Repellent and insecticidal activities of Pinus halepensis and Cupressus sempervirens extracts against the West Nile virus vector Culex pipiens

Mosquitoes are major disease vectors that pose serious public health threats. Extensive use of synthetic insecticides against mosquitoes has caused resistance, environmental pollution, and health risks, making it imperative to use natural alternatives. This study evaluated the larvicidal and repellent activities of Pinus halepensis and Cupressus sempervirens leaf extracts and essential oils against Culex pipiens, the vector of West Nile virus, and profiled their phytochemical composition. Methanol, acetone, ethyl acetate, and n-hexane extracts, along with EOs, were tested for larvicidal toxicity and analyzed by UPLC/MS and GC/MS. EOs exhibited the highest larvicidal potency, with LC₅₀ values of 71.96 ppm for P. halepensis and 96.38 ppm for C. sempervirens, followed by solvent extracts in the order acetone > n-hexane > methanol > ethyl acetate. Both oils provided complete repellency (100%) for 150 min at 1% concentration. UPLC/MS identified 58 secondary metabolites, mainly flavonoids and diterpenoids, while GC/MS revealed 20 components from monoterpenes, sesqui-, di-, and triterpenes side by side with fatty acids. Biochemical assays showed that P. halepensis extract caused greater inhibition of acetylcholinesterase, esterases, and antioxidant enzymes (SOD, GST, CAT, and GSH), with elevated oxidative stress markers (LPO and TPC) compared to C. sempervirens. These findings demonstrate the potential of P. halepensis and C. sempervirens extracts, particularly EOs, as eco-friendly botanical larvicides and repellents against Cx. pipiens.