backyard five times per
week from January 8, 2005 to December 22,
2005. Collections were made using resting
wooden boxes (0.5 m3) painted red on both
the inside and outside (Reisen and Pfunter
1987). One resting box was placed in each
backyard. Resting boxes were placed on the
ground in a sheltered position facing west to
prevent morning sunlight from entering.
Mosquitoes were removed from resting boxes
between 0600 and 0900 hours using hand-
held, battery-operated aspirators. Mosquitoes
were transported alive to the laboratory,
euthanized in a -70oC freezer, and then
identified on chill tables according to species,
sex, and blood feeding
morphological characteristics (Carpenter and
LaCasse 1955; Darsie and Ward 1981).
status using
Census of vertebrate hosts
A census was taken of humans and domestic
animals (birds and mammals) at each site.
This was done by interviewing the occupants
of each residence. If the number of vertebrate
animals at a site changed (i.e. due to death),
the site was no longer used for this study.
Sites were only used if the number and
species composition of vertebrates remained
constant during the study period. Due to
practical constraints, the numbers of free-
ranging birds temporally and spatially
associated with each study site were not
estimated. The numbers of humans and
domestic vertebrates in neighboring houses
were not counted.
Blood meal identification
Abdomens were removed from engorged
females and individually placed into 1.5 ml
eppendorf tubes. Abdomens were manually
homogenized in 600 μl of phosphate-buffered
saline (pH 7.4) using a sterile micro-pestle.
Homogenates were applied to QIAshredder
spin columns (Qiagen, www.qiagen.com) and
centrifuged (14,000 g for 3 minutes at 4oC).
DNA was extracted from supernatants using
the QIAamp DNA extraction kit following the
manufacturer’s instructions. Extracted DNA
was analyzed by PCR using universal avian-
and mammalian-specific primers that amplify
508 and 772-nt fragments, respectively, of the
mitochondrial cytochrome b gene (Ngo and
Kramer 2003; Cicero and Johnson 2001).
DNA from each avian-derived blood meal
was further examined in a single PCR reaction
using 3 pairs of order-specific primers that
differentiate among
Galliformes and Columbiformes;
primers amplify 165, 210 and 333-nt
fragments, respectively, of the mitochondrial
cytochrome b gene. PCR products derived
from mammalian blood meals were subjected
to restriction enzyme analysis using Alu I to
differentiate between human-, dog-, cat-, pig-
and horse-derived blood meals (Zehner et al
1998). The performance of the restriction
enzyme assay was validated using DNA
extracted from the blood of known vertebrate
species. Species used for the validation
experiments were: chicken (Galliformes), rock
pigeon (Columbiformes),
(Passeriformes), human, dog, cat, horse and
Passeriformes,
these
Yucatan jay

Page 5

Journal of Insect Science: Vol. 10 | Article 32
pig. Prior to the analysis of field-caught
mosquitoes, the specificity of each primer pair
was validated by PCR using DNA from the
above mentioned vertebrate species. Each
primer pair produced a PCR product of the
expected size when tested with DNA from its
intended target(s). Nucleotide sequencing
confirmed that the amplified products were
indeed mitochondrial cytochrome b DNA and
that the expected Alu I restriction enzyme
sites were present (Genbank Accession
numbers FJ160756, FJ160757, FJ160758,
FJ160759, FJ160760, FJ160761, FJ160762
and FJ160763) None of the primer pairs
generated a detectable PCR product when
tested with DNA from non-target species
(data not shown).
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 5
Data analysis
The human blood index (HBI), which is
defined as the proportion of freshly engorged
mosquitoes containing human blood, was
calculated as described by Garrett-Jones
(1964). The forage ratio (FR), which
quantifies vector selection of a particular
vertebrate host rather than other available
hosts, was also measured (Boreham and
Garrett-Jones 1973). FRs were calculated by
determining the
quinquefasciatus females containing blood of
a particular host, divided by the percent of the
total available host population represented by
that particular host (Hess et al. 1968). An FR
of 1.0 indicates neither a selective bias nor
avoidance of a particular host animal; FRs
significantly > 1.0 indicate a selective bias,
and values < 1.0 indicate avoidance of a host
in favor of other available hosts.
percent of Cx.
The host feeding index (HFI), which is
defined as the observed proportion of feeds on
one host with respect to another divided by
the expected comparative proportion of feeds
on these two hosts, was calculated using the
formula described by Richards et al. (2006).
The formula is as follows:
where Nx and Ny are the mean numbers of
blood meals taken from hosts x and y per
study site, respectively, and Ax and Ay are the
mean numbers of hosts x and y per study site,
respectively. An index of 1.0 indicates equal
feeding on the two hosts. Results < 1.0 and >
1.0 indicate a decrease
respectively, in feeding on the first host
relative to the second. HFIs were calculated
for each pair of hosts. One advantage of the
HFI versus the FR is that it does not require a
full animal census (Kay et al. 1979)
or increase,
Results and Discussion
Mosquito collections
A total of 4,644 Cx. quinquefasciatus were
captured in this study (Table 1). Of these,
1600 were female, and 3,044 were male. A
total of 658 females were classified as
engorged, 233 as gravid, and 709 did not
contain blood. Cx. quinquefasciatus were
present year-round, but they were most
abundant in August (17.4% of the total
collection was made at this time) and
November (15.7%).
Hood feeding preferences
For the blood meal identification experiments,
240 engorged females were used (20 per
month). Overall, 197 (82.1%) mosquitoes
contained avian-derived blood meals and 43
(17.9%) contained mammalian-derived blood
meals (Figure 1). The proportion of
mosquitoes containing avian-derived blood
each month ranged from 60% (May) to 100%
(December). No mosquitoes contained mixed
blood meals. Forty percent of the DNA
samples failed to yield a detectable PCR

