Content uploaded by Wadaka Mamaï
Author content
All content in this area was uploaded by Wadaka Mamaï on Jan 12, 2021
Content may be subject to copyright.
insects
Article
Does Tap Water Quality Compromise the Production of Aedes
Mosquitoes in Genetic Control Projects?
Wadaka Mamai 1,2,*, Hamidou Maiga 1,3 , Nanwintoum Sévérin BimbiléSomda 1,3,4, Thomas Wallner 1,
Odet Bueno Masso 1, Christian Resch 5, Hanano Yamada 1and Jérémy Bouyer 1
Citation: Mamai, W.; Maiga, H.;
Bimbilé Somda, N.S.; Wallner, T.;
Masso, O.B.; Resch, C.; Yamada, H.;
Bouyer, J. Does Tap Water Quality
Compromise the Production of Aedes
Mosquitoes in Genetic Control
Projects? Insects 2021,12, 57.
https://doi.org/10.3390/insects1201
0057
Received: 24 November 2020
Accepted: 7 January 2021
Published: 12 January 2021
Publisher’s Note: MDPI stays neu-
tral with regard to jurisdictional clai-
ms in published maps and institutio-
nal affiliations.
Copyright: © 2021 by the authors. Li-
censee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and con-
ditions of the Creative Commons At-
tribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
1Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture,
Vienna, Austria; h.maiga@iaea.org (H.M.); N.S.Bimbile-Somda@iaea.org (N.S.B.S.); T.Wallner@iaea.org (T.W.);
odetbueno123@hotmail.com (O.B.M.); H.Yamada@iaea.org (H.Y.); J.Bouyer@iaea.org (J.B.)
2Institut de Recherche Agricole pour le Développement (IRAD), PO. Box 2123 Yaoundé, Cameroon
3Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), 01 PO. Box 545
Bobo-Dioulasso, Burkina Faso
4
Laboratoire d’Entomologie Fondamentale et Appliquée (LEFA), UniversitéJoseph Ki-Zerbo, 03 PO. Box 7021
Ouagadougou, Burkina Faso
5Soil and Water Management and Crop Nutrition Laboratory, Joint FAO/IAEA Division of Nuclear
Techniques in Food and Agriculture, Vienna, Austria; CH.Resch@iaea.org
*Correspondence: mwjosephfr@yahoo.fr
Simple Summary:
Scientists all over the world are continually rearing and producing insects in
laboratories for many purposes including pest control programmes. Aedes aegypti and Ae. albopictus
are mosquitoes of public health importance due to their ability to vector human and animal pathogens
and thus vector control represents an important component of many disease control programmes.
Water is a factor of great importance in the larval environment of mosquito species. However,
obtaining sufficient water of reliable quality for mosquito rearing is still challenging, especially in
developing and least developed countries, where access even to clean drinking water is limited. In
prospect of cost-effective methods for improved mass-rearing toward SIT application, we assessed
the impact of using tap water on the development and quality of Aedes mosquitoes. Results showed
that, tap water with hardness/electrical conductivity beyond certain levels (140 mg/L CaCO
3
or
368
µ
S/cm) was shown to have a negative impact on the production of Ae. albopictus and Ae. aegypti
mosquitoes. These results suggest that the quality of water should be checked when using for rearing
mosquitoes for release purposes in order to optimize the production performance of mass-rearing
facilities. This may have important implications for the implementation of the sterile insect technique
in areas where reverse osmosis water is a scarce or costly resource.
Abstract:
A mosquito’s life cycle includes an aquatic phase. Water quality is therefore an important
determinant of whether or not the female mosquitoes will lay their eggs and the resulting immature
stages will survive and successfully complete their development to the adult stage. In response to
variations in laboratory rearing outputs, there is a need to investigate the effect of tap water (TW) (in
relation to water hardness and electrical conductivity) on mosquito development, productivity and
resulting adult quality. In this study, we compared the respective responses of Aedes aegypti and Ae.
albopictus to different water hardness/electrical conductivity. First-instar larvae were reared in either
100% water purified through reverse osmosis (ROW) (low water hardness/electrical conductivity),
100% TW (high water hardness/electrical conductivity) or a 80:20, 50:50, 20:80 mix of ROW and
TW. The immature development time, pupation rate, adult emergence, body size, and longevity
were determined. Overall, TW (with higher hardness and electrical conductivity) was associated
with increased time to pupation, decreased pupal production, female body size in both species
and longevity in Ae. albopictus only. However, Ae. albopictus was more sensitive to high water
hardness/EC than Ae. aegypti. Moreover, in all water hardness/electrical conductivity levels tested,
Ae. aegypti developed faster than Ae. albopictus. Conversely, Ae. albopictus adults survived longer
than Ae. aegypti. These results imply that water with hardness of more than 140 mg/l CaCO
3
or
electrical conductivity more than 368
µ
S/cm cannot be recommended for the optimal rearing of Aedes
Insects 2021,12, 57. https://doi.org/10.3390/insects12010057 https://www.mdpi.com/journal/insects
Insects 2021,12, 57 2 of 13
mosquitoes and highlight the need to consider the level of water hardness/electrical conductivity
when rearing Aedes mosquitoes for release purposes.
Keywords: water quality; Aedes mosquitoes; vectors; water hardness; electrical conductivity; ions
1. Introduction
All organisms are directly or indirectly affected by the physico-chemical attributes of
the environment in which they develop [
1
]. A mosquito’s life cycle includes an aquatic
phase. They require water bodies for oviposition and completing the larval and pupal
stages. Therefore, water is an important determinant for oviposition, developmental
success of immature stages [
2
] and adult life traits [
3
]. Extensive literature exists across
diverse insect taxa describing the influence of physico-chemical parameters of breeding
sites in relation to their abundance, and each species has its preferred water bodies. Aedes
aegypti lay eggs in rainwater generally in artificial containers which has a very low hardness
and is similar to reverse osmosis water. Several studies have found that dissolved oxygen,
pH, temperature, conductivity and vegetation seem to be driving variables for larval
abundance of several mosquito species [
4
–
7
]. In various laboratories all over the world,
scientists are continually rearing and producing insects for many scientific purposes and
for pest control programmes [
8
–
10
]. However, the rearing of mosquitoes is complex and
demands careful assessment of water quality, larval density, nutrition and environmental
conditions. Although most insectaries use deionized or ROW for rearing mosquitoes, many
countries located in arid zones often use other water sources including TW [
11
], surface
water, groundwater, and desalinated water for rearing mosquitoes. Various parameters
such as water hardness, electrical conductivity, salinity and total dissolved solids are
commonly used as indicators of water quality [
12
–
14
]. The total hardness is the measured
content of all divalent cations in the water. Traditionally, it is a measurement of the capacity
of water to react with soap and describes the ability of water to bind soap to form lather,
which affects the washing process. Calcium (Ca
2+
) and magnesium (Mg
2+
) are the main
contributors to the total hardness in most freshwater systems [
15
,
16
]. Salts that dissolve
in water break into positively and negatively charged ions. In this regard, salinity is a
measure of the amount of salts in the water, while the electrical conductivity a parameter
used to estimate the level of dissolved salts in water refers to the ability of the material to
allow the flow of an electric current, which is carried by ions in the solution [
17
]. Therefore,
high conductivity indicates high water mineralization [
18
]. Because dissolved ions increase
salinity as well as conductivity, the two measurements are strongly related. The term “total
dissolved solids” is often used for salinity. In this study, we will refer to water hardness
and electrical conductivity.
