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Leaf litter decay process and the growth performance of Aedes albopictus larvae (Diptera: Culicidae)

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Larvae of the mosquito Ae. albopictus typically develop in small aquatic sites such as tree holes and artificial containers. Organic detritus, in particular decaying leaves, is therefore their major carbon source. Here we demonstrate the importance of leaf characteristics, and in particular their rates of decay, in determining the development and survivorship of larvae. We compared the effects of a rapidly decaying leaf, the maple Acer buergerianum (Angiospermae: Aceraceae) and a slowly decaying leaf, the camphor Cinnamomum japonicum (Angiospermae: Lauraceae), on the larval development of Ae. albopictus at different larval densities in laboratory microcosms. Overall, the maple leaves provided a better substrate and the observed growth patterns could be explained on the basis of a difference in nutritive and chemical contents of the two leaf types. At the highest population density, the duration of the larval period was much shorter in maple litter microcosms. Larval mortality gradually increased with population density in the camphor treatment. In contrast in the rapidly decaying leaf litter microcosms, mortality remained low even as densities increased. Mean pupal size was greater in the individuals fed on the rapidly decaying leaf litter as well as at lower density. Size is likely to be correlated with fitness in the field. In general, rapidly decaying leaf litter will favor mosquito growth resulting in quicker development and higher population sizes. This work emphasizes the importance of the local environment on the development of vector mosquitoes and has important implications for control.
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June, 2002 Journal of Vector Ecology 31
Leaf litter decay process and the growth performance of
Aedes albopictus larvae (Diptera: Culicidae)
Hamady Dieng, Charles Mwandawiro, Michael Boots, Ronald Morales, Tomomitsu Satho,
Nobuko Tuno, Yoshio Tsuda, and Masahiro Takagi
Department of Medical Entomology, Institute of Tropical Medicine,
1-12-4, Sakamoto, 852-8523 Nagasaki, Japan
Received 9 March 2001; Accepted 8 July 2001
ABSTRACT: Larvae of the mosquito Ae. albopictus typically develop in small aquatic sites such as tree holes
and artificial containers. Organic detritus, in particular decaying leaves, is therefore their major carbon source.
Here we demonstrate the importance of leaf characteristics, and in particular their rates of decay, in determining
the development and survivorship of larvae. We compared the effects of a rapidly decaying leaf, the maple Acer
buergerianum (Angiospermae: Aceraceae) and a slowly decaying leaf, the camphor Cinnamomum japonicum
(Angiospermae: Lauraceae), on the larval development of Ae. albopictus at different larval densities in laboratory
microcosms. Overall, the maple leaves provided a better substrate and the observed growth patterns could be
explained on the basis of a difference in nutritive and chemical contents of the two leaf types. At the highest
population density, the duration of the larval period was much shorter in maple litter microcosms. Larval mortality
gradually increased with population density in the camphor treatment. In contrast in the rapidly decaying leaf
litter microcosms, mortality remained low even as densities increased. Mean pupal size was greater in the individuals
fed on the rapidly decaying leaf litter as well as at lower density. Size is likely to be correlated with fitness in the
field. In general, rapidly decaying leaf litter will favor mosquito growth resulting in quicker development and
higher population sizes. This work emphasizes the importance of the local environment on the development of
vector mosquitoes and has important implications for control. Journal of Vector Ecology 27(1): 31-38. 2002.
Keyword Index: Leaf litter, decay, tree hole, performance, microcosm.
INTRODUCTION
Mosquito population dynamics largely depend on
biological and environmental conditions (Tsuda et al.
1991). However, the interactions between the various
population parameters and the environment are so
complex that it is still problematic to fully understand
the dynamics of some vectors. In view of this complexity,
it is instructive to examine individual responses in
controlled laboratory conditions. Here we examine the
role that different types of leaf litter play in the
performance of the important vector mosquito Ae.
albopictus.
Mosquito larvae use allochthonous leaf detritus as
food (Walker et al. 1997) by browsing on the associated
microbial fauna (Cummins and Klug 1979, Fish and
Carpenter 1982). Aedes mosquitoes of the subgenus
Stegomyia use various aquatic sites including
phytotelmata and artificial containers (Sota et al. 1992)
that provide the same general nature of food, principally
comprised of detritus (Clements 1992). Among these,
Ae. albopictus, a known vector of dengue in Southern
Asia (Chan et al. 1971, Jumali et al. 1979), is expanding
its distribution throughout the world (Rai 1991, Reiter
1998). The adults occur in both forested and urban areas
while the larvae breed in tree holes and various artificial
containers (Makiya 1968, Eshita and Kurihara 1978,
and Hawley 1988).
In recent years, much effort has been directed
towards understanding the invasive properties of Ae.
albopictus from forested areas, where it originates, as
well as from indigenous to non-indigenous countries
(Reiter 1998). In particular, there has been a substantial
body of work looking at the response of environmental
conditions of both the larvae and the adults. Density
has been shown to have a negative effect and food level
a positive effect on immature survival, duration of
development, and size at emergence (Mori 1979, Lord
1998). Habitat food level has also been previously
documented to influence the susceptibility to parasite
32 Journal of Vector Ecology June, 2002
infection (Willis and Nasci 1994).
The internal properties of containers such as the
color (Trimble 1979) and chemical properties (Benson
et al. 1988) of their contents have been shown to be
important cues that a gravid female must consider in
oviposition site choice. High levels of decay products
are a signal of good food in quality and quantity and
are known to attract ovipositing females to tree holes
(Wilton 1968, Beehler et al. 1992, and Paradise 1999).
It is likely that there is a close relationship between
these properties and the decay process of plant materials.
Although decaying leaf detritus is the major source of
organic carbon for the container inhabitants (Kitching
1983), leaf substrate, varies widely in nutritional quality
by the associated microbial flora (Ward and Cummins
1979) and their decomposition rates (Young et al. 1997).
It seems likely, therefore, that Ae. albopictus populations
in nature are largely determined by competition for
detrital food.
Although a few experimental studies on Ae.
albopicus have used leaves (Sota 1993, Sunahara and
Mogi 1997), they did not focus on litter quality known
to be an important factor in the productivity of
mosquitoes (Leonard and Juliano 1995, Paradise 1999,
and Strand et al. 1999). So, there is little analysis of
the significance of the detritus type on Ae. albopictus
larval performance.
We report here experiments on Ae. albopictus
nutritional ecology with special reference to the quality
of decaying leaves. We examined the role of two
senescent leaves from the maple (Acer buergerianum
Miq. Angiospermae: Aceraceae) and from the
camphorous laurel (Cinnamomum japonicum Sieb. Ex
Nakai Angiospermae: Lauraceae) and density-
dependence in the development of Ae. albopictus larvae.
In this paper we demonstrate that leaf litter from these
two species have different abilities to support larval
development. These affect larval dynamics and the
differences interact with population density.
MATERIALS AND METHODS
Trees and leaves
Acer buergerianum is well-distributed deciduous
tree in urban forests, parks and along roads in Nagasaki
possessing lightly colored leaves from 4 to 8 cm long.
Cinnamomum japonicum is a laurel forest tree widely
distributed in Kyushu, used in gardening and commonly
found in urban areas. It is an evergreen species with
hard leaves having a lustrous superior surface. The fresh
leaves are highly aromatic.
Leaves of these two trees are found in a diverse
range of containers associated with different densities
of mosquito larvae, including Ae. albopictus, from May
to October in the small forest when mosquito breeding
takes place. Observations have shown that containers
under the maple tree hold higher densities of
mosquitoes, in particular Ae. albopictus, when
compared to those under the camphor tree.
Bioassays
We established a series of microcosms with the two
types of whole senescent leaves without petiole at
different larval densities. Microcosms consisted of a
plastic container, 18.5 cm length x 12.5 cm width x 4.5
cm deep, filled with 350 ml of tap water.
Leaves were collected in roughly equal amounts
from both trees and the ground, cleaned of debris, stored
dry, and their petioles were removed before use. In each
case 0.75g of either dried A. buergerianum or dried C.
japonicum was added to microcosms as larval food.
Five larval densities (4, 8, 16, 32 and 64) of newly
hatched Ae. albopictus (Nagasaki strain field-collected
in 1998) were added to the microcosms maintained
under 25-27 °C, 60-80 % RH and 16L : 8D.
