Chemical composition and larvicidal activity againstAedesmosquitoes of flower extracts fromClitoria Ternatea
Authors: Ravindran Darvin R. , Bharathithasan Madhuri , Ramaiah Patmani , Rasat Mohd Sukhairi Mat , Rajendran Dinesh , Srikumar Shakila , Ishak Intan H. , Said Abd Rahman , Ravi Rajiv , Amin Mohamad Faiz Mohd 
Published: April 2020

Background

Mosquito is a human health tread nowadays, the major health problems caused by them are malaria, dengue fever, yellow fever, zika as well as several other outbreaks. The major problem in controlling dengue vectors are the resistant problems. Different classes of insecticides used for public have raised the concern of resistant problem with mosquitoes and environmental pollution. Thus, alternative chemical compounds search is necessary to be searched for overcoming the resistance problem of using pesticides in vectors and the chemical free environment respectively. Thus, to solve these problems, purpose of this study is to identify the larvicidal mechanism, metabolite, antioxidant, chemical compounds and its structure fromC. ternateaflower and to test its efficacies against early 4thinstar larvae ofAe. aegyptiandAe albopictus.

Methods

Clitoria ternateaflowers were collected from the Garden of the Faculty of Medicine in International Quest University, Ipoh, Perak and used for crude extraction. Then, the metabolite test, antioxidant test, chromatography techniques were conducted to identify chemical composition of extracts and their chemical structures were identified using GCMS-QP2010 Ultra (Shimadzu). Next, following WHO procedures for larval bioassays, the extracts were used to evaluate against early 4thinstar larvae ofAedesmosquito vectors.

Results

The larvicidal activity ofClitoria ternateaflowers extracts evidently affected the early 4thinstar larvae ofAedesmosquito vectors. The highest larvicidal activity was observed against early 4thinstar larvae ofAe. aegyptiwith the LC50 and LC95 values of 1056 and 2491 mg/L, respectively. Meanwhile larvae bioassay test forAe.albopictusrecorded with the LC50 and LC95 values of 1425 and 2753 mg/L. Moreover, the results for non target organism test on Guppy fish,Poecilia reticulateshowed no mortalities with flower extracts at 2500 mg/L and posses no toxic effects on fish. In this study, total of 16 chemical compounds and 6 chemical compounds have been reported to posse’s direct effects on insecticidal, larvicidal and pupicidal effects. Namely 6 chemicals used for insecticidal properties were Glycerin, 2-Hydroxy-gamma-butyrolactone, Neophytadiene, n-Hexadecanoic acid, cis-Vaccenic acid, and Octadecanoic acid with total of 28.7%.Clitoria ternateaflower extracts also showed different types of phenols such as anthocyanin, flavonoid and tannin.

Conclusions

Our findings showed that crude extract ofClitoria ternateaflower bioactive molecules to be effective and may be developed as biolarvicides forAedesmosquito vector control. Furthermore, this study also provided a baseline understanding for future research work on the field applications ofClitoria ternateaflower extracts which could be tested for its long term effects on other non target organisms, including human health.