The majority of the world’s population lives in areas where mosquitoes are present,
and the worldwide incidence of mosquito-borne diseases is enormous. Aedes aegypti
(Linnaeus, 1762) and Ae. albopictus (Skuse, 1894) are invasive species and continue to
expand their distribution range. They are very efficient to transmit several viruses between
vertebrate hosts causing deadly diseases such as dengue, chikungunya, yellow fever, West
Nile fever and Zika [
19
]. Expansion of the transmission season in endemic areas, re-
emergence in certain areas after a prolonged absence of transmission, spread to areas where
transmission had not previously occurred, and outbreaks of these diseases are becoming
more frequent in both developed and developing countries. With limited commercially
available vaccines and antiviral therapies, Aedes spp. populations control is a cornerstone
to prevent disease transmission. Since the world has observed the outbreak of Zika in
the Americas in late 2015, there are renewed interests globally, to use the sterile insect
technique (SIT) as part of area wide integrated pest management (AW-IPM) programmes
to control mosquito-borne diseases [
9
,
10
,
20
–
23
]. The SIT relies on the mass production
of mosquitoes, which demands a huge amount of water [
24
,
25
]. However, obtaining
Insects 2021,12, 57 3 of 13
sufficient water of reliable quality is still challenging due to aridity, lack of environmental
protection and adequate treatment techniques, especially in developing and least developed
countries, where access even to clean drinking water is limited [
26
]. Aedes mosquitoes
are being mass-reared for release in disease control programs around the world. While
researchers strive to provide optimum rearing conditions and are establishing standard
operating procedures [
27
,
28
], water quality can differ between countries and seasons [
29
,
30
].
In response to variations in the mass-rearing outputs in many Food and Agriculture
Organization of the United Nations (FAO) and International Atomic Energy Agency (IAEA)
Member States, there is an urgent need to investigate the effect of water quality on mosquito
development, productivity and resulting adult quality. Recent evidence demonstrated
the influence of water hardness on the development of Anopheles [
31
] and Culex [
32
]
mosquitoes. However, to the best of our knowledge, the impact of the TW quality (in
relation to hardness or electrical conductivity) on Aedes mosquito species is insufficiently
documented. In this study, we aim to explore the respective responses of Ae. aegypti and
Ae. albopictus to different TW hardness and electrical conductivity levels (ROW, TW and
mixtures of varying proportions of ROW and TW). Parameters assessed include time to
pupation, pupation rate, emergence rate, adult production rate, adult body size and adult
longevity.
2. Materials and Methods
2.1. Source of Experimental Mosquitoes
In this study, we used colonies of Ae. aegypti and Ae. albopictus originating from
Juazeiro, Brazil (provided by Biofabrica Moscamed, IAEA Collaborative Center since
2012) and Italy (provided by Centro Agricoltura Ambiente, IAEA Collaborative Center
since 2018), respectively. They were established and maintained at the Insect Pest Control
Laboratory (IPCL) under controlled environmental conditions: the larval rearing room was
maintained at 28
±
2
◦
C, 80
±
10% RH and the adult rearing room at 26
±
2
◦
C, 60
±
10%
RH, with a 14:10 h light:dark (L:D) cycle with 1 h periods of simulated dusk and dawn in
both rooms. Aedes aegypti and Ae. albopictus eggs used in these experiments were obtained
following mass-rearing procedures developed at the IPCL [28,33–35].
2.2. Preparation of Water Media and Determination of Their Hardness/Electrical Conductivity
and pH
Water media (n= 5) with increasing hardness or electrical conductivity were prepared
for tests by adding TW to ROW as follows: (1)100% ROW, (2) 80% ROW + 20% TW, (3) 50%
ROW + 50% TW, (4) 20% ROW + 80% TW, (5) 100% TW. The ROW water was considered as
the baseline water hardness level and the control treatment as it represents water routinely
and successfully used for rearing Aedes mosquitoes. TW was considered as the highest
level of hardness in this experiment. After dilution in large containers, four samples of
each water treatment were taken to determine the hardness and the conductivity values.
The remaining water was used for rearing.
The water hardness was measured using the Dosatest
®
test strips which is a semi-
quantitative method. Clear colour changes from green to red ensure reliable results within
seconds. The strip was simply and properly dipped and the colour compared with the
colour chart provided on the bottle with range values indicated in mmol/m
3
; values
expressed in mmol/m
3
were later converted into mg/L CaCO
3
following the formula:
1 mmol/m
3
= 10
◦
f = 5.60
◦
d = 7022
◦
e = 100.09 mg/l CaCO
3
(
◦
f = degrees French hardness,
◦d = degrees German hardness), ◦e = degrees Clark hardness).
The electrical conductivity was measured using Go Direct
®
Conductivity Probe
(Vernier Go Direct
®
, 13,979 SW Millikan Way Beaverton, OR, USA) with a range of 0
to 20,000
µ
S/cm. It connects via Bluetooth
®
wireless technology or via USB to the elec-
tronic device (computer or telephone). Dosatest
®
test strips and electrical conductivity
measurements were carried out for each experiment and thus twice in this study and gave
Insects 2021,12, 57 4 of 13
similar results. The pH values were measured using a pH meter (WTW pH 3110, Xylem
Analytics, Weilheim, Germany).
2.3. Assessment of the Effects of Water Treatments on Larval Development and Adult Quality
The five water treatments described above (1) 100% ROW, (2) 80% ROW + 20% TW, (3)
50% ROW + 50% TW, (4) 20% ROW + 80% TW, (5) 100% TW were applied to both species.
For each species, eggs were hatched in glass jars overnight following standard proce-
dures developed at the IPCL [
28
,
33
–
35
]. After hatching, batches of 200 first-instar larvae
were manually counted and haphazardly allocated to the different water media prepared.
