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Commercial Mosquito Repellents and Their Safety Concerns

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Mosquitoes are serious vectors of diseases threading millions of humans and animals worldwide, as malaria, filariasis, and important arboviruses like dengue, yellow fever, chikungunya, West Nile virus, and Zika viruses. The swift spread of arboviruses, parasites, and bacteria in conjunction with the development of resistance in the pathogens, parasites, and vectors represents a great challenge in modern parasitology and tropical medicine. Unfortunately, synthetic insecticides had led to some serious health and risk concerns. There are no vaccines or other specific treatments for arboviruses transmitted by mosquitoes. Accordingly, avoidance of mosquito bites remains the first line of defense. Insect repellents usually work by providing a vapor barrier deterring mosquitoes from coming into contact with the skin surface, and this chapter focused on assets and liabilities, mechanism of action, improving efficacy, safety, and future perspective of synthetic and natural repellents that could potentially prevent mosquito-host interactions, thereby playing an important role in reducing mosquito-borne diseases when used correctly and consistently.
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Chapter
Commercial Mosquito Repellents
and Their Safety Concerns
Hanem Fathy Khater, Abdelfattah M. Selim, Galal A. Abouelella,
Nour A. Abouelella, Kadarkarai Murugan, Nelissa P. Vaz
and Marimuthu Govindarajan
Abstract
Mosquitoes are serious vectors of diseases threading millions of humans and
animals worldwide, as malaria, filariasis, and important arboviruses like dengue,
yellow fever, chikungunya, West Nile virus, and Zika viruses. The swift spread of
arboviruses, parasites, and bacteria in conjunction with the development of resis-
tance in the pathogens, parasites, and vectors represents a great challenge in mod-
ern parasitology and tropical medicine. Unfortunately, synthetic insecticides had
led to some serious health and risk concerns. There are no vaccines or other specific
treatments for arboviruses transmitted by mosquitoes. Accordingly, avoidance of
mosquito bites remains the first line of defense. Insect repellents usually work by
providing a vapor barrier deterring mosquitoes from coming into contact with the
skin surface, and this chapter focused on assets and liabilities, mechanism of action,
improving efficacy, safety, and future perspective of synthetic and natural repel-
lents that could potentially prevent mosquito-host interactions, thereby playing
an important role in reducing mosquito-borne diseases when used correctly
and consistently.
Keywords: repellent plants, synthetic repellents, treated clothes, nanoparticles,
microencapsulation
1. Introduction
Parasites since antiquity [1] are a serious threat for millions of humans and
animals worldwide which bring about chronic debilitating, periodically disabling
disease and are responsible for the overwhelming financial loss [26]. Mosquitoes
(Diptera:Culicidae) [7, 8] are among them as they can act as vectors for serious
parasites and pathogens, including malaria, filariasis, and important arboviruses,
such as dengue, yellow fever, chikungunya, West Nile virus, and Zika viruses
[9, 10]. Mosquito control and personal protection from mosquito bites are the most
meaningful measures for controlling several life-threatening diseases transmitted
exclusively by bites from bloodsucking mosquitoes. Repellents evolved, dates back
to antiquity; the Pharaoh Sneferu, reigned from around 26132589 BCE and the
founder of the fourth dynasty of Egypt, and Cleopatra VII, the last pharaoh of
ancient Egypt, used bed nets as protection against mosquitoes; the ancient
Egyptians used essential oils (EOs) for repelling insects, medicinal benefits, beauty
1
care, and spiritual enhancement and in literally all aspects of their daily life [1].
Insect-repellent plants have been applied traditionally for thousands of years
through different civilizations [11]. Such plants were used in various forms such as
hanged bruised plants in houses, crude fumigants where plants were burnt to drive
away mosquitoes, and oil formulations applied to the skin or clothes [12]. Smoke is
undoubtedly the most extensively exploited means of repelling mosquitoes,
typically by burning plants in rural tropics and by utilizing spiral-shaped incenses
like Katori Senkan archetypal icon of the humid Japanese summers [13].
Mosquitoes have been considered as a major obstacle to the tourism industry and
socioeconomic development of developing countries particularly in the tropical and
endemic regions [14]. Mosquito problems are ancient as old as the pyramids, and
the presence of malaria in Egypt from circa 800 BCE onward has been confirmed
using DNA-based methods, and antigens produced by Plasmodium falciparum lead-
ing to tertian fever in mummies from all periods were detected, and all mummies
were suffering from malaria at the time of their death [1]. Herodotus noted down
that the builders of the Egyptian pyramids (circa 27001700 BCE) were given large
amounts of garlic almost certainly to protect them against malaria [1]. Despite
recent considerable efforts to control vector-borne diseases, malaria alone produces
250 million cases per year and 800,000 deaths including 85% of children under
5 years [15]. Global warming has moved the mosquitoes on the way to some tem-
perate and higher altitudes, affecting people who are vulnerable to such diseases
[16]. Recently, malaria is a great problem in Africa, but it was well controlled in
Egypt [1]. Ahead of the development and commercial success of synthetic insecti-
cides in the mid-19301950s, botanical insecticides were the leading weapons for
insect control. Synthetic insecticides are distinguished by their efficacy, speed of
action, ease of use, and low cost. Therefore, they drove many natural control
methods as botanicals, predators, and parasitoids to shadows [8, 17, 18]. Insecticidal
treatment of house walls, in particular, could provide a very helpful reduction of
mosquito incidence, but such measures need financial and organizational demand,
but poor rural areas in endemic regions do not have sufficient resources for such
costly protective measures. Because of health and environmental concerns [8, 17],
there is an urgent need to identify new nonhazardous vector management strategies
that replace harmful chemical insecticides and repellents. There are no vaccines or
other specific treatments for arboviruses transmitted by mosquitoes; therefore,
avoidance of mosquito bites remains the first line of defense [9, 18]. Hence, the use
of the mosquito repellents (MRs) on exposed skin area is highly recommended.
Insect repellents usually work by providing a vapor barrier deterring mosquitoes
from meeting the skin surface. Insect repellents had been used for thousands of
years against biting arthropods. Several species of primates were observed
anointing their pelage via rubbing millipedes and plants as Citrus spp., Piper
marginatum, and Clematis dioica. Wedge-capped capuchins (Cebus olivaceus) were
observed rubbing the millipede Orthoporus dorsovittatus onto their coat during the
period of maximum mosquito activity [19]. Such millipede contains benzoquinones
and insect-repellent chemicals, and it was hypothesized that the anointing behavior
was intended to deter biting insects. Laboratory studies revealed a significant
repellent effect of benzoquinones against Aedes (Stegomyia)aegypti (the yellow
fever mosquito) and Amblyomma americanum (the lone star tick). Such anointing
behavior to deter blood-feeding arthropods is also common among birds, and it
could be genetically expressed as an extended phenotypeas it has an obvious
adaptive advantage. Evidence for this lies in the fact that benzoquinones applied to
filter paper elicited anointing activity among captive-born capuchins [12]. The
World Health Organization (WHO) also recommends repellents for protection
against malaria as the resistance of Plasmodium falciparum to anti-malarial drugs
2
Malaria
such as chloroquine is increased. Most of the commercial MRs are prepared using
non-biodegradable, synthetic chemicals like N,N-diethyl-3-methylbenzamide
(DEET), dimethylphthalate (DMP), and allethrin which may lead to the environ-
ment and, hence, the unacceptable health risks in the case of their higher exposure.
With an increasing concern for public safety, a renewed interest in the use of
natural products of plant origin is desired because natural products are effective,
environmentally friendly, biodegradable, inexpensive, and readily available [7, 8,
13, 17, 20]. Repellent application is a reliable mean of personal protection against
annoyance and pathogenic infections not only for local people but also for travelers
in disease risk areas, particularly in tropical countries; therefore, this chapter
focused on assets and liabilities, safety, and future perspective of synthetic and
natural MRs that could potentially prevent mosquito-host interactions, thereby
playing an important role in reducing mosquito-borne diseases when used correctly
and consistently.
2. Synthetic repellents
The history of synthetic repellents had been reviewed [12]; before World War II,
MRs were primarily plant-based with the oil of citronella being the most widely
used compound and the standard against which others were evaluated. At that time,
the emergence of synthetic chemical repellents starts. There were only three prin-
cipal repellents: dimethylphthalate discovered in 1929, Indalone® (butyl-3,3-
dihydro-2,2-dimethyl-4-oxo-2H-pyran-6-carboxylate) patented in 1937, and
Rutgers 612 (ethyl hexanediol), which became available in 1939. Later on and for
military use, 6-2-2 of M-250 (a mixture of six parts DMP and two parts each
Indalone® and Rutgers 612) was used [13]. The event of World War II was the
primary switch on in the development of new repellent technologies because the
Pacific and North African theaters posed significant disease threats to allied military
personnel. Over 6000 chemicals had been tested from 1942 to 1947 in a variety of
research institutions led to the identification of multiple successful repellent
chemistries. Such great aim established several independent research projects that
inevitably identified one of the most effective and widely used insect repellents to
date, DEET. From then on, several compounds have been synthesized relying on
previous research, which identified amide and imide compounds as highly success-
ful contact repellents. Among these are picaridin, a piperidine carboxylate ester,
and IR3535, which are currently considered DEET competitors in some repellency
bioassays [21]. The chemical structures of some synthetic repellents are shown in
Figure 1.
2.1 DEET
DEET (N,N-diethyl-3-methylbenzamide) is the standard and most effective
broad-spectrum insect-repellent component with a long-lasting effect on mosqui-
toes, ticks, as well as biting flies, chiggers, and fleas. DEET was discovered as a
mosquito repellent by the US Department of Agriculture and patented by the US
Army in 1946. It was allowed for public use in 1957, and since then it has been a
standard repellent for several insects and arthropods [14]. DEET is the most
studied insect repellent and mainly used as a positive control to compare the
efficacy of many repellent substances. DEET has a dose-dependent response: the
higher the concentration, the longer the protection. DEET, 2025%, is the con-
ventional concentration used in commercial products. The shorter protection
time depended on the mixture as well [14]. In fact, DEET plays a limited role on
3
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
disease control in endemic regions because of its high cost, unpleasant odor, and
inconvenience of the continuous application on the exposed skin at high concen-
trations [22, 23].
