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Culex Pipiens
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Ochler. Caspius
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Aedes Albopic.
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Other Ematophagi
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Xilophagi
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These insects, belonging to the order of Diptera, have a very bad reputation for the vexation
they inflict on humans with their feeding habits.
Their presence considerably lowers the quality of life and particularly in touristic
areas this may have dramatic repercussions on the local economy.
All this causes, as immediate consequence, a series of chemical treatments with wide-spectrum insecticides.
Rain and tides give place to several reproduction hotbeds. The profound modifications induced by man
on the environment with the pollution of waters, hydraulic harnessing, urbanization works such as gutters and drains,
the creation of inundated fishless areas such as rice fields and phyto-purification basins, present mosquitoes
with countless places where they can reproduce themselves undisturbed,
The variety of species, each one with its own biology, the diversity in space and timing of the territory and its extension
as well as the number of sundry products for sale, make control a delicate matter!…
Spraying about irrationally with insecticides determines a heavy environmental impact at high costs, often with unsatisfactory results. |
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1.0 BIOLOGY
Not all mosquitoes sting humans; the majority of the species feed on the blood of birds,
anphibians and other vertebrates. Among the anthropophilian species, in order to achieve the maturation of their eggs,
only the females need the proteins contained in the blood they suck. The males feed on sugary liquids and are therefore utterly harmless..
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Eggs
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Eggs
The eggs are laid on the water surface one by one (Anopheles and Orthopodomya)
or in floating clusters (Culex, Culiseta, Coquillettidia). Genera like Aedes and Ochlerotatus instead,
lay their eggs on the ground or on a substratum immediately above water level. When the level raises for whatever reason,
water will wet the eggs,causing them to hatch and to release their larvae. |
Larvae
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Larvae
The hatching of the eggs releases tiny larvae which grow feeding on bacteria and plancton
and going through four stages until they become pupas and adult individuals. Although they live in the water,
larvae breathe the oxygen of the air generally through a syphon, save for the genus Anopheles which lacks this organ.
Another exception is genus Coquillettidia whose larvae pierce the stems of aquatic plants absorbing the oxygen directly from their tissues. |
Pupae
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Pupae
Pupae look completely different from larvae and they move faster.
They dont’ feed, which makes them more resistant towards insecticides.
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Adults |
Adults
Following a brief pause on the water’s surface, the adult individuals will swarm away from thir pupal stage,
in order to feed and to reproduce themselves. In the genus Culex, the first laying of eggs can occur even though
the female has not had her bloody banquet yet. Males can be told from females from the shape of their antennas,
which look like plumes, and from that of their mouth which is apt to lick sweet liquids but is incapable of stinging.
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2.0
ITALIAN KINDS OF MOSQUITOS
In the italian reality, the mosquito species responsible for the highest annoyance level are mainly three
2.1 SYSTEMATIC ARRANGEMENT OF CULICIDES
Mosquitoes belong to the order Diptera, sub-order Nematocera, super-family Culocoidea, family Culicides.
Europe over 100 species can be found whereas in the whole world over 3000 species are known.
In Italy over 60 species are present, all belonging to two sub-families only: Anopheline and Culicine.
Anofelines include the genus Anopheles Anopheles only
which is further divided into two sub-genera: Anopheles
and Cellia. Culicines include the following genera: Aedes, Ochlerotatus,
Culex, Culiseta, Coquillettidia, Orthopodomia and Uranotenia.
Culicides present in Italy:
| Subfamily |
Genus |
Subgenus |
N° Species |
 |
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| Anophelinae |
Anopheles |
Anopheles |
13 |
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Cellia |
3 |
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| Culicinae |
Aedes |
Aedes |
1 |
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Aedimorphus |
1 |
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Finlaya |
2 |
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Ochlerotatus |
16 |
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Rusticoidus |
1 |
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Stegomia |
3 |
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Coquillettidia |
Coquillettidia |
2 |
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Culex |
Barradius |
1 |
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Culex |
7 |
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Maillota |
1 |
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Neoculex |
3 |
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Culiseta |
Alletheobaldia |
1 |
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Culicella |
3 |
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Culiseta |
2 |
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Orthopodomya |
Orthopodomya |
1 |
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Uranotaenia |
Pseudoficalbia |
1 |
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The medical importance of Culicides is connected with their capability of transmitting pathogenous agents
to man and animals. There’s no doubt that the most important desease in the world is malaria, considerig
the 2.6 billions of people living in areas exposed to high risks of infection, of which 300 millions become
infected yearly with a mortality rate of 1%, almost all children.
