Efficacy of Citrus sinensis Peel Essential Oil and its Copper Nanoparticle-Based Formulation as Eco-Friendly Larvicides and Adulticides for Anopheles gambiae Management
Amarachi Keziah Ezeike
Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.
Valentine Chukwuma Ezenwa *
Integrity Research Laboratory, Oko. Anambra State, Nigeria.
Simon Pierre Yinyang Danga
Department of Biological Sciences, Faculty of Science, University of Garoua, Cameroon.
Chinaza Favour Chukas
Integrity Research Laboratory, Oko. Anambra State, Nigeria.
C. Nwangwu Udoka
Federal Ministry of Health, National Arbovirus and Vectors Research Centre Enugu, Enugu State, Nigeria.
A. Dogunro Festus
Federal Ministry of Health, National Arbovirus and Vectors Research Centre Enugu, Enugu State, Nigeria.
Chukwuebuka Michael Nwosu
Federal Ministry of Health, National Arbovirus and Vectors Research Centre Enugu, Enugu State, Nigeria.
Ijeoma Ngozi Ebenebe
Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.
Chidimma Ruth Chukwunwejim
Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.
Angus Nnamdi Oli
Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.
Charles Okechukwu Esimone
Department of Pharmaceutical Microbiology and Biotechnology, Nnamdi Azikiwe University, Awka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Introduction: The increasing resistance of Anopheles gambiae to synthetic insecticides necessitates the development of eco-friendly and sustainable alternatives for malaria vector control. This study evaluated the larvicidal and adulticidal efficacy of Citrus sinensis peel essential oil and its copper nanoparticle-based formulation counterpart
Methodology: This study employed a laboratory-based completely randomized experimental design. Essential oil was extracted via hydrodistillation and subsequently formulated into a copper nanoparticle (CuNP)-based nano-formulation for enhanced bioactivity. Larvicidal bioassays were conducted at concentrations of 5-25 mg/L based on preliminary range-finding assays, using three replicates per treatment (20 larvae per replicate), while adulticidal activity was assessed using WHO cone bioassay at 100-500 µL/mL (crude oil) and 400-1200 µL/mL (CuNP-based nano-formulation), each performed in four replicates per concentration.
Results: Both the crude essential oil and its CuNP-based nano-formulation exhibited concentration- and time-dependent larvicidal and adulticidal activity against A. gambiae. The nano-formulation demonstrated higher efficacy, achieving a maximum larval mortality of 93.33% compared to 85.00% for the crude oil at 25 mg/L after 24 hours. Probit analysis revealed lower LC₅₀ values for the nano-formulation (9.54 mg/L) than the crude oil (15.93 mg/L), indicating greater potency. In adulticidal assays, the nano-formulation produced rapid knockdown and achieved 100% mortality within 1 hour across all tested concentrations, whereas the crude oil showed delayed toxicity.
Conclusion: The nano-formulated essential oil demonstrated enhanced efficacy, faster action, and improved dose-response characteristics. These findings highlight the potential of C. sinensis peel-derived nano-insecticides as sustainable alternatives for malaria vector management under laboratory conditions.
Keywords: A. gambiae, Citrus sinensis peel, essential oil, nano-formulation, larvicidal activity, adulticidal activity, mosquito control