2.2 Permethrin
Permethrin is a pyrethroid insecticide derived from the plant Chrysanthemum
cinerariifolium. It was registered in the US in 1979 as both repellent and insecticide.
Recently, it is the most common insecticide available for use on fabrics such as
clothing, bed nets, etc. for its exclusive role as a contact insecticide via neural
toxicity and equally as an insect repellent [7, 8, 13, 17]. The protection offered
against a broad range of bloodsucking arthropods with negligible safety concerns
ranked permethrin-treated clothing an important arthropod protection technique
especially when used in combination with other protection strategies as applying
topical repellents [13].
2.3 Picaridin
Picaridin (1-piperidinecarboxylic acid 2-(2-hydroxyethyl)-1-methylpropylester)
is a colorless, nearly odorless piperidine analog that was developed by Bayer in the
1980s through molecular modeling [12]. It is also known as KBR 3023, icaridin,
hydroxyethyl isobutyl piperidine carboxylate, and sec-butyl-2-(2-hydroxyethyl)-
piperidine-1-carboxylate. Its trade names include Bayrepel and Saltidin, among
others. Picaridin was first marketed in Europe in the 1990s and later in the US in
2005 [24, 25]. The efficacy of picaridin is as good as DEET, and notably, 20%
picaridin spray was found to protect against three main mosquito vectors, Aedes,
Anopheles, and Culex for about 5 h with better efficacy than that of DEET. There-
fore, repeated application is required every after 46 h [13]. In Australia, a formu-
lation containing 19.2% picaridin provided similar protection as 20% DEET against
Verrallina lineata [26]. The same formulation provided >95% protection against
Culex annulirostris for 5 h but only 1-hour protection against Anopheles spp. [26].
Picaridin at concentrations of 213% v/v in 90% ethanol showed better protection
against anophelines in Africa than comparable formulations containing DEET [27].
Field studies against mosquitoes in two locations in Australia indicated that a 9.3%
formulation only provided 2-hour protection against V. lineata [26, 28]. It had been
concluded that studies showed little significant difference between DEET and
picaridin when applied at the same dosage, with a superior persistence for
picaridin [29]. To maintain effectiveness than with the higher concentrations
(>20%) of picaridin used in the field.
Figure 1.
Chemical structures of some synthetic repellents.
4
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2.4 DEPA
N,N-diethyl-2-phenyl-acetamide (DEPA) is a repellent developed around the
same time as DEET and repels a wide range of insects, but DEPA did not get its
reputation. The repellency of DEPA has demonstrated almost similar to DEET
against mosquito vectors as Ae. aegypti,Ae. albopictus,An. stephensi, and C.
quinquefasciatus [13]. It has regained interest recently and could prove to be an
important competitor to DEET especially in developing countries due to its low
cost, $25.40 per kg compared to $48.40 per kg for DEET [30].
2.5 Insect repellent 3535
Learning from nature offered a molecule with an impressive performance in
comparison to a natural and pure synthetic repellent solution called insect repellent
3535 (IR3535). Scientists got inspirations from nature for the development of the
topical IR 3535 with the intention to create a molecule with optimized protection
times and low toxicity. The naturally occurring amino acid β-alanine was used as a
basic module, and the selected end groups were chosen to avoid toxicity and
increase efficacy. IR 3535 was developed by Merck in 1970 and thus named as Merck
IR3535; it has been available in Europe, but it was not available in the USA until
1999 [12]. IR3535 is used for humans and animals, as it is effective against mosqui-
toes, ticks, flies, fleas, and lice. Its chemical formula is C
11
H
21
NO
3
, and its other
names are ethyl-N-acetyl-N-butyl-β-alaninate, ethyl butylacetylaminopropionate
(EBAAP), β-alanine, and N-acetyl-N-butyl-ethyl ester. The protection of IR 3535
may be comparable to DEET, but it requires frequent reapplication in every 68h.
IR3535 is found in products including Skin So Soft Bug Guard Plus Expedition
(Avon, New York, NY) [31]. Although 20% IR 3535 provides complete protection
against Aedes and Culex mosquitoes (up to 710 h), it offers lesser protection against
Anopheles (about 3.8 h), which affects its application in malaria-endemic areas [13].
Several field studies were identified and indicated that IR 3535 is as effective as
similarly, DEET in repelling mosquitoes of the Aedes and Culex genera but may be
less effective than DEET in repelling anopheline mosquitoes; an uncontrolled field
study of a controlled release formulation of IR 3535 reported that these formulations
may provide complete protection against mosquito biting for 7.110.3 h [32].
2.6 Ethyl anthranilate
Ethyl anthranilate (EA) is a new member in the scope of entomology which
drew a significant attention in repellent research in the recent years and is being
considered as an improved alternative to DEET [13, 33]. It is a nontoxic, the US
FDA approved volatile food additive. EA is novel and repellent against Ae. aegypti,
An. stephensi, and Cx. quinquefasciatus as its ED
50
values of EA were 0.96, 5.4, and
3.6% w/v, respectively, and CPTs of EA, 10% w/v, throughout the arm-in-cage
method were 60, 60, and 30 min, respectively. Moreover, its spatial repellency was
found to be extremely effective in repelling all the three tested species of mosqui-
toes. EA provided comparable results to standard repellent DEPA. As a result, the
repellent activity of EA is promising for developing effective, safe, and eco-friendly
alternative to the existing harmful repellents for personal protection against differ-
ent mosquito species [34].
2.7 Comparative efficacy of synthetic repellents
The comparative efficacy of synthetic repellents had been summarized [14] as
follows: Aedes species demonstrated an aggressive biting behavior and Ae. Aegypti,
5
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
above all, proved to be tolerant to many repellent products. Ae. albopictus was easier
to be repelled than Ae. aegypti. DEET is the most studied insect repellent; at higher
concentrations, it presented superior efficacy against Aedes species, providing up to
10 h of protection. Although IR3535 and picaridin showed good repellency against
this mosquito genus, their efficacy was on average inferior to that provided by
DEET. Fewer studies have been conducted on the mosquito species Anopheles and
Culex. The repellency profile against Anopheles species was similar for the four
principal repellents of interest: DEET provided on average 511 h, IR 3535 410 h,
picaridin 68 h, and Citriodora 112 h of protection, depending on study conditions
and repellent concentration. Culex mosquitoes are easier to repel, and each repellent
provided good protection against this species. DEET showed 514 h of protection
and IR 3535 215 h, depending on product concentration, while the test proving the
efficacy of picaridin and commercial products containing PMD was discontinued
after 8 h of protection. To go over the main points, DEET remains probably the
most efficient insect repellent against mosquitoes, effective against sensitive species
as Culex as well as more repellent-tolerant species such as Aedes and Anopheles. Even
though fewer studies have been conducted on these non-DEET compounds,
picaridin and to some extent IR 3535 represent valid alternatives. Consequently, the
choice of repellents could be adjusted somehow according to the profile of biting
vectors at the travelersdestination.
3. Botanicals
Nature is an old unlimited source of inspiration for people [1, 11, 18, 35] as well
as for scientific and technological innovations. Recently, global attention has been
paid toward exploring the medicinal benefits of plant extracts [4, 11, 36, 37].
Repellents of natural origin are derived from members of the families as Asteraceae,
Cupressaceae,Labiatae,Lamiaceae,Lauraceae,Meliaceae,Myrtaceae,Piperaceae,
Poaceae,Rutaceae,Umbelliferae, and Zingiberaceae. They have been evaluated for
repellency against various mosquito vectors, but few compounds have been found
commercially. Increased curiosity in plant-based arthropod repellents was gener-
ated after the United States Environmental Protection Agency (US EPA) added a
rule to the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) in 1986
exempting compounds considered to be minimum hazardous pesticides [30].
Increased interest has also been driven by the rapid registration process of plant-
based repellents by US EPA, which are often registered in less than a year, while the
conventional pesticides are registered in an average of 3 years [30]. The public
considers botanicals as safer and suitable alternative repellents; most of them are
produced and distributed locally and appear on the market for only a short time.
Even though many studies have shown that almost all registered commercial prod-
ucts based on botanical active ingredients offer limited protection and require
frequent reapplication than even a low concentration of DEET-based repellents, the
growing demand for natural alternative repellents in the community illustrates
further need to evaluate new botanical repellents critically for personal protection
against mosquitoes and mosquito-borne illnesses [7, 8, 13, 17]. The repellent activity
of EOs includes some metabolites, such as the monoterpenes α-pinene, cineole,
eugenol, limonene, terpinolene, citronellol, citronellal, camphor, and thymol that
are repellents against mosquitoes; the sesquiterpene, β-caryophyllene, is repellent
against A. aegypti, and phytol, a linear diterpene alcohol, is repellent against
Anopheles gambia. Most of the arthropod-repellent compounds are oxygenated,
having the hydroxyl group linked to a primary, secondary, or aromatic carbon. In
some metabolites having a hydroxyl group linked to a tertiary carbon, as linalool, α-
6
Malaria
terpineol, and limonene, the repellent activity is suppressed against A. gambiae,
suggesting the likelihood that the type of carbon where the hydroxyl substitution is
there modulates repellency. Most insect repellents are volatile terpenoids such as
terpinen-4-ol. Other terpenoids can act as attractants. More information is widely
discussed [7, 38], and chemical structures of some natural repellent compounds are
shown in Figure 2.