Malaria has been for the peoples of the mediterranean area one of the most outstanding problems,
heavily conditioning their lives expecially in the proximity of humid environments such as swamps and rice fields.
In Italy, following the utter elimination of malaria in the 50’es and the consequent rarefaction in the number of vectors,
for a long time mosquitoes have ceased to be a problem for the public health. In these last years, though, mosquitoes
have been re-considered as possible vectors of deseases because of some sanitary issues arisen (Romi 1997):
• some species, among which Culex
pipienspipiens stands out, are becoming ever more fit to densely populated areas
because here new reproductive hotbeds are created continuosly.
• the appearance of populations of Culicides
ever more resistent to the most commonly used insecticides (Culex
pipiens).
• invasion of tipical rural species such as Cx.
modestus, Oc. caspius, Ae. detritus, in earlier scarcely populated areas following the creation of new touristic resorts.
• the immigration of new species such as Aedes albopictus
, a potential vector for arbovirus and, in 1996, and Aedes
atropalpus (Romi et al. 1997).
• the sly raising of malaria’s potential vectors such as
Anopheles
labranchiae.
The eventuality that in Italy sporadic cases of malaria may arise is real, at least as far as Plasmodium
vivax is concerned,considering the rising number of malaria cases imported every year
and the presence in the rural center-southern zones of african and asian subjects for seasonal agricultural jobs (Sabatinelli et al. 1994-1995).
It seems that An. labranchiae cannot be infected with
afro-tropical stocks of Plasmodium
falciparum (Falleroni, 1926)); instead, specimen infected with P. vivax have been found..
The majority of arbovirosis are infections concerning animals: some are transmitted from animals to man
(zoonosis), a small percentage is transmitted from man to man only (anthroponosis)
(i.e., denengue).
Aedes
albopictus can transmit both arbovirus and philariosis.
Denengue is perhaps the most dangerous arbovirus.
Earlier it was believed that the bug was capable of transmitting only the least serious forms
of the ailment, but the latest researches have proved that it can also trasmit the two most
serious forms: hemorragical fever (DHF) and the shock syndrome (DDS) (Jumali et al. 1979, Chang 1987).
It can also transmit Chicungunya ‘s virus and that of some japanese encephalitics.
In Italy these ailments are, until today, only a theoretical issue because no infection hotbed is present.
Instead, Aedes albopictus can become a vector for the transmission
of canine philariosis (Dirofilaria
repens) in urban areas.
Cx.
pipiens, Oc. caspius, Ae. vexans have been indicated as potential vectors for arbovirus
and suspected agents for encephalitis (Saccà et al. 1968);
all three culicides are vectors for philariae of the Dirophilaria kind (canine) which can also be transmitted to man where,
though, they are unable to reproduce themselves.
Even when there isn’t a sanitary hazard, the vexation that mosquitoes inflict with their stings is not to be underestimated.
These bugs often jeopardize open-air activities rendering urban and touristic areas impossible to live in, expecially
when nearby uncontrollable larval hotbeds exist.
Indexes of disturbance and intervention thresholds have been defined, in order to guide exterminating
actions against adult populations and to verify the effectiveness of those against larvae.
These efficiency tests, based on the capture of females, are carried out by means of traps activated with
carbon anhydride (R. Pantaleoni1996).These indexes are based only on the degree of disturbance
inflicted by insects and NOT on the possible sanitarian implications that could derive.
The method’s calibration should be performed in each single zone considering that the levels of toleration
change depending on cultural and customary factors which often are indipendent from the actual level of infestation.
Such indexes are not decisive but together with a careful watch of larval hotbeds,
they can actually represent a valid aid to disinfestation programs.
3.0 THE MAIN SPECIES FOUND IN THE ITALIAN CONTEXT
3.1
Culex pipiens (Linné)
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Culex pipiens' eggs
Culex pipiens' larvae
Culex pipiens' hotbed
Culex pipiens' hotbed
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A very diffused kind in urbanized environments, it has thrived in
these last years following the towns’ expansions and taking advantage of any water at disposal.
