author(s)
Simon Pierre Yinyang Danga, Oumarou Bibi Farouck Aboubakar, Honore Menga Tissebe Ndouwe, Bouladji Yonki, David Ngadvou, Lame Younoussa, Eze Elijah Ajaegbu, Charles Okechukwu Esimone and Elias Nchiwan Nukenine

abstract
The extensive use of synthetic mosquitocides has affected our ecosystem, environment, and health of living beings. Mosquitoes also gained resistance toward those chemicals. Botanicals, which showed their activities against various mosquito species, may be exploratory sources. This study aimed at evaluating the toxicity of different solvent extracts and essential oils against three adult mosquito vectors. Four solvents viz hexane, chloroform, ethyl acetate and methanol fractions from the crude methanol extract and essential oil of Plectranthus glandulosus and Callistemon rigidus were used against female Culex quinquefasciatus, Anopheles gambiae and Aedes aegypti adults. The standard Centres for Disease Control and Prevention Bottle Bioassay for mosquito adulticidal agents was performed. Under the laboratory conditions, the mortality was observed 24 h post-treatment for extracts and fractions and 10 minutes for essential oils and WARRIOR^®. All the extracts and fractions of both plants showed good adulticidal activity except chloroform, ethyl acetate and methanol fractions of Callistemon rigidus which exhibited no toxicity whereas essential oils, very good mosquito adulticidal activity. The LC₅₀ values of P. glandulosus’ essential oil were 62.6, 48.23 and 45.5 μg/250ml while those of C. rigidus were 412.7, 273.1 and 334.3 μg/250ml against Cx. quinquefasciatus, An. gambiae and Ae. aegypti, respectively. No dead mosquito was registered in negative controls and no mosquito was found alive in positive controls (WARRIOR^®). These results give way to conclude that eco-friendly extracts from Cameroonian C. rigidus and P. glandulosus leaves are good potentials which may replace the synthetic WARRIOR^® for the control of malaria, yellow fever, dengue and filariasis vector mosquitoes.