3.1 PMD and lemon-scented eucalyptus
Compound p-menthane-3,8-diol (PMD is derived from lemon-scented eucalyp-
tus (Eucalyptus citriodora,Myrtaceae) leaves, and its importance as a repelling agent
is increasing due to its good efficacy profile as well as its natural basis. PMD is a
potent and commercially available repellent discovered in the 1960s via mass
screening of plants for repellent activity, for instance, lemon eucalyptus and
Corymbia citriodora (Myrtaceae) formerly known as Eucalyptus maculata citriodora.
Lemon eucalyptus EO contains 85% citronellal and is already used in cosmetic
industries due to its fresh smell. It was discovered when the waste distillate
remaining after hydro-distillation of the EO was far more effective at repelling
mosquitoes than the EO itself, and it provides very high protection from a broad
range of insect vectors for several hours as well [7, 39]. The EO from C. citriodora
also contains active constituents like citronella, citronellol, geraniol, isopulegol, and
δ-pinene which play important roles in repelling both mosquitoes and ticks. Such
compounds provide short-term repellency against mosquitoes, but PMD has a lon-
ger protection time than other plant-derived compounds because it is a monoter-
pene with low volatility than volatile monoterpenes found in most EOs and does not
tend to evaporate rapidly after skin application [7, 8, 14].
There have been attempts to commercialize and market the insecticides/repel-
lent products containing eucalyptus oil as such or based upon them. Crude euca-
lyptus oil was primarily registered as an insecticide and miticide in the USA in 1948,
and 29 of such compounds have been registered in the USA until the year 2007 for
use as natural insecticide/insect repellent/germicide. Only four products of them
Figure 2.
Chemical structures of some natural repellent compounds found in botanical species.
7
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
have been active, whereas 25 have been canceled. These include Citriodiol, Repel
essential insect repellent lotion (two variants), Repel essential insect repellent pump
spray, and Repel insect repellent 30 by the United Industrial Corp., USA. Some
eucalyptus-based products include the following: Quwenling is successfully
marketed as an insect repellent in China and provides protection against anopheles
mosquitoes parallel to DEET and has exchanged the widely used synthetic repellent
dimethylphthalate; Quwenling contains a mixture of PMD, citronellol, and
isopulegone. Mosiguard Natural contains 50% eucalyptus oil, Buzz Away is a com-
mercially available product in China based on citronellal, and MyggA1 Natural is
based on PMD from lemon eucalyptus and is shown to repel ticks. More details are
widely discussed [40].
3.2 Citronella
The name Citronellais derived from the French word citronellearound
1858. It was extracted to be used in perfumery and used by the Indian Army to repel
mosquitoes at the beginning of the twentieth century and was then registered for
commercial use in the USA in 1948. Today, citronella (510%) is one of the most
widely used natural repellents on the market; such concentrations are lower than
most other commercial repellents, whereas higher concentrations can cause skin
sensitivity. Among plant-derived substances, products containing Citriodiol
showed the most effective repellent profile against mosquitoes. EOs and extracts
belonging to plants in the Citronella genus (Poaceae) are commonly used as ingre-
dients of plant-based mosquito repellents, mostly Cymbopogon nardus that is sold in
Europe and North America in commercial preparations [39]. Citronella contains
citronellal, citronellol, geraniol, citral, α-pinene, and limonene giving an effect
similar to that of DEET, but the oils rapidly evaporate causing loss of efficacy and
leaving the user unprotected. Among plant-derived substances, products containing
Citriodiol showed the most effective repellent profile against mosquitoes. For trav-
elers heading to disease-endemic areas, citronella-based repellents should not be
recommended, but if efficacious alternatives are prohibitively expensive or not
available, the use of citronella to prevent mosquito bites may provide important
protection from disease vectors. Even though citronella-based repellents only give
protection from host-seeking mosquitoes for a short time (2 h), formulations could
prolong such time (please see the formulation section).
3.3 Neem and methyl jasmonate
The aromatic plants of the Meliaceae family which include neem, Azadirachta
indica,Carapa procera,Melia azedarach,Khaya senegalensis, and Trichilia emetica
contain substances of the limonoid group and insecticidal and repellent effects on
insects [18]. Neem provided a protection of 98.2% for 8 h against An. darlingi.
Regardless of being not approved by US EPA for use as a topical insect repellent,
neem is widely advertised as a natural alternative to DEET, and it has been tested
for repellency against a wide range of arthropods of medical and veterinary impor-
tance. MiteStop®, based on a neem seed extract, had a considerable repellent effect
on bloodsucking mosquitoes, tabanids, ceratopogonids, simuliids, as well as licking
flies [41]. Several field studies from India have shown the very high efficacy of
neem-based preparations, contrasting with findings of intermediate repellency by
other researchers. However, these contrasting results may be due to differing
methodologies and the solvents used to carry the repellents.
Methyl jasmonate (MJ) is derived from the nonvolatile jasmonic acid and has the
ultimate vapor pressure for a repellent (0.001 mmHg at 25°C) which is quite higher
8
Malaria
than DEET. It repels only Cx. quinquefasciatus but does not repel Ae. aegypti,An.
gambiae,Phlebotomus flies, and Glossina morsitans, which restricts the application of
MJ to C. quinquefasciatus mosquitoes only. On the other hand, MJ has been found to
cause aversion in a number of ticks such as nymphal I. ricinis and Hyalomma
marginatum rufipes Koch, etc. [30].
3.4 Essential oils
EOs are used against insects [20, 4250] throughout the globe. EOs are distilled
from members of the Lamiaceae (mint family), Poaceae (aromatic grasses), and
Pinaceae (pine and cedar family). EOs could be used for farm animal protection
against nuisance flies and lice [47]. Almost all of the botanical repellents are also
used for food flavoring or in the perfume industry, indicating that they are safer
than DEET. The most effective oils include thyme, geraniol, peppermint, cedar,
patchouli, and clove that have been found to repel malaria, filarial, and yellow fever
vectors for a period of 60180 mins. Most of these EOs are highly volatile, and this
contributes to their poor longevity as mosquito repellents. As a result, repellents
containing only EOs in the absence of an active ingredient such as DEET should not
be recommended as repellents for use in disease-endemic areas, whereas those
containing high levels of EOs could cause skin irritation, especially in the presence
of sunlight [39]. Although EOs effectively repel mosquitoes as irritants, repellents,
antifeedants, or maskants, unfortunately, relatively few have been commercialized,
despite being widely used in candles and as topical insect repellents. Botanical,
herbal, or natural-based repellents include one or several plant EOs. These oils are
considered safe by the EPA at low concentrations but provide a limited duration of
protection against mosquitoes (<3 h). Citronella (discussed previously) is the prin-
cipal and sometimes only active ingredient in many plant-based insect repellents
[7]. Eucalyptus oil is used as an antifeedant mainly against biting insects as
eucalyptus-based products used on humans as insect repellent can give protection
from biting insects up to 8 h depending upon the concentration of the essential oil.
Such repellent activity could be extended up to 8 days when eucalyptus EOs are
applied on the clothes. Eucalyptus oil (30%) can prevent mosquito bite for 2 h;
however, the oil must have at least 70% cineole content [40]. On the other hand,
E. citriodora EO alone showed an insufficient protection against the three main
mosquito species [14].
4. Safety of repellents
4.1 Safety of synthetic repellents
Insect repellents containing DEET are broadly used among populations. DEET
should be used with caution as it may damage spandex, rayon, acetate, and
pigmented leather and it could dissolve plastic and vinyl (e.g., eyeglass frames).
Moreover, DEET damages synthetic fabrics and painted and varnished surfaces,
precluding its use in bed nets and in many urban settings [51]. Being the gold
standard of repellents, the safety profile of DEET is largely studied. There is an
estimated 15 million people in the UK, 78 million people in the USA, and 200 mil-
lion people globally that use DEET each year safely when it is applied to the skin at
the correct dose indicated at the commercial preparation (in the case of it not being
swallowed or rubbed into the mucous membranes). DEET has been used since 1946
with a tiny number of reported adverse effects, many of which had a history of
excessive or inappropriate use of repellent. Its toxicology has been more closely
9
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
scrutinized than any other repellent, and it has been deemed safe for human use,
including its use on children, pregnant women, and lactating women [39]. Even
though insect repellents containing DEET are safe, some side effects have been
described, mainly after inappropriate use such as dermatitis, allergic reactions,
neurologic and cardiovascular side effects, as well as encephalopathy in children. In
addition, there are a small number of reports of systemic toxicity in adults following
dermal application. The safety profile in the second and third trimester of preg-
nancy has been well known through inspection of very low placental cord concen-
trations after maternal application of DEET, but animal models do not indicate any
teratogenic effects. DEET also blocks mammalian sodium and potassium ion chan-
nels contributing to the numbness of lip following the application of DEET [13].
Approval for use in young children is a controversial issue between countries, with
some recommending lower concentrations, whereas others suggesting that higher
strengths can be used. However, the causation between the few reported cases of
encephalopathy in children and the topical use of DEET cannot be supported by a
good evidence base [14, 39].
When permethrin is impregnated appropriately in cloths and nets, toxicity
fearfulness is minimal [52]. Although synthetic pyrethroids are utilized worldwide
as active ingredients in MRs [15] due to their relatively low toxicity to mammals
[53], inappropriate application at high doses initiates neurotoxic effects such as
tremors, loss of coordination, hyperactivity, paralysis, and an increase in body
temperature. Other side effects include skin and eye irritation, reproductive effects,
mutagenicity, alterations in the immune system, etc. [13]. Recent studies also
showed that some pyrethroids are listed as endocrine disruptors and possible car-
cinogens [53] and pyrethroids might cause behavioral and developmental neuro-
toxicity, with special concern revolving around infants and children, due to their
potential exposure during a sensitive neurodevelopmental stage [54]. More evi-
dence in the recent years indicates that pyrethroid insecticides can reduce sperm
count and motility, cause deformity of the sperm head, increase the count of
abnormal sperm, damage sperm DNA, induce its aneuploidy rate, affect sex hor-
mone levels, and produce reproductive toxicity [55]. Moreover, an elevated con-
centration of transfluthrin in the gaseous phase during the indoor application of an
electric vaporizer was detected, but they found inhalation risk of airborne
transfluthrin was low. The exposure levels and potential risk of pyrethroids during
the applications of other types of commonly used MRs remain unknown [53]. On
the other hand, long-term exposure to pyrethroid-based MRs in indoor environ-
ments causes chronic neurotoxicity, for example, dysfunction of blood-brain bar-
rier permeability, oxidative damage to the brain, [56] and cholinergic dysfunction
which cause learning and memory deficiencies [57]. Even though ventilation
through natural air exchange and conditioner dissipate of airborne pollutants,
residues persisting in the air and/or on indoor surfaces could potentially cause
continuous exposure to the residents.
