Seasonal Change in Quantity of Phyto-chemicals in Leaf of Tiliacora acuminate and Their Effect on Mortality of Culex vishnui Larvae

Japanese Encephalitis is one of the vectors borne disease created major public health problem in Indian peninsular and Culex vishnui is the key vector of this disease. Lots of plant extract were also reported for their mosquito larvicidal activity but correlation between season wise quantitative change in phyto-chemical and their effect on larvicidal potentiality was tried to establish though this research work. The study was conducted to established larvicidal activity of T. acuminate against Cx. vishnui larvae.

Crude extract of T. acuminate leaves were used for larvicidal bioassay against 3rd instars larvae of Cx. vishnui in three different seasons i.e. summer, rainy and winter. 0.5% concentration of crude extract show 100% mortality after 72 h in summer whereas 86% and 92% mortalities were recorded in rainy and winter seasons respectively against same dose and same time of exposure.

When crude extract with LC50 for 3rd instars larvae of Cx. vishnui at 72 h of exposure was tested against non target organisms i.e. Chironomus and Daphnia sp no mortalities were recorded.

Quantitative estimation of different phytochemicals of leaf of T. acumination was recorded in three prevalent seasons i.e. summer, winter and rainy.

The carbohydrate is raw metabolic substance which is used for generation of heat, to tolerate extreme temperature and it was found with higher concentration (7.91 mg/g) in winter. Starch is the non-structural carbohydrate which are assist in bud initiation, leaf maturation and flowering and it was found at highest dose in summer. (.81mg/g) Protein is used as building block of plant and highest protein content was recorded in summer. (132mg/g) The phenol is used as natural defence mechanism of plant and it was found at highest concentration in summer. (16.5 mg/g) Ash and moisture contents are used as senescence and decomposition of plant respectively.

Crude extract of leaf of T. acuminata show positive result for alkaloids, cardiac glycosides, saponins and flavonoids, in which alkaloids and cardiac glycosides are found with higher doses i.e. 0.72mg/g and 0.65 mg/g respectively. Numbers of phyto-chemicals are recorded at higher dose in summer. Plant phyto-chemicals are mainly used for their own defence mechanism by controlling different pest and pathogens population. Correlation between seasonal variation of plant phytochemicals (quantity) and mosquito larvicidal potentiality of T. acuminate leaves was established in this research work.