A.P. Madhumathy, Ali-Ashraf Aivazi , V.A. Vijayan

Journal of Vector Borne Diseases

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Larvicidal efficacy of Capsicum annum against Anopheles stephensiand Culex quinquefasciatusA.P. Madhumathy, Ali-Ashraf Aivazi & V.A. VijayanVector Biology Research Lab, Department of Studies in Zoology, University of Mysore,  Manasagangotri, Mysore, IndiaKey words Anopheles stephensi – Capsicum annum – Culex quinquefasciatus – larval bioassayJ Vect Borne Dis 44, September 2007, pp. 223–226It is estimated that every year at least 500 millionpeople in the world suffer from one or the othertropical diseases that include malaria, lymphaticfilariasis, schistosomiasis, dengue, trypanosomiasisand leishmaniasis. Of late chikungunya, a seriousmosquito borne epidemic has gained momentum inIndia. One to two million deaths are reported annuallydue to malaria worldwide. Lymphatic filariasis affectsat least 120 million people in 73 countries in Africa,India, Southeast Asia, and Pacific Islands.  Thesediseases not only cause high levels of morbidity andmortality, but also inflict great economic loss andsocial disruption on developing countries such asIndia, China, etc. India alone contributes around 40%of global filariasis burden and the estimated annualeconomic loss is about 720 corers1.Due to the lack of awareness among people, earlydetection and complete treatment of these diseases arevery difficult. Consequently several chemicalmethods are available for the interruption of theirtransmission which has been limited by logisticproblems, development of resistance, high cost etc.So the most effective and easiest approach to controlthese diseases requires interruption of the life cycleof the vectors by applying larvicides to their breedingplaces. Further, toxicity of synthetic insecticidestowards non-target animals and environment has beenwidely observed and recognised. To avoid thepropensity of bioaccumulation and induction ofmalignancy in non-target animals, a safe and morecongenial method of vector control by natural andcheaper means of using plants as insecticides becamepopular2.  The development of resistance by pests andvectors against botanicals has not been reported sofar. Active principles from many plants have beenrecognised, isolated, purified and formulated asinsecticides.The species of Capsicum (Solanacae) is a typicalshrub, commonly found in almost all parts of theworld.  The fruits of Capsicum annum contain hotflavour, which is due to the presence of a group ofseven closely related compounds called capsai-cinoids, among which capsaicin and dihydro capsai-cin are responsible for 90% of the pungency3.Capsaicin (8-methyl-N-vanillyl-6-nonemide) is anactive ingredient responsible for the heat in chillipeppers. It is colourless, pungent crystalline alkaloid,thermoliable and more soluble in alcohols and oils3.Short Research CommunicationCapsaicinJ  VECT  BORNE  DIS  44, SEPTEMBER 2007224 It is important to note that capsaicin containingproducts are primarily used to repel insects ratherthan to kill them from ancient times. Literature surveyhas revealed that capsaicin has significant lethal andantifeedent effects on various invertebrates. Capsai-cin has been proven as an oleoresin used againstcotton pest4. Extracts of capsicum were also provenas repellent to some species of stored product beetlessuch as Sitophilus zeamais Motschulsky (Coleoptera:Curculinidae) and Tribolium castaneum (Herbst)(Coleoptera: Tenebriouidae)5. There are reports ofusing capsicum as biopesticides against Alfalfaweevil larvae6. Capsicum has proven its insecticidalactivity against rice grain pest, Sitotroga cerealellaalso7.  In the light of above said information, thepresent study was conducted to investigate the effectof natural crude extracts of Capsicum annum fruits(capsaicinoids) against IV instar larvae of Anophelesstephensi and Cx. quinquefasciatus (Diptera:Culicidae) as a part of the search for alternativenatural products, by screening botanicals onmosquito vectors.Fresh ripe fruits of  C. annum (Guntur chilli) werepurchased from market, dried and powdered usingelectric blender as it is unaffected by cold or heat, andextraction was carried out with excess of ethanol.Forty gram of chilli powder was subjected toextraction with 800 ml of absolute alcohol, bycontinuous stirring for 24 h. The crude extract wasfiltered through Whatmann No. 1 filter paper and thefiltrate was collected in round bottom flask. Theexcess of alcohol was removed by distillation. Theextract residue was poured into a test tube and keptin a boiling water bath till alcohol completely getsevaporated. The thick red crude residue, whichcontains capsaicinoids, was stored at roomtemperature (25 ± 2°C). It has been reported thatcrude extract of Guntur chilli contains 12.5% (w/w)oleoresin, 0.20% capsaicin, 0.6% dihydrocapsaicinand its pungency is recorded as 53250 SHU (ScovilleHeat Units)8.   The crude extracts were prepared at0.3% concentration in absolute alcohol and dilutedusing the same solvent for subsequent experiments.Laboratory reared An. stephensi and Cx. quinque-fasciatus larvae were used for the experiments. Theexperiments were conducted at 26 ± 2°C and relativehumidity of 65 ± 5%.Larval bioassay was conducted according to thestandard WHO procedure9. The required quantity ofchilli fruit extract of different concentrations (0.004–0.3%) in one ml of alcohol was mixed thoroughlywith 249 ml of tap water in 500 ml  glass beakers.Twenty-five early IV instar larvae were introducedinto each beaker and mortality was observed at 24 hperiod. Three replicates were maintained for eachconcentration along with control. The experimentswere repeated four times and analysis of data wascarried out by employing probit analysis10.So far no work has been reported to asses themosquito larvicidal activity of oleoresin present inCapsicum.  