Page 6

Journal of Insect Science: Vol. 10 | Article 32
product. By comparison, 27% of field-
collected engorged Culiseta and Anopheles
spp. mosquitoes from New York did not yield
a detectable PCR product (Ngo and Kramer
2003). Additional mosquitoes were analyzed
when PCR negative
encountered, until the monthly total of PCR
positive samples reached 20.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 6
samples were
The most frequent vertebrate hosts for Cx.
quinquefasciatus were Galliformes (47.1%),
Passeriformes (23.8%) and Columbiformes
(11.2%) (Table 2). These findings suggest that
Cx. quinquefasciatus populations in Merida
are strongly ornithophilic. The proportion of
mosquitoes that had acquired blood meals
from galliformes each month ranged from
20% (September) to 85% (March) (Figure 1).
The proportion of mosquitoes that had
acquired blood meals from passeriformes also
exhibited considerable seasonal variation, as
this avian order was fed upon more frequently
in the latter half of the year. From January to
July, the proportion of mosquitoes that had
acquired blood meals from passeriformes each
month ranged from 10% to 25% (mean:
13.6%). From August to December, the
proportion of mosquitoes that had acquired
blood meals from passeriformes each month
ranged from 30% to 45% (mean: 38.0%).
August is the beginning of the long-distance
migration season for many species of
passerine birds that migrate from the United
States to the Yucatan Peninsula of Mexico.
Thus, the increase in the number of
mosquitoes feeding on passerines in the latter
half of the year could have been due to an
increase in the relative abundance of
passerines as a consequence of long-distance
migration.
The most frequent mammalian hosts for Cx.
quinquefasciatus were dogs (8.8%) and
humans (6.7%) (Table 2). Cats, horses, and
pigs were not a common source of blood. The
Figure 1. The source of blood meals for engorged Culex quinquefasciatus captured outdoors, in the backyards of houses, each
month in Merida, Yucatan State. DNA was extracted from engorged mosquitoes and analyzed by PCR using universal avian-
and mammalian-specific primers. DNA extracted from avian-derived blood meals was further examined by PCR using primers
that differentiate between Passeriformes, Columbiformes and Galliformes. Data are presented as the percentage of
mosquitoes containing blood derived from mammals, avians, Passeriformes, Columbiformes and Galliformes each month. High
quality figures are available online.