Data collection
Pupae were removed and recorded for sex and body
size. The sex of the mosquito pupae was determined by
the method of Moorefield (1951). The width of the last
abdominal segment of the pupae was used as a measure
of their body-size.
As a control to measure the changes in water
4 8 16
32
64
Larval density
0
10
20
30
40
50
60
Loss of labile substances
(%)
A. buergerianum
F=68.00
P<0.001
Figure 1. Decay of leaves of the maple A. buergerianum and the
camphorous laurel C. japonicum liters/350 ml of water in
containers with five developing larval populations of Aedes
albopictus in laboratory microcosms. (For larval number 64, error
bars were not provided for both leaf types because only one
replicate was used. The others replicates were discarded from
the analysis of decay because of technical errors during
manipulations; same thing for larval number 32 for the maple).
June, 2002 Journal of Vector Ecology 33
quality, microcosms were established with no larvae and
the absolute pH recorded every two days during the
decay process for two weeks. At the end of the
experiments, all the remaining leaf litter was collected
from the microcosms, oven-dried (50°C, 24 hours) and
weighed. In the experimental microcosms we measured
the pH, the percentage of dry matter mass lost by decay,
pupation time, mortality and pupal body-size. Loss of
dry matter by the leaves was determined by the
difference between the initial and the final dry masses.
The pupation time corresponded to the number of days
from larval introduction into the microcosm till the day
of pupation. Larval mortality was calculated by dividing
the total number of dead larvae by the initial number of
first instars.
Statistical analysis
The SYSTAT statistical software package
(Wilkinson 1996) was used to perform statistical
analysis. We used Students paired t-test of significance
to compare the pH of the two leaf solutions. A two-way
analysis of variance was applied to compare pupation
time, larval mortality, and pupal body-size according
to the two treatments. Tukey statistic was used for the
comparison of individual larval density effects of each
treatment on these parameters.
RESULTS
Decay processes
Both substrates were acid but the maple solution
was significantly more acid than that of the camphor
solution (maple: 5.85 ± 0.20, camphor: 6.47 ± 0.10, t =
12.72, P < 0.001). Visually the maple solution had a
darker color than the camphor solution. The loss of
labile substances was much higher in the microcosms
with the maple leaves than in those with the camphor
leaves (Figure 1). It is clear that the maple leaf decayed
more rapidly than the camphor and it is therefore likely
that the maple-microcosms have more nutritional
resources.
Pupation time
Both larval density and leaf species as well as their
interactions significantly affected the larval period of
4 8 16
32
64
Larval density
0
10
20
30
40
50
Age at pupation (day)
c
b
a
a
a
1
3
1
1
2
4 8 16
32
64
0
10
20
30
40
50
a
1
1
1
1
1
a
a
a
b
C. japonicum
A. buergerianum
Larval density
4
8
16
32
64
Larval density
0
10
20
30
40
50
60
70
80
Larval mortality (%)
A. buergerianum
C. japonicum
F = 56.00
P
< 0.001
Figure 2. Mean pupation time (± SD) of Aedes albopictus reared at five larval populations in microcosms with the maple A.
buergerianum and the camphorous laurel C. japonicum leaves as nutritional substrates for larvae [bars of the same color and with
the same letter or number do not show a significant difference (P < 0.05) based on Tukey statistic for means comparison].
Figure 3. Mortality rates (± SD) of Aedes albopictus reared at
five larval populations in microcosms with A. buergerianum and
C. japonicum leaves as nutritional substrates [bars of the same
color and with the same letter do not show a significant difference
(P < 0.05) based on Tukey statistic for means comparison].
34 Journal of Vector Ecology June, 2002
4 8 16
32
64
0.5
0.6
0.7
0.8
0.9
1.0
1.1
A. buergerianum
C. japonicum
1
1
2
2
3
a
a
b
b
b
4 8 16
32
64
Larval density
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Body size at pupation (mm)
1
1
2
3
3
a
a
a
a
a
Ae. albopictus (Table 1). Individuals reared with the
maple litter had shorter developmental periods than
those fed on the camphor (Figure 2). In both treatments,
larval period tended to increase with increasing
densities. In the maple treatment, the larval period of
the males did not differ significantly between the lower
density microcosms, but was shorter when compared
to that in the highest-density microcosm containing 64
larvae (Figure 2). The larval period of the females in
the low-density microcosms of the maple treatment had
a shorter time to pupation than that of the two highest
density microcosms (32 and 64 larvae) (Figure 2). The
pattern in the camphor treatment was similar, with both
males and females showing significantly longer
development periods at the two highest densities (Figure
2). The increased development time with larval density
is therefore a result of extended development at the
highest densities (Figure 2).
Larval mortality
The mortality rate of Ae. albopictus during
development was consistently lower in the maple leaf
microcosms (Figure 3). In the camphor treatment,
pairwise comparisons using the Tukey test reveal that
the mortality in the highest density microcosm was
significantly different to all the others. There were no
other significant pairwise differences among lower
densities. Clearly, therefore, mortality is affected by
density in the camphor treatment leaf microcosms, but
this effect is mostly seen at high densities. The maple
treatment showed similar patterns but in contrast, there
was no significant variation of mortality between the
two highest densities (Figure 3).
Pupal size
The leaf species and density significantly affected
the size at pupation. There was also a significant
interaction between the leaf species and the density,
showing that density had different effects in the two
leaf treatments (Table 1). Larvae reared with the
camphor leaf litter were smaller than those produced
from the maple microcosms (Figure 4). In both types of
microcosms and for both sexes, the pupal size tended
to decrease with increasing densities (Figure 4). This
density effect tended to be stronger in the maple
microcosms as compared to camphor microcosms (Table
1, Figure 4).
DISCUSSION
The most important observation from our results
is that maple leaf litter is a more suitable substrate for
mosquito development than camphor leaf litter. The
developmental period was clearly shorter in the maple-
microcosms, especially in those with high densities. The
camphor litter produced higher mortality rates as
densities increased. The size at pupation was also
reduced in the camphor microcosms.
Within the experimental units, we showed a major effect
of both nutritional resources and density on development
time. Clearly, in the field an increased development time
will tend to result in higher cumulative mortality. With
an extended developmental period, larvae are more
exposed to possible parasites and predators as well as
Figure 4. Average width of the last abdominal segment (± SD) of Aedes albopictus pupated from microcosms where the nutritional
substrate was senescent leaves from the maple Acer buergerianum or from the camphorous laurel Cinnamomum japonicum [bars
of the same color and with the same letter do not show a significant difference (P < 0.05) based on Tukey statistic for means
comparison].
June, 2002 Journal of Vector Ecology 35
an increased risk of desiccation as habitats dry up prior
to adult emergence. The increased developmental period
on the slow decaying litter will therefore lead to smaller
population sizes of mosquitoes. The smaller adult size
of mosquitoes is also likely to have an impact on the
population density of the mosquito. Size is often
correlated with fitness in the field, because it can affect
both the reproductive potential and feeding behavior of
adult mosquitoes. Small size in females can lead to fewer
eggs per batch and a slower post-emergence pre-blood
meal ovarian development (Jalil 1974, Livdahl 1984).
Larger females are suggested to have greater vector
potential, because they may be more successful at finding
a second blood meal (Nasci 1986). In Ae. albopictus
males, small size can cause delayed spermatogenesis
(Smith and Hartberg 1974).
It is interesting to note that the type of leaf detritus
had less effect on the males of Ae. albopictus than
females. Males require less energy to complete
development (Haramis 1984) probably due to the sex-
related differences in larval nutrient metabolism and
physiological roles after emergence. The different roles
of adult females and males are frequently reflected in
differences in larval development. Females need a long
developmental time in order to accumulate sufficient
nutrients for egg production.
