Household Wastes as Larval Habitats of Dengue Vectors: Comparison between Urban and Rural Areas of Kolkata, India

Abstract

Porcelain and plastic materials constitute bulk of household wastes. Owing to resistibility and slow degradability that accounts for higher residence time, these materials qualify as potential hazardous wastes. Retention of water permits these wastes to form a congenial biotope for the breeding of different vector mosquitoes. Thus porcelain and plastic wastes pose a risk from public health viewpoint. This proposition was validated through the study on the porcelain and plastic household wastes as larval habitats of Dengue vectors (Aedes spp.) in rural and urban areas around Kolkata, India. The wastes were characterized in terms of larval productivity, seasonal variation and a comparison between urban and rural areas was made using data of two subsequent years. The number of wastes positive as larval habitats and their productivity of Aedes spp. varied among the types of household wastes with reference to months and location. Multivariate analysis revealed significant differences in the larval productivity of the household wastes based on the materials, season, and urban-rural context. Results of Discriminant Analysis indicated differences in abundance of Ae. aegypti and Ae. albopictus for the urban and rural areas. The porcelain and plastic wastes were more productive in urban areas compared to the rural areas, indicating a possible difference in the household waste generation. A link between household wastes with Aedes productivity is expected to increase the risk of dengue epidemics if waste generation is continued without appropriate measures to limit addition to the environment. Perhaps, alternative strategies and replacement of materials with low persistence time can reduce this problem of waste and mosquito production.

Full text

RESEARCH ARTICLE
Household Wastes as Larval Habitats of
Dengue Vectors: Comparison between Urban
and Rural Areas of Kolkata, India
Soumyajit Banerjee
1
, Gautam Aditya
1,2
*, Goutam K. Saha
1
1Department of Zoology, 35, BC Road, University of Calcutta, Kolkata 700019, India, 2Department of
Zoology, The University of Burdwan, Burdwan 713104, India
*gautamaditya2001@gmail.com
Abstract
Porcelain and plastic materials constitute bulk of household wastes. Owing to resistibility
and slow degradability that accounts for higher residence time, these materials qualify as
potential hazardous wastes. Retention of water permits these wastes to form a congenial
biotope for the breeding of different vector mosquitoes. Thus porcelain and plastic wastes
pose a risk from public health viewpoint. This proposition was validated through the study
on the porcelain and plastic household wastes as larval habitats of Dengue vectors (Aedes
spp.) in rural and urban areas around Kolkata, India. The wastes were characterized in
terms of larval productivity, seasonal variation and a comparison between urban and rural
areas was made using data of two subsequent years. The number of wastes positive as lar-
val habitats and their productivity of Aedes spp. varied among the types of household
wastes with reference to months and location. Multivariate analysis revealed significant dif-
ferences in the larval productivity of the household wastes based on the materials, season,
and urban–rural context. Results of Discriminant Analysis indicated differences in abun-
dance of Ae.aegypti and Ae.albopictus for the urban and rural areas. The porcelain and
plastic wastes were more productive in urban areas compared to the rural areas, indicating
a possible difference in the household waste generation. A link between household wastes
with Aedes productivity is expected to increase the risk of dengue epidemics if waste gener-
ation is continued without appropriate measures to limit addition to the environment. Per-
haps, alternative strategies and replacement of materials with low persistence time can
reduce this problem of waste and mosquito production.
Introduction
Plastic and porcelain wastes of household origin qualify as hazardous materials owing to their
resistance to physical and chemical factors and slow degradability [1]. As a result, porcelain
and plastic wastes may interfere with natural processes and influence environmental quality.
In absence of suitable management, porcelain (including glass) and plastic wastes sustain
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 1/21
OPEN ACCESS
Citation: Banerjee S, Aditya G, Saha GK (2015)
Household Wastes as Larval Habitats of Dengue
Vectors: Comparison between Urban and Rural
Areas of Kolkata, India. PLoS ONE 10(10):
e0138082. doi:10.1371/journal.pone.0138082
Editor: Jiang-Shiou Hwang, National Taiwan Ocean
University, TAIWAN
Received: October 16, 2014
Accepted: August 26, 2015
Published: October 8, 2015
Copyright: © 2015 Banerjee et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any
medium, provided the original author and source are
credited.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information files.
Funding: The project was partially funded by UGC
through SAP-RFSMS Junior Research Fellowship
[Sanction no. F4-1/2006 (BSR)/7-45/2007(BSR)] and
CSIR Senior Research Fellowship to SB [Sanction
no. 09 /020 (0832) / 2010- EMR-1, dated 29.03.2011].
The funders had no role in study design, data
collection and analysis, decision to publish, or
preparation of the manuscript.
Competing Interests: The authors have declared
that no competing interests exist.

pathogens and parasites of medical importance [2], posing concern from public health view-
point [3,4] in different regions of the world [5–7]. The organic residues and entrapped water in
porcelain (including glass) and plastic wastes create suitable biotope for breeding of vector
mosquitoes, particularly Aedes spp. [8–10]. Theshape of the containers and residence time in
the environment determine the quality of porcelain (glass) and plastic wastes as larval habitats
of Aedes aegypti and Aedes albopictus [11,12]. This observation justifies porcelain and plastic
wastes as contributors to breeding of dengue vectors and thus increases the corresponding risk
of dengue transmission.
Dengue and Chikungunya are examples of mosquito borne viral diseases posing concern for
public health worldwide, in the tropics and subtropics [13,14]. Monitoring of vectors of these
diseases is necessary for predicting the population variations and intervention of the vector
population. Thus assessment of the prospective breeding grounds of the vector mosquitoes
forms an integral part of management of dengue and chikungunya [15,16]. Linking household
wastes with the mosquito breeding enable characterization and classification of these wastes as
key larval habitat of Aedes mosquitoes [12,17]. Household waste generation varies in urban
and rural background, owing to characteristic population density, social, economic and envi-
ronmental factors [18–21]. The distinction between the urban-rural areas in Kolkata, India is
based on density of human settlements and source of livelihood. Consequently, the contribu-
tions of wastes as larval habitats are expected to vary according to rural and urban background
[22–24]. In recent years, dengue and chikungunya outbreak in India is recorded mostly from
urban areas [25–27], with few reports from rural areas [28,29]. With increased usage of plastic
in various forms, the possible wastes generation in the rural areas cannot be ruled out [30–33].
Based on these observations and propositions, an attempt was made to evaluate the differences
in the pupal productivity in rural and urban areas using Kolkata, India as the geographical
study area. Earlier studies from eastern India including Kolkata, indicate expansion of the geo-
graphical range of dengue vectors [34,35]. While dengue epidemics have been largely restricted
to urban areas, expansion of geographical range increases chance of dengue epidemics in rural
areas. A comparative study of abundance of dengue vectors in rural and urban areas will enable
highlighting the role of porcelain and plastic wastes as contributors to the sustenance of dengue
vector populations. Apart from supplementing information to develop strategies for source
reduction of the breeding habitats, the results of the study will enable predictions about possi-
ble expansion of the geographical boundaries of dengue and chikungunya vector mosquitoes in
Kolkata, India and its adjoining areas.
