INTRODUCTION

Aedes aegypti is a main vector for disease like dengue, chikunguniya and yellow fever. Culex quinquefasciatus is one of the most common and widely spread species and is a vector of avian malaria, arbiviruses and west Nile viruses.

Controlling of mosquito for public health is impor- tant. Presently use of chemical pesticides is considered as one of the preventive methods to control mosquito population(Hemingway et al., 2000).

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*Corresponding Author Received 15th April, 2015

Accepted after revision 28th June, 2015 BBRC Print ISSN: 0974-6455

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However development of resistance and environmen- tal concern limits their use (Brown et al., 1964; Brattsten et al., 1986; Hemingway et al., 2000).

Control of these vectors by biological means can be used as suitable alternatives to chemical pesticides. Bac- teria such as Pseudomonas fluorescens have been show- ing lethal effect against the vector mosquitoes (Murty et al., 1994 and Padmanabhan et al., 2005).

P. fluorescens is a Gram-negative, rod shaped bac- teria which formed yellowish-green, opaque, elevated

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and smooth colonies. The bacteria grew well at optimum temperature of 25-300C. It also showed fluorescence when exposed to UV. When prepared liquid formulation, it showed fluorescence when exposed to UV. Liquid for- mulation of metabolites from P. fluorescens was devel- oped and its efficacy was observed on the larval stage of A. aegypti and C.quinquefaciatu (Padmanabhan et al., 2005; Murty et al., 1994; Prabakaran et al., 2003). This liquid formulation is not harmful to mammals as well as plants but it is also curable against some plant diseases.

MATERIALS AND METHODS

a) Bacterial Strains

Two strains of P. fluorescens namely NCIM 2099 and NCIM 2100 were obtained from National Collection of

Vankudre, Balpande, Athale, and Deshpande

Industrial Microorganisms, National Chemical Labora- tory (NCL) Pune.

b) Maintainance of strain

These strains were sub-cultured on liquid nutrient broth medium and were also streaked on agar plates for the purpose of growth rate and were maintained at 300C for 24 hours (Murty et al., 1994 and Roy et al., 2010).

c) Preparation of liquid formulation

The liquid nutrient broth was incubated at 300C in rota- tor shaker for 24 hours. This was followed by centrifu- gation at 12,000 g for 10 minutes which separates pel- let from supernatant (Padmanabhan et al., 2005; Murty et al., 1994; Prabakaran et al., 2003). Supernatant was further used in the preparation of liquid formulation.

Vankudre, Balpande, Athale, and Deshpande

d) Bioassay

Third instars larvae of both species (Aedes aegypti and Culex quinquefasciatus) were transferred to small disposable test cup each containing 100ml of water (Abbott et al., 1925; Mulla et al., 1975). The appro- priate volumes for liquid formulation (0.5ml, 1ml and 2ml) were added to obtain desire target dosage starting with lowest concentration. Four replicates were set up for each concentrations and equal number of control were set up with tap water. Larval food was added to each test cup.

After 24 hours of exposure, larval mortality was recorded. Bioassay was repeated three times using new solutions and different groups of larvae (Abbott et al., 1925; Mulla et al., 1975).

RESULTS AND DISCUSSION

The present results indicated that NCIM 2100 metabo- lites exhibit highest larval mortality (94%) in A. aegypti as compared to C. quinquefasciatus (64%) when higher amount (2ml) were used for experiment. (Table 1) How- ever, at lowest amount (0.5ml) did not exhibit any lar- val mortality in both the species. In case of NCIM 2099 metabolites larval mortality in both mosquito species at higher amount (2ml) values more or less at par (Table 2).

Mosquitoes which come under insects are most destructive group which cause dreadful diseases in human beings. As far as their control is concerned in Indian con- ditions it is difficult because of unhygienic conditions. Methods commonly used for control are the chemical

methods, but it is documented that as this insect develops resistance often for the chemicals this methods are not full proof methods (Brown et al., 1964; Brattsten et al., 1986; Hemingway et al., 2000).