There was clearly a relationship between the
decomposition of the leaves and the availability of
nutrients in the experimental units. A number of studies
have reported a correlation between the decomposition
pattern of leaves and their nutritional value. Rapidly
decomposing leaves are known to produce higher
nutrients concentration when compared to slowly
decomposing leaves (Kaushik and Hynes 1971) while
pH has been reported to have little effect on mosquito
larvae (MacGregor 1929). Cummins et al. (1973)
observed a higher development rate in the Tipula
populations when fed on rapidly decaying leaf litter. In
a related work, Otto (1974) also found that when alder
leaves were plentiful, there was a steady increase in the
fat content of Trichoptera larvae, but when beech leaves
were the principal food, fat content dropped. In feeding
trials, the same author further demonstrated that larvae
fed on beech leaves were 27% below; and those fed alder
leaves were 25% above the weights of the field
population. He attributed both effects to an increase of
alder leaves that were rapidly decaying. Differences in
larval development pattern have been also reported in
mosquitoes. Fish and Carpenter (1982) compared the
larval dynamics of Ae. triseriatus on beech, black oak
and maple litters and recorded that the fastest decaying
leaf, the maple, was most suitable substrate for the
development of the mosquito. Carpenter (1983) studied
TABLE 1. ANOVA test for effects of leaf-treatment and density on pupation time and pupal size of Aedes albopictus.
Males Females
pupation time (day) pupal size (mm) pupation time (day) pupal size (mm)
Source variables df F-value P-value df F-value P-value df F-value P-value df F-value P-value
Leaf species* 1 36.403 < 0.000 1 98.750 < 0.000 1 101.643 < 0.000 1 138.757 < 0.000
Density** 4 65.048 < 0.000 4 43.020 < 0.000 4 131.705 < 0.000 4 60.441 < 0.000
Leaf species x Density 4 36.221 < 0.000 4 3.851 0.005 4 48.921 < 0.000 4 6.043 < 0.000
* = Camphor and Maple; ** = 4, 8, 16, 32 and 64 larvae; x = Interaction
36 Journal of Vector Ecology June, 2002
the regulation of larval populations and concluded that
slowly decomposing beech litter limited the growth and
reduced the survivorship of Ae. triseriatus.
However, decay rate may not be the single factor
that affected the growth performance and mortality
patterns observed in the present study even though Fish
and Carpenter (1982) and Carpenter (1983) have argued
this case. Walker et al. (1997) in an experiment where
leaves came from the same species of tree but of differing
quality, found that decay rate (measured as loss of matter
per unit time) could explain only about half of the
observed difference in Ae. triseriatus biomass
production. Here we have two different leaf species with
different decay rates as well as different chemical
compositions. Low ability of slowly decomposing leaf
litter can be due to high concentrations of polyphenols
which are toxic to a number of insects (Feeny 1970),
and by a high level of lignin (Kaushik and Hynes 1971).
Phytochemicals were previously documented to reduce
extracellular enzyme activity of fungi resulting in
retarded fungal growth (Suberkropp et al. 1976) that
affects their ability to cause rapid leaf decay. The leaves
of Cinnamomum sp contain chemicals that inhibit
microbes (Mau et al. 2001). It is possible that these
chemicals inhibited microbial growth and consequently
stalled larval growth in camphor microcosms. There
may have also been direct effects of chemical substances
on the camphorous laurel leaves that could have caused
the mortality observed here. Lederhouse et al. (1992)
showed that leaves of lauraceous plants including the
genera Persea and Lindera, species related to C.
japonicum were toxic to two lepidoptera caterpillars
that used these leaves as food. According to the same
author, aside from toxicity effects, some other
compounds of laurel leaves may also function as feeding
inhibitors of the caterpillar larvae. Thus, with regard
to these reports, the differences seen here between the
maple and camphor leaves are more likely due to the
difference in their ability to release labile substances
that could function as nutrients and/or larval feeding
inhibitors which may affect microbial production and
thus Ae. albopictus larvae growth. Although the extracts
of Acer sp have been reported toxic (Plumlee 1991), C.
japonicum seem to be more toxic and one wonders if it
might not have an inhibitory effect on Ae. albopictus
larvae in the present study.
Regardless of other factors involved in the overall
population dynamics in areas with different vegetation,
one may expect maple-dominated areas to support
higher densities of mosquitoes than areas where the
camphor tree predominates. Ae. triseriatus population
densities have been shown to be higher in maple habitats
compared to mixed hardwood sites (Nasci et al. 2000).
In contrast Eshita and Kurihara (1978) and Miyagi and
Toma (1978, 1980) reported that Ae. albopictus is rare
or absent in natural forests with evergreen broad-leaved
trees.
As well as providing insight into the nutritional
ecology of Ae. albopictus, this work suggests the
importance of removing vegetation from artificial
containers near residences since leaves provide resources
for the development of larvae. Careful choice of trees
planted close to inhabited areas clearly has the potential
to reduce densities of this vector mosquito. This
approach is likely to be most successful in areas where
many of the trees are planted decoratively in gardens
and parks.
Acknowledgments
The authors are grateful to Dr. Pradya Somboon,
Ms. E. Urakawa for their assistance in laboratory works.
We also thank Gerry Marten and Steven A. Juliano for
their review of this manuscript and their valuable
suggestions.
REFERENCES CITED
Beehler, J., S. Lohr, and G. Defoliart. 1992. Factors
influencing oviposition in Aedes triseriatus
(Diptera : Culicidae). Great Lakes Entomol. 25:
259-264.
Benson, G. L., C. S. Apperson, and W. Clay. 1988.
Factors affecting oviposition site preference by
Toxorhynchites splendens in the laboratory. J. Am.
Mosq. Contr. Assoc. 4: 20-22.
Carpenter, S. R. 1983. Resource limitation of larval
treehole mosquitoes subsisting on beech detritus.
Ecology. 64: 219-223.
Chan, Y. C., B. C. Ho, and K. L. Chan. 1971. Aedes
aegypti (L.) and Aedes albopictus (Skuse) in
Singapore city. Observations in relation to dengue
haemorrhagic fever. Bull. Wld. Hlth. Org. 44: 651-
658.
Clements, A. N. 1992. The biology of mosquitoes. Vol.
1. Chapman and Hall, London. 509 pp.
Cummins, K. W., R. C. Petersen, F. O. Howard, J. C.
Wuycheck, and V. I. Holt. 1973. The utilization of
leaf litter by stream detritivores. Ecology 54: 336-
345.
Cummins, K. W. and M. J. Klug. 1979. Feeding ecology
of streams invertebrates. Annu. Rev. Ecol. System.
10: 147-172.
Eshita, Y. and T. Kurihara.1978. Studies on the habitats
of Aedes albopictus Aedes riversi in the
Southwestern part of Japan. Japn. J. Sanit. Zool.
June, 2002 Journal of Vector Ecology 37
30:181-186.
Feeny, P. 1970. Seasonal changes in oak leaf tannins
and nutrients as a cause of spring feeding by winter
moth caterpillars. Ecology 51: 565-581.
Fish, D. and S. R. Carpenter. 1982. Leaf litter and larval
mosquito dynamics in tree-hole ecosystems.
Ecology 63: 283-288.
Haramis, L. D. 1984. Aedes triseriatus: a comparison
of density in tree holes vs. discarded tires. Mosq.
News 44: 485-489.
Hawley, W. A. 1988. The biology of Aedes albopictus.
J. Am. Mosq. Contr. Assoc. (Suppl.). 1: 1-40.
Jalil, M. 1974. Observations of the fecundity of Aedes
triseriatus (Diptera: Culicidae). Entomol. Exp.
Appl. 17: 223-233.
Jumali, Suarto, D. J. Gubler, S. Nalim, S. Eram, and J.
S. Saroso. 1979. Epidemic dengue haemorrrhagic
fever in rural Indonesia III. Entomological studies.
Am. J. Trop. Med. Hyg. 28: 717-724.
Kaushik, N. K. and H. B. N. Hynes. 1971. The fate of
the dead leaves that fall into streams. Arch.
Hydrobiol. 68: 465-515.
Kitching, R. L. 1983. Community structure in water-
filled treeholes in Europe and Australia
comparisons and speculations. In Phytotelmata:
terrestrial plants as hosts for aquatic insect
communities. (J.H. Frank and L.P. Lounibos, eds).
pp. 205-222. Plexus, Medford, NJ.
Lederhouse, R. C., P. A. Matthew, K. N. Nitao, and S.
Mark. 1992. Differential use of lauraceous hosts
by swallowtail butterflies, Papilio troilus and P.
palamedes (Papilionidae). Oikos. 63: 244-252.