A total of 8000 first-instar were used for each experiment. Larvae were reared in transparent
plastic containers (L
×
W
×
H = 150
×
90
×
50 mm) and filled with 500 mL of rearing
medium. The IAEA black soldier fly-based-diet (4% (vol/wt) which consists of 50% tuna
meal + 15% brewer’s yeast + 35% black soldier fly larvae powder [
34
,
36
] was used with
the following daily amounts: 5 mL on day 1, 10 mL on day 2, 20 mL on day 3, 10 mL on
day 6. Four replicates were performed for each water treatment and the experiment was
carried out twice for each species. Larvae were checked daily for pupation, and pupae were
collected and counted on a daily basis. For all experimental water treatments, we recorded:
(i) time to pupation (the number of days from hatching to pupation), (ii) pupation rate, (iii)
emergence rate, (iv) male and female body size: after emergence, 20 females and 20 males
per treatment (5 per replicate) were randomly selected and the right wings detached and
mounted on glass microscope slides under a cover slip. A photograph of each wing was
taken under a dissecting microscope (Leica MZ16 FA, Leica Microsystems (Switzerland)
Ltd, Heerbrugg, Switzerland.). Wing length was measured from the tip of the wing (ex-
cluding fringe) to the distal end of the alula using analySIS
®
FIVE software. Wing length is
considered to be a proxy for mosquito body size, (v) male and female longevity: 40 males
and 40 females that emerged the same day (10 per replicate) from each water treatment
were transferred and maintained in a cage separately (15
×
15
×
15 cm, Bugdorm.com,
Taichung, Taiwan) for measurement of longevity. A 10% sugar solution was supplied in
a 150-mL plastic bottle containing a sponge and mortality was recorded daily. For the
longevity monitoring, adults were maintained at 28
±
2
◦
C, 80
±
10% RH and 14:10 h
photoperiod.
2.4. Assessment of the Effects of Water Treatments on Larval Development and Production with
Low Food Quantity
Based on the variable and low pupation rates obtained in the previous experiment, and
in order to verify that the resulting effects were caused only by water treatments, a second
experiment was conducted. The amount of daily food provided to larvae was halved to
give 5 mL on day 1, 5 mL on day 2, 10 mL on day 3, 5 mL on day 6. Subsequently, the effect
of different water treatments (as described in the experiment above) on larval development
was assessed. Four replicates for each water treatment were performed. Time to pupation,
pupation and the emergence rates were assessed and compared to experiment 1.
2.5. Statistical Analysis
Statistical analyses were performed using R Software version 3.5.2 (R Development
Core Team 2008, URL http://www.R-project.org/). A Gaussian linear mixed-effects model
was used with time to pupation, male and female body size assigned as response variables,
water media as a fixed effect and replicate as a random effect [
37
]. We also used binomial
generalized linear mixed models fit by maximum likelihood (Laplace Approximation) with
pupation rate, emergence rate and adult as response variables, water media as fixed effect
and the replicate as a random effect. The full models were checked for overdispersion using
Bolker’s function for validation. The longevity of mosquitoes was analysed using Kaplan-
Meier survival analyses using GraphPad Prism v.5.0 ((Windows, Graphpad Software, La
Jolla, CA, USA; www.graphpad.com). The log-rank (Mantel-Cox) test was used to compare
the level of survival between different treatments. The Bonferroni correction method was
applied for each pair of groups to account for the multiplicity comparisons.
Insects 2021,12, 57 5 of 13
3. Results
3.1. Hardness, Electrical Conductivity and pH of the Rearing Media
Hardness, electrical conductivity and pH of the rearing media are presented in
Table 1
.
Water hardness values were notably different between water media, ranging from 0 to
400.36 mg/L CaCO
3
. EC ranged from 11.04
±
0.01 to 686.50
±
0.23
µ
S/cm and pH from
5.85
±
0.005 to 7.32
±
0.006. Based on standard classification of water hardness as described
by the World Health Organization (WHO) [
38
], our rearing media can be classified as soft
(100% ROW), moderately hard water (80% ROW + 20% TW), hard water (50% ROW + 50%
TW), and very hard water (20% ROW + 80% TW and 100% TW).
Table 1.
Measured hardness, conductivity and pH of the water media used for rearing Aedes mosquitoes in the present
experiment. Conductivity and pH values are expressed as mean ±SE. ROW = reverse osmosis water, TW = tap water.
Parameters 100% ROW 80%ROW +
20%TW
50%ROW +
50%TW
20%ROW +
80%TW 100% TW
Hardness Dosatest®
hardness test strips
(mmol/m3)0–0.3 0.7–1.2 1.4–2.5 2.8–3.7 3.7–4
(mg/L CaCO3) 0–30.03 70.06–120.11 140.13–250.23 280.25–370.33 370.33–400.36
Conductivity (µS/cm) 11.04 ±0.01 154.53 ±0.10 368.45 ±0.14 557.83 ±0.17 686.50 ±0.23
pH 5.85 ±0.005 6.82 ±0.005 7.09 ±0.005 7.24 ±0.006 7.32 ±0.006
3.2. Effects of Water Treatments on Time to Pupation
Time to pupation was affected by the level of water hardness in both species (
Figure 1
).
As water hardness level increased, time to pupation gradually increased (i.e., delayed
development at higher hardness levels), with cohorts reared at the highest hardness levels
spending the longest time as immature. In Ae. aegypti, time to pupation in water treatments
80% ROW + 20% TW, 50% ROW + 50% TW and 20% ROW + 80% TW did not differ with
the control treatment, although they were slightly increased (Table S1). However, time to
pupation in the 100% TW was significantly increased compared to control treatment (df
= 12, t = 2.66, p= 0.021). In Ae. albopictus, time to pupation in the treatments 20% ROW +
80% TW and 100% TW were significantly higher than the control treatment (Table S2, df
= 12, t= 2.65, p= 0.021 and df = 12, t= 5.14, p< 0.001, respectively). Interestingly, with
this feeding regime, whatever the water hardness treatment, the time to pupation was
significantly higher in Ae. albopictus than Ae. aegypti (df = 25, t= 4.11, p< 0.001).
Figure 1.
Time to pupation of Aedes aegypti and Aedes albopictus reared at different hardness/electrical
conductivity levels of larval rearing water. As water hardness/electrical conductivity level increased,
time to pupation gradually increased. Each box denotes the median as a line across the middle, the
quartiles (25th and 75th percentiles), the minimum and maximum values at the ends of the vertical
lines. Results are expressed as mean ±SE. ROW = reverse osmosis water, TW = tap water.
Insects 2021,12, 57 6 of 13
3.3. Effects of Water Treatments on Pupal Production, Emergence Rate and Adult Production
In Ae. albopictus, pupae production significantly decreased with increasing water
hardness as compared to the control medium (Table S2, p< 0.05). In Ae. aegypti, pupation
rate was negatively affected by water hardness ranging from 140.126 to 400.36 mg/CaCO
3
i.e., the water media 50% ROW + 50% TW to 100% TW (Table S1). In both species, the emer-
gence rates were not significantly different between water treatments (
Tables S1 and S2
).
Consequently, adult production was negatively affected in both species, similarly to the
pupation rate (Tables S1 and S2).