P.fluorescens have effectiveness against different mosquito larval populations. In the present investigation only two species of metabolites were examined for larval toxicity. The study showed that P. fluorescens can also be used for controlling mosquito population. However, this preliminary investigation may not hold good to draw any immediate conclusion. Therefore, a detailed study is necessary (appropriate formulation, stimulated and field trials and toxicology) is before coming to any conclusion.

ACKNOWLEDGEMENTS

Authors are thankful to Dr. Magan Ghatule, Principal of Sinhgad College of Science for his continuous support and for providing required facilities.

REFERENCES

Abbott W. S. (1925). A method of computing the effective- ness of an insecticide. Journal of Economic Entomology 18: 265–267.

Brattsten L.B., Holyoke C.W., Leeper J.R., Affa K.F. (1986). Insecticide resistance: challenge to pest management and basic research. Science 231: 1255-60.

Howell C. R. and Stipanovic R. D. (1979). Control of Rhizocto- nia solani on cotton seedlings with Pseudomonas fluorescens and with an antibiotic produced by the bacterium. Phytopa- thology 69:480-482.

Hemingway J. and Ranson H. (2000). Insecticide resistance in insect vectors of human disease. Annu. Rev. Entomol 45: 371–391.

Roy M., Chatterjee1 S.N., Roy P. and Dangar T.K. (2010). Sig- nificance of the midgut bacterium Pseudomonas fluorescens on Culex vishnui (Diptera: Culicidae) larval development. Inter-

Vankudre, Balpande, Athale, and Deshpande

national Journal of Tropical Insect Science Vol. 30, No. 4, pp. 182–185.

Madi et al., (2010). Psudomonas fluorescens alters epithelial permeability and translocates across Caco-2/TC7 intestinal cell. Gut Pathogens 2:16.

Mulla M. S., Darwazeh H. A. (1975). Activity and longevity of insect growth regulators against mosquitoes. Journal of Eco- nomic Entomology 68:791–794.

Murty M. G., Srinivas G., Sekar V. (1994) Production of a mosquitocidal exotoxin by a Pseudomonas fluorescens strain. J Invertebr Pathol 64: 68-70.

Dighe N. S., Pattan S. R., Dighe S. B., Bhawar S. B., Saudagar R. B., Gaware V. M., Hole M. B. and Tambe V. B. (2009). Chikun- gunya Disease: A Review. Research J, Pharmacology and Phar- macodynamics 1(1):07-12.

Prabakaran G., Paily K.P., Padmanabhan V., Hoti S.L., Balara- man K. (2003). Isolation of a Pseudomonas fluorescens metab- olite/ exotoxin active against both larvae and pupae of vector mosquitoes. Pest Manag Sci 59 : 21-4.

Patil R., Makhija T., Suryawanshi H. P., Pawar S. P. (2013). A review on-Dengue. Research J. Pharma and Tech. 6(9): Sepem- ber 930-936.

Paessler S. and Walker D. H. (2013). Pathogenesis of the Viral Hemorrhagic Fevers. Annu. Rev. Pathol. Mech. Dis. 8:411-440.

Techniques to detect insecticide resistance mechanisms (field and laboratory manual). Geneva, World Health Organization, 1998 (WHO/CDS/CPC/MAL/98.6).

Walsh U. F., Morrissey J. P. and O’Gara F. (2001). Pseudomonas for biocontrol of phytopathogens: from functional genomics to commercial exploitation. Current Opinion in Biotechnology 12:289–295.

Padmanabhan V., Prabakaran G., Paily K.P. and Balaraman K. (2005). Toxicity of a mosquitocidal metabolite of Pseudomonas fluorescens on larvae & pupae of the house fly, Musca domes- tica. Indian J Med Res 121: 116-119.

Brown W. A., Klassen W., Pillai M. K. K. and Hooper G. S. H. (1964). Insecticide Resistance in Mosquitoes and Root Mag- gots. The Canadian Entomologist 96(1-2): 100-101.