Larvicidal and Pupicidal Activity of Unripened Fruit of Coccinia grandis (L) against Filarial Vector Culex quinquefasciatus

chronic disease caused by nematode Wuchereria bancrofti ,


Introduction
Mosquitoes can transmit large number of diseases than any other group of arthropods and may affect millions of people in the world.WHO has declared mosquitoes as "public enemy number one" 1,2 .They can transmit most threatening diseases like malaria, yellow fever, dengue fever, chikungunya fever, filariasis, encephalitis, West Nile virus infection.Among these, lymphatic filariasis is second leading cause of long-term and permanent disability in the world 3 .It is a vector-borne chronic disease caused by nematode Wuchereria bancrofti, which is mainly transmitted by Culex quinquefasciatus.There are many control measures using synthetic chemicals.The synthetic chemicals used for mosquitoes may cause unwanted side effects to human population and environment and also the mosquito can develop resistance to chemicals.Hence, the control of vector mosquito is still a challenge to the medical field.
evaluate the larvicidal and pupicidal activity of unripened fruit of Coccinia grandis against dengue transmitting mosquito C. quinquefasciatus.

Study Plant
The unripe fruit of the C. grandis was collected from local area.They were dried under shade and powdered.Then the powder was used for the preparation for extracts.Different solvents like ethanol, ethyl acetate, chloroform and aqueous were used for the preparation of plant extracts.The plant extract was prepared by cold extraction method and the extracts were concentrated by rotary evaporator.

Study animal
Larvae and pupae of C. quinquefasiatus selected for larvicidal and pupicidal activity and the larvae and pupae were collected from Vector Control Research Centre, ICMR, Madurai.

Larvicidal activity test of plant extract
The larvae of C. quinquefasiatus were used for larvicidal activity.Six numbers of fourth instars larvae were kept in 500 ml beaker containing 249 ml of distilled water and 1ml of desired concentration of plant extracts were added and incubated for 24 hours and 48 hours.The mortality of larvae was observed for every 3 hours and recorded 7 .Mortalities were corrected by Abbott's formula 7 .Abbott's formula and formula for percent mortality are given below.

Pupicidal activity
Laboratory colony of five pupae was used for pupal toxicity test.Five numbers of freshly emerged pupae were kept in 500 ml glass beaker containing 249 ml of distilled water and 1ml of desired concentrations of plant extract was added.Control was set up by mixing 1ml of desired solvent respectively with 249 ml of dechlorinized water.Percentage of mortality was calculated through Abbott's corrected mortality formula 7 .

Statistical analysis
All data were expressed as mean ± SD.LC50 was calculated by probit analysis.All the statistics were performed using windows based SPSS software.

Results and Discussion
In the past few decades, the plant kingdom has been great interest as a potential source of insecticidal products because of the bioactive principles present in the plant materials.Many species of the plant kingdom synthesize a variety of secondary metabolites which are play vital role against insects/mosquito 8 .

Larvicidal activity of different extracts of C. grandis gourd
High concentration (100%) of ethanol extract of C. grandis yielded about 65% mortality of mosquito larvae (Table 1).The LC50 value of ethanol extract was observed in 78.20% (Table 3) for 24 hours.One way ANOVA test showed that there was a significant difference (F4,25= 66.24; p<0.05) among mortality of different concentrations.
Ethyl acetate extract C. grandis produced 67% of larval mortality at 100% concentration.The LC50 value of ethyl acetate extract was about 68.46% for 24 hours (Table 2).One way ANOVA test proved that there were significant differences (F4,25= 354.09; p<0.05) in the mortality of larvae when treated with different concentrations of ethyl acetate extract of C. grandis.About 75% of mortality was observed when treated with 100 % concentration of chloroform extract of C. grandis and the mortality was gradually decreased when the concentration decreases (Table 1).The LC50 value of chloroform extract was about 66.35% (Table 2).There was a significant different (F4,25=176.19;p<0.05) in the larval mortality.Similarly 100% aqueous extract yielded high mortality at 24 hours.The LC50 value was about 61.97%.Percent mortality increased when extract concentration increases (One way ANOVA; F4,25=186.12;p<0.05) (Tables 1  and 2).

Pupicidal activity of different extracts of C. grandis gourd.
High concentration i.e., 100% of ethanol extract of C. grandis gourd showed 70% mortality (Table 3).LC50 of ethanol extract was 74.81% (Table 4).Ethyl acetate extract showed that 60% mortality in 100% concentration and LC50 was 88.67% (Table 3 and 4).High concentration of chloroform extract showed high mortality rate (Table 2).The LC50 was 75.73% (Table 4).The aqueous extract showed high mortality rate in high concentration (100%) (Table 3).Products of secondary plant metabolisms are responsible for the chemical communication between plants and insects.Phytochemicals obtained from plants were proved mosquito control potential and can be used as an alternative to synthetic potential insecticides or along with other insecticides under the integrated vector control.These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes 5 .
In the present study, the different extracts of C. grandis unripened fruit showed potential larvicidal and pupicidal activities against filarial vector C. quinquefasciatus.The LC50 value of different extracts of C. grandis gourd against larvae of C quinquefasciatus showed minimum vaules.Phytochemicals derived from plant sources act as larvicides, insect growth regulators, repellent, ovipositor attractant and have different activities which have been observed by many researchers 9 .Triterpenoids are generally credited with mosquito larvicidal activities 10 .Preliminary phytochemical screening of extract of leaves of Coccinia grandis indicated the presence of phenols, tannins, saponins, terpenoids, and flavonoids 11 .The potent larvicidal activity of C. grandis could be attributed to the strong presences of terpenoids, triterpenoids and alkaloids.

Conclusion
From the result it is concluded that the different extracts of C. grandis gourd possesses larvicidal and pupicidal activity against filariasis transmitting vector C. quinquefasciatus.The phytochemicals such as terpenoids, saponins might be useful for the control of vector mosquitoes.Thus the C. grandis gourd may be used for control of mosquitoes.
treatment − Observed mortality in control 100 − Mortality of Control  100 % mortality = Number of dead larva      100

Table 1 :
Larvicidal activity of different extracts of Coccinia grandis gourd against filariasis transmitting vector C. quinquefasciatus

Table 2 :
LC50 value of different extracts of C. grandis gourd against larvae filariasis transmitting vector C. quinquefasciatus

Table 3 :
Pupicidal activity of different extracts of Coccinia grandis gourd against filariasis transmitting vector C. quinquefasciatus.

Table 4 :
LC50 value of different extracts of C. grandis gourd against pupae of filariasis transmitting vector C. quinquefasciatus