The larva’s distinctive morphological characteristics are: tegument of the thorax and abdomen not covered
with spiculae. Scales in the eighth segment shaped like spatula with a serrated edge and lacking a separate middle thorn.
A stubby syphon with one or more locks of bristles in a distal and also a sub-dorsal position.
The adult’s distinctive morphological characteristics are: palps much shorter than the trunk,
the abdomen’s terminal part is truncated, lack of pre-spiracular bristles, nails equipped with pulvilli,
first article of the back tarsus longer than the tibia, abdomen striped across with clear, close bands having a uniform width in each segment.
Actually, the species consists of TWO sub-species: Cx. pipiens molestus
and Cx. pipiens pipiens,
which make the so-called “complex”. The two strains often share the same territories and
it’s not easy to tell one kind from the other. Considering the different, normally colonized environments,
Cx. pipiens molestus
is known as the urban kind whereas the second one is known as the rural kind.
The morphological characteristic which permits to distinguish the two sub-species (in the larval stage)
is a different syphonic factor (i.e., the ratio between the syphon’s length and its larger diameter).
Its value is about 3.5 for the molestus and about 3.8 for pipiens.
Adults can be distinguished by analyzing, with electrophoresis, some enzymatic loci in their genetic inheritance (Urbanelli et al. 1980).
Both strains don’t fly long distances and are active mainly at dusk and at night near the same areas of their larval development
from which they originated. They can get inside the dwellings attracted by light and by the presence of people and remain active
all through the night. The rural strain is also ornitophilic, whereas molestus is anthropophilic only.
The molestus
kind is capable of mating even in narrow environments (stenogamy) like gutters or sewerages,
it doesn’t need to suck blood in order to bring its first eggs to maturation (autogeny) and it doesn’t enter into winter diapause.
Also different are the environements chosen for their larval development: while molestus
prefers filthy waters with a high organic content, although strongly polluted, pipiens
has a preference for clear waters containing organic matters of vegetable origin. Reproduction sites are as sundry as can be: gutters,
water reservoirs, depurators, sewers, drains and whatever other type of water disposal although of temporary nature,
is fit to do the job provided that no fish or predator arthropodes be present. These animals, in fact, are normally
very effective in containing infestations. These two sub-species are active from March through November
with intensity fluctuations depending on the seasonal trend. Usually, both strains winter as fecundated females
by seeking refuge in secluded, quiet and often man-built hideaways, such as barns, cellars,
stockrooms and so forth. Molestus,
however, is able to pass the winter in any vital stage included that of adult male (R. Pantaleoni 1997).
Females can sting for short periods of time if conditions become favourable. The growth rate is variable depending
on temperature and food abundance, ranging from a little over one week to over one month;
during one season it is therefore possible to count several generations.
Culex pipiens è presente nella regione oloartica,
can be found in the holarctic, afro-tropical and neo-tropical regions and surely is the most diffused species in Italy. |
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3.2 Ochlerotatus caspius
(Pallas)
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Ochlerotatus caspius' larvas
Ochlerotatus caspius
Ochlerotatus' hotbed
Ochlerotatus' hotbed
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This is a palearctic specie commonly found in Italy expecially in the coastal areas
( in these last years, though, hotbeds of it can be found inland too). Larval distinctive morphological characteristics:
syphonic bristle inserted in a distal position with respect to the last pecten’s tooth, syphonic index smaller than 4,
the eighth segment in larvae of the fourth age shows 18-28 scales placed along several rows and with a neatly detectable middle tooth.
The anal segment’s saddle is ventrally interrupted, internal front bristles generally simple, antennas with spiculae, multifidal antennal bristle.
The adult’s distinctive morphological characteristics are: palps much shorter than the trunk, point-shaped terminal part of the abdomen,
back tarsuses with a dark central band, upper part of the abdomen (tergite) showing a light central band and light dots on the side.
Oc. Caspius overwinters as egg usually laid on the ground awaiting the best conditions to hatch.
The first hatching generally occurs in april-may and the other follow suite according to water disposal and proper climatic conditions.
In fact, since the eggs were laid above water level, they can hatch only if the water submerges them.
Adults and larvae can be found as late as november. Larvae usually develop in swamps lagoons, pools,
drainage canals and they tolerate very different degrees in the water’s saltness, ranging from fresh to brackish.