3.4. Effects of Water Treatments on Adult Body Size
In comparison to the control medium, the media 20% ROW + 80% TW (t=
−
2.151,
df = 92, p= 0.034) and 100% TW (t=
−
2.192, df = 92, p= 0.031) significantly decreased
female body size (Figure 2) in Ae. aegypti. In Ae. albopictus, the media 50% ROW + 50% TW
(t=
−
2.073, df = 92, p= 0.041) and 100% TW (t=
−
2.715, df = 92, p= 0.008) significantly
decreased female body size. No significant effect was found in male body size in either
species (Figure 2,p> 0.05).
Figure 2.
Body size of male and female Aedes aegypti and Aedes albopictus reared at different hard-
ness/electrical conductivity levels of larval rearing water. Each box denotes the median as a line
across the middle, the quartiles (25th and 75th percentiles), the minimum and maximum values at
the ends of the vertical lines. Results are expressed as mean
±
SE. ROW = reverse osmosis water, TW
= tap water.
3.5. Effects of Water Treatments on Adult Longevity
The survival curves, the mean and median survival durations of males and females
reared with different water media are presented in Figure 3and Table 2. Overall, in
Ae. aegypti, the longevity of males and females was not affected negatively by the water
hardness level compared to the control medium (graphical observation, Figure 3, Log-rank
(Mantel-Cox) test, p> 0.005). However, the longevity of males was higher when reared in
Insects 2021,12, 57 7 of 13
the water medium 20% ROW + 80% TW (Log-rank (Mantel-Cox) test,
χ2
= 11.25, df = 1, p<
0.001) as compared to the control.
Figure 3.
Longevity of male and female Aedes aegypti and Aedes albopictus reared in different hardness/electrical conductivity
levels of larval rearing water. ROW = reverse osmosis water, TW = tap water.
Table 2.
Mean
±
se (days) and median survival (days) of Aedes aegypti and Aedes albopictus males and females reared under
different water hardness treatments. ROW = reverse osmosis water, TW = tap water.
Species Sex Parameters 100% ROW 80%ROW +
20%TW
50%ROW +
50%TW
20%ROW +
80%TW 100% TW
Ae. aegypti
Males Mean 23.05 ±3.12 23.68 ±3.28 23.88 ±4.06 28.08 ±6.47 23.05 ±4.91
Median 24 22 23 28.5 24
Females Mean 25.50 ±4.75 25.73 ±3.43 26.86 ±3.25 24.70 ±3.64 25.25 ±3.85
Median 27 27 27 27 24
Ae. albopictus
Males Mean 39.00 ±7.36 34.90 ±4.88 36.70 ±6.50 30.00 ±6.35 32.21 ±4.92
Median 42 31 38 30 34
Females Mean 39.50 ±6.43 43.51 ±5.70 38.90 ±4.84 35.24 ±5.60 34.21 ±6.65
Median 41.5 43 41 37 36
In Ae. albopictus, there was a significant variation in longevity of males and females
between water treatments (Log-rank (Mantel-Cox) test,
χ2
= 17.31, df = 4, p= 0.002 and
Log-rank (Mantel-Cox) test,
χ2
= 12.76, df = 4, p= 0.01 for males and females, respectively).
Compared to the control, increased water hardness decreased the longevity of adult males
(Figure 3, Log-rank (Mantel-Cox) test,
χ2
= 11.66, df = 1, p< 0.001 and Log-rank (Mantel-
Cox) test,
χ2
= 14.41, df = 1, p< 0.001 for the media 20% ROW + 80% TW and 100% TW
respectively). Moreover, in females, the longevity decreased in media 20% ROW + 80% TW
Insects 2021,12, 57 8 of 13
and 100% TW in comparison to the medium 80% ROW + 20% TW (Log-rank (Mantel-Cox)
test,
χ2
= 11.7, df = 1, p< 0.001 and Log-rank (Mantel-Cox) test,
χ2
= 9.86, df = 1, p= 0.002).
Whatever the rearing medium, Ae. albopictus survived longer than Ae. aegypti (Figure 3).
3.6. Effects of Water Treatments on Time to Pupation, Pupation and Emergence Rates at Low
Feeding Amounts
In the second experiment with low larval food quantities, time to pupation gradually
increased with increased water hardness in Ae. albopictus. The treatments 20% ROW +
80% TW and 100% showed a significant increase in time to pupation in comparison to
the control treatment 100% ROW (Table 3, df = 11, t= 3.82, p= 0.003 and df = 11, t= 3.39,
p= 0.006, respectively), consistent with first experiment. No significant difference was
observed in Ae. aegypti, although there was a trend for increased time to pupation. As
compared to the control treatment 100% ROW, pupae production significantly decreased in
all water treatments whatever the species, consistent with results obtained in experiment
1. However, with this feeding regime, the pupation rate was slightly higher (89.88
±
1.19%) in Ae. albopictus, but not in Ae. aegypti (77.93
±
3.74%), as compared to the previous
experiment. No difference was observed in emergence rates between water treatments in
both species as shown in experiment 1.
Table 3.
Mean time to pupation, pupation and emergence percentages (mean
±
se) in Aedes aegypti and Aedes albopictus
reared under different water hardness treatments. ROW = reverse osmosis water, TW = tap water. Within a row, different
letters with the control treatment (100% ROW) indicate a statistically significant difference (p< 0.05).
Species 100% ROW 80%ROW +
20%TW
50%ROW +
50%TW
20%ROW +
80%TW 100% TW
Aedes aegypti
Time to pupation 7.09 ±0.08 a7.22 ±0.04 a7.26 ±0.08 a7.22 ±0.08 a7.04 ±0.15 a
Pupation % 77.93 ±3.74 a62.56 ±712 b64.63 ±3.67 b51.06 ±6.26 b52.38 ±6.22 b
Emergence % 98.48 ±0.42 a98.92 ±0.40 a98.50 ±0.30 a98.36 ±0.37 a98.68 ±0.41 a
Aedes albopictus
Time to pupation 7.97 ±0.05 a8.06 ±0.03 a7.94 ±0.01 a8.24 ±0.04 b8.21 ±0.11 b
Pupation % 89.88 ±1.19 a87.13 ±1.30 b83.67 ±1.48 b83.75 ±2.09 b74.00 ±9.26 b
Emergence % 99.01 ±0.85 a99.51 ±0.33 a98.53 ±1.70 a99.46 ±0.36 a99.51 ±0.34 a
4. Discussion
The ionic composition of water can be critical for the development and survival of
aquatic organisms and every organism has a typical range that it can tolerate. Despite
the plethora of information on the physico-chemical properties of the larval habitats,
including pH, temperature, humidity, resource availability and larval crowding as key
factors in determining the presence, development, survival and population dynamics
and distribution of mosquitoes [
3
,
39
–
43
], little or no work has been done on the isolated
or specific effects of water hardness/electrical conductivity, pH on Aedes mosquito’s life-
history traits. This investigation was undertaken to evaluate the tolerance of Ae. aegypti and
Ae. albopictus mosquitoes to variations of water quality in relation to hardness, electrical
conductivity and pH, and to thereby determine whether hard water (generally TW) can
be a suitable medium for rearing Aedes mosquitoes in laboratory settings. Data obtained
in the present study showed that TW quality had measurable effects on the development
and quality of Aedes mosquito species. Indeed, results showed that the increase in water
hardness/electrical conductivity level increased the average larval development time in
both species. Slower larval development was observed in mosquitoes reared at higher
water hardness/electrical conductivity levels. This suggests that depending on the quantity,
ions in the aquatic environment may affect the growth and the metabolism during moulting
of the larvae, and thus the speed and extent of their development. Similar results have been
found in Cx quinquefasciatus. The duration of the development of this species gradually
increases as water hardness/electrical conductivity levels increase [
32
]. Furthermore, the
present study revealed a reduction in pupation rate with increasing hardness/electrical
Insects 2021,12, 57 9 of 13
conductivity levels, particularly in Ae. albopictus, indicating significant larval mortality. It
is worth mentioning that water media with high levels of hardness/electrical conductivity
were prone to scum (biofilm) formation on water surface during rearing, which can lead
to fouling and ultimately to increased mortality or inferior adults especially in case of
excess amounts of food (overfeeding). This suggests that ion content in the water might
affect the microbial/bacterial community in the diet and in the water mix over time and
therefore the growth of larvae due to a reduced availability of nutriments caused by
bacterial competition.