Material and Methods
Study area
Following identification and subsequent screening of household hazardous waste containers as
Aedes larval habitats, sampling studies were carried out from selected sites of Kolkata and
adjoining rural areas of eastern India. Each sampling site within the study area included four
sampling spots each from the urban and rural areas. The urban sites considered for the present
study included Baranagar (22°38'36"N, 88°21'55" E), Ballygunge (22°32'0"N, 88° 22' 0" E), Che-
tla (22°31'0"N, 88°20'24"E), and Patuli (22°47’22”N, 88°38’78”E), Kolkata India; the rural spots
consisted of Serampore (22°75’00”N, 88°34’00”E), Baidyabati (22°79’00”N, 88°32’00”E), Sin-
gur (22°81’00”N, 88°23’00”E) and Haripal (22°83’33”N, 88°11’67”E) of district Hooghly adja-
cent to Kolkata. In the present study, the areas where there is a population of minimum 5,000
individuals with a density of 400 persons per sq. km and 75% of the males were engaged in
non-agricultural pursuits, were denoted as urban areas (viz. Baranagar, Ballygunge, Chetla, and
Patuli) whereas areas having a population of maximum 15,000 individuals with a density of
Household Wastes and Dengue Vectors in Rural-Urban Gradient
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<400 individuals/Km
2
and agriculture as the chief source of livelihood followed by fishing, cot-
tage industries, pottery etc were categorized as rural (Serampore, Baidyabati, Singur and
Haripal).
Sampling procedure
No specific permissions were required for any locations / activities for the study. The GPS coor-
dinates are being added in the Materials and methods section. The field studies did not involve
endangered or protected species both in the urban and rural sites. In each month between July
2009 and December 2010, random stratified sampling was employed to monitor prospective
Aedes larval habitats in the study area (Table 1). The study included survey of the urban (U)
and rural (R) areas based on 4 sites (1–4) in each area. Four selected spots of equal space
(~100m
2
) formed each site, under which randomly chosen 20 sub-spaces were surveyed for the
presence of porcelain and plastic waste containers. In each spot within the study area, the
Aedes mosquito larval habitats [11] were chosen randomly, based on two broad types, porce-
lain (including glass) and plastic waste containers. The sampling was carried out using WHO
methods and following Krebs [36] and Focks & Alexander [11]. A total of 80 numbers of each
habitat (cluster X sub- space) was considered per sampling spot per month. In the context of
the sampling method, the term larval habitat denoted the different household non-reusable
and non-degradable containers of either porcelain (including glass) or plastic material that was
used by the Aedes for breeding. The different porcelain and plastic containers of household
hazardous waste were checked both outdoor and indoor the human settlements for the Aedes
immature. The features of the habitats surveyed are presented in Table 2. Each of the habitats
was sampled either using an inverted glass pipette (100ml) fitted with rubber teats or emptying
the whole contents in a glass beaker (500ml), according to the aptness of the habitats. There
Table 1. Outline of design and objective of the study.
Attributes Details Remarks
Study area Two Urban and Rural
Sampling sites Eight
Urban: U1, U2, U3, U4 U1- Baranagar, U2- Ballygunge, U3-
Chetla, and U4- Patuli
Rural: R1. R2, R3, R4 R1- Serampore, R2- Badidyabati, R3
-Singur and R4- Haripal
Habitats Two categories Plastic and porcelain containers
Study period Two years 2009–2010
Sampling
months
Six; July—December Post monsoon months
Total habitats
sampled
Eighty habitats of each type over the
period of study in each area
80 x 2 x 8 x 2 x 2 x 6 = 30720
Observation Larva and pupa, collectively considered as
immature were sampled; reared under
laboratory conditions for identifying species
and sex
Waste containers having either Ae.aegypti
or Ae.albopictus individually were only
taken into account; cases where both
the species occurred were excluded
Analysis ANOVA; Discriminant function analysis To comment on species specific variation
habitat and area wise in number of
positive habitats and abundance;
Similarity pattern of house hold waste
based on the abundance
Hypothesis
tested
Variation of house hold hazardous wastes
in urban and rural context and their linkage
with mosquito productivity
Detection and prioritization of house hold
generated hazardous wastes as key
mosquito habitats
doi:10.1371/journal.pone.0138082.t001
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were cases where other species of vector mosquitoes (viz. Culex spp., Anopheles spp.) were
encountered but for the present study, the number of individuals of Ae.aegypti and Ae.albopic-
tus were considered only for analysis.
Observations
From each of the positive larval habitats, the immature comprising of the larva and pupa were
sampled, put in sample containers (100ml sample container Tarsons
1
) and brought to the lab-
oratory to note the number of immature collected. Following counting, the immature were
allowed to develop to adults in the sample containers marked with the site and area of collec-
tion. Depending on the density of the immature (<100 individuals), the sample containers
were supplemented with 5–15 grains of fish food (
1
Tokyu fish food) in adequate amount of
water ~ 30 mL –50 mL. The water was changed regularly and the adult emerging was counted
further. For densities greater than 100 individuals collected from a larval habitat, immature
were reared in plastic trays (15 X 11 X 3 inches) to adult stage for identification to the species
level. The sex and species of the adults were identified based on appropriate keys [37,38]. In
case of larval habitats that were positive for both the species, data was recorded against a single
species (based on relative abundance) to avoid pseudoreplication [39]. Thus larval habitats
Table 2. Characteristics features of household hazardous materials (HHM), plastic (PL)and porcelain (glass) (GLP) wastes that were considered
as potential Aedes mosquito larval habitats in the survey in Kolkata and rural areas of adjacent districts and were found positive for the Aedes
mosquitoes. Figures in parenthesis reveal the percentage of the containers found positive for the mosquitoes. The containers were surveyed with respect to
human dwelling and categorized as: located outside human house = O, located inside human houses = I.
House hold
hazardous
material
(HHM)
Location
(L)
Common name
and abbreviation
used in the text
Utility Diameter/
Length (in
cm)
Height
(in cm)
Breadth
(in cm)
Water
holding
capacity
(ml)
Positive
containers
Ae.aegypti
Positive
containers
Ae.