Since larvae can take advantage of very small, often temporary water reserves, their development rate
is very fast consenting them to pass from the larval to the adult stage, provided that food disposal and temperature
are optimal, in less than one week. Ochlerotatus caspius can be found, in larval hotbeds, together with
Cx. pipiens, An.
maculipennis, Cs. Annulata.
Females sting both during light hours and at night, with a peak at dusk when the temperature lowers;
they can become aggressive and reach an alarming density expecially in the coastal zones where they represent one of the prevailing species.
They usually are anthropophiliac but they can attack any other animal, but only in the case of abnormal levels of infestation
they dare to get inside dwellings. Those with wings can fly for several miles, taking advantage of the winds,
invading inhabited centers thus making the local anti-larval actions taken so far, useless.
For this reason, the general employment of adulticides becomes mandatory, even though it certainly is not desirable. |
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3.3
Aedes albopictus (Skuse, 1984)
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Aedes albopictus' eggs
Aedes albopictus' larvae
Aedes albopictus
Albopictus' hotbed
Albopictus' hotbed
Albopictus' hotbed
Albopictus' hotbed
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This species belongs, together with Aedes
aegypti, , to the sub-genus Stegomyia,
from which it differs (in the larval stage) because of the scales in the eighth segment where they look
as a single, big tooth and because of the syphon’s pecten in which all the teeth are evenly brought together.
The larva’s distinctive morphological characteristics are: forked or multifidal internal and frontal bristles,
antennas without spiculae (smooth), simple antennal bristle, eighth segment with 6-13 scales placed along
a single row and brought together to form a single, large thorn, a breathing syphon’s index smaller than 4, a syphonic
bristle fitted in a distal position compared to the last pecten’s theet and not long enough to reach the syphons
end with its apex, syphon’s pecten with evenly-clustered, point-shaped teeth, anal segment’s saddle ventrally interrupted.
The adult’s distinctive morphological characteristics are: palps much shorter than the trunk, point–shaped terminal part of the abdomen.
Typical black coloration of the body with a white band crossing length-wise the torax’s back side.
Legs marked cross-wise by white bands: in particular, the hind-pair shows white basal bands on the first four segments
whereas the fifth one is entirely white and the tibia is uniformely dark. The kind is native of south-eastern Asia,
originally linked to the tropical forests where it colonized, as a larva, small puddles of water; then, slowly,
it started to leave the forests and to approach the inhabited areas exploiting any small, man-made container
of water as a reproduction site. In the open spaces it could enjoy higher temperatures, but it was also
exposed to much more frequent periods of drought. That’s why, through natural selection, a kind of mosquitoes
whose eggs were capable of enduring dry spells much better than the original stock were
created (T. Sota and M: Mogi 1992). The territory where Aedes albopictus
is present is very large and not all stocks are able to live through the winter: only those living in the northernmost places
can lay diapausant eggs. In Italy, larval hotbeds are located mainly in residential areas with vegetation where it is easier
to find natural puddles of rain water or, much more frequently, small containers such as saucers or used tires.
High summer temperatures and abundance of food allow to pass from egg to adult in just one week.
Wintering is faced in the form of durable eggs which are laid between august and september. Adults show up around may;
then the first layings of eggs follow and they’ll continue through all summer.
The number of generations is related to the meteorological precipitations because eggs are laid
on a rugged substratum just above water-level and they hatch as soon as they become submerged.
About 10% of the eggs, anyway, is laid directly on the water’s surface and this is why larvae can be found even if no precipitation occurs.
This species is strongly anthropophilian and can sting all day through even though it has a preference for the hours that precede the evening.
The raising of a certain degree of endophilia should be stressed together with the constantly
increasing cases of a nocturnal trophic activity over midnight.
3.3.1 Diffusion of the species
The species is diffused in the tropical and sub-tropical belt of south-eastern Asia, in several islands of the
Indian Ocean and Madagascar; its territory ranges from the 42nd northern parallel to the 10th south. In 1985,
the first steady colony of it has been reported in the U.S.A. and in a few years it spread to twenty states in that Country and to Mexico.
After 1986, it has been reported in four brasilian States also. In 1992, Ae.
albopictus has been found for the first time in Nigeria also (Savage et al. 1992).
In Europe, the States where it has become diffused are only two so far: Italy and Albania.