Page 7

Journal of Insect Science: Vol. 10 | Article 32
Table 1. Numbers of Culex quinquefasciatus captured outdoors (in the backyard of houses) each month in Merida, Yucatan
State.
Number of mosquitoes captured
MonthFemales
FedUnfed
January 4454
February4871
March39 103
April4988
May3020
June 4317
July3751
August12594
September4736
October 5337
November 12789
December 3449
TOTAL658709
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 7
Gravid
0
17
18
10
4
18
20
48
16
21
49
12
233
Males TOTAL (%)
103
252
246
254
102
203
361
542
141
216
466
158
3044
201 (4.3)
388 (8.4)
406 (8.7)
401 (8.6)
156 (3.4)
281 (6.0)
469 ( 10.1)
809 (17.4)
240 (5.2)
327 (7.0)
731 (15.7)
253 (5.4)
4644 (100)
aA consistent trapping strategy was used throughout the year. Mosquitoes were collected in the backyards of 40 houses five
times a week using one resting box per site.
Resting collections were conducted from January to December 2005.
Data are presented as the numbers of females (fed, unfed and gravid) and males captured each month.
Table 2. The proportion of blood meals taken from different avian orders and mammalian species by Culex quinquefasciatus in
Merida, Yucatan State from January to December, 2005.
HostSource of blood
Number
113
57
27
21
16
3
2
1
240
Percentage
47.1
23.8
11.2
8.8
6.7
1.2
0.8
0.4
100
Galliformes
Passeriformes
Columbiformes
Dog
Human
Cat
Horse
Pig
TOTAL
Table 3. The source of mammalian-derived blood meals from engorged Culex quinquefasciatus captured in Merida. DNA
extracted from mammalian-derived blood meals was examined by restriction enzyme digestion to identify the host to the
species levela.
Number (and %) of mammalian blood meals
Month
DogHuman Cat
January1 (5)2 (10) 0 (0)
February1 (5)0 (0)1 (5)
March1 (5) 0 (0)0 (0)
April 0 (0)1 (5)0 (0)
May3 (15)3 (15) 2 (10)
June0 (0)2 (10)0 (0)
July0 (0)2 (10)0 (0)
August 3 (15)2 (10)0 (0)
September5 (25)1 (5)0 (0)
October 3 (15)1 (5)0 (0)
November 4 (20)2 (10)0 (0)
December 0 (0)0 (0)0 (0)
TOTAL21163
Horse
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
1 (5)
0 (0)
1 (5)
0 (0)
0 (0)
2
Pig
0 (0)
0 (0)
0 (0)
1 (5)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
1
Mammalian Total
3 (15)
2 (10)
1 (5)
2 (10)
8 (40)
2 (10)
2 (10)
6 (30)
6 (30)
5 (25)
6 (30)
0 (0)
43
aA total of 20 mosquitoes were assayed for mammalian- and avian-derived blood each month

Page 8

Journal of Insect Science: Vol. 10 | Article 32
proportion of mosquitoes that had acquired
blood meals from dogs was highest in
September (25%) and November (20%)
(Table 3). No blood meals were obtained from
mammals in December.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 8
One limitation of this study is that a subset of
mosquitoes could have acquired blood meals
from vertebrate hosts that were located in
nearby houses and therefore were not included
in the census. Mark-release-recapture studies
have shown that Cx. quinquefasciatus can
travel up to 1.0 km/day to acquire blood meals
(Reisen et al. 1991). However, the census was
restricted to the 40 houses used for the
mosquito collections because mosquitoes are
more likely to feed on vertebrate hosts in their
immediate vicinity and because of the
logistical restraints associated with censusing
all vertebrate hosts
quinquefasciatus flight path.
within the Cx.
Human blood index and forage ratio values
The overall HBI was 6.7% (Table 2). On five
occasions, the monthly HBI values were 10%.
The highest monthly HBI values occurred in
May (15%), and three months were 0%
(February, March, and December) (Table 3).
The numbers of humans and domestic animals
(mammals and birds), residing at each house
sampled in this study were counted. Overall,
88 (41%) of the vertebrates were human, 45
(21%) were chickens
(galliformes), 32 (15%) were dogs, 14 (7%)
were cats, 5 (3%) were passeriformes and 4
(2%) were horses. There were no pigs, cows
or columbiformes Humans were the most
common vertebrate species in the study area.
However, the FR for humans was < 1.0,
indicating that Cx. quinquefasciatus had a
preference for other vertebrate hosts (Table 4).
Forage ratios were calculated for other
vertebrate hosts; and those with FRs > 1.0
and turkeys
were Passeriformes (9.1) and Galliformes
(2.0) birds.
Host feeding indices
Calculation of the HFIs for each pair of
vertebrate hosts revealed that humans were
the least preferred source of blood relative to
species of Passeriformes, and Galliformes
birds, and dogs, horses and cats (Table 5). HFI
values could not
Columbiformes or pigs because none were
present at any study sites. In congruence with
the FR values, the HFI data suggested that
Passeriformes were the preferred source of
blood for Cx. quinquefasciatus, followed by
Galliformes.
be calculated for
Table 4. Forage ratios for Culex quinquefasciatus mosquitoes
in Merida, Yucatan State.
Host % host
population
%
blood
meals
6.7
8.7
1.3
0.4
0.8
47.1
23.7
11.3
forage
ratio
Human
Dog
Cat
Pig
Horse
Galliformes
Passeriformes
Columbiformes
47
17
7.4
0
2.1
23.9
2.6
0
0.1
0.5
0.2
-
0.4
2
9.1
-
Table 5. Host feeding indices for each pair of vertebrate
hosts fed upon by Culex quinquefasciatus in Merida, Yucatan
State.
Host 1Host 2
aHFI
Passeriformes0
Galliformes
Dog
Cat
Horse
Galliformes
Dog
Cat
Horse
Dog
Cat
Horse
Cat
Horse
Horse
0.1
0.3
0.8
0.4
4.5
17.4
53.2
22.8
3.8
11.7
5
3.1
1.3
0.4
Human
Passeriformes
Galliformes
Dog
Cat
aHFIs for vertebrates not present at the study sites could not
be calculated

