Introduction

Mosquitoes are responsible for the transmission of more diseases than any other group of arthropods and play an important role as etiologic agents of malaria, filariasis, dengue, yellow fever, Japanese encephalitis, and other viral diseases (James 1992). In 2001, resistance to insecticides concerned 540 species of arthropod, of which 198 were of medical and veterinary importance (Bills 2001).

Culex quinquefaciatus is a predominant house-resting mosquito in many tropical countries. It is important as a vector of filariasis in some countries as well as a nuisance mosquito. Mosquitoes breed in polluted waters such as blocked drains, damaged septic tanks, or soak age pools close to human habitations. Lymphatic filariasis is probably the fastest spreading insect-borne disease of man in the tropics, affecting about 146 million people (WHO, 1992). C. quinquefasciatus is the most widely distributed mosquito in India, mainly found in urban and suburban areas. The most efficient approach to control the vector is to target the immature stages of the life cycle. Lymphatic filariasis is a mosquito-borne disease caused by mosquito-transmitted filarial nematodes, including Wuchereria bancrofti and Brugia malayi. The infected people carry the nocturnally periodic W. bancrofti, which has C. quinquefasciatus as the main mosquito vector. C. quinquefasciatus is a vector of lymphatic filariasis, which is a widely distributed tropical disease with around 120 million people infected worldwide, and 44 million people have common chronic manifestation (Bernhard et al. 2003). According to WHO, about 90 million people worldwide are infected with W. bancrofti, the lymphatic dwelling parasite, and ten times more people ate at the risk of being infected. In India alone, 25 million people harbor microfilaria (mf) and 19 million people suffer from filarial disease manifestations (NICD, 1990; Maheswaran et al. 2008).

Biopesticides provide an alternative to synthetic pesticides because of their generally low environmental pollution, low toxicity to humans, and other advantages (Liu et al. 2000). Many herbal products have been used as natural insecticides before the discovery of synthetic organic insecticides (ICMR Bulletin, 2003). Natural products of plant origin with insecticidal properties have been tried in the recent past in order to control a variety of insect pests and vectors. Many approaches have been developed to control mosquito menace. One such approach to prevent mosquito-borne disease is by killing mosquito at larval stage. The current mosquito control approach is based on synthetic insecticides. Even though they are effective, they created many problems like insecticide resistance (Liu et al. 2005). This has necessitated the need for a research and development of environmentally safe, biodegradable indigenous method for vector control. Phytoextracts are emerging as potential mosquito control agents, with low-cost, easy-to-administer, and risk-free properties as compared to isolated or synthesized biopesticides and can be used successfully in mosquito management (Rahuman and Venktesan 2008).

Plants may be a source of alternative agents for control of vectors because they are rich in bioactive chemicals, are active against a limited number of species including specific target insects, and are biodegradable. Phytochemical insecticides have received much attention, in this regard, as they are considered to be more environmentally biodegradable and considered safer than synthetic insecticides (Moretti et al. 2002; Cetin et al. 2004). Many researchers have reported on the effectiveness of plant extract against mosquito larvae (Kalyanasundaram and Das 1985; Govindarajan et al. 2008; Kovendan et al. 2011c, d).

The Solanaceae family comprises about 90 genera and 3,000 species which are widely distributed in the world. They are a rich source of active secondary metabolites (Coletto da Silva et al. 2004). Within this family, the genus Solanum is the largest and most complex with more than 1,500 species (Chowdhury et al. 2007), which yield a great variety of steroidal saponins and glycoalkaloids of interest from ecological and human health viewpoints (Roddick et al. 2001). Numerous species of Solanum are known to possess a variety of biological activities including antimycotic (Singh et al. 2007), antiviral (Arthan et al. 2002), molluscicidal (Silva et al. 2006), teratogenic, and cytotoxic properties (Nakamura et al. 1996; Lu et al. 2009).

Solanum xanthocarpum (Family: Solanaceae) is an important medicinal herb in Ayurvedic medicine. Various studies indicated that S. xanthocarpum possesses antiasthmatic, hypoglycemic, hepatoprotective, antibacterial, and insect repellent properties. The fruits are reported to contain several steroidal alkaloids like solanacarpine (Gupta and Dutt 1938), and solamargine. Other constituents like caffeic acid coumarins like aesculetin and aesculin (Tupkari et al. 1972), steroids carpesterol, diosgenin, campesterol, daucosterol, and triterpenes like cycloartanol and cycloartenol were reported from the fruits (Sato and Latham 1953). Steroidal glycoalkaloids are naturally occurring, secondary plant metabolites that are formed in a number of foods including potatoes, tomatoes, and eggplants (Friedman and McDonald 1997).

