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Culex pipiens mosquitoes considered as vectors for many arboviruses such as the West Nile virus and encephalitis virus showing a global impact on human health. The natural management of the aquatic stages of this pest is crucial for maintaining an insecticide-free and sustained environment. The present work focused on studying the biological and biochemical effects of the entomopathogenic fungi: Metarhizium anisopliae, Beauveria bassiana , and Paecilomyces lilicanus , against 3 rd instar larvae of Culex pipiens laboratory colony. The results revealed that M. anisoplia e showed maximum larval mortality (88%) with the lowest lethal time (LT 50 ) (22.6 hrs) at 10 8 spores/ml followed by B. bassiana (73.33%) with LT 50 (38.35 hrs), while P. lilicanus showed minimum percent mortality (65%) with highest LT 50 (51.5 hrs). The median lethal concentration (LC 50 ) values were found to be 1.027 × 10 5 spores/ml for M. anisopliae , 1.24 × 10 6 spores/ml for B. bassiana , while it was 8.453 × 10 6 spores/ml for P. lilicanus . A reduction in female fecundity, number of hatched eggs, pupation and adult emergence percentage were recorded. The biochemical analysis of the treated larvae revealed different quantitative decrease in total soluble proteins, lipids, and carbohydrate hydrolyzing enzymes compared to control. Histopathological effects of fungal infection upon insect cuticles, muscles, and midgut were investigated. Based on the obtained results, M. anisoplia e proved its superior virulent effect as a bio-control agent against Cx. pipiens.

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Infections associated with the emergence of multidrug resistance and mosquito-borne diseases have resulted in serious crises associated with high mortality and left behind a huge socioeconomic burden. The chemical investigation of Lavandulacoronopifolia aerial parts extract using HPLC–MS/MS led to the tentative identification of 46 compounds belonging to phenolic acids, flavonoids and their glycosides, and biflavonoids. The extract displayed larvicidal activity against Culex pipiens larvae (LC50 = 29.08 µg/mL at 72 h). It significantly inhibited cytochrome P-450 monooxygenase (CYP450), acetylcholinesterase (AChE), and carboxylesterase (CarE) enzymes with the comparable pattern to the control group, which could explain the mode of larvae toxification. The extract also inhibited the biofilm formation of Pseudomonas aeruginosa by 17–38% at different Minimum Inhibitory Concentrations (MICs) (0.5–0.125 mg/mL) while the activity was doubled when combined with ciprofloxacin (ratio = 1:1 v:v). In conclusion, the wild plant, L.coronopifolia, can be considered a promising natural source against resistant bacteria and infectious carriers.