Leonard, P. M. and S. A. Juliano. 1995. Effect of leaf
litter and density on fitness and population
performance of the treehole mosquito Aedes
triseriatus. Ecol. Entomol. 20: 125-136.
Livdahl, T., R. Koenekoop and S. G. Futterweit. 1984.
The complex hatching response of Aedes eggs to
larval density. Ecol. Entomology. 9: 437-442.
Lounibos, P.L., N. Naoya, and L. E. Richard. 1993.
Fitness of a treehole mosquito: influences of food
type and predation. Oikos. 66: 114-118.
Lord, C. C. 1998. Density dependence in larval Aedes
albopictus (Diptera: Culicidae). J. Med. Entomol.
35: 825-829.
MacGregor, M. E. 1929. The significance of the pH in
the development of the mosquito larvae.
Parasitology, 21: 132-157.
Makiya, K. 1968. Population dynamics of larvae
overwintering in southern Japan. Japn. J. Sanit.
Zool. 19: 223-229.
Mau, J. L., C. P. Chen, and P. C. Hsieh. 2001.
Antimicrobial effects from Chinese chive,
Cinnamon, and Corni fructus. J. Agric. Food Chem.
49: 183-188.
Miyagi, I. and T. Toma. 1978. Studies on the mosquitoes
in the Yaeyama Islands, Japan 2. Notes on the non-
anopheline mosquitoes collected at Ishigakijima,
1975-1976. Japn. J. Sanit. Zool. 29: 305-312.
Miyagi, I. and T. Toma. 1980. Ditto 5. Notes on the
mosquitoes collected in forest areas of Iriomotejima.
Japn. J. Sanit. Zool. 31: 81-91.
Moorefield, H. H. 1951. Sexual dimorphism in mosquito
pupae. Mosq. News 11: 175-177.
Mori, A. 1979. Effects of larval density and nutrition
on some immature and adults Aedes albopictus.
Trop. Med. 21: 85-103.
Nasci, R. S. 1986. The size of emerging and host-seeking
Aedes aegypti and the relation of size to blood-
feeding success in the field. J. Am. Mosq. Contr.
Assoc. 2: 61-62.
Nasci, R. S, C. G. Moore, B. J. Biggerstaff, N. A. Panella,
H. Q. Liu, N. Karabatsos, B. S. Davis, and E. S.
Brannon. 2000. La Crosse encephalitis virus
habitats associations in Nicholas County, West
Virginia. J. Med. Entomol. 37: 559-570.
Otto, C. 1974. Growth and energetics in larval
population of Potamophylax cingulatus (Steph.)
(Trichoptera) in a south Swedish stream. J. Anim.
Ecol. 43: 339-361.
Paradise, C. J and K. L. Kuhn. 1999. Interactive effects
of pH and leaf litter on a shredder, the scirtid beetle,
Helodes pulchella, inhabiting tree-holes.
Freshwater Biol. 41: 43-49.
Plumlee, K. H. 1991. Red maple toxicity in horse. Vet.
Hum. Toxicol. 33: 66-67.
Rai, K. S. 1991. Aedes albopictus in the Americas.
Annu. Rev. Entomol. 36: 459-484.
Reiter, P. 1998. Aedes albopictus and the world trade
in used tires, 1985-1995: the shape of things to
come? J. Am. Mosq. Control. Assoc. 14: 83-94.
Smith, R. P. and W. K. Hartberg. 1974. Spermatogenesis
in Aedes albopictus (Skuse). Mosq. News 34: 42-
47.
Sota, T., M. Mogi, and E. Hayamizu. 1992. Seasonal
distribution and habitat selection by Aedes
albopictus and Aedes riversi (Diptera : Culicidae)
in Northern Kyushu, Japan. J. Med. Entomol. 29:
296-304.
Sota, T. 1993. Performance of Aedes albopictus and
Aedes riversi larvae (Diptera : Culicidae) in waters
that contain tannic acid and decaying leaves: is the
treehole species better adapted to treehole water?
Ann. Entomol. Soc. Am. 86: 450-457.
Strand, M., D. A. Hermes, M. P. Ayers, M. E. Kubiske,
M. G. Kaufmann, E. D. Walker, K. S. Pregitzer,
38 Journal of Vector Ecology June, 2002
and R. W. Merritt. 1999. Effects of atmospheric
CO2, light availability, and tree species on the
quality of leaf detritus as a resource for treehole
mosquitoes. Oikos 84: 277-283.
Suberkrop, K., and M. J. Klug. 1976. Fungi and
bacteria associated with leaves during processing
in a woodland stream. Ecology 57: 707-719.
Sunahara, T. and M. Mogi. 1997. Can tortoise beat the
hare? A possible mechanism for the coexistence of
competing mosquitoes in bamboo grooves. Ecol.
Res. 12: 63-70.
Trimble, R. M. 1979. Laboratory observations on
oviposition by the predacious tree-hole mosquito
Toxorhynchites rutilus septentrionalis (Diptera:
Culicidae). Can. J. Zool. 57: 1104-1108.
Tsuda, Y., M. Takagi and Y. Wada. 1991. Preliminary
laboratory study on population growth of Aedes
albopictus. Trop. Med. 33: 41-46.
Walker, E. D. and R. W. Merritt. 1991. Behavior of
larval Aedes triseriatus (Diptera : Culicidae). J.
Med. Entomol. 28: 581-589.
Walker, E. D., M. G. Kaufmann, M. P. Ayres, M. S.
Riedel and R. W. Merritt. 1997. Effects of variation
in quality of leaf detritus on growth of the eastern
tree-hole mosquito, Aedes triseriatus (Diptera:
Culicidae). Canad. J. Zool. 75: 706-718.
Ward, G. M., and K. W. Cummins. 1979. Effects of
food quality on growth of a stream detritivore,
Paratendipes albimanus (Meigen) (Diptera:
Chironomidae). Ecology 60: 57-64.
Willis, F. S. and R.S. Nasci. 1994. Aedes albopictus
(Diptera: Culicidae) population density and
structure in southwest Louisiana. J. Med. Entomol.
31: 594-599.
Wilkinson, L. 1996. Systat 6.0 for windows: Statistics.
SPSS Inc.,751 pp.
Wilton, D. P. 1968. Oviposition site selection by the
tree hole mosquito, Aedes triseriatus (Say). J. Med.
Entomol. 5: 189-194.
Young, R., L. Kirk, and A. Huryn. 1997. Organic matter
production; utilization and transport: an ecoregion
comparison of rivers throughout Southern New
Zealand. Taeri and Rivers Program, 4th Annual
Report, 27-28.
... In breeding grounds, larvae exploit the leaf debris by ltering, browsing microbes on the surface (Cummins and Klug, 1979;Fish and Carpenter, 1982;Walker and Merritt, 1991;Kaufman et al., 2001;Kaufman and Walker, 2006;Walker et al., 2010;Murrell and Juliano, 2014). e larval growth rate depends on leaf decomposition, chemical properties and microbial contents of leaf litter (Cummins and Klug 1979;Dieng et al., 2002). We anticipated that Ae. albopictus is going to expand in their northern distribution and increase the more in number with the expansion of unmanaged bamboo groves. ...
... avopictus (Alam and Tuno, unpublished data). Other studies noted that beech (Mau et al., 2001;Dieng et al., 2002) and cherry (Kelly et al., 2010;Kim and Muturi, 2012) contain lethal components. e components inhibit the microbial production that a ects nutrient availability resulting in low levels of larval growth and mortality (Rey et al., 1999;David et al., 2000David et al., , 2002Tilquin et al., 2002;Dieng et al., 2002;Ansari et al., 2005). ...
... Other studies noted that beech (Mau et al., 2001;Dieng et al., 2002) and cherry (Kelly et al., 2010;Kim and Muturi, 2012) contain lethal components. e components inhibit the microbial production that a ects nutrient availability resulting in low levels of larval growth and mortality (Rey et al., 1999;David et al., 2000David et al., , 2002Tilquin et al., 2002;Dieng et al., 2002;Ansari et al., 2005). Consequently, cherry and beech may a ect the physiological process of Ae. albopictus larvae. ...