Taxonomy

Kingdom:

Plantae

Subkingdom:

Tracheobionta

Division:

Magnoliophyta

Class:

Magnoliopsida

Subclass:

Asteridae

Order:

Solanales

Family:

Solanaceae

Genus:

Solanum

Species:

xanthocarpum

Botanical name:

Solanum xanthocarpum (Schrad. & Wendl.)

Bacillus thuringiensis is an insecticide with unusual properties that make it useful for pest control in certain situations. B. thuringiensis is a naturally occurring bacterium common in soils throughout the world. Several strains can infect and kill insects. Because of this property, B. thuringiensis has been developed for insect control. At present, B. thuringiensis is the only “microbial insecticide” in widespread use. The gram-positive endospore-forming bacterium B. thuringiensis produces parasporal crystalline inclusions that contain polypeptides (δ-endotoxin) that are toxic to a variety of insect species. The toxin induces the formation of a lytic pore in the midgut epithelial membrane that results in cell lysis, cessation of feeding, and death of the larva (Charles and de Barjac 1983; Singh et al. 1996; Daniel et al. 1995).

B. thuringiensis strains, pathogenic to insects, produce two distinct types of toxin proteins, Cry and Cyt proteins (Crickmore et al. 1995). Generally, the genes encoding these proteins are located on large plasmids, and the proteins are synthesized and form crystalline inclusions during sporulation. More than 100 different cry genes have been identified and sequenced, and significant homologies among the amino acid sequences of this group, in combination with experimental studies, suggest they have a common mode of action, colloid-osmotic lysis (Crickmore et al. 1998; Höfte and Whitely 1989).

The use of bacterial agents for mosquito control, especially B. thuringiensis is gaining widespread importance (de Barjac 1978; Abdel-Hameed et al 1980; Priest 1992; Porter 1996). The strategy of combining different vector control agents has proven to be advantageous in various pest management programs (Caraballo, 2000; Seyoum et al. 2002). Many biological control agents have been evaluated against larval stages of mosquitoes, of which the most successful ones comprise bacteria such as B. thuringiensis and Bacillus sphaericus (NICD 1990). Well-known bacterial agents which have been used successfully for mosquito control are B. thuringiensis and B. sphaericus. Two bacterial agents such as the B. thuringiensis and B. sphaericus are being widely used for control of mosquito breeding in a variety of habitats (Balaraman et al. 1983; 1987; Armengol et al. 2006; Medeiros et al. 2005; Geetha and Manonmani 2010; Kovendan et al. 2011a, b).

The purpose of the present investigation was to explore the mosquito control agent under laboratory as well as field conditions. The plant extracts and B. thuringiensis are reported to have mosquitocidal properties of the control, the lymphatic filarial vector, C. quinquefasciatus.

Materials and methods

Collection of eggs and maintenance of larvae

The eggs rafts of C. quinquefasciatus were collected from National Centre for Disease Control (NCDC) field station of Mettupalayam, Tamil Nadu, India, using an “O” type brush. These eggs were brought to the laboratory and transferred to 18 × 13 × 4 cm enamel trays containing 500 ml of water for hatching. The mosquito larvae were fed with pedigree dog biscuits and yeast at 3:1 ratio. The feeding was continued until the larvae transformed into the pupal stage.

Maintenance of pupae and adults

The pupae were collected from the culture trays and transferred to plastic containers (12 × 12 cm) containing 500 ml of water with the help of a dipper. The plastic jars were kept in a 90 × 90 × 90-cm mosquito cage for adult emergence. Mosquito larvae were maintained at 27 + 2°C, 75–85% RH under a photoperiod of 14L:10D. A 10% sugar solution was provided for a period of 3 days before blood feeding.

Blood feeding of adult C. quinquefasciatus

The adult female mosquitoes were allowed to feed on the blood of a rabbit (a rabbit per day, exposed on the dorsal side) for 2 days to ensure adequate blood feeding for 5 days. After blood feeding, enamel trays with water from the culture trays were placed in the cage as oviposition substrates.