In this experiment, male longevity was negatively impacted by high levels of water
hardness/electrical conductivity in Ae. albopictus. Akpodiete et al. [
31
] found that dif-
ferent strains of An. Gambiae showed a longer development time, higher larval survival
and smaller body size when reared with deionized water as compared to mineral water.
However, the conductivity and hardness conditions of this mineral water are low and are
representative of the second level of hardness of this study, i.e., 80% ROW + 20% TW or
moderately hard water. Body size, along with longevity, is among the valuable indicators
of insect quality [
44
], and is therefore crucial for the success of any male release programme.
Small size will likely lead to poor performance in the field. In some insects, such as tephritid
fruit flies, it has been demonstrated that insects that completed larval development tend
to more rapidly become larger and are of higher quality than those that developed more
slowly [
45
]. It has also been shown that female body size correlates with fecundity [
46
],
as large females are more likely to ingest a larger volume of blood than small ones, and
therefore successfully oviposit and lay more eggs. For any male release programme, if the
longevity is reduced, the number of males to be released should be increased.
Although negative effects of water hardness/electrical conductivity were observed in
both species, these results have demonstrated the potential of these mosquito species to
exhibit some degree of tolerance to water hardness/electrical conductivity. For example,
Ramasamy et al. [
47
] reported that Ae. aegypti and Ae. albopictus have successfully exploited
brackish water collections in unused wells and discarded artificial containers of up to 15 ppt
salinity in the peri-urban environment to oviposit and undergo preimaginal development.
Although hardness, conductivity and salinity are not exactly the same, salinity as a measure
of the amount of salts in the water may have other impacts on mosquito life cycle to a greater
extent due to the presence of sodium chloride. Because dissolved ions increase salinity as
well as conductivity, the two measures are strongly correlated. However, every organism
has a typical hardness/electrical conductivity range that it can tolerate. Aedes albopictus
was found to be more susceptible to increasing water hardness/electrical conductivity
than Ae. aegypti, underlining differences between these species, although they coexist
throughout most of their geographical distribution. In natural environments, Ae. aegypti
and Ae. albopictus are thought to differ only subtly in their preferred larval breeding sites.
The lower adaptive capacity of Ae. albopictus found in this study is somewhat surprising,
given that it was demonstrated that this species has higher survivorship than Ae. aegypti in
the laboratory (this study and [
48
]). Additionally, its superior larval competitive ability
has been proposed as a reason to explain the recent displacement of Ae. aegypti by Ae.
albopictus in parts of the southeastern U.S. [
19
,
49
]. However, Wigglesworth [
50
] showed
that larvae of Ae. aegypti and Cx pipiens can osmoregulate and ionoregulate very effectively
in essentially all media more diluted than their haemolymph by producing a diluted urine
to get rid of water and replace lost salts by active ion uptake through the cuticle.
Potential ions present in the TW include calcium (Ca
2+
), magnesium (Mg
2+
), sodium
(Na
+
), potassium (K
+
), chloride (Cl
−
), nitrate (NO
3−
), sulfate (SO
42−
), bicarbonate (HCO
3−
),
fluoride, lead, and zinc [
51
]. Water ions have a beneficial concentration range above which
they may have an adverse effect [
52
]. The physiological mechanisms which may account
for this effect in mosquitoes are not well understood, and are beyond the scope of this
study. However, insects exposed to salty environments are generally challenged by osmotic
stresses. In aqueous environments, larval survival depends on the ability to regulate the
hydromineral balance of the haemolymph to maintain homeostasis [
53
]. In this study,
Insects 2021,12, 57 10 of 13
presumably, insects exposed to increased water hardness/electrical conductivity might
have faced a considerable osmoregulatory challenge as many organisms like marine os-
moconformers lacking the capacity to regulate osmolarity and the ion content of their
internal fluids. It is likely that excess ions derived from ingestion create problems for the
maintenance of homeostasis. High ingestion of ions through the high rate of drinking water
has been demonstrated in Ae. taeniorhychus [
54
,
55
]. On the other hand, knowing that the
cuticle of fresh-water species is more permeable to water than that of saline-water mosquito
larvae [
56
], high water hardness could increase the permeability to ions, increasing their
respective effluxes and, potentially, larval mortality. Osmoconformation and osmoregu-
lation are well known as regulatory mechanisms for dealing with ionic environments in
aquatic organisms [
57
]. Kengne et al. [
58
] showed that both Ae. aegypti and Ae. albopictus
are hyper osmoregulators. It has also been shown that An. gambiae mosquitoes can adjust
their biological program through proteome changes to counter heavy metal pollution [
59
].
Higher salinity tolerance in the Enochrus species was also associated with an increase in
the relative abundance of branched alkanes (cuticule hydrocarbons) [
60
] or overexpression
of ions channels aquaporines (osmoregulation) [
61
]. However, the mechanisms of water
hardness effects or tolerance need to be further elucidated. Knowledge of rearing water
quality and its impact on mosquito development (from the results of this study) have clear
applied relevance, as the success of the sterile insect technique depends critically on the
number and quality of mass-produced and released males. Mineral levels of TW vary
among countries, and even among different water sources. Yasin et al. [
51
] reported the
electrical conductivity of TW from Ethiopia was 366.93
µ
S/cm, which is almost 50% lower
than the value of the TW used in this study, and which correspond to the mix of 50% ROW
+ 50% TW. With regard to the results of this study, TW from Ethiopia is more suitable
for rearing Aedes mosquitoes than TW in Austria. It is, therefore, of interest to evaluate
the quality (in relation to hardness or electrical conductivity) of the rearing water before
its use for rearing Aedes mosquitoes. In a recent SIT experiment organized in Brazil, TW
had such a negative impact on the survival of Ae. aegypti larvae that mineral water had
to be purchased [
62
]. Further studies, including flight ability, fecundity, and fertility in
mass-rearing conditions, are needed to elucidate the impact of water hardness in SIT and
other related techniques, including Wolbachia-based and transgenic approaches.