albopictus
PL O Cup (OP1) Drinking 4–4.5 3.8–4.5 NA <100 1184 (15.42) 1155 (15.04)
PL O Broken Bucket
(OP2)
Washing 18–30 15–30 NA >250 248 (3.23) 417 (5.43)
PL O Bowl(OP3) Drinking/
utensil
8.0–11.0 3–6.5 NA 100–250 686 (8.93) 700 (9.11)
PL O Short container
(OP4)
Cosmetic/
baby food/
utensil
4.5–26 5.0–
12.0
NA <100 309 (4.02) 307 (4.0)
PL O Box (OP5) Utensil/
carrying
eatables
5.0–29.0 4.2–8.4 4.1–20.0 100–250 526 (6.85) 295 (3.84)
PL I Cup (IP1) Drinking 3.8–4.5 3.8–4.5 NA <100 925 (12.04) 1131 (14.73)
PL I Bowl (IP2) Drinking/
utensil
7.2–10.0 3–6.5 NA 100–250 452 (5.89) 303 (3.95)
PL I Short container
(IP3)
Cosmetic/
baby food/
utensil
2.0–8.0 5.0–
12.0
NA <100 518 (6.74) 539 (7.02)
GLP O Sink (OPR1) Toiletries 26–55 10.0–
15.0
20–38 >250 276 (57.5) 282 (58.75)
GLP O Vase (OPR2) Decoration NA 100–250 1089 (68.06) 1495 (93.44)
GLP O Soup Bowl
(OPR3)
Utensil 6.1–18.5 5.0–7.0 NA <100 1103 (45.96) 1588 (66.17)
GLP O Broken showpiece
(OPR4)
Decoration <100 1040 (43.33) 859 (35.79)
GLP I Sink (IPR1) Toiletries 24–55 10.0–
17.0
22–40 >250 335 (41.88) 529 (66.13)
doi:10.1371/journal.pone.0138082.t002
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were categorized for only two species separately. The discarded containers harbouring either
Ae.aegypti or Ae.albopictus individually were taken into account only. There were cases where
both the species occurred in tandem in a container, but those samples were included as positive
for a particular species based on relative density to exclude the possibility of pseudo replication
[39]. The problem of pseudo replication arises due to lack of appropriate replicate (randomiza-
tion and interspersion) or the replicates fail to be statistically independent. For the present
study the smallest experimental unit to which a treatment is independently applied is a single
porcelain (glass) or plastic waste. Thus a single porcelain (including glass) or plastic waste
could be considered only once as a replicate, either for Ae.albopictus or for Ae.aegypti. Consid-
ering the single unit for larval habitat of both would increase the number of sampling units and
add error to the analysis. The co-occurrence of Ae.aegypti and Ae.albopictus in the habitats, is
a mutually inclusive phenomenon where one species may occur at the same time and in the
same habitat with the other. The density of Ae.aegyptiwas higher in the plastic containers.
Hence in cases where the both species coexist in the same container (viz. plastic) depending on
the relative density, the species with higher density were included to a particular category.
However, it was noted that in porcelain (glass) containers, in cases of ‘both’, relative density of
Ae.aegypti and Ae.albopictus were more or less equal. In such cases, numbers of positive habi-
tats were assigned equally between them.
Statistical analysis
To comment on the habitat and area, data on positive larval habitats and abundance were sub-
jected to three-way factorial ANOVA [40] using habitats, area and month as variables. Further
to reveal species specific variation, the data on immature abundance were analyzed for five-
way factorial ANOVA using species, month, habitat, area and location as variables. The data
on the positive larval habitats, relative abundance of larvae and pupae in house hold generated
wastes of porcelain and plastic containers were subjected to discriminant function analysis [41]
to comment on the differences in immature abundance in urban- rural context and months.
Discriminant function analysis (DA) is a multivariate procedure that enables segregation
among target variables using certain explanatory variables. DA is reverse of multivariate analy-
sis of variance (MANOVA) in the sense that dependent variables are the groups (Aedes spp.
productivity) and the predictor or input variables (urban-rural gradient, months) are the inde-
pendent variables. In MANOVA, the independent variables are the groups and the dependent
variables are the predictors. The DA is divided into two phase study, beginning with, first, the
test of significance for a determined number of Discriminant functions, followed by, second—
the categorization. In Discriminant Analysis (DA) [41] classification of the heterogeneity in
the data based on particular parameters can be carried out so as to segregate the variables based
on observed data. This helps to determine if there is any significant difference among the dif-
ferent groups with regards to the various parameters considered. In the present study, the
urban-rural gradient and months were considered as predictor variables to discriminate the
productivity of Ae.aegypti and Ae.albopictus.
The results of DA would enable portraying the productive months and sites in terms of
abundance of immature Aedes mosquitoes thereby highlighting the differences among the
response variables. The statistical analyses were performed using SPSS ver. 10 software and
XLSTAT [42].
Results
The number of habitats recorded positive for the species Ae.aegypti and Ae.albopictus, was
found to vary with the type of habitat and material of the house-hold generated wastes
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(Table 2). In terms of positive number of breeding sites for the immature, porcelain (glass)
objects (OPR1, OPR2, OPR3, OPR4, and IPR1) were more productive for Ae.albopictus. The
plastic containers (OP1, OP2, OP3, OP4, IP1, IP3, and IP4) were equivalent in terms of har-
bouring both the species. IP1 and OP1 among the plastic types and OPR3 and OPR2 among
the porcelain (glass) containerswere documented to sustain more Aedes spp. Probably the
dimension of the varied household generated waste containers and the water retention ability/
residence time played a pivotal function in maintaining the abundance of the dengue vectors.
The relative occurrence of the Ae.aegypti in the plastic containers was noted to be more than
that of Ae.albopictus whereas the porcelain container types showed equivalence in holding
both the species irrespective of the spots and the study period. Monthly variations in positive
habitats and pupal productivity for both Ae.aegypti and Ae.albopictus were prominent both in
the urban and rural spots of the study areas (Fig 1). Possibly due indiscriminate use of the plas-
tic and porcelain materials in the urban areas as compared to the rural spots, the relative inten-
sity of immature abundance of both the species was noted to be more in urban areas. Variation
in the immature productivity may probably be an indication in the difference in generation of
house-hold waste and thereby the extent of urbanization. In rural areas porcelain containers
were preferred by Ae.albopictus compared to Ae.aegypti; while for plastic containers in both
rural and urban spots Ae.aegypti seemed to be dominant contrasts to Ae.albopictus. Irrespec-
tive of locations, plastic containers were more productive with Aedes immature than glass con-
tainers, though significant variations among the months was evident (Fig 2A). Considerable
variation in the number of pupa to larva was also noted during the period (Fig 2B). The post
monsoon months, from July to October, were most productive perhaps due to accumulation
and retention of water within the varied container types. Following a peak in August and Sep-
tember, the immature density declined gradually to almost nil in December. Five-way factorial
ANOVA on the abundance of Aedes spp. revealed significant values for species, months, habi-
tats, area and location of the habitats. Except for the interactions between species-location, hab-
itat-area and month-habitat-area-location all other interactions were significant (Table 3A).
The results of the 3-way factorial ANOVA on the positive habitats for Ae.aegypti exhibited sig-
nificant values for material, area and month and material-area interaction; for Ae.albopictus
values for material and month were significant along with material-area, material-month, area-
month and material-area-month interactions. Similar results were obtained from the 3-way
factorial ANOVA on the abundance of the Aedes immature where material, area and month
exhibited significant values for both the species. Significant interactions between material-area,
material-month, area-month and material-area-month were noted for Ae.aegypti and mate-
rial-area, material-month for Ae.albopictus (Table 4).
Results of discriminant analysis (DA) indicated variations in immature productivity of Ae.
aegypti and Ae.albopictus with respect to months (Figs 3and 4) and urban-rural scenario (Figs
5and 6). These characteristic differences between the urban and rural sites reflect prospective
differences in the glass and plastic wastes generation and subsequent conversion as larval habi-
tats. The discriminant function coefficients were derived from the construction of sum of
squares and cross product matrices of the explanatory variables. The coefficients represent the
contribution of the variables against the three discriminant functions (F1, F2 and F3; Tables 5
through 8). The canonical correlation coefficients for each of the discriminant functions (F1
through F3) represent the strength of the overall relationship between a variate for the indepen-
dent variables (immature productivity) and one for the dependent variables (Sites or months as
applicable). For both the mosquito species Ae.aegypti and Ae.albopictus, the Fisher’s distances
were found to be significant (P <0.05) with respect to months (Tables 5and 6) and urban-
rural areas as well (Tables 7and 8). The ordination of the variables (months and sites) along
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Fig 1. Different household hazardous disposable plastic and porcelain containers observed to be positive (Mean±SE) for either (a) Ae.aegypti or
(b) Ae.albopictus during the two years course of study (July-December of 2009 and2010)in Kolkata and adjoining areas of West Bengal, India.