Collection of plant and preparation of extract

The S. xanthocarpum plant was collected in and around Bharathiar University, Coimbatore, India. S. xanthocarpum plant was washed with tap water and shade dried at room temperature (27 ± 2°C). An electrical blender powdered the dried plant materials (leaves). From the powder, 300 g of the plant materials was extracted with 1 L of organic solvents of ethanol for using a Soxhlet apparatus (Vogel 1978) boiling point range 60–80°C for 8 h. The extracts were filtered through a Buchner funnel with Whatman number 1 filter paper. The crude plant extracts were evaporated to dryness in rotary vacuum evaporator. One gram of the plant residue was dissolved in 100 ml of acetone (stock solution) and considered as 1% stock solution. From this stock solution, different concentrations were prepared ranging from 50 to 650 ppm, respectively.

Microbial bioassay

B. thuringiensis subsp. israelensis was obtained from Tuticorin Alkali Chemicals and Fertilizers Limited, Chennai, India. B. thuringiensis subsp. var israelensis, 630 ITU/mg (a.i.) 5% w/w; total proteins (including the active ingredient 5% w/w), 10% w/w; fermentation solids, 10% w/w; inert ingredient, 48% w/w; non-ionic surfactant, 0.2 w/w; food grade preservative, 0.3%; UV protectant, 0.1%; and water, 71.4% were used. Total 100% w/w was active specifically against mosquito larvae. The required quantity of B. thuringiensis subsp. var israelensis was thoroughly mixed with distilled water and prepare to various concentrations, ranging from 50 to 250 ppm, respectively.

Larval/pupal toxicity test

Laboratory colonies of mosquito larvae/pupae were used for the larvicidal/pupicidal activity. Twenty-five numbers of first to fourth instar larvae and pupae were introduced into 500-ml glass beaker containing 249 ml of de-chlorinated water, and 1 ml of desired concentrations of plant extract and B. thuringiensis were added. Larval food was given for the test larvae. At each tested concentration, two to five trials were made, and each trial consisted of five replicates. The control was set up by mixing 1 ml of acetone with 249 ml of dechlorinated water. The larvae and pupae were exposed to dechlorinated water without acetone which served as control. The control mortalities were corrected by using Abbott's formula (Abbott 1925).

$$ {\text{Corrected}}\;{\text{mortality}} = \frac{{{\text{Observed}}\;{\text{mortality}}\;{\text{in}}\;{\text{treatment}}\;{ - }\;{\text{Observed}}\;{\text{mortality}}\;{\text{in}}\;{\text{control}}}}{{{100}\;{ - }\;{\text{Control}}\;{\text{mortality}}}} \times 100 $$
$$ {\text{Percentage}}\;{\text{mortality}} = \frac{{{\text{Number}}\;{\text{of}}\;{\text{dead}}\;{\text{larvae}}/{\text{pupae}}}}{{{\text{Number}}\;{\text{of}}\;{\text{larvae}}/{\text{pupae}}\;{\text{introduced}}}} \times 100 $$

The LC50 and LC90 were calculated from toxicity data by using probit analysis (Finney 1971).

Field trail

For the field trial, the quantity of plant extract residues and Bti required (based on laboratory LC50 and LC90 values) quantity for each treatment was determined by calculating the total surface area of sewage water bodies in each habitat. The required quantities of S. xanthocarpum and Bti were mixed thoroughly with water in a bucket with constant agitation. Teepol was used as emulsifying agent (0.05%). Field applications of the S. xanthocarpum plant extracts and Bti were done with the help of a knapsack sprayer (Sujatha Products, India, Private Limited, 2010) and uniformly on the surface of the sewage water bodies in each habitat. Dipper sampling and counting of larvae monitored the larval density before 24, 48, and 72 h after the treatment. A separate sample was taken to determine the composition of each larval habitat. Six trails were conducted for S. xanthocarpum of the plant extracts and B. thuringiensis alone and combined the treatment. The percentage of reduction was calculated by the following formula:

$$ {\text{Percentage}}\;{\text{of}}\;{\text{Reduction}} = \frac{{{\text{C}} - {\text{T}}}}{\text{C}} \times {100} $$

Where C is the total number of mosquitoes in control, T is the total number of mosquitoes in treatment.

Statistical analysis

All data were subjected to analysis of variance; the means were separated using Duncan's multiple range tests (DMRT) by Alder and Rossler (1977). The average larval mortality data were subjected to probit analysis, for calculating LC50 and LC90, values were calculated by using the (Finney 1971) method. SPSS (Statistical software package) 16.0 version was used. Results with P < 0.05 were considered to be statistically significant.

