The document summarizes a study that evaluated the mosquitocidal properties of leaf extracts from Bougainvillea spectabilis against Aedes aegypti. Leaf extracts were tested on egg hatchability, larval and pupal mortality. A relationship was observed between extract dose and mortality rates, with mortality increasing at higher doses. Based on probit analysis, the LC50 values for egg, larval and pupal stages ranged from 31 mg/l for eggs to 2637 mg/l for pupae, indicating the extract is toxic to all development stages. The results suggest B. spectabilis leaf extracts have potential for use in mosquito control programs targeting Aedes aegypti.

1. JournalofResearchinAnimalSciences
Mosquitocidal property of leaf extract of Bougainvillea spectabilis (Nictaginaceae) against
the growth and development of the mosquito, Aedes aegypti. l. (Diptera: Culicidae)
Keywords:
Aedes aegypti, Bougainvillea spectabilis, LC50
ABSTRACT:
Mosquitocidal property of leaf extract of Bougainvillea spectabilis was
evaluated for the egg hatchability, larvicidal and pupicidal activity of mosquito,
Aedes aegypti under the room temperature in the laboratory. A relationship was
observed between the plant extract dose and the percentage of egg hatchability,
larval and pupal mortality. Dosage value as expressed in % was 0.01 to 4.0 for
Aedes aegypti. The percentage of egg hatchability, larval and pupal mortality were
found to increase with the dosage indicating a relationship between the two. Based
on the probit analysis the LC50 (mg/l) value of egg (31), I instar (59), II instar (231),
III instar (606), IV instar (1578) and pupa (2637) were observed.
028-032 | JRAS | 2012 | Vol 1 | No 1
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Journal of Research in
Animal Sciences
An International Open Access Online
Research Journal
Authors:
Rajmohan D and
Logankumar K.
Institution:
PG and Research
Department of Zoology
Kongunadu Arts and Science
College, Coimbatore -
641 029, Tamilnadu, India.
Corresponding author:
Rajmohan D
Email:
rajmohandevadass@gmail.com
Web Address:
http://ficuspublishers.com/
documents/AS0012.pdf
Dates:
Received: 16 Jul 2012 Accepted: 25 Jul 2012 Published: 14 Aug 2012
Article Citation:
Rajmohan D and Logankumar K.
Mosquitocidal property of leaf extract of Bougainvillea spectabilis (Nictaginaceae)
against the growth and development of the mosquito, Aedes aegypti. l.
(Diptera: Culicidae)
Journal of Research in Animal Sciences (2012) 1(1): 028-032
Journal of Research in Animal Sciences
An International Online Open Access
Publication group
Original Research

2. INTRODUCTION
Mosquitoes are the most important single group
of insects well- known for their public health importance,
since they act as a vector for many tropical and
sub tropical diseases such as dengue fever, yellow fever,
malaria, filariasis and encephalitis of different types
including, Japanese encephalitis. (Service and
Youdeowei, 1983). Mosquitoes transmit some of the
world’s worst life threatening and debilitating parasitic
and viral diseases including malaria, filariasis and
dengue fever. These diseases are on the rise in many
tropical and subtropical areas (WHO, 1986).
Insect- transmitted diseases remain a major source of
illness and death world wide. Mosquitoes alone transmit
diseases to more than 700 million people annually
(Taubers. 1997). Aedes aegypti is a principal vector of
dengue fever and dengue hemorrhage fever and it is
reported to infect more than hundred million people
every year in more than 100 countries in the tropics
(Halstead, 2000). Mosquitoes cause annoyance to man
and other animals and affect health for centuries.
These are the carriers of malaria, yellow fever, filariasis
and Encephalitis (Perich et al., 1994). Control of such
mosquito borne diseases is becoming more and difficult,
because of the increasing resistance to pesticides, lack of
effective vaccines and drugs against disease causing
mosquitoes. Hence, an alternative approach for mosquito
control is the use of extract of plant origin (El Hag et al.,
1999). Search of natural insecticides, which do not have
any ill effects on the non-target population and are easily
degradable, remains to be one of the top priority issues
for the tropical countries (Redwane et al., 2002).
Recently the workers have shifted their focus from
synthetic insecticides to botanicals because plant
materials are non-toxic to non-target animals, have no
phytotoxic properties and leave no residues in the
environment. Plants and their products could be used in
the control of insects, offering a safer alternative to the
conventional use of pesticides (Mulla et al., 2003).
Keeping this in view, the present study has been carried
out to evaluate the effect of Bougainvillea spectabilis on
the growth and development of Aedes aegypti.
MATERIALS AND METHODS
Important vector species of mosquito,
Aedes aegypti (L) is selected for the present
study (Jan 2007- July 2007). Leaves of
Bougainvillea spectabilis were collected from wasteland
and brought to the Kongunadu Arts and Science College
research laboratory. The separated leaves were dried
under shade at room temperature (29±1°C) for about
20 days. The completely dried leaves were powdered and
sieved to get fine powder of leaf. The acetone leaf extract
from the sieved fine leaf powder was obtained by using
Soxhlet apparatus. One gram of the concentrated extract
of dried leaf of Bougainvillea spectabilis was dissolved
in 100ml of acetone and kept as stock solution
(10mg/ml). This stock solution was used to prepare the
desired concentration of the extract for exposure of the
mosquito egg, larvae and pupae.
The eggs of Aedes aegypti were procured from
the research laboratory of Indian Center for
Communicable Diseases at Mettupalayam and were
maintained in the laboratory conditions (29±1°C). On the
next day, the eggs were observed to hatch out into first
instar larvae. Appropriate amount of nutrients
(Yeast powder and glucose) were added to the culture
medium. For the treatment of egg, larvae and pupae with
the leaf extract of Bougainvillea spectabilis 100ml of tap
water was kept in a series of glass beakers (of 200ml
capacity). Required quantity of stock solution
(containing 10 mg/ml) was added into each beaker
(containing 100 ml of tap water) to obtain a particular
concentration of the extract. Control medium was also
maintained with 100ml of tap water added with
maximum quantity of acetone present in the stock
solution of the extract. Separate series of exposure
medium with desired concentration of extract were kept
029 Journal of Research in Animal Sciences (2012) 1(1): 028-032
Rajmohan and Logankumar, 2012

