## 3 Results and Discussion
### Response of A. gambiae to the Essential Oil and Selected Compounds  
Figure 10 indicates five ligands identified in the V.negundo essential oil, and these results are reported in Table S1. Figures 3-5 depict the behavioral responses of the 150 female _A. gambiae_ to the _V. negundo_ oil, positive control (DEET), and pure compounds.  
The observed repellency of the essential oil compared to the chemical-based repellent underlines the potency of the oil, which is in tandem with the ethno-application of the _V. negundo_ as a mosquito repellent as reported by [PERSON] et al. [55] and [PERSON] et al. [56].  
As the exposure time increases, the repellency activity of the compounds increases to a concentration where there are no observable changes in activity. The essential oil showed a significant increase in the percentage of mosquitoes repelled at 49.9 min compared to the compounds; however, no significant difference (\(p>0.05\)) was observed in the percentage of mosquitoes repelled between the pure compounds.  
The contact time of the tested samples varied depending on their diffusivity (Figures 3-5); in the first 10 min of exposure to _V. negundo_ oil and DEET, they repelled about 76% and 85%  
Figure 9: The RMSD of the odorant-binding protein 7 complexed the lead phytochemicals (**A–D**) in the selected trajectory across the MD simulation period of 100 ns.  
In 60 min, sulcstone, \(\alpha\)-ylangene, \(\beta\)-caryophellene, and \(\beta\)-selinene, repelled 75%, 77%, 85%, and 83%, while the oil and DEET repelled 100% of the _A. gambiae_. There is a significant difference in the responses of the _A. gambiae_ to the oil and DEET compared to the pure compounds (Figure 11c-f). The optimal repellencies of the oil and DEET were recorded at 29.8 min and 35.9 min. Pure compounds showed an increase in the amount of mosquitoes repelled with time, with an optimal % repellency activity attained at approximately 45.6-49.9 min.  
However, the sensitivities of the _A. gambiae_ to the test compounds vary slightly, with _A. gambiae_ being most and least sensitive to sulcstone at 15 min and \(\beta\)-selinene at about 26.7 min. Further, the time required to repel 50% of the _A. gambiae_ varies from one pure  
Figure 11: Percentage mosquito repelled by (**a**) 0.48% _v/v V. negundo_ essential oil and (**b**) 0.01% _v/v_ DEET: N,N-diethyl-3-methylbenzamide amide after 60 min exposure, (**c**) sulcstone (**d**) \(\alpha\)-ylangene after 60 min exposure, (**e**) \(\beta\)-caryophellene, and (**f**) \(\beta\)-selinene after 60 min exposure.  
compound to another. Sulcatone and \(\beta\)-caryophellene showed 50% repellency activity in the shortest time of 23.9 min, contrary to the observed repellency of \(\alpha\)-ylangene at 25.3 min. Sulcatone has been reported to be potent against _Drosophila melanogaster_ and _Toxorhynchites amboinensis_[57]. This inference is in consonance with the studies of [PERSON] et al. [58] and [PERSON] et al. [59; 60].  
Most insect repellents, including DEET, have a species-specific method of action that is sometimes unknown. Activation of specific odorant receptors (ORs), inhibition of specific ORs, and modulation of multiple ORs, according to [PERSON] et al. [34] and [PERSON] et al. [61], may be suggestive of functional blocking of the olfactory receptor co-receptor, resulting in _A. gambiae_ susceptibility to the molecules in the repellent.