Results

Larval and pupal mortality of C. quinquefasicatus after the treatment of ethanol S. xanthocarpum was observed. Table 1 provides the results of larval and pupal mortality of C. quinquefasicatus (first to fourth instar larvae) after the treatment at different concentrations (50 to 650 ppm). Forty three percent mortality was noted at first instar larvae by the treatment of S. xanthocarpum at 50 ppm, whereas it has been increased to 92% at 650 ppm; 21.2% mortality was noted at 50 ppm of S. xanthocarpum leaf extract treatment. Similar trend has been noted for all the instars of C. quinquefasicatus at different concentration of S. xanthocarpum treatment. The LC50 and LC90 values were represented as follows; LC50 value of first instar was 155.29 ppm, second instar was 198.32 ppm, third instar was 271.12 ppm, fourth instar was 377.44 ppm, and pupa was 448.41 ppm, respectively. The LC90 value of first instar was 687.14 ppm, second instar was 913.10 ppm, third instar was 1,011.89 ppm, fourth instar was 1,058.85 ppm, and pupa was 1,141.65 ppm, respectively.

Table 1 Larval and pupal toxicity effect of ethanolic extract of S. xanthocarpum against filarial vector, C. quinquefasciatus
Full size table

Table 2 shows the results of larval and pupal mortality of C. quinquefasicatus (first to fourth instar larvae and pupae) after the treatment of B. thuringiensis at different concentrations (50 to 250 ppm). Mortality (30.8%) was noted at first instar larvae by the treatment of B. thuringiensis at 50 ppm, whereas it has been increased to 81.8% at 250 ppm of B. thuringiensis treatment, and 16.6% mortality was noted at pupae by the treatment of B. thuringiensis at 50 ppm, and it has been increased to 51.6% at 250 ppm, respectively. Similar trend has been noted for all the larval instars and pupae of C. quinquefasciatus at different concentrations of B. thuringiensis treatment. The LC50 and LC90 values were represented as follows: LC50 value of first instar was 133.88 ppm, second instar was 157.14 ppm, third instar was 179.44 ppm, fourth instar was 206.80 ppm, and pupa was 240.74 ppm, respectively. The LC90 value of first instar was 321.04 ppm, second instar was 346.89 ppm, third instar was 388.86 ppm, fourth instar was 430.95 ppm, and pupa was 492.70 ppm, respectively.

Table 2 Larval and pupal toxicity effect of B. thuringeinsis against filarial vector, C. quinquefasciatus
Full size table

Table 3 provides the considerable larval and pupal mortality after the combined effect of B. thuringiensis and S. xanthocarpum extract against all the larval instars and pupae. The concentration at 50 + 20 ppm combined treatment of S. xanthocarpum and B. thuringiensis for first instar larval mortality and pupal mortality was 32.4%, respectively. The LC50 and LC90 values were represented as follows: LC50 value of first instar was 126.81 ppm, second instar was 137.62 ppm, third instar was 169.14 ppm, fourth instar was 238.27 ppm, and pupa was 316.02 ppm, respectively. The LC90 value of first instar was 476.36 ppm, second instar was 613.49 ppm, third instar was 705.29 ppm, fourth instar was 887.85, and pupa was 1,041.73 ppm, respectively. The χ 2 values are significant at P < 0.05 level. The 95% confidence limits LC50, LC90 (LFL–UFL) values were also calculated. Larval and pupal mortality was observed after 24 h exposure. No mortality was observed in the control group.

Table 3 Combined effect of larval and pupal activity of ethanolic extract of S. xanthocarpum and B. thuringiensis against filarial vector, C. quinquefasciatus
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A total number of 1,600 C. quinquefasciatus larvae were observed in the sewage water body systems. After treatment with S. xanthocarpum against C. quinquefasciatus, larval density was reduced by 25.3%, 70.3%, 94.1%, and 23.8% at 24, 48, and 72 h, respectively. Similarly, the reduction of C. quinquefasciatus larval densities after treatment with B. thuringiensis were 23.87%, 67.5%, and 91.7%, respectively. Combined effect of S. xanthocarpum and B. thuringiensis were 15.34%, 68.12%, and 100% at 24, 48, and 72 h, respectively (Tables 4, 5).