Page 9

Journal of Insect Science: Vol. 10 | Article 32
Summary
This study suggests that Cx. quinquefasciatus
populations in Merida, Yucatan State feed
most frequently on birds year-round. These
findings suggest that Cx. quinquefasciatus
could be an important amplification vector of
WNV in this region. In addition, the data
refute the hypothesis that the low incidence of
WNV illness in Mexico is due to the lack of
interaction between Culex spp. mosquitoes
and avian reservoir hosts in this region.
Ornithophilic feeding behavior also was
reported recently for Cx. quinquefasciatus
populations in the city of Monterrey, northern
Mexico; 44% to 73% of engorged mosquitoes
collected outdoors had acquired their blood
meals from chickens (Elizondo-Quiroga et al.
2006). The overall HBI in the present study
was low (0.1) indicating that humans were not
a preferred host for Cx. quinquefasciatus in
Merida. Nevertheless, a small proportion
(6.7%) of engorged Cx. quinquefasciatus
contained human blood, indicating that this
mosquito species could also transmit WNV to
humans in this region. Vector competence
studies are needed to determine the role that
Cx. quinquefasciatus plays in the transmission
of WNV in Mexico.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 9
Acknowledgments
The authors thank Francisco Solis-Heredia
and Fernando Puerto-Manzano for providing
blood samples for the validation of the
restriction enzyme
Valenzuela-Nahuatl for support in the field.
This study was supported in part by grant
2004-01-131 from the Fondo Sectorial
Conacyt-Salud Mexico, by The National
Institutes of Health grant # 53-4569-2, and by
theCenters for Disease Control and
Prevention grant # G-4457-2. Sequencing
experiments were supported by The National
Institutes of Health, grant 5R21AI067281.
assays and Hugo
REFERENCES
Beasley DW, Davis CT, Estrada-Franco J,
Navarro-Lopez R, Campomanes-Cortes A,
Tesh RB, Weaver SC, Barrett AD. 2004.
Genome sequence and attenuating mutations
in West Nile virus isolate from Mexico.
Emerging Infectious Diseases 10: 2221-2224.
Blitvich BJ, Fernandez-Salas I, Contreras-
Cordero JF, Marlenee NL, Gonzalez-Rojas JI,
Komar N, Gubler DJ, Calisher CH, Beaty BJ.
2003. Serologic evidence of West Nile virus
infection in horses, Coahuila State, Mexico.
Emerging Infectious Diseases 9: 853-856.
Blitvich BJ, Fernandez-Salas I, Contreras-
Cordero JF, Lorono-Pino MA, Marlenee NL,
Diaz FJ, Gonzalez-Rojas JI, Obregon-
Martinez N, Chiu-Garcia JA, Black WC 4th,
Beaty BJ. 2004. Phylogenetic analysis of
West Nile virus, Nuevo Leon State, Mexico.
Emerging Infectious Diseases. 10: 1314-1317.
Boreham PFL, Garrett-Jones C. 1973.
Prevalence of mixed blood meals and double
feeding in a malaria vector (Anopheles
sacharovi Favre). Bulletin of the World Health
Organization 48: 605-614.
Carpenter SJ, LaCasse WJ. 1955. Mosquitoes
of North America (north of Mexico).
University of California Press.
Cicero C, Johnson NK. 2001. Higher-Level
phylogeny of New World Vireos (Aves:
Vireonidae) based on sequences of multiple
mitochondrial DNA genes molecular
phylogenetics and evolution. 20: 27-40.
Darsie RF, Ward RA. 1981. Identification and
geographical distribution of mosquitoes of
North America, north of Mexico. Mosquito
Systematics Supplement 1: 1-313.