US EPA-OPPs Biochemical Classification Committee classified IR 3535 as a
biochemical in 1997, because it is functionally identical to naturally occurring beta-
alanine in that both repel insects, the basic molecular structure is identical, the end
groups are not likely to contribute to toxicity, and it acts to control the target pest
via a nontoxic mode of action [58]. No reported toxicity has been made so far
against IR 3535, and it induces less irritation to mucous membranes and exhibits
safer oral and dermal toxicity than DEET which makes it an attractive alternative to
DEET in disease-inflicted endemic regions [13]. The ester structure of the propio-
nate grants essential advantages because of a short metabolic degradation and quick
excretion as a simple water-soluble acid [58]. Picaridin has the advantage of being
odorless and non-sticky or greasy. Moreover, unlike DEET, picaridin does not
10
Malaria
damage plastics and synthetics. In some studies, picaridin induces no adverse toxic
reactions in animal studies but exhibits low toxicity and less dermatologic and
olfactory irritant in other studies. Consequently, picaridins comparable efficacy to
DEET and its suitability of application and favorable toxicity profile ranked it as an
attractive option and unquestionably an acceptable alternative for protection
against mosquitoes and other hematophagous arthropods to control the menace of
vector-borne diseases in endemic areas [13]. DEPA does not show cytotoxicity or
mutagenicity [59], thereby increasing its suitability in direct skin application. It also
exhibits moderate oral toxicity (mouse oral LD
50
900 mg/kg) and low to moderate
dermal toxicity (rabbit and female mouse LD
50
of 3500 and 2200 mg/kg, respec-
tively) [60]. Acute and subacute inhalation toxicity studies of DEPA have also been
reported [61] which indicate its applicability as aerosol formulations. Indalone was
an early synthetic repellent effective against both mosquitoes and ticks. It was even
more effective than DEET; however, its chronic exposure induced kidney and liver
damage in rodents which restricted its application [13]. EA is approved by the US
FDA, WHO and European Food Safety Authority (EFSA) [62, 63]. Furthermore,
EA has been listed in the generally recognized as safe[64] list by the Flavour and
Extract Manufacturers Association (FEMA) [65]. EA does not damage synthetic
fabrics, plastics, and painted and varnished surfaces which further widen the utility
of EA in bed nets, cloths, and different surfaces in the endemic settings [14, 66].
4.2 Safety of plant-based repellents
Because many conventional pesticide products fall into disfavor with the public,
botanical-based pesticides should become an increasingly popular choice as repel-
lents. There is a perception that natural products are safer for skin application and
for the environment, just because they are natural and used for a long time com-
pared to synthetic non-biodegradable products [14]. In contrast to DEET, some
natural repellents are safer than others, and plant-based repellents do not have this
strictly tested safety evidence, and many botanical repellents have compounds that
need to be used with caution [39]. PMD has no or very little toxicity to the envi-
ronment and poses no risks to humans and animals. PMD has been developed and
registered for use against public health pests and is available as a spray and lotion.
Not much is known about the toxicity of eucalyptus oils; however, they have been
categorized as GRAS by the US EPA. Further, the oral and acute LD
50
of eucalyptus
oil and cineole to rat is 4440 mg/kg body weight (BW) and 2480 mg/kg BW,
respectively, making it much less toxic than pyrethrins (LD
50
values 350
500 mg/kg BW; US EPA, 1993) and even technical grade pyrethrum (LD
50
value
1500 mg/kg BW) [40]. PMD is an important component of commercial repellents
in the US and registered by US EPA and Canadian Pest Management Regulatory
Agency in 2000 and 2002, respectively [13]. In contrary, lemon eucalyptus EO does
not have US EPA registration for use as an insect repellent. PMD is the only plant-
based repellent that has been advocated for use in disease-endemic areas by the
Centers for Disease Control (CDC), due to its proven clinical efficacy to prevent
malaria, and is considered to pose no risk to human health [39]. In 2005, the US
Centers for Disease Control and Prevention made use of its influence by endorsing
products containing oil of lemon eucalyptus(PMD), along with picaridin and
DEET as the most effective repellents of mosquito vectors carrying the West Nile
virus [67]. PMD provides excellent safety profile with minimal toxicity. In studies
using laboratory animals, PMD demonstrated no adverse effects apart from eye
irritation. It is safe for both children and adults as the toxicity of PMD is very low.
However, the label indicates it should not be used on children under the age of 3 [7].
11
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
The safety of neem is extensively reviewed; azadirachtin is nontoxic to mam-
mals and did not show chronic toxicity. Even at high concentrations, neem products
were neither mutagenic nor carcinogenic, and they did not produce any skin irrita-
tions or organic alterations in mice and rats. On the other hand, reversible repro-
duction disturbances could occur due to the daily feeding of aqueous leaf extract for
6 and 9 weeks led to infertility of rats at 66.7 and 100%, respectively. Using
unprocessed and aqueous neem-based products should be encouraged if applied
with care. The pure compound azadirachtin, the unprocessed materials, the aque-
ous extracts, and the seed oil are safe to use even as insecticides to protect stored
food for human consumption, whereas nonaqueous extracts turn out to be rela-
tively toxic [8]. From the ecological and environmental standpoint, azadirachtin is
safe and nontoxic to fish, natural enemies, pollinators, birds, and other wildlife.
Azadirachtin is classified by the US EPA as class IV (practically nontoxic) [7, 8, 17]
as azadirachtin breaks down within 50100 h in water and is degraded by sunlight
as the half-life of azadirachtin is only 1 day, leaving no residues. Safety and advan-
tages of EOs are widely discussed [7, 8, 17, 39]. There is a popular belief that EOs are
benign and harmless to the user. Honestly, increasing the concentration of plant
EOs as repellents could increase efficacy, but high concentrations may also cause
contact dermatitis. Some of the purified terpenoid ingredients of EOs are moder-
ately toxic to mammals. Because of their volatility, EOs have limited persistence
under field conditions. With few exceptions, the oils themselves or products based
on them are mostly nontoxic to mammals, birds, and fish. Many of the commercial
products that include EOs (EOs) are on the generally recognized as safe[64] list
fully approved by the US FDA and EPA for food and beverage consumption.
Moreover, EOs are usually devoid of long-term genotoxic risks, and some of them
show a very clear antimutagenic capacity which could be linked to an
anticarcinogenic activity. The prooxidant activity of EOs or some of their constitu-
ents, like that of some polyphenols, is capable of reducing local tumor volume or
tumor cell proliferation by apoptotic and/or necrotic effects. Due to the capacity of
EOs to interfere with mitochondrial functions, they may add prooxidant effects and
thus become genuine antitumor agents. The cytotoxic capacity of the essential oils,
based on a prooxidant activity, can make them outstanding antiseptic and antimi-
crobial agents for personal uses, that is, for purifying air, personal hygiene, or even
internal use via oral consumption and for insecticidal use for the preservation of
crops or food stocks. Some EOs acquired through diet are actually beneficial to
human health [68, 69]. Eugenol is an eye and skin irritant and has been shown to be
mutagenic and tumorigenic. Citronellol and 2-phenylethanol are skin irritants, and
2-phenylethanol is an eye irritant, mutagen, and tumorigenic; they also affect the
reproductive and central nervous systems [30]. Hence, it is advised that EOs with
toxic profile should be used for treating clothing rather than direct application to
individuals skin [13]. Although EOs are exempt from registration through the US
EPA, they can be irritating to the skin, and their repellent effect is variable, depen-
dent on formulation and concentration. The previously mentioned safety and
advantages designate that EOs could find their way from the traditional into the
modern medical, insecticidal, and repellent domain.
5. Conclusions and challenges for future research
Several diseases transmitted by mosquitoes cause high losses of human and
animal lives every year. DEET is considered as a gold standardto which other
candidate repellents are compared; therefore, DEET is the most ever-present active
ingredient used in commercially available repellents, with noteworthy protection
12
Malaria
against mosquitoes and other biting insects. Unfortunately, the widespread use and
effectiveness of commercial formulations containing DEET and other synthetic
substances could lead to resistance [70, 71]. Some health and environmental con-
cerns lead to the search for natural alternative repellents. The use of repellent plants
has been used since antiquity [1], and it is the only effective protection available for
the poor people against vectors and their associated diseases [71]. Ethnobotanical
experience is passed on orally from one generation to another, but it needs to be
preserved in a written form and utilized as a rich source of botanicals in repellent
bioassays. Then again, the growing demand for natural repellents points up the
further necessity to evaluate new plant-based products critically for personal pro-
tection against mosquitoes and mosquito-borne diseases [7, 8, 17, 18]. Regarding
environmental and health concerns, plant-based repellents are better than synthetic
molecules. Even though many promising plant repellents are available, their use is
still limited; therefore, advance understanding of the chemical ecology of pests and
the mode of repellency would be helpful for identifying competitor semiochemicals
that could be incorporated into attractant or repellent formulations. There are
numerous commercially available formulations enhancing the longevity of repel-
lent, by controlling the rate of delivery and the rate of evaporation. Such formula-
tions are very useful to people living in the endemic areas in the form of sprays,
creams, lotions, aerosols, oils, evaporators, patch, canister, protective clothing,
insecticide-treated clothing, and insecticide-treated bed nets [7, 8, 17]. The poten-
tial uses and benefits of microencapsulation and nanotechnology are enormous
including enhancement involving nanocapsules for pest management and
nanosensors for pest detection [7, 8]. Nanoparticles are effectively used to control
larvae [7276] and to repel adults of mosquitoes [77, 78].