Table 4 Field trial by using plant extracts of S. xanthocarpum and bacterial insecticide B. thuringiensis sewage water bodies 2.0 × 1.8 × 1.4 against C. quinquefasciatus
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Table 5 Field trial by using combined effect of sewage water bodies 2.0 × 1.8 × 1.4 against C. quinquefasciatus
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Discussion

C. quinquefasciatus is one of the potential vectors of W. bancrofti, the causative agent of human lymphatic filariasis infecting over 120 million people all over the world (Terranella et al. 2006). Singh Karam and Bansal (2003) and Bansal et al. (2009) also observed that extracts from fresh green and yellow fruits of this plant were very much effective to the vectors of malaria and dengue. Mohan et al. (2005) also observed that the fruits of this plant were very effective against the larvae of Anopheles stephensi (24 h LC50 of CCl4 extract being 5.1 ppm) and C. quinquefasciatus (24 h LC50 of petroleum ether extract being 62.2 ppm), respectively.

The petroleum ether S. xanthocarpum extract exhibited maximum larvicidal activity against A. stephensi compared to the other extracts. Results regarding the larvicidal efficacy of this plant are supported by findings of Singh Karam and Bansal (2003), who studied the larvicidal activity of aqueous fruit (LC50 = 0.058%) and root extract (LC50 = 1.08%) of S. xanthocarpum against A. stephensi. Mohan et al. (2005) reported the larvicidal activity of carbon tetrachloride fruit extracts of the same plant (LC50 = 5.11 ppm) against the same vector species. The individual bioefficacy of petroleum ether root extract of S. xanthocarpum and temephos was studied and noted their LC50 values 41.28 and 38.48 ppm; 0.0041 and 0.0029 ppm and LC90 111.16 and 80.83 ppm; 0.0164 and 0.0116 ppm after 24 and 48 h of exposure, respectively (Mohan et al. 2006; 2008). In the present results, 43% mortality was noted at first instar larvae by the treatment of S. xanthocarpum at 50 ppm, whereas it has been increased to 92% at 650 ppm; 21.2% mortality was noted at 50 ppm of S. xanthocarpum leaf extract treatment at 24 h exposure; the LC50 values of first to fourth instars and pupae were 155.29, 198.32, 271.12, 377.44, and 448.41 ppm, respectively. The LC90 value of first instar was 687.14 ppm, second instar was 913.10 ppm, third instar was 1,011.89 ppm, fourth instar was 1,058.85 ppm, and pupa was 1,141.65 ppm, respectively.

Various compounds including phenolics, terpenoids, and alkaloids exit in plants (Wink 1993) which may jointly or independently contribute to the generation of larvicidal activities in mosquitoes (Hostettmann and Potterat 1997). Earlier authors reported that the effect of water extract of citrus-seed extract showed LC50 values of 135, 319.40, and 127,411.88 ppm against the larvae of Aedes aegypti and C. quinquefasciatus (Sumroiphon et al. 2006). Dua et al. (2006) have reported that the mean median lethal concentration values of the aqueous extract from the roots of Hibiscus abelmoschus against the larvae of Anopheles culicifacies, A. stephensi, and C. quinquefasciatus were 52.3, 52.6, and 43.8 ppm, respectively. The aqueous extract of Rhinacanthus nasutus showed LC50 values of 5,124 and 9,681 mg/l against C. quinquefasciatus and A. aegypti, respectively (Chansang et al. 2005).

In a previous study, the oils of 41 plants were evaluated for their effects against third instar larvae of A. stephensi, A. aegypti, and C. quinquefasciatus. At first, the oils were surveyed against A. aegypti using a 50 ppm solution. Thirteen oils from 41 plants (camphor, thyme, amyris, lemon, cedarwood, frankincense, dill, myrtle, juniper, black pepper, verbena, helichrysum, and sandalwood) induced 100% mortality after 24 h, or even after shorter periods. The pest oils were tested against third instar larvae of the three mosquito species in concentrations of 1, 10, 50, 100, and 500 ppm. The lethal concentration 50 values of three oils ranged between 1 and 101.3 ppm against A. aegypti, between 9.7 and 101.4 ppm for A. stephensi and between 1 and 50.2 ppm for C. quinquefasciatus (Amer and Mehlhorn 2006a).

