Molecular Synergy of GC-Identified Volatile Compounds from Chromolaena Odorata, Hyptis Suaveolens and Cymbopogon Citratus against Anopheles Gambiae

Abstract

Introduction: :Malaria, a life-threatening disease, is one of the major deadly infectious diseases worldwide. The disease is caused by the protozoan Plasmodium and it is transmitted in humans by an effective bite of an infected adult female Anopheles mosquito.   In various parts of the world, malaria has been widespread for many decades, yet it still remains a major public health burden in affected areas, predominantly the tropical and subtropical areas in Africa.

Objectives:  This research  aimed to explore the synergistic potential of plant-derived volatile compounds from Chromolaena odorata, Hyptis suaveolens and Cymbopogon citratus as novel mosquito control agents, specifically targeting Anopheles gambiae, a major vector of malaria in Africa.  

Methods: The chemical compositions of the leaf extracts  were analyzed using Gas Chromatography (GC-) to identify bioactive compounds responsible for their bioactivity. The combined extract was tested at five different concentrations (0.125,  0.25, 0.50, 1.0 and 2.0mg/l) by exposing  laboratory reared Anopheles gambiae mosquitoes and observing the time and effects on the mosquitoes. The Effective dose (ED₅₀) was also determined.

Results:  Results showed a dose-dependent increase in mosquito control efficacy. At the lowest concentration (0.125mg/l), 20% of mosquitoes were killed within 5min, while 100% mortality was achieved with  0.50 to 2.0mg/l concentrations within  20min and 5min  respectively, showing a quicker action. Also the ED₅₀ for the combined extract was significant 0.002mg/l, (P<0.05) which competed with N,N-diethyl-meta-toluamide (DEET) control  (0.0009mg/l),  whereas the ED₅₀ for the single extracts were; C. odorata (0.70mg/l), H. suaveolens (0.50mg/l) and Cymbopogon citratus (0.50mg/l) which were not significant (P>0.05). The high insecticidal activity was attributed to compounds such as citral, citronella, geraniol, beta-    caryophyllene, and flavonoids found in the plant extracts.  

Conclusions: The study concluded that the combined extracts provided a quick, effective, and eco-friendly solution for mosquito control. The superior efficacy can be attributed to  high synergistic effect of the essential oils, affirming that plant-based volatile compounds are viable alternatives to synthetic repellents, offering environmental, affordability, sustainability and reduced health risks.