Evaluation of the bioinsecticidal potential of selected plant extracts against malaria and arboviral vectors

Abstract Background : Escalating environmental concerns and widespread resistance to synthetic insecticides have intensified the search for sustainable, plant-based alternatives. Botanical bioinsecticides offer a safer profile for non-target organisms and leave minimal environmental residue while effectively suppressing target vector populations. Methods Crude extracts from eight native medicinal plants— Ocimum lamiifolium , Lepidium sativum , Amaranthus hybridus , Premna schimperi , Ocimum gratissimum , Argemone mexicana , Lippia adoensis , and Calpurnia aurea —were prepared using 80% methanol & n-hexane solvents. Larvicidal and adulticidal bioassays were conducted under controlled laboratory conditions at concentrations ranging from 62.5200–2000 ppm against An. arabiensis , An. stephensi , and Ae. aegypti . Mortality data were recorded after 24 hours and evaluated via probit analysis to determine LC₅₀ & LC₉₀ values. Results Among the tested botanicals, O. gratissimum and A. mexicana exhibited the highest larvicidal potency against An. arabiensis , yielding LC₅₀ & LC₉₀ ranges of 596.51–1084.48 ppm and 650.88–1039.50 ppm, respectively. These were followed by L. adoensis (LC₅₀/LC₉₀: 763.03–1158.01 ppm) and A. mexicana (LC₅₀/LC₉₀: 768.00–995.17 ppm) against Ae. aegypti . Notably, O. gratissimum , A. mexicana , and C. aurea induced 100% larval mortality in An. arabiensis at peak concentrations. Furthermore, n-hexane crude extracts of O. lamiifolium , L. sativum , A. hybridus , P. schimperi , A. mexicana , L. adoensis , and C. aurea demonstrated robust adulticidal efficacy against both An. arabiensis and Ae. aegypti across the evaluated concentration spectrum. Conclusions the n-hexane and methanolic crude extracts of these evaluated plants demonstrate strong potential for development as eco-friendly bioinsecticides against major malaria and arboviral vectors. Future research should focus on isolating and characterizing the specific active phytochemical constituents driving this bioactivity.