Larvicidal and adulticidal activities of essential oil of Helianthus annuus (L.) seed and molecular docking of its GCMS constituents against Aedes aegypti acetylcholinesterase

Essential oils (EOs) are known to possess lethal effects on various pests and insects and are ecologically safe. The larvicidal and adulticidal activities of Helianthus annuus (L.) seed EO (HASEO) against Aedes aegypti mosquitoes and in silico inhibitory action of its GCMS constituents against Ae. aegypti acetylcholinesterase (AChE) were investigated. Larvae and adult Ae. aegypti (320 of each) were grouped into 4 (A - D) and exposed to DMSO, 1500, 3000 and 4500 ppm HASEO in DMSO respectively. Mortality was recorded after 0, 15, 30 and 45 min. HASEO exhibited stronger larvicidal activity than adulticidal activity against Ae. aegypti. The larvicidal and adulticidal activities of HASEO increased with increasing exposure time, with the highest mortality recorded after 45 min of exposure (larvicidal activity LC50- 2121.32 ppm; adulticidal activity LC50- 2565.20 ppm). Increase in the concentration of HASEO resulted in an increase in the larvicidal and adulticidal activities of HASEO. After 45 min of exposure, 100 % larvae mortality was recorded at 3000 and 4500 ppm HASEO while 100 % adult mortality was recorded at 4500 ppm HASEO. GCMS analysis revealed the presence of 21 compounds in HASEO with 1-chlorononadecane (23.67 %) being the most abundant compound. Two compounds of HASEO; isopinocamphone and oxazol-5(4H)-one, 4-(4-trifluoromethylbenzylidene)-2-(2-methylphenyl)- demonstrated potential inhibitory activity against Ae. aegypti AChE with comparable binding affinity to standard ligand (1S)-2,2-difluoro-1-[1-(pentan-3-yl)-1H-pyrazol-4-yl]ethan-1-ol. The present findings reveal that HASEO may be useful as an effective biopesticide for the control of Ae. aegypti adult and larvae and may serve as an alternative to synthetic insecticides.