Although this research was designed to answer practical questions about the use of
TW for rearing Aedes mosquitoes and achieved this goal, there were some limitations and
shortcomings. The fact that TW can differ from the ROW in many other factors, together
with the limited range of variables measured (three), represents a potential bias that may
interact with the specific effect of the hardness or electrical conductivity. In experiment 1
with higher larval food quantities, we found variable pupation rates including rates falling
below the expected rates generally observed in most routine rearing conditions. In the
second experiment with a reduced food quantity (half of the initial amount), there was a
slight increase in pupation rates. Whatever the feeding regimes used in this study, there
was evidence of the negative effect of tap water on rearing outputs. However, care should
be taken regarding food quantities delivered to larvae to avoid negative effects on outputs.
5. Conclusions
Water quality is a factor of great importance in the larval environment of mosquito
species. Increasing hardness/electrical conductivity level beyond 140 mg/L CaCO
3
(or
368
µ
S/cm) was found to be a limiting factor, as it influenced time to pupation, pupation
rate, body size and longevity of Ae. aegypti and Ae. albopictus. While ROW is highly rec-
ommended, with respect to cost-effective methods for improved mass-rearing toward SIT
application, TW or a mix of TW with ROW up to certain limit of water hardness/electrical
conductivity could provide adequate conditions for rearing these two mosquito species.
Differences in the ability to maintain homeostatic control of water and ion balance may
explain large parts of the observed interspecific variation. These results may have impor-
tant implications for the implementation of the SIT in areas where ROW is a scarce or
Insects 2021,12, 57 11 of 13
costly resource. For any other source of water, characteristics such as hardness, electrical
conductivity and pH should be considered when using water for rearing mosquitoes for
release purposes in order to optimize the production performance of mass-rearing facilities.
Supplementary Materials:
The following are available online at https://www.mdpi.com/2075-4
450/12/1/57/s1, Table S1: Results of linear mixed models and binomial generalized linear mixed
models for the effect of water hardness/electrical conductivity on Aedes aegypti life history trait
parameters. Table S2: Results of linear mixed models and binomial generalized linear mixed models
for the effect of water hardness/electrical conductivity on Aedes albopictus life history trait parameters.
Author Contributions:
Conceptualization, W.M. and J.B.; methodology, W.M., H.M., N.S.B.S., T.W.,
O.B.M., and C.R..; validation, W.M., H.M., and J.B.; formal analysis W.M; investigation, W.M., H.M.,
N.S.B.S., T.W., O.B.M., and C.R.; resources, W.M. and J.B.; data curation, W.M. and J.B.; writing of
original draft W.M.; review and editing, W.M., H.M., N.S.B.S., C.R., C.R., H.Y., J.B.; supervision,
J.B; project administration, J.B. All authors have read and agreed to the published version of the
manuscript.
Funding:
The research presented in this paper was funded by the United States of America under
the grant to the IAEA entitled: Surge expansion for the sterile insect technique to control mosquito
populations that transmit the Zika virus. This article reflects only the authors’ views, and the agency
is not responsible for any use that may be made of the information it contains.
Data Availability Statement:
All data generated or analysed during this study are included in this
published article.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Gillis, P.; Mitchell, R.; Schwalb, A.; McNichols, K.; Mackie, G.; Wood, C.; Ackerman, J. Sensitivity of the glochidia (larvae)
of freshwater mussels to copper: Assessing the effect of water hardness and dissolved organic carbon on the sensitivity of
endangered species. Aquat. Toxicol. 2008,88, 137–145. [CrossRef] [PubMed]
2.
Oyewole, I.; Momoh, O.; Anyasor, G. Physico-chemical characteristics of Anopheles breeding sites: Impact on fecundity and
progeny development. Afr. J. Environ. Sci. Technol. 2009,3, 447–452.
3.
Mwangangi, J.; Mbogo, C.; Muturi, E.; Nzovu, J.; Kabiru, E.; Githure, J.; Novak, R.; Beier, J. Influence of biological and physico-
chemical characteristics of larval habitats on the body size of Anopheles gambiae mosquitoes (Diptera: Culicidae) along the Kenyan
coast. J. Vect. Borne Dis. 2007,44, 122–127.
4.
Minakawa, N.; Mutero, C.; Githure, J.; Beier, J.; Yan, G. Spatial distribution and habitat characterization of anopheline mosquito
larvae in western Kenya. Am. J. Trop. Med. Hyg. 1999,61, 1010–1016. [CrossRef]
5.
Olayemi, I.; Omalu, I.; Famotele, O.; Shegna, S.; Idris, B. Distribution of mosquito larvae in relation to physico-chemical
characteristics of breeding habitats in Minna, north central Nigeria. Rev. Infect. 2010,1, 49–53.
6.
Dejenie, T.; Yohannes, M.; Assmelash, T. Characterization of mosquito breeding sites in and in the vicinity of Tigray microdams.
Ethiop. J. Health Sci. 2011,21, 57–66. [CrossRef]
7.
Kenea, O.; Balkew, M.; Gebre-Michael, T. Environmental factors associated with larval habitats of anopheline mosquitoes (Diptera:
Culicidae) in irrigation and major drainage areas in the middle course of the Rift Valley, central Ethiopia. J. Vect. Borne Dis.
2011
,
48, 85–92.
8.
Cohen, A. Ecology of insect rearing systems: A mini-review of insect rearing papers from 1906–2017. Adv. Entomol.
2018
,6,
86–115. [CrossRef]
9.
Zheng, X.; Zhang, D.; Li, Y.; Yang, C.; Wu, Y.; Liang, X.; Liang, Y.; Pan, X.; Hu, L.; Sun, Q.; et al. Incompatible and sterile insect
techniques combined eliminate mosquitoes. Nature 2019,572, 56–61. [CrossRef]
10.
Crawford, J.; Clarke, D.; Criswell, V.; Desnoyer, M.; Cornel, D.; Deegan, B.; Gong, K.; Hopkins, K.; Howell, P.; Hyde, J.; et al.
Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations.
Nat. Biotechnol. 2020,38, 482–492. [CrossRef]
11.
Spitzen, J.; Takken, W. Malaria mosquito rearing—Maintaining quality and quantity of laboratory-reared insects. Proc. Neth.
Entomol. Soc. Meet. 2005,16, 95–100.
12.
Alam, J.B.; Islam, M.R.; Muyen, Z.; Mamun, M.; Islam, S. Water quality parameters along rivers. Int. J. Environ. Sci. Tech.