3. Table 1.7 LC50 (ppm) of the leaf extract of Bougainvillea spectabilis on the different stages of Aedes aegypti.
Concentration (%)
Mean percentage
Egg hatchability
Control 0.01 0.02 0.03 0.04 0.05 0.06
100 78 72 62 40 24 14
Concentration (%)
Mean percentage
mortality
Control 0.03 0.04 0.05 0.06 0.07 0.08
0 14 20 34 46 70 84
Concentration (%)
Mean percentage
mortality
Control 0.06 0.07 0.08 0.09 1.0 1.1
0 32 52 62 74 78 84
Concentration (%)
Mean percentage
mortality
Control 0.07 0.08 0.09 1.0 1.5 2.0
0 18 34 52 64 82 96
Concentration (%)
Mean percentage
mortality
Control 1.0 1.5 2.0 2.5 3.0 3.5
0 30 44 62 68 86 94
Concentration (%)
Mean percentage
mortality
Control 1.5 2.0 2.5 3.0 3.5 4.0
0 18 32 44 56 72 86
Plant Stages LC50 (mg/l)
95%Fiducial limit (mg/l)
Lower Upper
Bougainvillea spectabilis
Egg
I Instar
II Instar
III Instar
IV Instar
Pupa
31
59
231
606
1578
2637
19
48
65
298
843
2044
71
103
726
889
2117
4102
Mortality percentage of different stages of Aedes aegypti against the leaf extract of Bougainvillea spectabilis
Table 1.1 Egg
Table 1.2 I instar
Table 1.3 II instar
Table 1.4 III instar
Table 1. 5 IV instar
Table 1.6 Pupae
Journal of Research in Animal Sciences (2012) 1(1): 028-032 030
Rajmohan and Logankumar, 2012

4. for Aedes aegypti. The egg hatchability, larval and pupal
mortality of Aedes aegypti were observed separately.
Twenty numbers of eggs, first instar to the fourth larvae
and pupa of Aedes aegypti were separately introduced
into control and different concentrations of the seed
extract. At the end of 24 h the number of survival
organisms were recorded and the percent mortality
values were calculated. Based on the percent
mortality values, LC50 value of leaf extract of
Bougainvillea spectabilis for Aedes aegypti was obtained
separately by calculating the regression line employing
probit analysis of Finney (1964) as described by Busvin
(1971).
The e ffe ct o f le a f e xt r act o f
Bougainvillea spectabilis on the mortality of the egg,
larvae and pupae of Aedes aegypti following 24h were
corrected for natural response by Abbot’s formula
(Abbot, 1925) as follows: corrected % kill= (Proportion
of less mortality -Proportion of control mortality)/
(1- Proportion of control mortality) 100. Busvin (1971)
suggested that the critical doses of susceptibility could be
estimated with sufficient accuracy from a probit/log
concentration graph. Based on the log concentration and
the probit mortality percentage values, regression
equation was obtained. LC50 (median lethal
concentration) values of the leaf extract of
Bougainvillea spectabilis for 24 h of exposure of egg,
larvae and pupae (Aedes aegypti) and their fiducial limits
(95% upper fiducial limit and lower fiducial limit) were
calculated.
RESULTS AND DISCUSSION
Mortality values of egg, larvae and pupae treated
with different concentration (ranging from 0.01% to
4.0%) of the leaf extract of Bougainvillea spectabilis at
the end of 24hrs are represented in Tables 1.1 to 1.6 for
egg, different instar larvae and pupae of Aedes aegypti.
The LC50 values and their 95% upper and lower fiducial
limits of the leaf extract of Bougainvillea spectabilis for
24h of exposure of Aedes aegypti are given in Table 1.7.
Based on the probit analysis, the 24h LC50 (mg/l) value
of the leaf extract of Bougainvillea spectabilis for egg,
different instar larvae and pupae of Aedes aegypti was
found to be 31 mg/l (egg), 59mg/l (I instar), 231 mg/l
(II instar), 606 mg/l (III instar), 1578mg/l (IV instar) and
2637 mg/l (pupa) (Table. 1.7). The results of the
study revealed that the experimental plant,
Bougainvillea spectabilis is more toxic against all the
developmental stages of Aedes aegypti. Therefore it is
understood that the plant, Bougainvillea spectabilis could
be employed for the mosquito control programme.
`The control of mosquito borne diseases can be
achieved either by killing or preventing mosquitoes from
biting human beings (by using repellents) or by causing
larval mortality in a large scale at the breeding centers of
the vectors in the environment. A survey of literature on
the control of different species of mosquito revealed that
the assessment of the efficacy of different
phytochemicals obtained from various plants exhibited
more pronounced inhibition over the developmental
stages of mosquito. Despite many plants of
mosquitocidal property, a very few plant products only
have shown practical utility for mosquito control in an
effective manner (Sukumar et al., 1991). Development of
insecticides from plant origin is essential because of their
biodegradable, non-toxic quality and also safe for the
public health. Thus the observations made in the present
study have come as yet another evidence for the
significant influence of the plant desired botanical
pesticide like Bougainvillea spectabilis in the control of
the mosquito, Aedes aegypti.
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