Household Wastes and Dengue Vectors in Rural-Urban Gradient
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the biplot axes represent sufficient discrimination of the months and urban-rural sites based
on their abundance for both the species.
All the data set for the tables and figures have been provided in the supporting information
file (S1 File).
Discussion
Surveillance of Aedes mosquitoes in rural and urban areas around Kolkata, India, reveals that
the household plastic and glass wastes contribute to the existence of the dengue vectors to a
considerable extent. The number of plastic and glass wastes serving as larval habitats of Ae.
aegypti and Ae.albopictus varied among the months in both rural and urban areas. Exploitation
of glass and plastic wastes as breeding sites varied between indoor and outdoor locations of
urban and rural areas, perhaps due to differences in the anthropogenic activities and thus gen-
eration of household wastes. The observations of the present study is a pioneer effort to
(Sample size n = 20 numbers of each of the type of habitats. Cumulative total positive is presented under thetwo main categories—porcelain and plastic.
Four each of urban and rural sites were considered for sampling in each month.
doi:10.1371/journal.pone.0138082.g001
Fig 2. The abundance (Mean ±SE) of Ae.aegypti and Ae.albopictus immature (a) and the pupa/ larvae ratio (Mean ±SE) (b) in various plastic and
porcelain household disposed containers, during the two years course of study (July-December of 2009 and 2010) in Kolkata and adjoining areas
of West Bengal, India. (Sample size n = 20 numbers of each of the type of habitats. Cumulative total positive is presented under the two main categories—
porcelain and plastic. Four each of urban and rural sites were considered for sampling in each month. The total immature (larva and pupa) from the positive
habitats of different types of porcelain and plastic containers are shown here. In figure b, the pupa/ larva ratio per habitat with reference line representing
equality of the two morphs. The *sign represents significant deviations from 1.
doi:10.1371/journal.pone.0138082.g002
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Table 3. Results of five-way factorial ANOVA (A) and Tukey test (B) on the abundance of Aedes immature considering species, months, habitats,
area (urban-rural) and location of the habitats as variables. The F values significant at P <0.05 level are marked in bold.
A
Source Sum of Squares df Mean Square F
Species (S) 10862.89 1 10862.89 657.44
Month (M) 99432.40 5 19886.48 1203.56
Habitat (H) 15315.07 1 15315.07 926.90
Area (A) 369.44 1 369.44 22.36
Location (L) 487.53 1 487.53 29.51
S*M 5144.21 5 1028.84 62.27
S*H 9370.77 1 9370.77 567.14
S*A 228.01 1 228.01 13.80
S*L 16.73 1 16.73 1.01
M*H 6337.05 5 1267.41 76.71
M*A 606.02 5 121.20 7.34
M*L 417.83 5 83.57 5.06
H*A 49.62 1 49.62 3.00
H*L 89.59 1 89.59 5.42
A*L 186.58 1 186.58 11.29
S*M*H 2920.77 5 584.15 35.35
S*M*A 262.06 5 52.41 3.17
S*M*L 383.30 5 76.66 4.64
S*H*A 2098.55 1 2098.55 127.01
S*H*L 404.19 1 404.19 24.46
S*A*L 76.11 1 76.11 4.61
M*H*A 233.45 5 46.69 2.83
M*H*L 242.66 5 48.53 2.94
M*A*L 449.99 5 90.00 5.45
H*A*L 105.56 1 105.56 6.39
S*M*H*A 647.03 5 129.41 7.83
S*M*H*L 357.48 5 71.50 4.33
S*M*A*L 1302.35 5 260.47 15.76
S*H*A*L 150.33 1 150.33 9.10
M*H*A*L 112.77 5 22.55 1.36
S*M*H*A*L 302.82 5 60.56 3.67
Error 505983.26 30623 16.52
Total 694727.94 30718
BPost hoc Tukey test. Studentized range q = [|(I-J)|/S.E.] S.E. = 0.08; df = 3071, 5
(I) Month (J) Month q (I) Month (J) Month q
July August 2.64 August December 4.31
July September 0.96 September October 1.28
July October 0.32 September November 2.64
July November 0.32 September December 4.69
July December 1.67 October November 1.36
August September 3.73 October December 3.41
August October 1.67 November December 2.06
August November 2.95
doi:10.1371/journal.pone.0138082.t003
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highlight the importance of rural areas as potential dengue breeding sites in the context of Kol-
kata and adjoining areas of India. Although rural areas were featured by fewer number of
wastes as Aedes larval habitats than urban areas, the consistency in the immature density
through the months, calls for consideration of rural areas as prospective sites for breeding of
dengue vectors and thus possibilities of dengue. Until now, resurgence of dengue and corre-
sponding vector management strategies are focused on urban areas of India [25–27,43,44],
though few studies have demonstrated the pattern of dengue vector abundance in rural areas
[29,45,46]. In rural areas, the alternative breeding habitats of mosquitoes like tree holes and
puddles are quite common [35,47,48]. Increased availability of the household wastes in rural
areas will increase the potential breeding sites of Aedes mosquitoes, as well as risk of dengue in
rural areas in and around Kolkata, India.
Improper usage and inappropriate disposal of various commodities of daily use including
different articles and containers made up of plastic pose a menace to the public health [49].
Due to high durability, low cost, and versatile forms, plastics and allied products have become
an indispensable part of modern life. Resistance to microbial and physical degradation routes
however, enables plastic wastes to act as environmental nuisance [50]. Porcelain (Glass) con-
tainers featured by frost-resistant and radiant glazes are non-biodegradable. Owing to slow
degradation by physical means, the residence time of glass wastes in environment increases the
burden of waste in environment. Improper disposal and management increases the possibilities
of plastic and glass wastes to serve as breeding habitats for containers breeding mosquitoes,
Aedes in particular. As observed in the present study, the pupal productivity varied with the
Table 4. Results of three way factorial ANOVA on the positive containers of Aedes aegypti and Ae.albopictus immature and mean abundance con-
sidering material, spot (urban-rural spots), and months of the surveyed habitats as variables. The F values significant at P <0.05 level are marked in
bold.