Polymer-based formulations allow entrapping active ingredients and provide
release control. Encapsulation into polymeric micro/nanocapsules, cyclodextrins,
polymeric micelles, or hydrogels constitutes an approach to modify physicochemi-
cal properties of encapsulated molecules. Such techniques, applied in topical for-
mulations, fabric modification for personal protection, or food packaging, have
been proven to be more effective in increasing repellency time and also in reducing
drug dermal absorption, improving safety profiles of these products. In this work,
the main synthetic and natural insect repellents are described as well as their
polymeric carrier systems and their potential applications [79]. Encapsulated EO
nanoemulsion is prepared to create stable droplets to increase the retention of the
oil and slow down release. The release rate correlates well to the protection time so
that a decrease in release rate can prolong mosquito protection time. Microencap-
sulation is another way to slowly release the active ingredients of repellents. In
laboratory conditions, the microencapsulated formulations of the EOs showed no
significant difference with regard to the duration of repellent effect compared to
the microencapsulated DEET used at the highest concentration (20%). It exhibited
>98% repellent effect for the duration of 4 h, whereas, in the field conditions, these
formulations demonstrated the comparable repellent effect (100% for a duration of
3 h) to Citriodiol®-based repellent (Mosiguard®). In both test conditions, the
microencapsulated formulations of the EOs presented longer duration of 100%
repellent effect (between 1 and 2 h) than non-encapsulated formulations [80].
Microencapsulation reduces membrane permeation of CO while maintaining a con-
stant supply of the citronella oil [81]. Moreover, using gelatin Arabic gum micro-
capsules also prolonged the effect of natural repellents. In addition, the
functionalization of titanium dioxide nanoparticles on the surface of polymeric
microcapsules was investigated as a mean to control the release of encapsulated
citronella through solar radiation. The results showed that functionalizing the
microcapsules with nanoparticles on their surface and then exposing them to
13
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
Repellent composition Dose Study variety Mosquito spp. Mean
CPT
Protection Reference
% Time
interval
Bio Skincare® Natural oil of jojoba, rapeseed, coconut, and vit. E 1.2 g/arm Arm-in-cage An. arabiensis 100
52
34h
6h
[85]
BioUD® spray 7.75% 2-undecanone 1 ml/600 cm
2
Arm-in-cage Ae. aegypti 96.1
86.7
81.7
79.5
70.1
68.2
1h
2h
3h
4h
5h
6h
[86]
Ae. albopictus 94.5
98.3
93.1
79.4
87.4
76.3
1h
2h
3h
4h
5h
6h
7.75% 2-undecanone 1 ml/600 cm
2
Field trial in North
Carolina (USA)
Ae. atlanticus/tormentor (23.3%)
Psorophora ferox (54.7%)
98.4
94.2
92.2
79
3h
4h
5h
6h
Field trial in
Canada
Ae. vexans (32%) Ae. euedes
(29.3%) Ae. stimulans (15.3%)
95.5
95.6
4h
6h
Bite Blocker®
lotion
Glycerin, lecithin, vanillin, oils of coconut, geranium, and
soybean (2%)
1 ml/650 cm
2
Arm-in-cage Ae. albopictus
Cx. nigripalus
5.5 h
8.3 h
[87]
Bite Blocker
Xtreme®
3% soybean oil
6% geranium oil
8% castor oil
Field trial in
Canada
Ae. vexans (32%)
Ae. euedes (29.3%)
Ae. stimulans (15.3%)
93.9
53.7
4h
6h
[86]
Buzz Off Insect
Repellent®
Natural plant extract 1 g/forearm Arm-in-cage Ae. aegypti
Ae. vigilax
Cx. Annulirostris
Cx. quinquefasciatus
0 min
0 min
160 min
50 min
[88]
Baygon® Oils of canola, eucalyptus, peppermint, rosemary, and sweet
birch
1 ml/650 cm
2
Arm-in-cage Ae. albopictus
Cx. nigripalus
0.2 h
4.7 h
[87]
14
Malaria
Repellent composition Dose Study variety Mosquito spp. Mean
CPT
Protection Reference
% Time
interval
Citronella
candles
3% citronella Field trial in
Canada
Aedes spp. 42.3 [89]
Citronella
incense
5% citronella Field trial in
Canada
Aedes spp. 24.2 [89]
GonE!® Aloe vera, camphor, menthol, oils of eucalyptus, lavender,
rosemary, sage, and soybean
1 ml/650 cm
2
Ae. albopictus
Cx. nigripalus
0.0 h
2.8 h
[87]
Green Ban for
People®
Citronella 10%, peppermint oil 2% Arm-in-cage Ae. aegypti 14 min [90]
Herbal
Armor®
Citronella 12%, peppermint oil 2.5%, cedar oil 2%, lemongrass
oil 1%, geranium oil 0.055
Arm-in-cage Ae. aegypti 18.9 min [90]
Kor Yor 15
DEET lotion®
DEET 24%, dimethylphthalate 24% 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 3 h [91]
DEET 24%, dimethylphthalate 24% 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 3 h [92]
MeiMei®
cream
Citronella and geranium oils Indoor test Ae. aegypti 97
97
85
44
27
30 min
50 min
70 min
90 min
120 min
[93]
Citronella and geranium oils Field trial in South
Korea
Aedes (7.8%)
Armigeres (5.9%)
Anopheles (42.2%)
Culex (44.1%)
90
57
56
34
30 min
90 min
150 min
210 min
[94]
Mistine
censor®
IR 3535 12%, rosemary, lavender, and eucalyptus 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 1 h [91]
IR 3535 12%, rosemary, lavender, and eucalyptus 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 1 h [92]
Mospel® Clove oil 10%
Makaen oil 10%
1 g/600 cm
2
Arm-in-cage An. stephensi 45 h [95]
1 g/lower leg Walk-in exposure
room test
78h
15
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
Repellent composition Dose Study variety Mosquito spp. Mean
CPT
Protection Reference
% Time
interval
MosquitoSafe® Geraniol 25%, mineral oil 74%, aloe vera 1% 1 ml/650 cm
2
Arm-in-cage Ae. albopictus 2.8 h [87]
Neem Aura® Aloe vera, extract of barberry, chamomile, goldenseal, myrrh,
neem, and thyme; oil of anise, cedarwood, citronella, coconut,
lavender, lemongrass, neem, orange, rhodium wood
1 ml/650 cm
2
Arm-in-cage Ae. albopictus
Cx. nigripalus
0.2 h
4.2 h
[87]
Odomos®
cream
Advanced Odomos (12% N,N-diethylbenzamide) 8 mg/cm
2
Arm-in-cage
(Duration of the
test: 4 h)
Cx. nigripalus 3.8 h [96]
10 mg/cm
2
>4 h 100
10 mg/cm
2
Ae. aegypti 4 h 96.5
12 mg/cm
2
>4 h 100
Advanced odomos 10 mg/cm
2
Field trial in India
Duration of the
test: 11 h
An. culicifacies
An. stephensi
An. annularis
An. subpictus
11 h 100
10 mg/cm
2
Cx. quinquefasciatus 9 h 98.8
10 mg/cm
2
Ae. aegypti 6.2 h 92.5
Raid Dual
Action and
Raid Shield
transfluthrin-based spatial repellent products Laboratory (wind
tunnel) and
Aedes aegypti 95
and
74
[97]
semi-field
(outdoor
enclosure) in
Florida
88
and
66
16
Malaria
Repellent composition Dose Study variety Mosquito spp. Mean
CPT
Protection Reference
% Time
interval
Repel Care® Turmeric oil 5%
E. citriodora 4.5%
2 ml/750 cm
2
Field trial in
Thailand
(duration of the
test: 9 h)
Ae. aegypti (1.2%)
Others (<1%)
Cx. vishnui (77.1%)
Cx. quinquefasciatus (13.8%)
Cx. gelidus (3.4%)
Cx. tritaeniorhynchus (1.6%)
100
Duration of the
test: 8 h
Ae. albopictus (99.9%)
Ar. subalbatus (0.01%)
100
96.9
92.4
91.8
Turmeric oil 5%
E. citriodora 4.5%
0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 1 h [92]
Sketolene®
lotion
DEET, E. citriodora oil 15% 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 3 h [92]
Soffell®
(citronella oil)
DEET 13%, citronella oil 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 4 h [92]
Soffell®
(floral
fragrance)
DEET 13%, geranium 4h
Soffell®
(fresh
fragrance)
DEET 13%, orange 4h
Soffell® lotion DEET, E. citriodora oil 15% 0.1 ml/30 cm
2
Field trial in
Thailand
(duration of the
test: 120 min)
Ae. gardnerii
Ae. lineatopennis
An. barbirostris
Cx. Tritaeniorhynchus
Cx. gelidus
100 (120 min) [91]
17
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
Repellent composition Dose Study variety Mosquito spp. Mean
CPT
Protection Reference
% Time
interval
Sumione® Metofluthrin-treated emanators 900-cm
2
paper fan emanators
impregnated with 160 mg
metofluthrin
Field trials in PA,
USA
Aedes canadensis 85
100
[98]
4000-cm
2
paper strip emanators
impregnated with 200 mg
metofluthrin
Laboratory-reared
Aedes aegypti
89
91
Metofluthrin-impregnated paper
strip emanator
In Florida Ochlerotatus spp. 91
95
Metofluthrin-impregnated paper
strip emanator
In Washington
State
Aedes vexans 95
97
SunSwat® Oils of bay, cedarwood, citronella, goldenseal, juniper,
lavender, lemon peel, patchouli, pennyroyal, tansy, tea tree,
and vetiver
1 ml/650 cm
2
Arm-in-cage Ae. albopictus
Cx. nigripalus
0.2 h
4.2 h
[87]
Tipskin® Bergamot oil, citronella oil, camphor oil, and vanillin 0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 0 h [91]
Bergamot oil, citronella oil,
camphor oil, and vanillin
0.1 ml/30 cm
2
Arm-in-cage Ae. aegypti 0.5 h [92]
OFF! Clip-On® Metofluthrin Field study in USA Ae. albopictus and Ae.
taeniorhynchus
3h 70
and
79
[99]
Anopheles quadrimaculatus,
Culex erraticus, and Psorophora
columbiae
Up
to
84
[100]
Mosquito
Cognito®
Linalool Anopheles quadrimaculatus,
Culex erraticus, and Psorophora
columbiae
Up
to
84
[100]
No-Pest Strip® Dichlorvos [100]
Thermacell® d-cis/trans allethrin [100]
Table 1.