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The climatic conditions are the most plausible reason for the potential outbreaks of Aedes albopictus. The effect of climate change on vegetation is expediting the mosquito breeding sites that have an impact on the larval and adult growth. Here, we compared the effects of vegetation, bamboo (Phyllostachys pubescens), cherry (Prunus×yedoensis) and beech (Castanopsis sieboldii), on the larval growth of Ae. albopictus. The highest larval mortality was observed in cherry, conversely, the lowest was in bamboo. Larval development and adult emergence of cherry and beech were slower than those of bamboo. Female body size was larger when larvae raised with the bamboo compared to cherry plants. Ae. albopictus females oviposited more eggs in bamboo vegetation, however, adults reared by cherry plants laid less amount of eggs. Per capita performance of Ae. albopictus on bamboo vegetation was higher for the population growth compared to cherry and beech. Thus, Ae. albopictus were affected by bamboo vegetation that might have influenced the larval and adult growth. Our findings suggested that bamboo plants should be avoided in future plantation programs near the urban areas, as it might harbor a potential habitat for Ae. albopictus.
... The results still suggest that shade created by abundant vegetation in the parks provides a suitable environment for A. albopictus. Nutrients from leaf litter may become an energy source and enhance the development of larvae [45]. Aedes albopictus adults are known to ingest sugars from understory vegetation [46,47], and they may seek blood meals more actively in the shade created by trees [48]. ...
... The results suggest that periodic removal of discarded containers in the parks is important for vector control. Managing over-grown understory vegetation not only reduces the quality of larval habitats [45], but also adult mosquito resting sites [63]. The study results regarding the distances from the parks suggest that the importance of the peripheral area for vector control; however, further studies are needed to confirm this notion. ...
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The primary dengue virus vectors, Aedes aegypti and Aedes albopictus , are primarily daytime biting mosquitoes. The risk of infection is suspected to be considerable in urban parks due to visitor traffic. Despite the importance of vector control for reducing dengue transmission, little information is available on vector populations in urban parks. The present study characterized mosquito habitats and estimated vector densities in the major urban parks in Ho Chi Minh City, Vietnam and compared them with those in adjacent residential areas. The prevalences of habitats where Aedes larvae were found were 43% and 9% for the parks and residential areas, respectively. The difference was statistically significant (prevalence ratio [PR]: 5.00, 95% CI: 3.85–6.49). The prevalences of positive larval habitats were significantly greater in the parks for both species than the residential areas (PR: 1.52, 95% CI: 1.04–2.22 for A . aegypti , PR: 10.10, 95% CI: 7.23–14.12 for A . albopictus ). Larvae of both species were positively associated with discarded containers and planters. Aedes albopictus larvae were negatively associated with indoor habitats, but positively associated with vegetation shade. The adult density of A . aegypti was significantly less in the parks compared with the residential areas (rate ratio [RR]; 0.09, 95% CI: 0.05–0.16), while the density of A . albopictus was significantly higher in the parks (RR: 9.99, 95% CI: 6.85–14.59). When the species were combined, the density was significantly higher in the parks (RR: 2.50, 95% CI: 1.92–3.25). The urban parks provide suitable environment for Aedes mosquitoes, and A . albopictus in particular. Virus vectors are abundant in the urban parks, and the current vector control programs need to have greater consideration of urban parks.
... Different species of detritus support different quantities (and possibly different species) of microbial food for mosquito larvae, which reduces resource competition and improves mosquito performance [10][11][12][13]. For example, larvae raised with animal detritus (e.g., dead insects) have higher survival and faster development than larvae raised with plant detritus [14][15][16][17]. Likewise, larvae raised with rapidly decaying plant detritus have similarly better larval performance than larvae raised with slow-decaying plant detritus [14][15][16][17]. ...
... For example, larvae raised with animal detritus (e.g., dead insects) have higher survival and faster development than larvae raised with plant detritus [14][15][16][17]. Likewise, larvae raised with rapidly decaying plant detritus have similarly better larval performance than larvae raised with slow-decaying plant detritus [14][15][16][17]. In turn, differences in larval performance as a result of detritus type have been related to adult body size [13,14,18] and survival [17,19], while variation in available larval food resources more generally have also been related to fecundity [20][21][22], biting rate [23], and susceptibility to viral infection [24][25][26], all of which are expected to affect disease transmission at the individual and population scales [27][28][29][30][31][32]. ...
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Species interactions that influence the performance of the exotic mosquito Culex pipiens can have important effects on the transmission risk of West Nile virus (WNV). Invasive plants that alter the vegetation communities of ephemeral ground pools may facilitate or resist the spread of C. pipiens (L.) by altering allochthonous inputs of detritus in those pools. To test this hypothesis, we combined field surveys of roadside stormwater ditches with a laboratory microcosm experiment to examine relationships between C. pipiens performance and water quality in systems containing detritus from invasive Phragmites australis (Cav.) Trin. Ex Steud., introduced Schedonorus arundinaceus (Schreb.) Dumort., or native Juncus effusus L. or Typha latifolia L. In ditches, C. pipiens abundance was unrelated to detritus species but female C. pipiens were significantly larger from ditches with S. arundinaceus and smaller with J. effusus. Larger and smaller C. pipiens were also produced in microcosms provisioned with S. arundinaceus and J. effusus, respectively, yet the per capita rate of population of change did not vary. Larger females from habitats with S. arundinaceus were likely caused by faster decay rates of S. arundinaceus and resultant increases in microbial food, but lower survival as a result of fouling and higher tannin-lignin concentrations resulted in little changes to overall population performance. Larger female mosquitoes have been shown to have greater potential for transmitting arboviruses. Our findings suggest that changed community-level interactions from plant invasions in urban ephemeral ground pools can affect the fitness of C. pipiens and possibly increase WNV risk.
... The nutrient content in a water-filled breeding container depends on water spilling which often leads to removal of nutrients or resource depletion (Dieng et al., 2002). This resource depletion and overcrowding are critical factors of survival for container breeding mosquitoes. ...
Article
Dengue is a fatal arthropod-borne disease that affects humans worldwide. The mosquito Aedes albopictus (Skuse) is the secondary vector of dengue in Sri Lanka, however, studies on oviposition preferences of Ae. albopictus is scarce. The objective of the current study was to investigate the oviposition attraction of Aedes albopictus to selected household containers; black colour basins, metal cans, rain gutter parts, curd pots, coconut shells and yoghurt cups. For this, water containers for oviposition were placed in three outdoor shady sites and at three different heights. The mosquito larvae were collected after 5 days. The larvae were reared to adult stage and then they were identified and enumerated. Wing lengths of adult female mosquitoes that developed in different containers were measured. In the meantime, temperature, pH, dissolved oxygen (DO) and total dissolved solids (TDS) were measured in each container. The Ae. albopictus larval density was higher in coconut shells. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution and reproduction in any medium provided the original work are properly credited. The effect of common household containers for oviposition of Aedes albopictus 47 The maximum mean number of mosquito larvae was observed in the containers at ground level. The oviposition attraction of Ae. albopictus was increased with the aging of coconut shells and old coconut shells were preferred than new coconut shells. Highest TDS level and neutral pH were observed in coconut shells which support the mosquito oviposition. The highest wing lengths were observed in female Ae. albopictus that developed in curd pots, representing higher fecundity. In conclusion, discarded coconut shells and curd pots should be carefully managed as means of eliminating dengue vector mosquito breeding sites.
... The similarity of the gut fungal community to the environment can be explained by the filter-feeding habit of mosquito larvae in general, which presumably captures a large portion of fungal taxa from the breeding water (41). A. albopictus larvae also display other feeding habits, including grazing and shredding on decaying leaf matter (69)(70)(71), which further contributes to the gut fungal diversity. This is supported by the results of the indicator species analysis where the gut indicator OTUs predominantly are saprophytes, endophytes, and pathogens that typically occur in plant tissues. ...
Article
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The Asian tiger mosquito, Aedes albopictus , is the dominant mosquito species in the United States and an important vector of arboviruses of major public health concern. One aspect of mosquito control to curb mosquito-borne diseases has been the use of biological control agents such as fungal entomopathogens.
... During the gut analysis of Aedes larvae, we found detritus as a major food source for both larvae. In artificial containers, the decaying leaf is the main source of organic matter where the habitats associated with vegetation organic matter content are higher [36]. ...
