Ochola, John BwireMutero, Clifford MainaMarubu, Rose MuthoniHaller, Barbara FreiHassanali, AhmedLwande, Wilber2023-08-112023-08-112022-02-16Ochola, J.B.; Mutero, C.M.; Marubu, R.M.; Haller, B.F.; Hassanali, A.; Lwande,W. Mosquitoes Larvicidal Activity of Ocimum kilimandscharicum Oil Formulation under Laboratory and Field-Simulated Conditions. Insects 2022, 13, 203. https://DOI.org/10.3390/insects13020203.2075-4450 (online)10.3390/insects13020203http://hdl.handle.net/2263/91887DATA AVAILABILITY STATEMENT : All data generated or analyzed during this study are included in this manuscript.Mosquitoes are vectors of many severe diseases, including malaria, yellow as well as dengue fever, and lymphatic filariasis. The use of synthetic chemical insecticides for mosquito control has been associated with resistance development and detrimental human, and ecological effects. For a safer alternative, the emulsified Ocimum kilimandscharicum oil formulation was evaluated for its larvicidal activity. The oil was analyzed by GC and GC/MS. The formulations were evaluated against third instar mosquito larvae in the laboratory and later compared with Bacillus thuringiensis subsp. israelensis against An. gambiae under field-simulated conditions. Thirty-nine compounds were identified in the oil, the main ones being D-camphor (36.6%) and limonene (18.6%). The formulation showed significant larval mortalities against An. gambiae and An. arabiensis larvae with LC50 of 0.07 and 0.31 ppm, respectively, at 24 h. Under the field-simulated trial, within 24 h, the formulation showed 98% mortality while Bti had achieved 54%. On day three, it caused 100% mortality while Bti achieved 76.5%. The high bioactivity and sublethal toxic effects to offspring of treated mosquito larvae, in terms of disruption of larval morphological aspects, suggest the high potential of the formulation as a botanical larvicide. The formulation, thus, may provide a valuable alternative for the effective and eco-friendly control of disease vectors.en© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.LarvicideMalariaMosquito controlBotanicalFormulationBiopesticideArticle