2007
,4,
159–167. [CrossRef]
13. Gorde, S.P.; Jadhav, M.V. Assessment of water quality parameters: A review. Int. J. Eng. Res. Appl. 2013,3, 2029–2035.
14.
Rahmanian, N.; Ali, S.H.B.; Homayoonfard, M.; Ali, N.J.; Rehan, M.; Sadef, Y.; Nizami, S.S. Analysis of physiochemical parameters
to evaluate the drinking water quality in the State of Perak, Malaysia. J. Chem. 2015. [CrossRef]
Insects 2021,12, 57 12 of 13
15.
Milad, K.; Mohammed, S.; Seyed, A. Effects of water hardness on egg hatchability and larval viability of angelfish (Pterophyllum
scalare). Int. J. Res. Fish. Aquac. 2011,1, 6–10.
16.
Luo, S.; Wu, B.; Xiong, X.; Wang, J. Effects of total hardness and calcium:magnesium ratio of water during early stages of rare
minnows (Gobiocypris rarus). Comp. Med. 2016,66, 181–187.
17.
Byrne, C.; Troy, D.; Buckley, D. Postmortem changes in muscle electrical properties of bovine M. longissimus dorsi and their
relationship to meat quality attributes and pH fall. Meat Sci. 2000,54, 23–34.
18. Rodier, J. Analysis of Water; Edition Dunod: Paris, France, 1976.
19. Lounibos, L. Invasions by insect vectors of human disease. Ann. Rev. Entomol. 2002,47, 233–266. [CrossRef]
20.
Bellini, R.; Medici, A.; Puggioli, A.; Balestrino, F.; Carrieri, M. Pilot field trials with Aedes albopictus irradiated sterile males in
Italian urban areas. J. Med. Entomol. 2013,50, 317–325. [CrossRef]
21.
Pleydell, D.; Bouyer, J. Biopesticies improve efficiency of the sterile insect technique for controlling mosquito-driven dengue
epidemics. Comm. Biol. 2019,2, 201. [CrossRef]
22.
Bouyer, J.; Yamada, H.; Pereira, R.; Bourtzis, K.; Vreysen, M. Phased conditional approach for mosquito management using sterile
insect technique. Trends Parasitol. 2020,36, 325–336. [CrossRef] [PubMed]
23.
WHO; IAEA. Guidance Framework for Testing the Sterile Insect Technique (SIT) as a Vector Control Tool against Aedes-Borne Diseases;
WHO: Geneva, Switzerland; IAEA: Vienna, Austria, 2020; p. 190.
24.
Mamai, W.; Hood-Nowotny, R.; Maiga, H.; Ali, A.; Somda, N.B.; Soma, D.; Yamada, H.; Lees, R.; Gilles, J. Reverse osmosis and
ultrafiltration for recovery and reuse of larval rearing water in Anopheles arabiensis mass production: Effect of water quality on
larval development and fitness of emerging adults. Acta Trop. 2017,170, 126–133. [PubMed]
25.
Mamai, W.; Lobb, L.; Somda, N.B.; Maiga, H.; Yamada, H.; Lees, R.; Bouyer, J.; Gilles, J. Optimization of mass-rearing methods for
Anopheles arabiensis larval stages: Effects of rearing water temperature and larval density on mosquito life-history traits. J. Econ.
Entomol. 2018,111, 2383–2390. [CrossRef] [PubMed]
26.
Profitós, J.; Mouhaman, A.; Lee, S.; Garabed, R.; Moritz, M.; Piperata, B.; Tien, J.; Bisesi, M.; Lee, J. Muddying the waters: A
new area of concern for drinking water contamination in Cameroon. Int. J. Environ. Res. Public Health
2014
,11, 12454–12472.
[CrossRef] [PubMed]
27.
FAO; IAEA. Guidelines for Standardised Mass Rearing for Anopheles Mosquitoes, Version 1.0. 2017. Available online: http:
//www-naweb.iaea.org/nafa/ipc/public/manuals-ipc.html (accessed on 20 May 2020).
28.
FAO; IAEA. Guidelines for Mass-Rearing of Aedes Mosquitoes. Version 1.0. 2020. Available online: http://www- naweb.iaea.
org/nafa/ipc/public/manuals-ipc.html (accessed on 20 May 2020).
29.
Udhayakumar, R.; Manivannan, P.; Raghu, K.; Vaideki, S. Assessment of physico-chemical characteristics of water in Tamilnadu.
Ecotox. Environal. Safe. 2016,134, 474–477. [CrossRef]
30.
Toure, A.; Wenbiao, D.; Keita, Z. An investigation of some water quality properties from different sources in Pelengana commune,
Segou, Mali. J. Water. Sanit. Hyg. Dev. 2018,8, 449–458. [CrossRef]
31.
Akpodiete, N.; Diabate, A.; Tripet, F. Effect of water source and feed regime on development and phenotypic quality in Anopheles
gambiae (s.l.): Prospects for improved mass-rearing techniques towards release programmes. Parasite Vect.
2019
,12, 210. [CrossRef]
32.
Ukubuiwe, A.; Ojianwuna, C.; Olayemi, I.; Arimoro, F.; Ukubuiwe, C. Quantifying the roles of water pH and hardness levels
in development and biological fitness indices of Culex quinquefasciatus Say (Diptera: Culicidae). J. Basic. Appl. Zool.
2020
,81, 5.
[CrossRef]
33.
Maïga, H.; Mamai, W.; Somda, N.B.B.; Konczal, A.; Wallner, T.; Herranz, G.; Herrero, R.; Yamada, H.; Bouyer, J. Reducing the cost
and assessing the performance of a novel adult mass-rearing cage for the dengue, chikungunya, yellow fever and Zika vector,
Aedes aegypti (Linnaeus). PLoS. Negl. Trop. Dis. 2019,13, e0007775. [CrossRef]
34.
Mamai, W.; Somda, N.B.; Maiga, H.; Konczal, A.; Wallner, T.; Bakhoum, M.; Yamada, H.; Bouyer, J. Black soldier fly (Hermetia
illucens) larvae powder as a larval diet ingredient for mass-rearing Aedes mosquitoes. Parasite 2019,26, 57. [CrossRef]
35.
Mamai, W.; Maiga, H.; Somda, N.B.; Wallner, T.; Konczal, A.; Yamada, H.; Bouyer, J. Aedes aegypti larval development and pupal
production in the FAO/IAEA mass-rearing rack and factors influencing sex sorting efficiency. Parasite
2020
,27, 43. [CrossRef]
[PubMed]
36.
Somda, N.B.; Maïga, H.; Mamai, W.; Yamada, H.; Ali, A.; Konczal, A.; Gnankiné, O.; Diabaté, A.; Sanon, A.; Dabiré, K.; et al.
Insects to feed insects-feeding Aedes mosquitoes with flies for laboratory rearing. Sci. Rep. 2019,9, 11403. [CrossRef] [PubMed]
37. Laird, N.; Ware, J. Random-effects models for longitudinal data. Biometrics 1982,38, 963–974. [CrossRef] [PubMed]
38.