Article
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Naturally occurring microbiota in mosquito larval habitats are among biotic factors which affect the population dynamics of developing larvae. Many microbiota species serve as food items for vector mosquito larvae, and food limitations within habitats adversely affect larval survival, developmental rate, adult fitness, and thereby vector competence. Therefore, identification of microbiota as associates with larvae reveals their relationship between each other as parasites, pathogens, epibionts, or diet organisms. Analysis of associated microbiota species in the dengue vector larval breeding habitats () and the mosquito larval gut content were conducted in Kandy District in Sri Lanka. Study revealed that a total of 22 microbiota species belong to nine phyla (Amoebozoa, Bacillariophyta, Ciliophora, Chlorophyta, Sarcodina, Cyanobacteria/Cyanophyta, Euglenozoa, Ochrophyta/Heterokontophyta, and Rotifera) were encountered from different Ae. aegypti mosquito breeding habitats while 26 microbiota species that belonged to ten phyla were recorded from Ae. albopictus mosquito breeding habitats with one additional phylum Arthropoda. Considering Ae. aegypti breeding habitats, only Philodina citrina in low roof gutters existed as constant species. Considering Aedes albopictus breeding habitats, Volvox aureus in plastic containers, Lecane luna in coconut shells, Phacus pleuronectes in concrete slabs, and Pinnularia sp. in tree holes existed as constant species. The rest of the microbiota existed as common or accidental/rare species in a variety of habitat types. The Shannon-Weiner diversity (21.01 and 19.36) and gamma diversity (eight and eight) of the microbiota associated with Ae. aegypti and Ae. albopictus larvae, respectively, in ponds were found to be higher than other types of breeding habitats recorded during the study. Twelve microbiota species were recorded from larval gut analysis as food organisms of both species of mosquito larvae. However, the distribution of gut microbiota species differed between Ae. aegypti and Ae. albopictus (, ). Identification of microbiota as food items of vector mosquito larvae led to a focus on larval food limitation by introducing food competitors, which could be a potential additional tool for integrated vector control approaches within the country. 1. Introduction In terms of public health, mosquitoes are the most important vectors for diseases, and therefore, studying their ecological and environmental conditions influencing their abundance is important. Mosquito habitat ecology plays an important role to determine the larval densities and species assemblage in a particular breeding habitat [1, 2]. Different types of aquatic habitats are utilized by mosquitoes for oviposition, and many mosquito species tend to select both natural and artificial containers as breeding places [3, 4]. In Sri Lanka, dengue has become a significant socioeconomic and public health burden and Aedes aegypti and Aedes albopictus are widely adapted to urban and suburban environments, acting as vectors of dengue within the country [5]. Water-holding containers were found to be the main larval habitats for Ae. aegypti and Ae. albopictus. Chan et al. [6] have stated that Ae. aegypti breed in indoor-type breeding habitats such as earthenware jars, tin cans, ant traps, rubber tires, bowls, and drums. Immature forms of Ae. albopictus prefer artificial containers with stagnant water and additionally found in tree holes, rock holes, hollow bamboo stumps, and leaf axils [7]. Mosquito distribution, abundance, and individual fitness in breeding habitats are known to be dependent on mainly two factors: biotic and abiotic factors. Biotic factors included the interaction of larvae with other associated macrobiota or microbiota taxa [8–10]. When considering the biotic factors associated with mosquito taxa, there is a diversified naturally occurring microbiota assemblage in mosquito breeding habitats which act as partly potential food organisms, controphic species, competitors, parasites, and/or potential mosquito predators, especially microcrustaceans. Species that belonged to Cladocera, Calanoida, Harpacticoida, Cyclopoida, and algae, bacteria, and protists are also found as microbiota associated with different species of mosquito larvae ([11–15] Nutritional requirements of immature mosquitoes are acquired through the consumption of both dead and living organic material [16]. The larval food items include heterotrophic microorganisms such as bacteria, fungi, and protists which make the largest portion of diet in larvae and organic matter from the environment such as plant debris. Therefore, there are many naturally occurring microbiota associated with larvae of which some may act as food items for them. The availability of suitable and sufficient food sources determine the proliferation of mosquitoes. Further, the quality and quantity of larval nutrition directly influence immature survivorship and their developmental rate which can ultimately alter the adult traits and population dynamics of larvae, such as larval survival rate and growth rate. Therefore, the mosquito population specially developed in container habitats can be regulated by the availability of food resources [17]. Very little information focusing the microbiota species association with vector mosquito breeding habitats are documented from studies conducted in Sri Lanka (Bambaradeniya et al., 2004; [18–20]). Therefore, the present study was conducted to identify naturally occurring microbiota species associated in a variety of dengue vector mosquito breeding habitats in Kandy District in Sri Lanka. 2. Methodology 2.1. Study Area Kandy District consists of the extent of land about 1940 km² in the Central Province of Sri Lanka. It is located in high elevated mountainous and thickly forested interior of the island. This has led to relatively wetter and cooler temperature with an average annual precipitation of 2083 mm and annual temperature of 24.5°C. At present, Kandy District is the fourth-highest risk area for dengue transmission in the country, contributing to 8.51% () of the total dengue cases reported from the whole country in 2019 [21]. 2.2. Sampling of Mosquito Breeding Habitats for Microbiota and Mosquito Larvae A total of forty mosquito breeding habitats were randomly sampled bimonthly between January and August 2019, and each sampling site was georeferenced (GARMIN-etrex SUMMIT) (Figure 1). A standard 250 mL dipper was used to collect water. When dipping was not possible, sampling was done using pipetting or siphoning methods (maximum 250 mL) into a larval rearing container (height 12 cm, diameter 6.5 cm). Five to eight mature larvae were carefully separated into a glass vial with 70% ethanol and labeled for mosquito species identification, and larvae in each sample were identified into species level using standard identification keys [22–25]. Samples positive with Aedes larvae were selected.
... Mosquito population dynamics are influenced by a variety of biological and environmental conditions (Clements, 1999;Dieng et al., 2001;Blaustein & Chase, 2007). For example, oviposition site selection can be influenced by many habitat characteristics, including habitat size, water quality, and the presence of competitor and predator species (Clements, 1999;Eitam et al., 2002;Blaustein et al., 2004). ...
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The mosquito Aedes phoeniciae is a potential disease vector that inhabits the coastal rock-pools of the Southeastern Mediterranean Sea. Our year-long study examined the abundance and distribution of Ae. phoeniciae in 49 rock-pools along HaBonim Beach Nature Reserve (Israeli coast) on a monthly basis (September 2016 to August 2017). Additionally, the physical, chemical, and biological characteristics of the rock-pools were measured. Our results showed a correlation between the abundance of Ae. phoeniciae and abiotic (salinity, pool volume, and pH) and biotic (bacterial, micro-phytoplankton, and chironomid abundance) characteristics. A complementary experiment was conducted to examine the role of bacteria and phytoplankton on Ae. phoeniciae larval performance by rearing larvae in seawater (SW) or seawater without microbes (FSW, 0.2-µm). Ae. phoeniciae grown in SW exhibited a high survivorship rate (~ 77%), while lower survivorship rate was measured in the FSW treatments (~ 45%). Furthermore, a higher number of adult females were found in the SW compared to FSW treatments (35 and 11, respectively), while the number of male adults remained similar. Our results suggest that Ae. phoeniciae larvae rely on the water characteristics and especially on the microbial communities that habitat the rock-pools. These results may enable improved mosquito control of Ae. phoeniciae along the Southeastern Mediterranean Sea.
... Mosquito population dynamics are influenced by a variety of biological and environmental conditions (Clements, 1999;Dieng et al., 2001;Blaustein & Chase, 2007). For example, oviposition site selection can be influenced by many habitat characteristics, including habitat size, water quality, and the presence of competitor and predator species (Clements, 1999;Eitam et al., 2002;Blaustein et al., 2004). ...
