Bioactivities of selected plant extract against the yellow fever mosquito Aedesaegypti larvae

ANJUKRISHNA.R

STUDENT TEACHER (B.Ed. degree)

ST.JOSEPH COLLEGE OF TEACHER EDUCATION FOR WOMEN KOVILAVATTOM ROAD ERNAKULAM KOCHI -682035

anjukrishna.r@gmail.com

PHONE NUMBER: 9497366192

Abstract

The article is based on the research work to explore the floral biodiversity and enter the field of using safer insecticides of botanical origin as a simple and sustainable method of mosquito control. Use of these botanical derivatives in mosquito control instead of synthetic insecticides could reduce the cost and environmental pollution..The scope of the study is to Identify bio-insecticides that are efficient, as well as being suitable and adaptive to ecological conditions, is imperative for continued effective vector control management. Plants have widespread insecticidal properties and will obviously work as a new weapon and in future may act as suitable alternative product to fight against mosquito borne diseases.   The present study assessed the role of larvicidal activities of Myristica fragrans (Jathikka) ,Indigo feratinctoria (NilamariAmri) and  Adhatoda vasica Nees ( Adalotakam), on Aedes aegypti  mosquito larvae.The results is concluded that Indigo feratinctoria have highest mortality rate than that of Myristica fragrans and Adhatoda vasica .

Key words:

Aedes aegypti, plant extracts of Jathikka, NilamariAmri, Adalotakam ,larvicide

INTRODUCTION

Mosquitoes transmit serious human diseases, causing millions of deaths every year and the development of resistance to chemical insecticides resulting in rebounding vectorial capacity. Plants may be alternative sources of mosquito control agents. The need and significance of present study is to eradicate the continuous application of synthetic insecticides that causes development of resistance in vector species, biological magnification of toxic substances through the food chain and adverse effects on environmental quality and non-target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes.(Roark RC. 1947) described approximately 1,200 plant species having potential insecticidal value, while (Sukumar et al  1991) listed and discussed 344 plant species that only exhibited  mosquitocidal activity. Shallan et al., in 2005 reviewed the current state of knowledge on larvicidal plant species, extraction processes, growth and reproduction inhibiting phytochemicals, synergistic, additive and antagonistic joint action effects of mixtures, residual capacity, effects on non-target organisms, resistance and screening methodologies, and discussed some promising advances made in phytochemical research.

METHODOLGY:

The method adopted for the study is experimentation method it includes the  statistical analysis of percentage of mortality of mosquito larvae on varying concentration (1ml, 2ml, and 5ml) of plant extract.

Procedure

The larvae of mosquito were reared for the experiment and are transferred into a beaker containing distilled water with the help of a fish net. The larvicidal assay larvae of mosquito larvae were exposed to test concentrations of 1ml, 2ml and 5ml leafs extract of of Myristica fragrans ,Indigo feratinctoria , Adhatoda vasica Nees  in 10 ml of water. All the petridishes were labeled which indicated the source plant and the concentration of leaf extract used. Each was filled with 10 ml of distilled water using the measuring cylinder. The different concentrations of plant extract used were 1ml, 2ml and 5ml. 10 larvae were transferred to each petridish. The observations were made after 1hr, 2hrs, 20hrs, 24hrs and 48hrs. 

ANALYSIS AND INTERPREATATION:

In preliminary comparative studies, Myristica fragrans (Jathikka) ,Indigo feratinctoria (NilamariAmri) and  Adhatoda vasicaNees ( Adalotakam),  were tested  against Ae. aegypti larvae. Among these Indigo feratinctoria showed similar levels of susceptibility to 1ml 2ml and 5ml extracts. The fresh extract of leaves showed much higher activity than the other parts, against Ae.aegypti.

·         The effect of 1ml extract of Myristica fragrans was shown after 2hrs where the mortality was only 20%.  It was doubled after 20 hrs and remained as such after 24hrs. But after 48 hrs all larvae died .In the case of 2ml extract 60% mortality after 20hrs.  80% of the larvae died after one day and all the remaining died after two days. 100% of the larval death was observed after 20 hrs when 5ml of the extract was used.

·         Effect of Indigo feratinctoria extract on mosquito larvae was very rapid leading to death of mosquito larvae in the case of 1ml, 2ml and 5ml extract.  100% mortality was observed after 1hr in all the varying concentrations of the extract used.

·         But in case of Adhatoda vasica extract on mosquito larvae, 50% mortality was observed after 20hrs with 1ml extract.  It was increased to 70% after 48hrs. 2ml extract showed the effect after 1hr where 20% larvae died.  Mortality was 70% and 100% after 24 and 48hrs respectively. But when 5ml of the extract was used all the larvae death within 20hrs. All the selected plants showed larvicidal activity.

·         Major effect was observed in the case of Indigo feratinctoria where 100% mortality was observed after 1hr in all the varying concentrations of the extract used.

·         Above all the results it is concluded that Indigo feratinctoria have highest mortality rate than that of Myristica fragrans and Adhatodavasica .

CONCLUSION:

Plants are considered as a rich source of bioactive chemicals and they may be an alternative source of mosquito control agents. To prevent proliferation of mosquito borne diseases and to improve quality of environment and public health, mosquito control is essential. The major tool in mosquito control operation is the application of synthetic insecticides such as organochlorine and organophosphate compounds. But this has not been very successful due to human, technical, operational, ecological, and economic factors. In recent years, use of many of the former synthetic insecticides in mosquito control programme has been limited. The activity of crude plant extract is often attributed to the complex mixture of active compounds. Plants have widespread insecticidal properties and will obviously work as a new weapon and in future may act as suitable alternative product to fight against mosquito borne diseases. The results reported here open the possibility of further investigation of efficacy on their larvicidal properties of natural product extracts.

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