The first warning came from Albania in 1987 (Adhami and Murati 1987); in Italy, the first samples were gathered
in the summer/ fall period of 1990 in Genoa’s urban center (Sabatini et al. 1990) but the place where these adult
individuals came from was not discovered. The first steady location of the species, i.e., where larval
hotbeds were found, was reported in Padua’s province during august 1991 ( Dalla Pozza and Majori 1992).
At the beginning, the first colonies were “passively” reported by the population; in other words, at that time
the species was already quite diffused making its uprooting impossible.
The species’ immigration is due to the importation of used tires infested with eggs from the southern area
of the United States, carried out by some Venetian firms which recycle such ware (Dalla Pozza and Majori 1994).
The high internal demand of this item has greatly helped the rapid diffusion of the vector in many other parts of Italy.
Another occasion for the diffusion of the mosquito may be offered by the “active” transportation
operated by man in his everyday moves: sometimes the insect sneaks inside the transportation media and
thus it can travel may kilometers in a short time. Without admitting these possibilities, it is difficult to explain
the enormous distances covered by the insect since its arrival in our Country, considering that its adults are
uncapable of flying very far (max. 2-2.5 Km. per year with wind in favour) (Romi 1996).
Aedes albopictus
is present in 10 regions and 20 provinces of our Country;
Veneto is one of the regions more committed with the issue since 5 of its 7 provinces (Venice,
Padua, Treviso, Vicenza and Rovigo) are already infested.
3.3.2 Biology of the eggs
The eggs’ mortality can be caused by de-hydration, predation and thermal lowerings.
The weight of each one of these factors depends on the geographical area and on the season considered.
The natural mortality, in absence of other limiting factors, is always very low whatever the stock taken into consideration (Hawley 1985).
From data cited in the biblography, we learn that eggs having completed their embryogenesis can withstand
long periods of time in conditions of low relative humidity; it must be stressed, though, that a neat difference exists
between diapausant and non-diapausant eggs.
The latter, if kept at a humidity between 73 and 90%, show that their thatching capability decreases starting
from the moment at which they are laid, whereas the diapausant ones show a thatching peak after 4 months.
If the relative humidity is brought to de-hydration levels (44%), all the non-diapausant eggs die after 2 months whereas the diapausant ones,
after the same period of time, show their thatching peak (in other words, they die only after 4 months) (T. Sota and M. Mogi 1992).
These characteristics can be due to a greater thickening of the corion and to a waxy coating of the eggs.
In the temperate zones, the capability of Aedes albopictus'
eggs to survive through many winter months has been stressed (Wang1962, Toma et al. 1982);
the summer mortality, though, has not been examined more closely. The winter mortality in the temperate zones can vary very much,
ranging from a 100% in the case tropical stocks are considered, to a very low percentage if stocks coming from
the northernmost borders of the territories infested by Aedes
albopictus from Asia or from America are taken into account. These latter stocks, following a 24 hours exposition to –10° C,
reveal a per cent thatching expectation ranging from 78 to 99% (Hawley et al. 1987). Non-diapausant eggs increase their endurance
to low temperatures after completing embryogenesis ( they are unable to survive through winter at our latitudes anyway) (Rosario1963).
Embryogenesis can be considered complete when the eggs start thatching which occurs 6-10 days after laying, depending on temperature.
If the eggs go underwater just after having been laid, a lower-than-normal percentage of thatching and at a scaled rate can be observed.
The interaction of many factors such as age, parching, temperature variations, oxygen’s tension, diapause, sets the thatching capability of
Aedes
albopictus' eggs. Oxygen’s tension appears to be one of the most important factors; it has been observed that
embryonated eggs submerged in water with an oxygen’s concentration ranging from 1.5 – 6.0 – 7.6 ppm, show
very different thatching percentages ranging from 94% - 79% - 62% respectively.
Anyway, if the same eggs face a dry spell before submersion, thatching occurs only if the
oxygen’s concentration in the water is very low (Imai and Maeda 1976). In some cases,
Aedes albopictus' eggs require several submersions before they open totally. In a lab,
one female has laid over 950 eggs (Galliard 1962) during its entire life span, when the average productivity is around 300 – 350 eggs per female.
The number of eggs laid following a meal on blood, is influenced by many factors but in average it is around 42 – 88
eggs for its first gonotrophic cycle. |
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3.3.3 Photo-periodism
As mentioned before, the stocks of Aedes
albopictus diffused in temperate environments, can lay diapausant eggs capable of surviving during the winter.