Article
The mosquito Aedes phoeniciae is a potential disease vector that inhabits the coastal rock-pools of the Southeastern Mediterranean Sea. Our year-long study examined the abundance and distribution of Ae. phoeniciae in 49 rock-pools along HaBonim Beach Nature Reserve (Israeli coast) on a monthly basis (September 2016 to August 2017). Additionally, the physical, chemical, and biological characteristics of the rock-pools were measured. Our results showed a correlation between the abundance of Ae. phoeniciae and abiotic (salinity, pool volume, and pH) and biotic (bacterial, micro-phytoplankton, and chironomid abundance) characteristics. A complementary experiment was conducted to examine the role of bacteria and phytoplankton on Ae. phoeniciae larval performance by rearing larvae in seawater (SW) or seawater without microbes (FSW, 0.2-lm). Ae. phoeniciae grown in SW exhibited a high survivorship rate (* 77%), while lower survivorship rate was measured in the FSW treatments (* 45%). Furthermore , a higher number of adult females were found in the SW compared to FSW treatments (35 and 11, respectively), while the number of male adults remained similar. Our results suggest that Ae. phoeni-ciae larvae rely on the water characteristics and especially on the microbial communities that habitat the rock-pools. These results may enable improved mosquito control of Ae. phoeniciae along the Southeastern Mediterranean Sea.
Article
Laboratory microcosm experiments were conducted to evaluate effects of bacteria isolated from senescent white oak leaves on the growth and survivorship of larval Aedes albopictus (Skuse). Larvae hatched from surface-sterilized eggs were reared in microcosms containing individual bacterial isolates, combined isolates (Porphyrobacter sp., Enterobacter asburiae, Acidiphilium rubrum, Pseudomonas syringae, and Azorhizobium caulinodans), a positive control containing a microbial community from an infusion of white oak leaves, and a negative control consisting of sterile culture media. Experiments were conducted for 21 d after which microcosms were deconstructed, larval survivorship was calculated, and bacteria contained in pupae, and adults that developed were quantified to determine rates of transstadial transmission. Positive control microcosms containing diverse microbial communities had an average (±SE) pupation rate of 89.3 (±5.8)% and average larval survivorship of 96.0 (± 2.3)%. Pupation in microcosms with bacterial isolates only occurred twice among all experimental replications; average larval survivorship ranged from 19 to 56%, depending on treatment. Larval growth was not found to be dependent on bacterial isolate density or isolate species, and larval survivorship was dependent on bacterial isolate density, not on isolate species. Potential mechanisms for failed development of larvae in microcosms with bacterial isolates are discussed. Bacterial isolates alone did not support larval development. High larval survivorship in positive control microcosms suggests that a diverse microbial community is required to complete larval development. Additional studies are needed to evaluate larval growth and survivorship on nonbacterial microbes, such as fungi and protozoa.
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Mosquitoes (Diptera: Culicidae) are one of the main threats for many people throughout the world; subsequently they act as vectors for indispensable pathogens for the following infections, malaria, dengue, yellow fever, West Nile, and parasites, such as filariasis (Murugan et al. 2015). Mosquitoes are the most critical group of insects in the context of public health, because they transmit numerous diseases, causing millions of deaths annually. An annual estimation of 390 million cases worldwide, growing incidence and more frequent epidemics, dengue is an increasingly important public health challenge (WHO 2012; Tran et al. 2015). As there is no vaccine or treatment for dengue, prevention and control of this disease depend on vector control to reduce viral transmission (Guzman and Kouri 2002). The key flight path of dengue is Aedes aegypti, a domestic mosquito that rears mostly in artificial water ampoules (Focks et al. 1981). In this situation, mosquito flight path rheostat is a main anticipation thing. In recent times, eco-friendly resistor tackles have been instigated to increase mosquito control. Substantial hard work has been conceded out investigating the efficacy of botanical products, and many plant-borne compounds have been reported as excellent toxins against mosquitoes, acting as adulticidal, larvicidal, ovicidal, oviposition deterrent, growth and/or reproduction inhibitors, and/or adult repellents (Conti et al. 2014; Murugan et al. 2015; Benelli et al. 2015a, b). Marine creatures are a gorgeous home of fundamentally new and biologically active metabolites, and cyclopoid copepods are noticeable predators in lots of aquatic ecosystems and have been acting as biological substitutes in efficacious programs to control mosquito larvae.
Article
In 1975 and 1976,a brief mosquito survey was carried out in Ishigakijima, the southern Ryukyus. Human- and dry ice-baited net-traps, unbaited net-trap and larval dipping were employed as collecting methods. The results were as follows : 1. Ten 5-hour nocturnal and six 2-hour daytime human-baited net catches were made during April, July and August 1976 and a total of 549 females consisting of 22 species was taken. In an urban area, Arakawa, the predominant species in the nocturnal catches were Cx. p. fatigans and Ar. subalbatus, together making up 91% of the total catch. In a mountain village, Hoshino C, Cx. p. fatigans was also predominant, forming 49% of the total catch. Ae. vexans nipponii and Cx. bitaeniorhynchus were the other common mosquitoes. In a forest area, Hoshino A and Noromizu, the species collected by nocturnal catches in considerable numbers were Ma. uniformis, Cx. bitaeniorhynchus, Cx. tritaeniorhynchus, Cx. pseudovishnui, Cq. crassipes and Ar. subalbatus. The predominant species in the daytime catches were Ae. riversi and Tr. bambusa. 2. One 5-hour nocturnal dry ice- and cowbaited net-trap catches were made at Hoshino A on April and July 1976,and a total of 113 and 950 female mosquitoes was collected respectively. The major mosquitoes were Cx. tritaeniorhynchus, Ma. uniformis, Cx. pseudovishnui, Ae. v. nipponii, Cq. crassipes, Mi. luzonensis and Cx. bitaeniorhynchus. 3. Seven 12-hour nocturnal unbaited net-trap catches were also tried at Hoshino A, on July and August. A total of 30 mosquitoes consisting of 10 species of 5 genera were found in the traps. They were small numbers of Ae. riversi, Ur. ohamai, Ur. macfarlanei, Cx. bitaeniorhynchus, Cx. tritaeniorhynchus, Cx. pseudovishnui, Cx. tuberis, Cx. fuscocephala, Cq. crassipes and Mi. elegans. 4. From April 1975 to August 1976,85 light-trap collections were made at four different areas and a total of 2,185 mosquitoes representing 20 species of 7 genera was taken. There was a marked difference between predominant mosquito species taken in the urban area, Misaki, and the forest and irrigated areas, Noromizu, Kabira and Nagura. On the urban area, 90% of the total catch was Cx. p. fatigans, while on the forest and irrigated areas, Cx. tritaeniorhynchus (29% of the total catch in the areas), Cx. pseudovishnui (29%), Ma. uniformis (10%), Ae. v. nipponii (6.0%) and Mi. luzonensis (6.0%) were predominant species.
Article
An ecological study was made on the larval populations of mosquito overwintering in Kagoshima City, southern Japan. The purpose of this report is to show the mode of overwintering habits of several mosquito species from the view point of seasonal change in population size and larval age structure. 1) Larvae of Uranotaenia bimaculata, Aedes japonicus and Tripteroides bambusa survived winter season, and their population size increased during winter months with appearance of the younger larvae and reached to a maximum in January, February and April, respectively. The older larvae and pupae became dominant in spring months, when a considerable number of pupal exuviae was observed. These facts apparently indicate that eggs of these species hatch in the course of overwintering and that the first adult populations of the next year originate mainly from the newly hatched larvae. 2) Population size of Armigeres subalbatus diminished gradually from December to March. Through these months, only the fourth stage larvae were observed except in March, when a number of pupae appeared. The larval population became extinct in April and a small number of pupal exuviae remained. These indicate that the fourth stage larvae survive the coldest months and pupate in March and that adults emerge in spring months. 3) Population size of Culex pipiens s. l. diminished gradually from December to March. During these months, however, a number of the fourth stage larvae grew to pupae and a few pupal exuviae were observed. Early in April, population size reached to a maximum with appearance of the first stage larvae, which hatched from the egg masses newly laid in March. These indicate that most larvae and pupae become extinct during the coldest months, even if a few of the pupae emerge into adults. So, the first adult population must be originated from the newly hatched larvae. 4) None of Aedes albopictus larvae and pupae was observed in the coldest months. The first population of younger larvae started in March and older larvae became dominant in May, when a considerable number of pupae and pupal exuviae were observed. These show that this species can not survive the coldest months as larvae and that the first adult population originates from the newly hatched larvae.