Page 10

Journal of Insect Science: Vol. 10 | Article 32
Deardorff E, Estrada-Franco J, Brault AC,
Navarro-Lopez R, Campomanes-Cortes A,
Paz-Ramirez P, Solis-Hernandez M, Ramey
WN, Davis CT, Beasley DW, Tesh RB,
Barrett AD, Weaver SC. 2006. Introductions
of West Nile virus strains to Mexico.
Emerging Infectious Diseases 12: 314-318.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 10
Elizondo-Quiroga A, Flores-Suarez A,
Elizondo-Quiroga D, Ponce-Garcia G,
Blitvich BJ, Contreras-Cordero JF, Gonzalez-
Rojas JI, Mercado-Hernandez R, Beaty BJ,
Fernandez-Salas I. 2006. Host-feeding
preference of Culex quinquefasciatus in
Monterrey, northeastern Mexico. Journal of
the American Mosquito Control Association
22: 654-661.
Elizondo-Quiroga D, Davis CT, Fernandez-
Salas I, Escobar-Lopez R, Velasco Olmos D,
Soto Gastalum LC, Aviles Acosta M,
Elizondo-Quiroga A, Gonzalez-Rojas JI,
Contreras Cordero JF, Guzman H, Travassos
da Rosa A, Blitvich BJ, Barrett AD, Beaty BJ,
Tesh RB. 2005. West Nile Virus isolation in
humans and mosquitoes, Mexico. Emerging
Infectious Diseases 11: 1449-1452.
Estrada-Franco JG, Navarro-Lopez R, Beasley
DW, Coffey L, Carrara AS, Travassos da
Rosa A, Clements T, Wang E, Ludwig GV,
Cortes AC, Ramirez PP, Tesh RB, Barrett
AD, Weaver SC. 2003. West Nile virus in
Mexico: Evidence of widespread circulation
since July 2002. Emerging Infectious Diseases
9: 1604-1607.
Farfán-Ale JA, Blitvich BJ, Loroño-Pino MA,
Marlenee NL, Rosado-Paredes EP, García-
Rejón JE, Flores-Flores LF, Chulim-Perera L,
López-Uribe M, Pérez-Mendoza G, Sánchez-
Herrera I, Santamaría W, Moo-Huchim J,
Gubler DJ, Cropp BC, Calisher CH, Beaty BJ.
2004. Longitudinal studies of West Nile virus
infection in avians, Yucatán State, México.
Vector Borne and Zoonotic Diseases. 4: 3-14.
Farfan-Ale JA, Blitvich BJ, Marlenee NL,
Lorono-Pino MA, Puerto-Manzano F, Garcia-
Rejon JE, Rosado-Paredes EP, Flores-Flores
LF, Ortega-Salazar A, Chavez-Medina J,
Cremieux-Grimaldi JC, Correa-Morales F,
Hernandez-Gaona G, Mendez-Galvan JF,
Beaty BJ. 2006. Antibodies to West Nile virus
in asymptomatic mammals, birds, and reptiles
in the Yucatan Peninsula of Mexico. The
American Journal of Tropical Medicine and
Hygiene 74: 908-914.
Garrett-Jones C. 1964. The human blood
index of malaria vectors in relation to
epidemiological assessment. Bulletin of the
World Health Organization 30: 241-261.
Goddard LB, Roth AE, Reisen WK, Scott
TW. 2002. Vector competence of California
mosquitoes for West Nile virus. Emerging
Infectious Diseases 12: 1385-1391.
Hayes EB, Komar N, Nasci RS, Montgomery
SP, O'Leary DR, Campbell GL. 2005.
Epidemiology and transmission dynamics of
West Nile virus disease. Emerging Infectious
Diseases 11: 1167-73.
Hess AD, Hayes RO, Tempelis CH. 1968. The
use of the forage ratio technique in mosquito
host preference studies. Mosquito News 28:
386-389.
Kay BH, Boreham PFL, Edman JD. 1979.
Application of the “feeding index” concept to
studies of mosquito host-feeding patterns.
Mosquito News 39: 68-72.
Loroño-Pino MA, Blitvich BJ, Farfan-Ale JA,
Puerto FI, Blanco JM, Marlenee NL, Rosado-
Paredes EP, Garcia-Rejon JE, Gubler DJ,
Calisher CH, Beaty BJ. 2003. Serologic
evidence of West Nile virus infection in