Biological control with entomopathogenic bacteria has been increasingly used as a larvicide to control populations of various medically important dipterans of the genera Culex and Aedes. Like chemical larvicides, these agents can cause drastic density-dependent mortality, killing all larvae within 24–48 h, after breeding site treatment. Moreover, they are selective to insects and are consequently considered soft to non-target fauna commercial products. Based on this, B. thuringiensis subsp. israelensis is currently available (Thiery et al. 1996). The combined effect of neem and pongamia oil with B. thuringiensis var. israelensis showed higher larval toxicity on C. quinquefasciatus (Murugan et al. 2002). Kuppusamy and Ayyadurai (2011) reported that lyophilized powders of purified Cyt1A crystals of B. thuringiensis were much more toxic yielding a 50% LC50 of 11.332 mg/l, respectively.

Garcia and Desrochers (1979) observed appreciable mortality only with high concentrations (1 × 107cells/ml) of B. thuringiensis var. israelensis. The biocide at 1 to 10 kg/ha (0.25 to 2.5 ppm) caused 18% to 88% mortality of midges during a 4-week evaluation period. Younger instars are more susceptible than older ones as shown by C. quinquefasciatus. Exposure periods longer than 48 h in the laboratory may produce better activity results of the B. thuringiensis var. israelensis formulations against the midges' species (Ali, 1981). It was recently reported that B. thuringiensis israelensis against the first to fourth instar larvae were of values LC50 = 9.332%, 9.832%, 10.212%, 10.622% and LC90 = 15.225%, 15.508%, 15.887%, and 15.986% larvae of C. quinquefasciatus, respectively (Kovendan et al. 2011a). In the present results, B. thuringiensis first to fourth instar larvae and pupae have LC50 values of 133.88, 157.14, 179.44, 206.80, and 240.74 ppm, respectively, against C. quinquefasciatus.

The persistency of larvicidal effects of 13 oils (camphor, thyme, amyris, lemon, cedarwood, frankincense, dill, myrtle, juniper, black pepper, verbena, helichrysum, and sandalwood) was examined by storage of 50-ppm solutions under different conditions (open, closed, in the light, and in the dark) for 1 month after the preparation of the solutions. The stored solutions were tested against A. aegypti larvae for four times during the storage period. Some oils under some conditions stayed effective until the last test, while some solutions had lost their toxicity during a short time after preparation. Thus, the mode of storage is absolutely important for the larvicidal effects. The fresh preparations were always the best (Amer and Mehlhorn 2006b).

Rao et al. (1995) reported that the field-tested relatively stable lipid-rich fractions of neem products were as effective as good quality crude neem products in the control of culicine vectors of Japanese encephalitis and produced a slight but significant reduction in population of anopheline pupae. According to Mustafa and Al Khazaraji (2008) Azadirachta excels Jack showed excellent larvicidal properties at low concentrations against Culex pipiens molestus. Its LC50 value after 1 day was 62.5 μg/mL. Dua et al. (2009) stated that emulsified concentration of neem oil formulation showed 95.5% reduction in larval population of C. quinquefasciatus in 1 day under field trials and thereafter 80% reduction was achieved up to the third week. In a recent study, the field trials were conducted by using Clerodendron inerme and Acanthus ilicifolius treatment in different habitats of three species of mosquito vectors namely malarial vector, A. stephensi, dengue vector, A. aegypti, and filarial vector, C. quinquefasciatus (Vadavalli, Mettupalayam, Navavoor privu, Pommanam palayam, Ooty, Mettupalayam (Kallaru) in Tamil Nadu, India. The percentage reduction of larval mortality also showed the variations among the different breeding habitats of mosquito vectors at 24, 48, and 72 h. This may be due to the impact of geographical distribution of A. stephensi, A. aegypti, and C. quinquefasciatus at the breeding sites (Kovendan and Murugan, 2011). The maximum highest percentage of larval mortality L. aspera and followed by Abutilon indicum, Hydnellum suaveolens, and Jatropha curcas plant extracts of field trial 60.4%, 81.9%, and 99.7% and 51.7%, 77.6%, and 92%; and 50%, 73.5%, and 90.4%; 46.7%, 71.7%, and 89.9% at 24, 48 and 72 h, respectively, against C. quinquefasciatus (Kovendan et al. 2011e). In the present results, combined effect of S. xanthocarpum and B. thuringiensis in the field were 15.34%, 68.12%, and 100% at 24, 48, and 72 h, respectively.

In the present study, the larvicidal, pupicidal, and filed evaluation of plant extracts and Bti against C. quinquefasciatus were evaluated. These plant extracts and bacterial insecticide showed that they have good effective mosquito control and this work shows promising results. The natural products of biopesticdes are eco-friendly for the vector control management programs.