Article
A survey of the habitats of Aedes albopictus and Ae. riversi was carried out in selected locations in the southwestern part of Japan during the summer seasons of 1975 and 1976. It was observed that Ae. albopictus attacked human bait predominantly in open areas near densely populated regions while Ae. riversi preferred mostly at sparsely populated forested areas for feeding. The larvae of both species were found equally in both artifical breeding containers such as discarded cans and natural breeding containers such as tree holes, bamboo stumps. Therefore, differences of the habitat of each species seemed to be due to their flight places whether in open areas or in forested areas.
Article
To know the mosquito fauna and biology in the forest areas of Iriomotejima, Southern Ryukyu Island, Japan, from 1977 to 1978,adult mosquitoes in these area were collected by light traps, human-baited net traps and daytime humanbaited catches, and the larvae were also collected at their breeding sites by a dipper and pipet. The results are summarized as follows : 1. In total, 53 mosquito species of 13 genera were found. Among the species collected, Ficalbia sp., Culex sitiens Wiedemann, Aedes lineatopennis (Ludlow) and Aedes nobukonis Yamada have no previous record in this Island. 2. The total number of nights for light trap operation was 29 in February, July and October, 1977 and 1978,and 2,650 females of 30 species were collected. The predominant species were Culex tritaeniorhynchus Giles and Anopheles sinensis Wiedimann including Anopheles lesteri Baisas and Hu, making up 63% of the total catch. A well-known malaria vector, Anopheles minimus Theoblad, was not so common though its 22 females (1%) were collected by the traps in Komiarea. 3. A total of 728 females and 37 males of 24 species was trapped by the human-baited net traps operated for 5 hours of 8 nights at Komi and Funaura areas. Culex tritaeniorhynchus Giles (24%), Aedes iriomotensis Tanaka and Mizusawa (20%), Anopheles sinensis Wiedemann (15%), Mansonia uniformis (Theobald) (13%) and Culex pseudovishnui Colles (10%) were predominant species. 4. A total of 330 females of 16 species were collected 15 times by daytime human-baited catches in different forest areas. The predominant species were Aedes iriomotensis Tanaka and Mizusawa (30%), Aedes riversi Bohart and Ingram (19%) and Armigeres subalbatus (Coquillett) (14%). A small number of Anopheles saperoi Bohart and Ingram (=Anopheles ohamai) came to bite. 5. Larvae were collected at about 2,000 breeding sites and 50 species of mosquitoes in total were found in these larvae. Anopheles minimus Theobald was not common but Anopheles saperoi Bohart and Ingram was commonly found along streams in the forest of Komi.
Article
The great importance of mosquitoes lies in their role as transmitters of pathogens and parasites, and in their use as experimental animals well suited to laboratory investigations into aspects of biochemistry, physiology and behaviour. The largest part of this latest volume of The Biology of Mosquitoes concerns interactions between mosquitoes and viruses and the transmission of arboviruses to their vertebrate hosts, while the remainder concerns symbiotic interactions between mosquitoes and bacteria. The introduction provides a timely review of the first major development in mosquito taxonomy for several decades. Further chapters describe the interactions between mosquitoes and the viruses that infect them, the transmission and epidemiology of seven very important arboviruses, and the biology of bacteria that are important control agents or of great biological interest. Like the earlier volumes, Volume 3 combines recent information with earlier important findings from field and laboratory to provide the broadest coverage available on the subject.
Article
Elevated CO2 could alter the productivity of heterotrophic aquatic ecosystems through effects on allochthonous litter inputs. The effects of atmospheric CO2 concentration, light availability to trees and tree species, on leaf detritus quality as a food resource for eastern treehole mosquitoes (Aeries triseriatus) were examined. Larvae were reared in laboratory microcosms (simulated treeholes) with naturally-senesced, abscised foliage from seedlings of red oak (Quercus rubra) and paper birch (Betula papyrifera) grown in ambient and elevated atmospheric CO2 environments. Elevated CO2 did not have significant effects on any measure of mosquito performance. In contrast, host species and light availability had dramatic effects on mosquito development time and survival; light availability had additional effects on adult size. Mosquito reproductive potential (± SE) averaged 8.4 ± 1.5 females female-1 generation-1 when litter input was from birch-sun leaves, but was 19.6 ± 1.8 when the litter was from birch-shade leaves and 13.0 ± 1.8 when from oak-sun leaves. Mosquito development time was nearly halved when the litter input was from oak-sun leaves versus birch-sun leaves, suggesting a potential for even greater demographic effects (e.g. two generations per year instead of one could yield a 20-fold increase in annual growth rate). Trophic transfer rates (mg insect detritivore g litter-1 d-1) were 3-fold greater on birch-shade leaves than on birch-sun leaves. Changes in insolation and tree species composition can have important consequences for forest ecosystems, because of effects on litter quality that impact microbial saprobes and, ultimately, invertebrate detritivores.
Article
Larvae of Aedes triseriatus mosquitoes feed on microbes that decompose leaf litter in tree-hole ecosystems. Scanning electron micrographs indicate that browsing by mosquitoes substantially reduces microbial abundance on decaying leaves. Experiments using laboratory microcosms demonstrate that increased larval density decreases larval survivorship, pupation rates, pupal biomass, and total yield. Rapidly decomposing leaf litter (sugar maple) supports more mosquito growth than slowly decomposing litter (beech and black oak). In our experiments, mosquito yield was apparently regulated by larval density and detrital dynamics.
Article
Investigations of large and fine particle feeding detritivores (shredders and collectors) fed on conditioned hickory leaves (Carya glabra) revealed density-dependent intra- and interspecific interactions. Shredder (Tipula and Pycnopsyche) growth rates ranged from 0.47 to 1.53% increase in body wt/day depending upon density, species combinations, and culture temperature. Collector (Stenonema) growth rate ranged from 0.13 to 1.80% body wt/day, being greatest at high densities, particularly in combination with shredders. Food consumption ranged from 15.7 to 33.2% body wt/day for shredders and 4.0 to 23.2% body wt/day for collectors. After non-shredder feeding losses are accounted for, estimated shredder standing crop required to account for processing of report leaf litter inputs compare generally to measured shredder standing crop.
Article
Laboratory-determined larval growth rates of the detritivore (collector-gatherer) Paratendipes albimanus (Chironomidae) responded proportionally to the microbial densities of 4 food sources. Substrates with higher microbial activities and biomasses produced greater growth rates in the order: pignut hickory (Carya glabra) leaves > white oak (Quercus alba) > insect feces > natural stream detritus. Laboratory growth rates of P. albimanus were linearly related to quantitative estimates of food quality based on substrate adenosine triphosphate (ATP) and respiration rates but were not statistically related to total N or C. Although P. albimanus is univoltine in Augusta Creek, Michigan, an experimental laboratory population of first-instar larvae completed a 2nd generation during the summer when fed detritus generated from hickory leaves. A second experimental population failed to develop past the first instar when fed natural detritus. The natural growth pattern of P. albimanus involves the interaction of temperature and food quality.
Article
Although both Papilio troilus and P. palamedes are Lauraceae specialists, the geographic range of P. troilus is much more extensive. To help understand the basis for this distributional difference, we examined their growth and behavior on several potential host species. Larvae of P. troilus and P. palamedes were fed foliage of Cinnamomum camphora, Lindera benzoin, Persea borbonia, and Sassafras albidum. We measured neonate mass, first instar growth rate, daily mortality, total larval duration, pupal mass, and adult emergence. Larval survival and first instar growth rate were highest for P. troilus on Lindera and for P. palamedes on Persea. The reciprocal combinations had the lowest survival and first instar growth rate. Survival of both swallowtails was intermediate on Sassafras, but larvae that survived had the highest lifetime growth rates and produced the heaviest pupae. Interspecific variation in growth performance was large compared to intraspecific variation, and unlike intraspecific variation, revealed a dramatic reciprocal inability to use different hosts. On their preferred hosts, lifetime growth rates of both specialist insects were much higher than that of related generalist swallowtails. Neonate larvae of P. troilus preferred Sassafras foliage to Persea, whereas larvae of P. palamedes either preferred Persea or showed no preference. With regard to adults, P. palamedes females laid 87% of their eggs on Persea and the rest on Sassafras in two-choice tests. In three-choice tests, P. troilus females placed equal numbers of eggs on Sassafras and Lindera, but only about 10% on Persea. The restricted geographic range of P. palamedes appears to be the result of oviposition preference rather than differential larval abilities.