Ae.aegypti
Positive habitats Immature abundance
Source df Mean Square F Mean Square F
MATERIAL (M) 1 5260.55 127.3 2033839.17 857.22
SITE (S) 7 257.166 6.221 10960.91 4.62
MONTH (MTH) 5 12974.4 313.9 1169999.54 493.13
M*S 7 189.952 4.595 37549.14 15.83
M*MTH 5 146.097 3.534 138230.76 58.26
S*MTH 35 30.9052 0.748 6621.34 2.79
ML *S*MTH 35 29.6731 0.718 6026.44 2.54
Error 96 41.3385 2372.59
Total 191
Ae.albopictus
Positive habitats Immature abundance
Source df Mean Square F Mean Square F
MATERIAL (M) 1 744.19 29.45 59925.33 13.50
SITE (S) 7 24.87 0.98 9700.58 2.19
MONTH (MTH) 5 15194.73 601.28 897908.87 202.33
M*S 7 80.40 3.18 17602.98 3.97
M*MTH 5 289.66 11.46 17621.62 3.97
S*MTH 35 72.09 2.85 2354.36 0.53
ML *S*MTH 35 73.99 2.93 4685.08 1.06
Error 96 25.27 4437.84
Total 191
doi:10.1371/journal.pone.0138082.t004
Household Wastes and Dengue Vectors in Rural-Urban Gradient
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Fig 3. Biplot representing the ordination of sampling months in terms of Ae.aegypti productivity in the surveyed household wastes (Wilk’λ=
0.015; F
30, 342
= 21.15; P<0.0001).
doi:10.1371/journal.pone.0138082.g003
Household Wastes and Dengue Vectors in Rural-Urban Gradient
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Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 12 / 21

shape and size of the plastic and glass waste containers, similar to the observations made in
Australia [51], Africa [52], Vietnam [53], North and South America [54–58]. It seems that
identification and classification of plastic and glass household wastes needs to be reviewed in
terms of hazard potential and adverse health impact in both urban and rural areas [21,59,60].
The present survey was carried out in the urban and rural regions of Kolkata metropolis as
model geographical region with the aim to identify and classify those hazardous containers
responsible for sustaining Aedes. Seasonal variations and periodicity was amply reflected in the
relative abundance of the Aedes immature in the waste containers similar to many other places
around the globe [9,12,17,23]. Preference of the dengue vectors for the waste container, based
on the location and type of material, could be deduced through the corresponding immature
productivity (Figs 1and 2). The monthly variations in the relative abundance of Ae.aegypti
and Ae.albopictus as reflected in the biplots (Figs 3and 4) can be attributable to the differences
in the availability of congenial breeding sites. Although Aedes can exploit varied kind of plastic
and glass wastes as larval habitats, the availability of such wastes in itself is a major concern for
vector management. Population regulation of Ae.aegypti and Ae.albopictus is constrained pri-
marily due to its exploitation of domestic environment for breeding and secondarily due to
human-mediated dispersal that enhances abundance at spatial scale [48,52,54]. Mosquito pro-
ductivity increases with the availability of the porcelain (including glass) and plastic waste con-
tainers, and thus appropriate measures should be taken to reduce the waste generation and
management [61–63]. Inappropriate use of the porcelain and plastic containers along with
poor waste management strategies lead to an extended life of the porcelain and plastic waste
products. Variation in waste generation in space leads to the diversification of the breeding
sites of Aedes mosquitoes, thereby leading to surge in mosquito abundance. Possibly the gener-
ation of the wastes varied over the months contributing to the differences in the abundance of
the mosquitoes in the area. Persistence of such waste products adds to the permanence of
breeding and growth of Aedes mosquitoes and thus the possibility of dengue episodes [64].
Effective solid waste management strategies for Kolkata [19,65] and other similar cities where
household wastes are contributing to mosquito breeding [66,67] should be prioritized for inter-
vention of Aedes population and reduce the risk of dengue and chikungunya.
Water retention capability and resource content enable porcelain (including glass) and plas-
tic containers as favourable breeding habitats of dengue vectors. In urban areas, the frequent
disposal of household plastic wastes is common contrast to the rural areas [31,32]. In Indian
context, waste generation is linked with the socioeconomic factors [30], which are expected to
differ between urban and rural communities. Although socioeconomic and life style patterns
differ between urban and rural areas, it appears that the generation of waste in rural areas differ
from urban areas quantitatively but not qualitatively. As a result, the breeding grounds of den-
gue vectors were more abundant in urban areas, with higher frequency of dengue incidence, as
portrayed in the biplots (Figs 5and 6). However, the present study suggests that the trend may
change, since the porcelain and plastic wastes generated in rural areas are equally compatible
for Aedes breeding. Thus vector control strategies should incorporate the rural and suburban
areas for regulation Aedes mosquito abundance. While only few discrete studies in rural areas
of North India [19,43,45] record the occurrence of the dengue vectors, planned dengue vector
control strategies are yet to be employed. In majority instances in India and other tropical
regions, dengue vector control is restricted to urban populated sites [4,45,49]. Extending the
previous observations on dengue vectors in rural areas through the present study, refined
Fig 4. Biplot representation of the ordination of sampling months in terms of Ae.albopictus productivity in the surveyed household wastes (Wilk’
λ= 0.021; F
30, 342
= 180576; P<0.0001).
doi:10.1371/journal.pone.0138082.g004
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 13 / 21

Fig 5. Biplot representation of the ordination of urban-rural areas in terms of productivity of Ae.aegypti in the household wastes surveyed(Wilk’λ=
0.0303; F
42, 393
=2.708;P<0.0001). Here, R(rural)1 = Serampore, R2 = Baidyabati,R3 = Singur and R4= Haripal and U (urban)1 = Baranagar,
U2 = Ballygunge, U3 = Chetla, and U4 = Patuli.
doi:10.1371/journal.pone.0138082.g005
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 14 / 21

Fig 6. Biplot representation of the ordination of urban-rural areas in terms of productivity of Ae.albopictus in the household wastes surveyed
(Wilk’λ= 0.477; F
42, 393
= 1.589; P<0.013). Here, R (rural)1 = Serampore, R2 = Baidyabati, R3 = Singur and R4 = Haripal and U (urban)1 = Baranagar,
U2 = Ballygunge, U3 = Chetla, and U4 = Patuli.
doi:10.1371/journal.pone.0138082.g006
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 15 / 21

strategies may be framed for dengue vector control inclusive of rural areas. Accessibility of
waste containers in indoor or outdoor locations depends on knowledge and attitude of the
Table 5. The results of Discriminant Analysis showing Fishers distance, standardized canonical correlations and Eigen values of the months and
explanatory variables, in case of Ae.aegypti.Porcelain and plastic habitats are denoted by pr and pl.
Ae.aegypti -Month
Fishers distance Aug Dec Jul Nov Oct
Dec 374.828
Jul 52.748 159.120
Nov 109.582 83.661 15.215
Oct 60.392 140.283 4.854 10.752
Sep 45.902 166.566 2.554 17.050 1.611
Standardized canonical discriminant function coefficients
F1 F2 F3
Positive pr 0.257 0.630 0.366
Larvae pr 0.598 -0.175 -0.907
Pupae pr -0.043 -0.382 0.580
Positive pl 0.519 0.445 -0.006
Larvae pl 0.382 -0.505 -0.115
Pupae pl 0.286 -0.271 0.732
F1 F2 F3
Eigen value 28.345 0.456 0.305
Discrimination (%) 96.752 1.557 1.042
Cumulative % 96.752 98.309 99.35
Canonical correlations 0.983 0.560 0.484
doi:10.1371/journal.pone.0138082.t005
Table 6. The results of Discriminant Analysis showing Fishers distance, standardized canonical correlations and Eigen values of the months and
explanatory variables in Ae.albopictus.Porcelain and plastic habitats are denoted by pr and pl.