Commercial mosquito-repellent products.
18
Malaria
ultraviolet radiation effectively increased the output of citronella into the air for
repelling the mosquitoes without human intervention, as the sunlight works as a
release activator [82].
It is recommended to use US EPA-registered insect repellents including one of
the active ingredients: DEET, Picaridin, IR3535, Oil of lemon eucalyptus (OLE),
Para-menthane-diol (PMD), and 2-undecanone. Synthetic MRs are applied for
years but induced some safety and environmental concerns; as a result, the
advancement in the development of repellents from the botanical origin is encour-
aged. But some obstacles are hindering botanical repellents which as the source
availability, standardization, commercialization, and analyses in order to certify the
efficacy and safety [7]. Commercially available repellents are provided in Table 1.
For saving time and efforts, a high-throughput chemical informatics screen via a
structure-activity approach, molecular-based chemical prospecting [83], as well as
computer-aided molecular modeling [84] would accelerate the exploration of new
environmentally safe and cost-effective novel repellents which activated the same
chemosensory pathways as DEET at a fairly shorter time and lower costs [13]. The
selection of various repellents could be tailored along with the profile of safety
concerns and biting vectors at the travelersand military destinations by reducing
annoyance and the incidence of illness. The use of these technologies to enhance the
performance of natural repellents may revolutionize the repellent market and make
EOs a more viable option for use in long-lasting repellents. Green technologies and
cash cropping of repellent plants afford a vital source of income for small-scale
farmers and producers in developing countries and raise the national economy.
Moreover, in some developing countries where tourism is a chief source of national
income, the use of repellents would increase the pleasure and comfort of tourists.
Finally, much faster work needs to be done to discover new and safe repellents for
personal protection from mosquitoes.
19
Commercial Mosquito Repellents and Their Safety Concerns
DOI: http://dx.doi.org/10.5772/intechopen.87436
Author details
Hanem Fathy Khater
1
*, Abdelfattah M. Selim
2
, Galal A. Abouelella
3
,
Nour A. Abouelella
3
, Kadarkarai Murugan
4
, Nelissa P. Vaz
5
and
Marimuthu Govindarajan
6
1 Department of Parasitology, Faculty of Veterinary Medicine, Benha University,
Toukh, Egypt
2 Department of Infectious Disease, Faculty of Veterinary Medicine, Benha
University, Toukh, Egypt
3 Faculty of Pharmacy, British University of Egypt, Egypt
4 Division of Entomology, Department of Zoology, School of Life Sciences,
Bharathiar University, Coimbatore, Tamil Nadu, India
5 Exact Sciences SectorDepartment of Chemistry, Federal University of Paraná
(UFPR), Curitiba, Paraná, Brazil
6 Unit of Vector Control, Phytochemistry and Nanotechnology, Department of
Zoology, Annamalai University, Annamalainagar, Tamil Nadu, India
*Address all correspondence to: hanemkhater@gmail.com;
hanem.salem@fvtm.bu.edu.eg
© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms
of the Creative Commons Attribution License (http://creativecommons.org/licenses/
by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.
20
Malaria
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... The prevention of arthropod-borne diseases relies on effective pest management strategies [4][5][6]. Even though the employment of conventional pesticides and repellents represent a worthy solution to avoid arthropod bites, they resulted in serious environmental risks and unfavorable effects on non-target creatures, animals, and humans, and contaminated dairy and meat products [6] and development of resistant strains of pests; therefore, searching for alternative ways of pests control is an urgent need [3,7,[8][9][10][11][12][13][14][15]. ...
... Botanicals have been well-known for their medicinal properties [24] since ancient times [25] and induce anthelmintic, antiprotozoal, antiviral, antifungal, and antibacterial [26][27][28][29][30][31][32] and pesticidal effects [14,15] such as ovicidal [33,34], larvicidal and insect growth regulating effects [19,[35][36][37][38][39][40][41][42][43][44][45][46][47][48] as well as adulticidal and repellent properties [8,33,34,39,45,46,[49][50][51][52][53]. Botanicals are characterized by high efficiency against pests and prevention of their associated diseases, safety to non-target organisms [5,10,44], and biodegradation [5,11]. ...
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Botanical insecticides are promising pest control agents. This research investigated the novel pesticidal efficacy of Araucaria heterophylla and Commiphora molmol extracts against four ecto-parasites through treated envelopes. Seven days post-treatment (PT) with 25 mg/mL of C. molmol and A. heterophylla, complete mortality of the camel tick, Hyalomma dromedarii and cattle tick, Rhip-icephalus (Boophilus) annulatus were reached. Against H. dromedarii, the median lethal concentrations (LC50s) of the methanol extracts were 1.13 and 1.04 mg/mL and those of the hexane extracts were 1.47 and 1.38 mg/mL, respectively. The LC50 values of methanol and hexane extracts against R. an-nulatus were 1.09 and 1.41 plus 1.55 and 1.08 mg/mL, respectively. Seven days PT with 12.5 mg/mL, extracts completely controlled Haematopinus eurysternus and Hippobosca maculata; LC50 of Ha. eu-rysternus were 0.56 and 0.62 mg/mL for methanol extracts and 0.55 and 1.00 mg/mL for hexane extracts , respectively, whereas those of Hi. maculata were 0.67 and 0.78 mg/mL for methanol extract and 0.68 and 0.32 mg/mL, respectively, for hexane extracts. C. molmol extracts contained sesquiter-pene, fatty acid esters and phenols, whereas those of A. heterophylla possessed monoterpene, ses-quiterpene, terpene alcohols, fatty acid, and phenols. Consequently, methanol extracts of C. molmol and A. heterophylla were recommended as ecofriendly pesticides.
... From the foregoing, avoiding mosquito bites is a logical primary method of preventing malaria, infection. However, the use of mosquito repellent creams, bed nets, window nets and outlet door nets prevent mosquito bites to a reasonable extent and also have the potential to reduce the prevalence of mosquitoborne illnesses, such as malaria [9,10]. Household aerosolized insecticide spraying has also been observed to reduce malaria prevalence [11]. ...
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Introduction: Living conditions in most rural African communities favour malaria transmission and threaten global eradication. Prevention strategies and interventions such as the use of bed nets have reduced the prevalence of malaria. This study described the various methods employed to prevent malaria and their effects on malaria parasite prevalence among children living in a rural community in Nigeria. Methodology: A community-based cross-sectional study conducted among 357 children aged 1-15 years, in a Nigerian rural community. Data was analyzed using SPSS version 25. Chi-squared test of association with a level of significance of p < 0.050 was used. Results: Only 110 (30.8%) participants owned mosquito nets. Mostly those from the high social class (45; 40.9%) used the nets, and these were mostly 'under-five' children. Thirty-six (10.1%) were routinely given antimalarial drugs for malaria prophylaxis. Also, 102 (28.6%), 151 (42.3%), 278 (77.9%), 99 (27.7%) and 15 (5.0%) children used insecticides, local herbs, window nets, outlet door nets and mosquito repellent creams respectively. None of the methods employed to prevent malaria had statistically significant effect on malaria parasite prevalence among participants (p > 0.050). Conclusions: Malaria prevention methods were mostly practiced by participants of the high social class while children under-five considerably used mosquito nets. This study highlights the need to address the socio-demographic imbalance regarding malaria preventive measures in the community where the study was conducted. There is also a need to regulate the use of antimalarial drugs for malaria prophylaxis in the rural community. These suggest that the current malaria prevention methods in the community be reviewed.
... The use of synthetic insecticides to control disease vectors (mosquitoes in particular) may sometimes be ineffective due to the resistance developed in vectors to these pesticides and their harmful effects on human health and the environment. Therefore, scientists have sought a safe and sustainable control method such as botanical insecticides that can naturally grow and be collected from different areas worldwide (Khater et al., 2019). In this study, the larvicidal efficiency of three solvent extracts from the leaves of R. epapposum showed solvent-concentration and time-dependent actions. ...
... The use of synthetic insecticides to control disease vectors (mosquitoes in particular) may sometimes be ineffective due to the resistance developed in vectors to these pesticides and their harmful effects on human health and the environment. Therefore, scientists have sought a safe and sustainable control method such as botanical insecticides that can naturally grow and be collected from different areas worldwide (Khater et al., 2019). In this study, the larvicidal efficiency of three solvent extracts from the leaves of R. epapposum showed solvent-concentration and time-dependent actions. ...
... Synthetic pesticides are widely used against mosquitoes but they cause environmental toxicity and are non-biodegradable. Moreover, the prolonged usage of such chemicals produces resistance in mosquitoes [3]. Several reviews have been published on the use of plant extracts having mosquitocidal activities [4][5][6][7][8]. ...