WHO. Hardness in Drinking-Water: Background Document for Development of WHO Guidelines for Drinking-Water Quality.
2011. Available online: https://apps.who.int/iris/handle/10665/70168 (accessed on 10 June 2020).
39.
Muirhead-Thomson, R. The ecology of vector snail habitats and mosquito breedings-places: The experimental approach to basic
problems. Bull. World Health Organ. 1958,19, 637–659.
40. Briegel, H. Physiological bases of mosquito ecology. J. Vector. Ecol. 2003,28, 1–11.
41.
Mutero, C.; Ng’ang’a, P.; Wekoyela, P.; Githure, J.; Konradsen, F. Ammonium sulphate fertilizer increases larval populations of
Anopheles arabiensis and culicine mosquitoes in rice fields. Acta Trop. 2004,89, 187–192.
42.
Mwangangia, J.; Mbogo, C.; Muturi, E.; Nzovu, J.; Githure, J.; Noboru, G.; Novak, M.; John, C. Spatial distribution and habitat
characterisation of Anopheles larvae along the Kenyan coast. J. Vect. Borne Dis. 2007,44, 44–51.
Insects 2021,12, 57 13 of 13
43.
Muturi, J.; Mwangangi, J.; Shililu, J.; Jacob, G.; Mbogo, C.; Githure, J.; Novak, J.J. Environmental factors associated with the
distribution of Anopheles arabiensis and Culex quinquefasciatus in a rice agroecosystem in Mwea, Kenya. J. Vect. Ecol.
2008
,33,
56–63. [CrossRef]
44. Beukeboom, L. Size matters in insects—An introduction. Entomol. Exp. Appl. 2018,166, 2–3. [CrossRef]
45.
FAO; IAEA; USDA. Product Quality Control for Sterile Mass-Reared and Released Tephritid Fruit Flies, Version 6.0; FAO: Rome, Italy;
IAEA: Vienna, Austria; USDA: Washington, DC, USA, 2014.
46.
Hurd, H.; Hogg, J.; Renshaw, M. Interactions between bloodfeeding, fecundity and infection in mosquitoes. Parasitol. Today.
1995
,
11, 411–416. [CrossRef]
47.
Ramasamy, R.; Surendran, S.; Jude, P.; Dharshini, S.; Vinobaba, M. Larval development of Aedes aegypti and Aedes albopictus
in peri-urban brackish water and its implications for transmission of arboviral diseases. PLoS. Negl. Trop. Dis.
2011
,5, e1369.
[CrossRef] [PubMed]
48.
Brady, O.; Johansson, M.; Guerra, C.; Bhatt, S.; Golding, N.; Pigott, D.; Delatte, H.; Grech, M.; Leisnham, P.; Maciel-de-Freitas, R.;
et al. Modelling adult Aedes aegypti and Aedes albopictus survival at different temperatures in laboratory and field settings. Parasite
Vect. 2013,6, 351. [CrossRef] [PubMed]
49.
Braks, M.; Honório, N.; Lounibos, L.; Lourenço-De-Oliveira, R.; Juliano, S. Interspecific competition between two invasive species
of container mosquitoes, Aedes aegypti and Aedes albopictus (Diptera: Culicidae), in Brazil. Ann. Entomol. Soc. Am.
2004
,97,
130–139. [CrossRef]
50. Wigglesworth, V. The adaptation of mosquito larvae to salt water. J. Exp. Biol. 1933,10, 27–37.
51.
Yasin, M.; Ketema, T.; Bacha, K. Physico-chemical and bacteriological quality of drinking water of different sources, Jimma zone,
Southwest Ethiopia. BMC Res. Notes 2015,8, 541. [CrossRef] [PubMed]
52.
De-Giglio, O.; Quaranta, A.; Lovero, G.; Caggiano, G.; Montagna, M. Mineral water or tap water? An endless debate. Ann. Ig.
2015,27, 58–65. [PubMed]
53.
Donini, A.; Gaidhu, M.; Strasberg, D.; O’Donnell, M. Changing salinity induces alterations in hemolymph ion concentrations and
Na
+
and Cl
-
transport kinetics of the anal papillae in the larval mosquito, Aedes aegypti.J. Basic. Appl. Zool.
2007
,210, 983–992.
[CrossRef]
54.
Bradley, T.; Phillips, J. The secretion of hyperosmotic fluid by the rectum of a saline-water mosquito larva, Aedes taeniorhynchus.J.
Exp. Biol. 1975,63, 331–342.
55.
Bradley, T.; Phillips, J. The effect of external salinity on drinking rates and rectal secretion in the larvae of the saline-water
mosquito larva, Aedes taeniarhynchus.J. Exp. Biol. 1977,66, 97–110.
56.
Nicholson, S.; Leader, J. The permeability to water of the cuticle of the larva of Opifexfucus (Hutton) (Diptera, Culicidae). J. Exp.
Biol. 1974,60, 593–604.
57. Charmantier, G.; Charmantier-Daures, M.; Towle, D. Osmotic and Ionic Regulation in Aquatic Arthropods. In Osmotic and Ionic
Regulation: Cells and Animals; Evans, D.H., Ed.; CRC Press: Boca Raton, FL, USA, 2009.
58.
Kengne, P.; Charmantier, G.; Blondeau-Bidet, E.; Costantini, C.; Ayala, D. Tolerance of disease-vector mosquitoes to brackish
water and their osmoregulatory ability. Ecosphere 2019,10, e02783. [CrossRef]
59.
Rono, M.; Muturi, C.; Ochieng, R.; Mwakubabanya, R.; Wachira, F.; Mwangangi, J.; Kinyanjui, S.; Njunge, J.; Mireji, P. Cadmium
tolerance pathway in Anopheles gambiae senso stricto. Acta Trop. 2019,198, 105033. [PubMed]
60.
Botella-Cruz, M.; Pallarés, S.; Millán, A.; Velasco, J. Role of cuticle hydrocarbons composition in the salinity tolerance of aquatic
beetles. J. Insect Physiol. 2019,117, 103899. [CrossRef] [PubMed]
61.
Kourghi, M.; Nourmohammadi, S.; Pei, J.; Qiu, J.; McGaughey, S.; Tyerman, S.; Byrt, C.; Yool, A. Divalent cations regulate the ion
conductance properties of diverse classes of aquaporins. Int. J. Mol. Sci. 2017,18, 2323. [CrossRef] [PubMed]
62.
Bouyer, J.; Culbert, N.; Dicko, A.; Gomez-Pacheco, M.; Virginio, J.; Pedrosa, M.; Garziera, L.; Macedo-Pinto, A.; Klaptocz, A.;
Germann, J.; et al. Field performance of sterile male mosquitoes released from an uncrewed aerial vehicle. Sci. Robot.
2020
,5,
eaba6251. [CrossRef] [PubMed]