Ae.albopictus-Month
Fisher distances Aug Dec Jul Nov Oct
Dec 219.374
Jul 22.104 107.852
Nov 129.626 12.158 48.602
Oct 56.649 55.841 9.407 16.102
Sep 6.155 226.379 26.217 134.638 58.483
Standardized canonical discriminant function coefficients
F1 F2 F3
Positive pr 0.579 -0.287 0.605
Larvae pr 0.184 -0.510 0.118
Pupae pr 0.097 0.286 -0.232
Positive pl 0.586 0.777 0.212
Larvae pl 0.230 -0.749 -0.294
Pupae pl 0.184 0.198 -0.614
F1 F2 F3
Eigen value 25.903 0.475 0.173
Discrimination (%) 97.460 1.788 0.650
Cumulative % 97.460 99.248 99.898
Canonical correlations 0.981 0.568 0.384
doi:10.1371/journal.pone.0138082.t006
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 16 / 21

people about likelihood of waste into prospective Aedes larval habitat [11,15]. Appropriate
management practice can reduce availability of waste containers, thereby reducing the prospec-
tive Aedes larval habitats. Possible limitations in such practices may have allowed conversion of
porcelain and plastic wastes as larval habitats in the present study area. The regulation or local
elimination of dengue vectors are often limited by the recurrent colonization in respective habi-
tats following availability of resources and water. The ability of the eggs of Aedes mosquitoes to
withstand desiccation is another factor that can facilitate re-colonization in the same habitat
following control. While natural larval habitats like tree hole can rarely be modified, restriction
of the waste generated forms a major way of creation of habitats for larval breeding. Appropri-
ate steps may therefore be taken to reduce the generation of the plastic and porcelain (including
glass) wastes along with scientific methods for disposal so that the reduction of the sources of
breeding is ensured. The citizens should be communicated about the potential harm owing to
these wastes, as well [33,68]. It is pertinent to mention that the present study is limited in terms
of exploring all the possible habitats of dengue vectors, including the tree holes and bromeliads.
The strategies for vector management should include such habitats where the pupal productiv-
ity of Aedes mosquitoes is equally a concern for public health. Restriction of breeding of Aedes
mosquitoes is of prime importance to reduce the incidence of dengue and chikungunya. In
order prioritize larval habitat based population intervention to reduce possibilities of dengue,
studies may be initiated to determine the pattern and preference of oviposition habitats by
Aedes mosquitoes in urban and rural areas of India and Kolkata in particular.
Table 7. The results of Discriminant Analysis showing Fisher’s distance, standardized canonical correlations and Eigen values of the urban-rural
areas and explanatory variables in Ae.aegypti.Porcelain and plastic habitats are denoted by pr and pl.
Ae.aegypti
Positive habitats Immature abundance
Source df Mean Square F Mean Square F
MATERIAL (M) 1 5260.55 127.3 2033839.17 857.22
SITE (S) 7 257.166 6.221 10960.91 4.62
MONTH (MTH) 5 12974.4 313.9 1169999.54 493.13
M*S 7 189.952 4.595 37549.14 15.83
M*MTH 5 146.097 3.534 138230.76 58.26
S*MTH 35 30.9052 0.748 6621.34 2.79
ML *S*MTH 35 29.6731 0.718 6026.44 2.54
Error 96 41.3385 2372.59
Total 191
Ae.albopictus
Positive habitats Immature abundance
Source df Mean Square F Mean Square F
MATERIAL (M) 1 744.19 29.45 59925.33 13.50
SITE (S) 7 24.87 0.98 9700.58 2.19
MONTH (MTH) 5 15194.73 601.28 897908.87 202.33
M*S 7 80.40 3.18 17602.98 3.97
M*MTH 5 289.66 11.46 17621.62 3.97
S*MTH 35 72.09 2.85 2354.36 0.53
ML *S*MTH 35 73.99 2.93 4685.08 1.06
Error 96 25.27 4437.84
Total 191
doi:10.1371/journal.pone.0138082.t007
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 17 / 21

The entire data set, tables (Tables 1through 8), and figures (Figs 1through 6) used in the
present manuscript are included in the supporting information files.
Supporting Information
S1 File. This file contains the entire data set related to Tables 1through 8of the present
manuscript.
(XLSM)
S2 File. This file contains the entire data set related to Fig 1 and Fig 2 of the present manu-
script.
(XLSM)
S3 File. This file contains the entire data set related to Figs 3through 6of the present man-
uscript.
(XLSM)
Acknowledgments
The authors thank the respective Heads of the Departments of Zoology, University of Calcutta,
Kolkata and The University of Burdwan, Burdwan for the facilities provided including DST-
FIST.
Table 8. The results of Discriminant Analysis showing Fishers distance, standardized canonical correlations and Eigen values of the urban-rural
areas and explanatory variables in Ae.albopictus.Porcelain and plastic habitats are denoted by pr and pl.
Ae.aegypti- Area
Fisher’s distance R1 R2 R3 R4 U1 U2 U3
R2 0.263
R3 1.080 1.146
R4 0.697 0.255 0.786
U1 1.300 1.166 0.438 1.009
U2 4.414 4.101 1.571 3.344 1.006
U3 3.469 3.497 2.822 3.863 1.164 1.818
U4 3.049 2.591 1.137 2.120 0.420 0.376 1.158
Standardized canonical discriminant function coefficients
F1 F2 F3
Positive pr 1.911 1.945 1.138
Larvae pr -2.205 0.410 -0.583
Pupae pr -0.556 -0.577 0.260
Positive pl 0.556 -0.573 0.314
Larvae pl 0.110 -2.388 2.312
Pupae pl 0.059 1.113 -3.536
F1 F2 F3
Eigen value 0.642 0.196 0.055
Discrimination (%) 70.999 21.611 6.040
Cumulative % 70.999 92.610 98.650
Canonical correlation 0.625 0.404 0.228
doi:10.1371/journal.pone.0138082.t008
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 18 / 21

Author Contributions
Conceived and designed the experiments: SB GA GKS. Performed the experiments: SB. Ana-
lyzed the data: SB GA. Contributed reagents/materials/analysis tools: GA SB GKS. Wrote the
paper: SB GA GKS. Carried out the field survey: SB. Carried out statistical analysis: SB GA.
Contributed equally in compiling the manuscript: SB GA GKS.
References
1. Blight GE, Mbande CM (1996) Some problems of waste management in developing countries. J Sol
Waste Technol Manage 23: 19–27.
2. Hamer G (2003) Solid waste treatment and disposal: effects on public health and environmental safety.
Biotechnol Adv 22: 71–79. PMID: 14623044
3. WHO (2009) Dengue: guidelines for diagnosis, treatment, prevention and control. WHO/HTM/NTD/
DEN/2009.1
4. WHO–SEARO (2011) Comprehensive guidelines for prevention and control of dengue and dengue
haemorrhagic fever. Revised and expanded edition. SEARO Technical Publication Series, New Delhi,
India.
5. Adeyeba OA, Akinbo JA (2002) Pathogenic intestinal parasites and bacterial agents in solid wastes.
East Afr Med J 79: 604–610. PMID: 12630495
6. Achudume AC, Olawale JT (2007) Microbial pathogens of public health significance in waste dumps
and common sites. J Environ Biol 28: 151–154. PMID: 17718005
7. Gerba CP, Tamimi AH, Pettigrew C, Weisbrod AV, Rajagopalan V (2011) Sources of microbial patho-
gens in municipal solid waste landfills in the United States of America. Waste Manage Res 29: 781–
790. doi: 10.1177/0734242X10397968
8. Barrera R, Avila J, Gonzalez–Tellez S (1993) Unreliable supply of potable water and elevated Aedes
aegypti larval indices: a causal relationship? J Am Mosq Control Assoc9: 189–196.