Page 11

Journal of Insect Science: Vol. 10 | Article 32
horses, Yucatan State, Mexico. Emerging
Infectious Diseases 9: 857-859.
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 11
Meece JK, Reynolds CE, Stockwell PJ,
Jenson TA, Christensen JE, Reed KD. 2005.
Identification of mosquito bloodmeal source
by terminal restriction fragment length
polymorphism profile analysis of the
cytochrome B gene. Journal of Medical
Entomology 42: 657-667.
Molaei G, Andreadis TG, Armstrong PM,
Bueno R Jr, Dennett JA, Real SV, Sargent C,
Bala A, Randle Y, Guzman H, Travassos da
Rosa A, Wuithiranyagool T, Tesh RB. 2007.
Host feeding pattern of Culex
quinquefasciatus (Diptera: Culicidae) and its
role in transmission of West Nile virus in
Harris County, Texas. The American Journal
of Tropical Medicine and Hygiene 77: 73-81.
Ngo KA, Kramer LD. 2003. Identification of
mosquito bloodmeals using polymerase chain
reaction (PCR) with order-specific primers.
Journal of Medical Entomology 40: 215-222.
Niebylski ML, Meek CL. 1992. Blood-
feeding of Culex mosquitoes in an urban
environment. Journal of the American
Mosquito Control Association 8: 173-177.
Reisen WK, Milby MM, Meyer RP, Pfuntner
AR, Spoehel J, Hazelrigg JE, Webb JP Jr
1991. Mark-release-recapture studies with
Culex mosquitoes (Diptera: Culicidae) in
Southern California. Journal of Medical
Entomology 28: 357-371.
Reisen WK, Meyer RP, Tempelis CH,
Spoehel JJ. 1990. Mosquito abundance and
bionomics in residential communities in
Orange and Los Angeles Counties, California.
Journal of Medical Entomology 27: 356-367.
Reisen WK, Reeves WC. 1990. Bionomics
and ecology of Culex tarsalis and other
potential mosquito vector species. In: Reeves
WC, editor. Epidemiology and control of
mosquito-borne arboviruses in California,
1943-1987. pp. 254-329. California Vector
Control Association.
Reisen WK, Pfuntner AR. 1987. Effectiveness
of five methods for sampling adult Culex
mosquitoes in rural and urban habitats in San
Bernardino County, California. Journal of the
American Mosquito Control Association 3:
601-606.
Richards SL, Ponnusamy L, Unnasch TR,
Hassan HK, Apperson CS. 2006. Host-
Feeding Patterns of Aedes albopictus (Diptera:
Culicidae) in relation to availability of human
and domestic animals in suburban landscapes
of central North Carolina. Journal of Medical
Entomology 43: 543-551.
Tempelis CH. 1975. Host feeding patterns of
mosquitoes, with a review of advances in
analysis of blood meals by serology. Journal
of Medical Entomology 11: 635-653.
Turell MJ, Dohm DJ, Sardelis MR, Oguinn
ML, Andreadis TG, Blow JA. 2005. An
update on the potential of North American
mosquitoes (Diptera: Culicidae) to transmit
West Nile virus. Journal of Medical
Entomology 42: 57-62.
Vinogradova EB. 2000. Culex pipiens pipiens
mosquitoes: taxonomy, distribution, ecology,
physiology, genetics, applied importance and
control, 1st edition. Pensoft Publishers.
Zehner R, Zimmermann S, Mebs D. 1998.
RFLP and sequence analysis of the
cytochrome b gene of selected animals and
man: Methodology and forensic application.
International Journal of Legal Medicine 111:
323-327.

Page 12

Journal of Insect Science: Vol. 10 | Article 32
Zinser M, Ramberg F, Willott E. 2004. Culex
quinquefasciatus (Diptera: Culicidae) as a
potential West Nile virus vector in Tucson,
Arizona: Blood meal analysis indicates
feeding on both humans and birds. Journal of
Insect Science 4: 20. Available online
http://insectscience.org/4.20
Garcia-Rejon et al.
Journal of Insect Science | www.insectscience.org? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? 12