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Mosquitoes are important vectors responsible for spreading a number of diseases affecting both humans and animals. Many diseases as dengue, chikungunya, yellow fever, malaria, filariasis and Japanese encephalitis are spread by mosquitoes. There are many reports of plant extracts and their active constituents showing anti-mosquito activities as larvicidal, pupicidal, ovicidal and adulticidal activities. Persea americana Mill. (Lauraceae), known as avocado, has been reported to show many pharmacological and antimicrobial activities. In this communication, the mosquito larvicidal activities of the three-active constituents, avocadene, avocadyne and avocadenol-A, from the methanolic extract of the unripe fruit peel are presented. The three mosquito species studied were Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi. All three compounds showed the highest larvicidal activity against An. stephensi, LC50 values being 2.80ppm for avocadene, 2.33ppm for avocadyne and 2.07ppm for avocadenol-A. Avocadene showed larvicidal activity of 3.73ppm against Ae. aegypti and 5.96ppm against Cx. quinquefasciatus. The LC50 value of avocadyne was 5.35ppm against Ae. aegypti and 3.98ppm against Cx. quinquefasciatus. Similarly, avocadenol-A showed 6.56ppm against Ae. aegypti and 2.35ppm against Cx. quinquefasciatus. The active constituents were isolated by bioactivity-guided fractionation by silica gel column chromatography and RP HPLC. The compounds were identified by physical and spectroscopic data and compared with literature values already reported. Graphical Abstract
... The medical applications of AuNPs raised significantly due to their less toxicity throughout the whole body (Crooks et al. 2001). Khater et al. (2019) reported commercial mosquito repellent prevents mosquito-host interactions, including synthetic and natural repellents, which could potentially prevent mosquito-host interactions. In previous report, eco-friendly botanical extract synthesized with various nanoparticles was used for the different vector diseases and mosquito controls (Govindarajan et al. 2016a,b;Murugan et al. 2015;Roni et al. 2015). ...
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The present study focused on preparing a nano-ointment base integrated with biogenic gold nanoparticles from Artemisia vulgaris L. leaf extract. As prepared, nano-ointment was characterized by using Fourier-transform infrared spectroscopy, and the morphology of the nano-ointment was confirmed through a scanning electron microscope. Initially, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide results showed nano-ointment cytocompatibility at different concentrations (20–200 μg/mL) against L929 cells. The in vitro hemolysis assay also revealed that the nano-ointment is biocompatible. Further studies confirmed that nano-ointment has repellent activity with various concentrations (12.5, 25, 50, 75, and 100 ppm). At 100 ppm concentration, the highest repellent activity was observed at 60-min protection time against the Aedes aegypti L. female mosquitoes. The results indicated that the increasing concentration of nano-ointment prolongs the protection time. Moreover, the outcome of this study provides an alternative nano-ointment to synthetic repellent and insecticides after successful clinical trials. It could be an eco-friendly, safer nano-bio repellent, which can protect from dengue fever mosquitoes.
... GST and MDA were calculated using separated cellular fluids. MDA and glutathione s transferase levels were measured using Warren's thiobarbituric acid test technique (14). The glutathione s transferase activity in the samples was evaluated using Goldberg DM's technique, and MDA was computed as a measurement of thiobarbituric acid reactive compounds (TBARS) (15). ...
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Aim: synthesis, characterization, and application of modifying nanocomposite TiO 2 doped with Magnesium for photodegradation of antioxidant system Larvae and Pupae of Aedes Aegypti Catalysts Preparation of Mg-doped TiO 2 to determine activity of oxidative stress (MDA) and glutathione S Transferase, were known as a parameter of defense system resistance and immune maintained. This study was undertaken to assess the potential role of growth of stages of Aedes Aegypti correspondence with oxidant and antioxidant balance triggered by nanoparticle exposure. The amounts of these parameters in cellular samples were investigated using the following materials and procedures, intake 100 larvae and 100 pupae as subjects with (study subjects) and 3-9 days’ age-matched with healthy subjects as controls. at the second of the admission, as a marker of lipid peroxidation, and therefore an indicator of the activity of standard free radicals Nanoparticles Photo Catalysts, TiO 2 doped with Mg, the standard prepared Nanopowder changes from the forbidden band TiO 2 standard doping with atoms of Mg ،Mg) using the sol-gel method, for Mg-doped TiO 2 nanoparticles, the estimated band gap energy is 2.92 eV. Tissue MDA was used to estimate thiobarbituric acid reactive substances (TBARS), and liquid glutathione reductase activity was assessed using Goldberg DM’s method. Results: When compared to controls, there was a dramatic rise in MDA content and glutathione s transferase efficiency in larvae and pupae populations exposed to photo catalyst modified nanoparticles. Conclusion: Increased MDA support to oxidative stress in larvae and pupae samples supports enhanced oxygen-free radical generation, as indicated by our findings. Increased antioxidant enzyme activity could be a compensatory mechanism in response to increased oxidative stress. The findings point to glutathione s transferase’s antioxidant activity in response to increasing oxidative stress in the treated group.
Chapter
Mosquitoes are notable vectors of various diseases, including dengue, malaria, filariasis and yellow fever. Conventional mosquito repellents or mosquitocidal agents are synthesized via chemicals that have exhibited adverse toxicity towards humans and the environment with several limitations. In recent times, nanomaterials are introduced as a potential alternative to conventional mosquitocidal chemicals due to their high surface-to-volume ratio and ability to inhibit their growth at the cellular level. However, nanomaterials prepared via physical and chemical approaches are either costly or toxic to plants, animals, humans and the environment. Thus, nanomaterials fabricated using plant extracts are widely used recently as an effective mosquitocidal agent. The synergistic mosquitocidal property of the phytochemicals from plants and the nanomaterials is beneficial in inhibiting the population of mosquitoes by targeting their egg, pupa, larva and adult. Moreover, the phytochemicals as surface functional groups in these nanomaterials are beneficial in reducing their adverse toxic effects. Hence, this chapter is an overview of the various synthesis approaches to fabricate metal nanoparticles and the significance of phytosynthesis approach. In addition, the mosquitocidal property of the metal nanoparticles and their mechanism of action are also discussed.
Chapter
Peppermint (Mentha piperita) is one of the most important EO(essential oil crops) and is cultivated worldwide. It is composed primarilyof monoterpenes, whose medicinal properties are mainly due to their EO composition, accumulated in glandular trichomes. Nowadays, agriculturerelies heavily on the use of synthetic chemicals, such as fertilizers andpesticides, to achieve high yields but without taking into account theirdeleterious effects on the environment. However, there is an interestingbiotechnological alternative using microorganisms to increase theavailability and intake of nutrients by crops and to control phytopathogenicorganisms and herbivorous insects. The group of bacteria termed plantgrowth-promoting rhizobacteria (PGPR) colonizes the rhizosphere andstimulates plant growth and development by direct or indirect mechanisms.Thus, in the search for new strategies of plant production to optimizeessential oil (EO) yield, inoculation with PGPR is an interesting candidate.We present here an integrated summary of our experimental findings froman analysis of the community of fluorescent Pseudomonas strains in therhizosphere of commercially grown Mentha piperita, including the effectsof inoculation and co-inoculation with different PGPR strains (native andwild type) on total EO yield and glandular trichome density. Thequalitative and quantitative compositions of the main monoterpenes(menthol, menthone, pulegone, limonene and linalool) were alsodetermined to analyze the effects of the volatiles emitted byPGPR rhizobacteria on EO production. The various PGPR strains(Bacillus amyloliquefaciens GB03, Pseudomonas fluorescens WCS417r,Azospirillum brasilense SP7, Pseudomonas putida SJ04-SJ25-SJ48) andco-inoculations evaluated produced significant increases in the productionof EO in peppermint plants, but at different magnitudes. Bacterialinoculants are thus an effective biotechnological tool for stimulating thesecondary metabolism in plants. Application of these techniques maycontribute to environmental conservation, increased crop productivity andsustainable agricultural practices.
Chapter
Aedes aegypti and Ae. albopictus are mosquitoes that can be vectors of Zika virus (ZIKV) in urban and suburban neotropical regions in the world (Plourde & Bloch, 2016). Despite the countless scientific papers suggesting multiple strategies to control these mosquitoes, there is a gap between the theory and the application of such strategies in the field. Additionally a unique prevention method against viral diseases such as the one caused by ZIKV or other arbovirus has not been developed yet. Even in a hypothetical situation that a useful vaccine existed, the vector control programs (VCP) must be yet mandatory because the vaccination coverage does not always reach total efficacy and it is always possible that the viral etiological agent mutates generating resistance to the vaccine (Achee et al., 2015; Barrett, 2018; Roiz et al., 2018). Despite the effects on human health caused by the arboviruses transmitted by Ae. aegypti, today we could say, sadly, that the efforts to reduce the mosquito populations have been null in all the tropical areas where the mosquito is distributed. As if this was not enough, global projections of the geographical distribution of this mosquito and the vector Ae. albopictus for the year 2050 are frightening. Both species will have broader dispersion areas and will spread arboviral diseases in places where humans are susceptible (Kraemer et al., 2019). According to these predictions the mosquito control programs (MCP) should have considerable changes to avoid the transmission of diseases caused by arboviruses such as ZIKV.