9. Macoris MLG, Mazine CAB, Anclrighetti MTM, Yasumaro S, Silva ME, Nelson MJ (1997) Factors favor-
ing houseplant container infestation with Aedesaegypti larvae in Manila, Sao Paulo, Brazil. Pan Am J
Public Health1: 280–286.
10. Pramanik MK, Aditya G, Raut SK (2007) Seasonal prevalence of Aedes aegypti immatures in Kolkata,
India. Southeast Asian J Trop Med Public Health 38: 442–447. PMID: 17877217
11. Focks DA, Alexander N (2006) Multicountry study of Aedes aegypti pupal productivity survey methodol-
ogy: Findings and recommendations. WHO TDR/IRM/DEN/06.1
12. Banerjee S, Aditya G, Saha GK (2013) Household disposables as breeding habitats of dengue vectors:
linking wastes and public health. Waste Manage 33: 233–239. doi: 10.1016/j.wasman. 2012.09.013
13. WHO (2002) Dengue and Dengue Hemorrhagic Fever: Fact Sheet. Available: http://www.who.int/
mediacentre/factsheets/fs117/en; 2002.
14. WHO–SEARO (2006) Dengue status of India in 2006. WHO South East Asian Regional Office, New
Delhi, India.
15. Arunachalam N, Tana S, Espino F, Kittayapong P, Abeyewickreme W, Wai KT, et al. (2010) Eco–bio–
social determinants of dengue vector breeding: a multi-country study in urban and periurban Asia. Bull
World Health Organ 88: 173–184. doi: 10.2471/BLT.09.067892 PMID: 20428384
16. Barrera R, Amador M, MacKay AJ (2011) Population dynamics of Aedes aegypti and dengue as influ-
enced by weather and human behavior in San Juan, Puerto Rico. PLoS Negl Trop Dis 5(12): e1378.
doi: 10.1371/journal.pntd.0001378 PMID: 22206021
17. Mazine CAB, Macoris MLG, Andrighetti MTM, Yasumaro S, Silva ME, Nelson MJ (1996) Disposable
containers as larval habitats for Aedes aegypti in a city with regular refuse collection: a study in Marilia,
São Paulo State, Brazil.Acta Trop 62: 1–13. PMID: 8971274
18. Misra V, Pandey SD (2005) Hazardous waste impact on health and environment for development of
better waste management strategies in future in India. Environ Int 31: 417–431. PMID: 15734194
19. Kumar S, Bhattacharyya JK, Vaidya AN, Chakrabarti T, Devotta S, Akolkar AB (2009) Assessment of
the status of municipal solid waste management in metro cities, state capitals, class I cities, and class II
towns in India: An insight. Waste Manage 29: 883–895.
20. Sharholy M, Ahmad K, Mahmood G, Trivedi RC (2008) Municipal solid waste management in Indian cit-
ies–A review. Waste Manage 28: 459–467.
21. Biswas AK, Kumar S, Babu SS, Bhattacharyya JK, Chakrabarti T (2010) Studies on environmental
quality in and around municipal solid waste dumpsite. Resour Conserv Recy 55: 129–134.
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 19 / 21

22. Harrington LC, Scott TW, Lerdthusnee K, Coleman RC, Castero A, Clark CG, et al. (2005) Dispersal of
the dengue vector Aedes aegypti within and between rural communities. Am J Trop Med Hyg 72: 209–
220. PMID: 15741559
23. Troyo A, Calderón-Arguedas O, Fuller DO, Solano ME, Avendaño A, Arheart KL, et al. (2008) Seasonal
profiles of Aedes aegypti (Diptera: Culicidae) larval habitats in an urban area of Costa Rica with a his-
tory of mosquito control. J Vector Ecol 33:76–88. PMID: 18697310
24. Tsuzuki A, Vu TD, Higa Y, Nguyen TY, Takagi M (2009) Effect of peridomestic environments on
repeated infestation by pre adult Aedesaegyptiin urban premises in Nha Trang city, Vietnam. Am J
Trop Med Hyg 81: 645–650. doi: 10.4269/ajtmh.2009.08-0175 PMID: 19815880
25. Balakrishnan N, Venkatesh S, Lal S (2006) An entomological study of dengue vectors during outbreak
of Dengue in Tiruppar town and its surroundings, Tamil Nadu, India. J Commun Dis 38: 164–168.
PMID: 17370680
26. Ramasamy R, Surendran SN, Jude PJ, Dharshini S, Vinobaba M (2011) Larval development of Aedes
aegypti and Aedes albopictus in peri–urban brackish water and its implications for transmission of arbo-
viral diseases. PLOS Negl Trop Dis 5(11): e1369. doi: 10.1371/journal.pntd.0001369 PMID: 22132243
27. Baruah S, Dutta P (2012) Seasonal pattern of abundance of Aedesalbopictus in urban and industrial
areas of Dibrugarh district Assam. Asian J Exp Biol Sci 3: 559–564.
28. Tewari SC, Thenmozhi V, Katholi CR, Manavalan R, Munirathinam A, Gajanana A (2004) Dengue vec-
tor prevalence and virus infection in a rural area in south India. Trop Med Int Health 9: 499–507. PMID:
15078269
29. Rao BB, George B (2010) Breeding patterns of Aedes (Stegomyia)albopictus in periurban areas of Cal-
icut, Kerala, India. Southeast Asian J Trop Med Public Health 41: 536–540. PMID: 20578539
30. Asian Productivity Organization (2007) Solid waste management: issues and challenges in Asia. Asian
Productivity Organization, Tokyo. Ed. Environmental Management Centre, Mumbai, India; 340 p.
31. Zhu D, Asnami PU, Zurbrügg C, Anapolsky S, Mani S (2008) Improving municipal solid waste manage-
ment in India. A source book for policy makers and practitioners. Washington, DC, USA: The World
Bank, Washington. 176 p.
32. Khajuria A, Yamamoto Y, Morioka T (2010) Estimation of municipal solid waste generation and landfill
area in Asian developing countries. J Env Biol 31: 649–654.
33. Shah R, Sharma US, Tiwari A (2012) Sustainable solid waste management in rural areas. Int J Theor
ApplSci 4: 72–75.
34. Aditya G, Pramanik MK, Saha GK (2009) Immatures of Aedes aegypti in Darjeeling Himalayas–
expanding geographical limits in India. Indian J Med Res 129: 455–457. PMID: 19535844
35. Aditya G, Tamang R, Sharma D, Subba F, Saha GK (2008) Bamboo stumps as mosquito larval habitats
in Darjeeling Himalayas, India–a spatial scale analysis. Insect Sci 15: 245–249. doi: 10.1111/j.1744–
7917.2008.00207
36. Krebs CJ (1999) Ecological Methodology. II ed. California, USA: Benjamin Cummings.
37. Reinert JF, Harbach RE, Kitching IJ (2009). Phylogeny and classification of Tribe Aedini (Diptera: Culi-
cidae). Zool J Linn Soc 157: 700–794.