The ethanol extract of C. annum provedto be sufficiently effective on both the species. Cx.quinquefasciatus was found to be more susceptiblethan An. stephensi in terms of LC50 and LC90 values(Table 1 & Fig. 1). The results showed that the LC50Fig. 1: Effect of Capsicum annum ethanol extract on Cx.quinquefasciatus and An. stephensi larvaeMADHUMATHY et al :  MOSQUITO LARVICIDAL EFFICACY OF CAPSICUM ANNUM 225and LC90 values of the extract against Cx.quinquefasciatus were 0.0097 and 0.022% and thatfor An. stephensi 0.011 and 0.027% respectively,proving its toxic nature against both the species. Theextract of C. annum at  0.004% concentration showedno significant mortality (p >0.05), whereas 0.024%at  24 h observations showed 99% mortality in caseof Cx. quinquefasciatus. A concentration of 0.024%showed 96% mortality in An. stephensi larvae.However, larvicidal activity obtained was less whencompared to other plant formulations2.The results of the present study illustrate  thepossibility of using C. annum for mosquito larvalcontrol,  as it is less toxic to mammals, where it isquickly metabolised in the liver and excreted in urinewithin a few hours, even in case of over indulgence3.The development of an in-soil repellent for pocketgopher (Thomomys talpoides) with capsicumoleoresin suggests its eco-friendly nature11. Perusalof literature shows that extracts from C. frutescenshas biocidal activity against Bemisia tabaci, a tomatopest12.It was observed that larvae became slowly inactivewithin 18 h and began to fall towards the bottom ofthe beaker.  Microscopic examination of dead larvaerevealed that the extract has penetrated into larvaldigestive system.  The treated larvae showed curlingup, agitation, vigorous body movements which arethe characteristic of neurotoxicity.  Further researchregarding the effect of capsaicin on larval nervoussystem is needed to understand the mechanism ofaction of capsaicinoids in mosquito larvae. Theresults suggest for a possible utilisation of the cheapand readily available chilli fruits for possible controlof mosquitoes as a part of the integrated vectormanagement programme.AcknowledgementAuthors are thankful to the Department of Scienceand Technology for financial assistance in WomenScientist Scheme-B and the Chairman, Departmentof Studies in Zoology, University of Mysore forproviding facilities to carry out the present work.References1. Hotez PJ, Remme JHF, Buss P, Alleyne G, Morel C,Breman JG. Combating tropical infectious diseases: reportof the disease control priorities in developing countriesproject. Clin Infect Dis 2004; 38: 871–8.2. Jill BP. Pesticidal compounds from higher plants. PesticSci 1993; 39: 95–102.3. Govindarajan VS,  Sathyanarayana MN. Capsicumproduction, technology, chemistry and quality, pt V.Impact on physiology, nutrition and metabolism: criticalreview. Food Sci  Nutr 1991; 29: 435–74.4. Mayeux JV. Hot shot insect repellent: an adjuvant forinsect control. Proceedings of the Beltwide cottonTable 1.   Larvicidal activity of ethanol extract of Capsicum annum againstIV instar larvae of  Cx. quinquefasciatus and An. stephensiConcentration Larvicidal activity (95% fiducial limits)LC50 LC90 LC99Cx. quinquefasciatus 0.0097 0.022 0.044(0.007–0.012) (0.017–0.037) (0.029–0.114)An. stephensi 0.011 0.027 0.057(0.008–0.014) (0.020–0.050) (0.036–0.167)Values are in percent.J  VECT  BORNE  DIS  44, SEPTEMBER 2007226Corresponding author: Dr. V.A. Vijayan, Professor of Zoology, Department of Studies in Zoology, University of Mysore,  Manasagangotri,Mysore–570  006, India.E-mail: vavunimys@rediffmail.comReceived: 18 January 2007 Accepted in revised form: 20 March 2007conferences, Nashville, T.N., USA. 9–12 January 1996;1: 35.5. Ho SH, Ma Y, Tan HTW, Halid H. Repellency of someplant extracts to the stored products beetles, Triboliumcastaneum (Herbist) and Sitophilus zeamais Motsch.Proceedings of the symposium on pest management forstored food and feed. Southeast Asian Regional Centrefor Tropical Biology. BIOTROP 1997; 59: 209–15.6. Al-Doghairi MA, Hag EE. Effect of several biopesticideson Alfalfa weevil larvae, Hyper brunneipennis. Pak J  BiolSci 2003; 6: 777–81.7. Prakash A, Rao J. Exploitation of newer botanicals as ricegrain protectents against Angoumois grain moth Sitotrgacerealella. Entomon  2006; 31: 1–8.8. Mathur R, Dangi RS, Das SC, Malhotra RC. The hottestchilli variety in India. Curr  Sci 2000; 79: 287–8.9. Instruction for determining the susceptibility or resistanceof mosquito larvae to insecticides. WHO/VBC 1981; 81:807.10. Finney DJ. Probit Analysis, III edn. London: CambridgeUniversity Press 1971; p. 25–325.11. Ray T, Sterner RT, Shumake SA, Gaddish SE, BourassaJB. Capsicum oleoresin: development of an in-soilrepellent for pocket gophers. Pest Manag Sci  2005; 12:1202–8.12. Bouchelta A, Boughdad A,  Blenzar A. Biocide effects ofalkaloids, saponins and flavinoids extracted fromCapsicum frutescens L. (Solanaceae) on Bemisia tabaci(Gennidus) (Homoptera: Aleyrodidae). Biotechnol AgronSoc Environ 2005; 94: 259–69.

Larvicidal efficacy of Capsicum annum against Anopheles stephensi and Culex quinquefasciatus

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Larvicidal efficacy of Capsicum annum against Anopheles stephensi and Culex quinquefasciatus

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