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Hypertension is a crucial risk factor for cardiovascular diseases. Diuretic drugs are frequently used to reduce blood pressure, even though many possess harmful and undesirable side effects. Therefore, the use of alternative treatments such as medicinal plants are considered a good strategy to treat hypertension and its related diseases. Fortunately, many efforts have been made to verify the efficiency of traditional medicinal plants such as the black seed Nigella sativa (Ranunculaceae) in benefit of health. Its seeds exhibit a wide variety of pharmacological actions to control diabetes, hypertension, cancer, inflammation, hepatic disorder, arthritis, kidney disorder, and cardiovascular complications. Several mechanisms have been proposed in the literature to explain the effect of N. sativa supplementation on lowering blood pressure levels. In this chapter, we discuss in detail the pharmacology, and phytochemical composition of N. sativa that acts in prevention, management, and treatment of hypertension. 222 RPMP Vol. 48-Metabolic Disorders: Hypertension
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Hypertension is a crucial risk factor for cardiovascular diseases. Diuretic drugs are frequently used to reduce blood pressure, even though many possess harmful and undesirable side effects. Therefore, the use of alternative treatments such as medicinal plants are considered a good strategy to treat hypertension and its related diseases. Fortunately, many efforts have been made to verify the efficiency of traditional medicinal plants such as the black seed Nigella sativa (Ranunculaceae) in benefit of health. Its seeds exhibit a wide variety of pharmacological actions to control diabetes, hypertension, cancer, inflammation, hepatic disorder, arthritis, kidney disorder, and cardiovascular complications. Several mechanisms have been proposed in the literature to explain the effect of N. sativa supplementation on lowering blood pressure levels. In this chapter, we discuss in detail the pharmacology, and phytochemical composition of N. sativa that acts in prevention, management, and treatment of hypertension. 222 RPMP Vol. 48-Metabolic Disorders: Hypertension
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Two transfluthrin-based spatial repellent products (Raid Dual Action Insect Repellent and Home Freshener and Raid Shield (currently not commercially available), SC Johnson, Racine WI) were evaluated for spatial repellent effects against female Aedes aegypti (L.) mosquitoes under laboratory (wind tunnel) and semi-field (outdoor enclosure) conditions. The placement of either product in the wind tunnel significantly reduced host-seeking behaviors. The mean baseline (control) landing counts for the Raid Dual Action and Raid Shield were reduced by 95% and 74% respectively. Mean probing counts for the Raid Dual Action were reduced by 95%, while the probing counts for the Raid Shield were decreased by 69%. Baseline blood-feeding success was significantly reduced for both treatments: Raid Dual Action (100%) and Raid Shield (96%). Semi-field evaluations were conducted in outdoor enclosures at the Navy Entomology Center of Excellence, Jacksonville, Florida. A moderate reduction in mosquito entry into military style tents resulted when either product was placed near the tent opening. The Raid Shield reduced mosquito entry into tents by 88%, while the Dual Action decreased entry by 66%.
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Background: Myiasis induced by the sheep blowfly, Lucilia sericata, represents a public health problem widely distributed throughout the world. L. sericata larval stages feed on both humans and animals. L. sericata adults and larvae can play a role in spreading agents of mycobacterial infections. Objectives: It is critical to establish new and safe alternative methods of controlling L. sericata. Methods: The insecticidal effectiveness and growth inhibition potential of three commercially available essential oils (EOs), vetiver (Chrysopogon zizanioides), cinnamon (Cinnamomum zeylanicum), and lavender (Lavandula angustifolia), as well as their blends, were tested against the second (L2) and third (L3) larval stages of L. sericata. Sunflower (Helianthus annuus) oil was used as a carrier and tested on L2 and L3 larvae. To the best of our knowledge, all applied essential oils, except lavender, and oil blends were tested against L. sericata for the first time. Results: All applied oils did not repel L2 from the treated liver but adversely affected their development. Contact treatments on L. sericata L3 indicated that vetiver and cinnamon oils significantly affected treated larvae. Total mortality rates were 93.33 and 95.56%, respectively. Furthermore, oil blends tested through contact assays killed larvae when used at higher concentrations; adult emergence was eliminated post-treatment with doses >30% for oil blend 1 and >10% for oil blend 2. Conclusion: Overall, cinnamon and vetiver oils (5%) were selected as reliable and cheap biopesticides for controlling larvae of L. sericata. The tested oils are inexpensive and represent new promising botanical insecticides in the fight against blowflies causing myiasis.
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Book Description: In an ideal world, we would get all the nutrients and medication we needed from the food we ate. Unfortunately, eating healthily in our modern life is a great challenge. Not to worry!! The solution to most of our troubles is closer to you than you think!! It is in your spice rack and backyard garden. For sure you have a rack, filled with seasonings that you grab in a rush, but what do you really know about their medicinal powers? Realizing the importance of tossing oregano or basil to your delicious pizza or spaghetti sauce, not as just a flavor but as a digestive aid is the primary key to turning your kitchen into a pharmacy. You will enjoy the fascinating journey of the mysteries world of culinary herbs and spices which not only enhance the color and flavor of your daily cuisine but also help you feel much better and give you the much-needed fire in a slothful and sluggish soul to refresh it inside out via their endless medicinal properties. To be fair, we put in your hand all the information that you might think about and discuss all aspects of their uses, side effects, interactions, and warnings. We also discussed the storage and preservation tips, the top 10 must-have herbs to grow in your kitchen garden, and horticultural therapy. A sedentary lifestyle is dangerous for your health, so break it up as much as you can with little spurts of activity in the healthy fresh air. You can appreciate the mother earth and your health by digging in the dirt and planting something; whether it is a herb in a pot for your kitchen window, a flower to add more cheerful colors and beauty to your surroundings, a vegetable or a fruit in your backyard or in a community garden. You’ll enjoy gardening so much; you won’t even realize it’s a work-out decreasing obesity, high blood pressure, type 2 diabetes, osteoporosis, heart disease, stroke, and some cancers and promoting longer and healthier lives. Like you pets, plants need food (water), care, and love, they give you bake things over weigh what you give, please keep reading and you will discover yourself. The whole work in this book comes with great love and passion; for what comes from the heart, touches hearts. Throughout this book, the book is enriched with a cheerful and self-explanatory image(s) and each chapter is prepared to be a complete and integrated subject; hence you can start reading from any chapter you want. After reading even few chapters, you will find yourself focusing on herbs and spices before you season your next meal to get the utmost benefits to energize and heal and maintain a sense of balance between their benefits and hazards. So, why don’t you treat your senses and spice up your life and garden with obscure treasures as old as pyramids!! Nature is your best medicine, you may not have time to take long nature walks, but you can spend a little time in your garden. Your therapeutic garden will offer you everything from bringing communities together to providing culinary benefits which overflow into your kitchens for eating pesticide-free fresh food at harvest time, filled with health-promoting antioxidants, fiber, and great taste. Finally, you will find yourself de-stressed and be grateful for all of the health and mental benefits of Horticultural Therapy. It’s amazing what a little knowledge can do for boosting one’s confidence in natural herbal healing. Wishing you everlasting health and tranquility, God's Will.
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The rapid spread of highly aggressive arboviruses, parasites, and bacteria along with the development of resistance in the pathogens and parasites, as well as in their arthropod vectors, represents a huge challenge in modern parasitology and tropical medicine. Eco-friendly vector control programs are crucial to fight, besides malaria, the spread of dengue, West Nile, chikungunya, and Zika virus, as well as other arboviruses such as St. Louis encephalitis and Japanese encephalitis. However, research efforts on the control of mosquito vectors are experiencing a serious lack of eco-friendly and highly effective pesticides, as well as the limited success of most biocontrol tools currently applied. Most importantly, a cooperative interface between the two disciplines is still lacking. To face this challenge, we have reviewed a wide number of promising results in the field of green-fabricated pesticides tested against mosquito vectors, outlining several examples of synergy with classic biological control tools. The non-target effects of green-fabricated nanopesticides, including acute toxicity, genotoxicity, and impact on behavioral traits of mosquito predators, have been critically discussed. In the final section, we have identified several key challenges at the interface between "green" nanotechnology and classic biological control, which deserve further research attention.
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Background: This review examines the published laboratory and field tests where the repellents DEET and picaridin have been compared for their efficacy as repellents against mosquitoes. The review is limited to an assessment of whether the duration of protection afforded by picaridin is similar to or better than DEET. Method: Identification and analysis of laboratory and field-based trials published in peer-reviewed journals that compared DEET to picaridin efficacy. Results: Only eight field studies and three laboratory studies met the review criteria for inclusion and most were considered to be of high risk of bias and of lower quality when judged against evidence-based principles. Overall, the studies showed little potential difference between DEET and picaridin applied at the same dosage, with some evidence pointing to a superior persistence for picaridin. Conclusion: Applied dosage is one important variable in determining the persistence of a repellent experienced by users but the maximum concentration in current picaridin formulation is <30%w/v. Therefore, where only 30% DEET or lower concentrations are available, then on current evidence, it is reasonable to offer DEET or picaridin as a first choice. Where >50% DEET products are available then the protection time advantage associated with these formulations reasonably can be invoked to consider them as first choice repellents.
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Growing concern on the application of synthetic mosquito repellents in the recent years has instigated the identification and development of better alternatives to control different mosquito-borne diseases. In view of above, present investigation evaluates the repellent activity of ethyl anthranilate (EA), a non-toxic, FDA approved volatile food additive against three known mosquito vectors namely, Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus under laboratory conditions following standard protocols. Three concentration levels (2%, 5% and 10% w/v) of EA were tested against all the three selected mosquito species employing K & D module and arm-in-cage method to determine the effective dose (ED50) and complete protection time (CPT), respectively. The repellent activity of EA was further investigated by modified arm-in-cage method to determine the protection over extended spatial ranges against all mosquito species. All behavioural situations were compared with the well-documented repellent N,N-diethylphenyl acetamide (DEPA) as a positive control. The findings demonstrated that EA exhibited significant repellent activity against all the three mosquitoes species. The ED50 values of EA, against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus were found to be 0.96%, 5.4% and 3.6% w/v, respectively. At the concentration of 10% w/v, it provided CPTs of 60, 60 and 30 min, respectively, against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Again in spatial repellency evaluation, EA was found to be extremely effective in repelling all the three tested species of mosquitoes. Ethyl anthranilate provided comparable results to standard repellent DEPA during the study. Results have concluded that the currently evaluated chemical, EA has potential repellent activity against some well established mosquito vectors. The study emphasizes that repellent activity of EA could be exploited for developing effective, eco-friendly, acceptable and safer alternative to the existing harmful repellents for personal protection against different hematophagous mosquito species.