This characteristic depends on the insect’s sensitivity to the photo-period which the adult females are exposed to.
In fact, if their exposition occurs when days are short, the females are induced to lay diapausant eggs.
The critical photo-period for many “sub-species” lasts 13 – 14 hours. If populations coming from tropical
zones are exposed to short photo-periodal conditions, they don’t show any sensitivity and will continue
to lay non-diapausant eggs (Hawley et al. 1987). Anyway, photo-period is not the sole factor conditioning diapause;
in fact, females result to be sensitive also to temperature. The data reported above have been taken at 21° C
and no differences have been noted even if the temperature rises to 26° C. Should autumn last longer maintaining
a high temperature (over 29° C.), induction on females is reduced or utterly suppressed; on the contrary,
low temperatures increase the photo-period’s effect (Hawley W.A. 1998). Larval feeding also has an influence on
diapause, extending the critical period to over 14 light-hours. Such behaviour should guarantee the species’
survival also when food is scarce, partially inhibiting the hatching of the eggs. Although adults born from these eggs
are generally smaller, no meaningful difference is noted in the size of their eggs (C. Pumpuni, J. Knepler, G. Craig 1992).
The stages sensitive to light are represented by pupae besides adult females. The factors responsible
for the diapause’s interruption are still unknown; anyway, lab data seem to indicate that diapausant eggs are
able to thatch after having been kept at 25° C. for 3 months (Wang 1966) apparently without a need
to undergo a cold period of time.
3.3.4
Larval biology
The larval stage lasts an average of 5 to 10 days, at a temperature of 25° C. and under optimal feeding conditions.
Differences may derive from diversities in the diet or because mosquito stocks are different. A lowering in temperature
triggers a slowing down in the development rate; at 15 – 18° C. it takes about 3 weeks to pass from egg to pupa. At 11° C.,
a total stopping of growth occurs (Udaka 1959). If larvae are raised in a lack of food, their cycle lengthens up to
58 days for the samples that will give origin to females (Mori 1979). For males, development is always faster
but in a lack of food condition the difference in cycle length is even greater.
Lab tests revealed that at an average water temperature of 27° C., the time needed to pass from egg to adult stage
is of 7 – 8 days ( Martini, not edited data). A raise in larval density or a lowering in food availability causes
an increase in larval mortality and a reduction of adult size (Mori 1979). It might be that larvae’s death is caused
by chemical substances they produce themselves. Pupae usually show a very low mortality rate.
Reduced dimensions influence fertility both in males and females. Small- size adult females’ ovaries have few ovariols
and therefore they can lay few eggs; in small-size males spermatogenesis begins later and their testicles also are smaller.
It seems that larval density has no influence over the determination of the sex of adults.
Third and fourth age larvae and pupae are able to survive one day without water, provided that
relative humidity stays at 90% at least.
4.0
FIGHTING AND PREVENTING |
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The
struggle against mosquitoes cannot be carried
on without the knowledge of the species we intend to
fight.The typologies of frequented hotbeds,
the moving capability of each species, its feeding
and reproductive habits, all are essential data to
reach an effective control together with a contained
cost and a respectful attitude towards the environment.
It is useful to know that:
• Mosquitos are greatly
influenced by climatic fluctuations, therefore a fighting
program based on actions scheduled studying the calendary
has, as a result, a high cost and an unsatisfactory success.
• Actions against adults
have a very high impact on the environment, are very
expensive and lead to modest results with regard to both
space and time.
• A control plan that
doesn’t take into account an accurate monitoring
of the territory, is bound to meet failure.
• Checking the results
obtained with disinfesting actions is mandatory in order
to avoid hard-to-control mass swarmings.
Reproduction hotbeds are created continually by athmosferic
precipitations and human activities: a
static disinfestation plan will never reach satisfactory
results. An accurate, continuous
monitoring of the territory in search for reproduction
hotbeds is therefore necessary.
In the case of the tiger-mosquito,
a disinfesting action limited to public areas won’t
allow satisfactory results. Thanks to the species’ typical
habit of colonizing any minimal water resource,
the co-operation of each single citizen is very important.
For this reason, an attentive
information campaign becomes necessary. Leaflets,
posters, informative soirees, documentaries and whatever
other means can be useful for this purpose, is welcome
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