38. Reinert JF, Harbach RE, Kitching IJ (2006) Phylogeny and classification of Finlaya and allied taxa (Dip-
tera: Culicidae: Aedini), based on morphological data from all life stages. Zool J Linn Soc 148: 1–101.
39. Hurlbert SH (984) Pseudoreplication and the design of ecological field experiments. Ecol Monogr 54:
187–192.
40. Zar KH (1999) BiostatisticalAnalysis( 4th ed.). New Delhi, India: Pearson Education (Singapore) Pte
Ltd., (Indian Branch). 663p.
41. Legendre P, Legendre L (1998) Numerical ecology, 2nd English edition. Elsevier Science BV, Amster-
dam. 852p.
42. Addinsoft SARL (2010) XLSTAT software, 2010. Version 10.0, Paris, France.
43. Ratho RK, Mishra B, Kaur J, Kakkar N, Sharma K (2005). An outbreak of dengue fever in peri urban
slums of Chandigarh, India, with special reference to entomological and climatic factors. Indian JMed
Res59: 518–527.
44. Mariappan T, Srinavasan R,Jambulingam P (2008)Defective rainwater harvesting structure and den-
gue vector productivity compared with peridomestic habitats in a coastal town in Southern India. J Med
Entomol 45, 148–156. PMID: 18283956
45. Katyal R, Kumar K, Gill KS (1997) Breeding of Aedes aegypti and its impact on dengue/DHF in rural
areas. Dengue Bull 21: 93–98.
46. Angel V, Joshi B (2009) Distribution of dengue virus types in Aedes aegypti in dengue endemic districts
of Rajasthan, India. Indian J Med Res 129:665–668. PMID: 19692746
Household Wastes and Dengue Vectors in Rural-Urban Gradient
PLOS ONE | DOI:10.1371/journal.pone.0138082 October 8, 2015 20 / 21

47. Mangudo C, Aparicio JP, Gleiser RM (2007) Tree holes as larval habitats for Aedes aegypti in public
areas in Aguaray, Salta province, Argentina. J Vector Ecol 36: 227–230.
48. Banerjee S, Aditya G, Saha N, Saha GK (2010) An assessment of macroinvertebrate assemblages in
mosquito larval habitats–space and diversity relationship. Environ Monit Assess 168: 597–611. doi:
10.1007/s10661-009-1137-9 PMID: 19760088
49. Medronho RA, Macrini L, Novellino DM, Lagrotta MTF, Câmara VM, Pedreira CE (2009) Aedes aegypti
immature forms distribution according to type of breeding site.Am J Trop Med Hyg 80: 401–404. PMID:
19270289
50. Topuz E, Talinli I, Aydin E (2011) Integration of environmental and human health risk assessment for
industries using hazardous materials: A quantitative multi criteria approach for environmental decision
makers. Environ Int 37: 393–403. doi: 10.1016/j.envint.2010.10.013 PMID: 21111481
51. Tun–Lin W, Kay BH, Barnes A, Forsyth S (1996) Critical examination of Aedes aegypti indices: Correla-
tions with abundance.Am J Trop Med Hyg 54: 543–547. PMID: 8644913
52. Adeleke MA, Mafiana CF, Idowu AB, Adekunle MF, Sam–Wobo SO (2008) Mosquito larval habitats
and public health implications in Abeokuta, Ogun State, Nigeria.Tanzan J Health Res 10: 103–107.
PMID: 18846789
53. Schmidt W-P, Suzuki M, Dinh Thiem V, White RG, Tsuzuki A, Yoshida LM, et al. (2011) Population
Density, Water Supply, and the Risk of Dengue Fever in Vietnam: Cohort Study and Spatial Analysis.
PLoS Med 8(8): e1001082. doi: 10.1371/journal.pmed.1001082 PMID: 21918642
54. Braks MAH, Hono´rio NA, Lourenço–de–Oliveira R, Juliano SA, Lounibos P (2003) Convergent habitat
segregation of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Southeastern Brazil and
Florida. J Med Entomol 40: 785–794. PMID: 14765654
55. Schreiber E, Chamberlain S, Thomas R, Parsons R, Baker G (1993) Surveys on artificial container
inhabiting–mosquitoes in Sarasota and Tallahassee, Florida I: Characterizations of larval habitats. J
Florida Mosq Control Assoc 63: 7–15.
56. Yee DA (2008) Tires as habitats for mosquitoes: a review of studies within the eastern United States. J
Med Entomol 45: 581–593. PMID: 18714856
57. Burke R, Barrera R, Lewis M, Kluchinsky T, Claborn D (2010) Septic tanks as larval habitats for the
mosquitoesAedes aegypti and Culex quinquefasciatus inPlaya–Playita, Puerto Rico.Med Vet Entomol
24: 117–123. doi: 10.1111/j.1365–2915.2010.00864.x PMID: 20374477
58. Vezzani D, Albicocco AP (2009) The effect of shade on the container index and pupal productivity of
the mosquitoes Aedes aegypti and Culex pipiens breeding in artificial containers. Med Vet Entomol 23:
78–84. doi: 10.1111/j.1365-2915.2008.00783.x PMID: 19239617
59. Nath KJ (2003) Home hygiene and environmental sanitation: a country situation analysis for India. Int J
Environ Health Res 13: S19–S28. PMID: 12775376
60. Giusti L (2009) A review of waste management practices and their impact on human health. Waste
Manage 29: 2227–2239.
61. Sujauddin M, Huda SMS, Rafiqul Hoque ATM (2008) Household solid waste characteristics and man-
agement in Chittagong, Bangladesh. Waste Manage 28: 1688–1695.
62. Jude PJ, Dharshini S, Vinobaba M, Surendran SN, Ramasamy R (2010) Anopheles culicifacies breed-
ing in brackish waters in Sri Lanka and implications for malaria control. Malar J 9:106. doi: 10.1186/
1475–2875–9–106 PMID: 20409313
63. Jeffery JAL, Clements ACA, Nguyen YT, Nguyen LH, Tran SH, Le NT, et al. (2012) Water level flux in
household containers in Vietnam–a key determinant of Aedes aegypti population dynamics. PLOS One
7(7): e39067. doi: 10.1371/journal.pone.0039067
64. Malandrakis GN (2008) Children’s understandings related to hazardous household items and waste.
Environ Edu Res 14: 579–601.
65. Gupta S, Mohan K, Prasad R, Gupta S, Kansal A (1998) Solid waste management in India: options and
opportunities. Resour Conserv Recy 24:137–154.
66. Irwin P, Arcari C, Hausbeck J, Paskewitz S (2008) Urban wet environment as mosquito habitat in the
upperMidwest. EcoHealth 5: 49–57.
67. Nguyen LAP, Clements ACA, Jeffery JAL, Yen NT, Nam VS, Vaughan G, et al. (2011) Abundance and
prevalence of Aedes aegypti immatures and relationships with house hold water storage in rural areas
in southern Vietnam. Int Health 3: 115–125. doi: 10.1016/j.inhe.2010.11.002 PMID: 24038184
68. Chakrabarti S, Majumder A, Chakrabarti S (2009) Public–community participation in household waste
management in India: An operational approach. Habitat Int 33: 125–130.
Household Wastes and Dengue Vectors in Rural-Urban Gradient
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