Larvicidal and Adult Emergence Inhibition Effects of Myrtus communis and Eucalyptus globulus Leaf Extracts against Culex molestus
Sarah Kadhim Al-Rahimy *
College of Science, University of Kerbala, Karbala, Iraq.
Rafid Abbas Al-Essa
College of Education for Pure Science, University of Kerbala, Karbala, Iraq.
*Author to whom correspondence should be addressed.
Abstract
Background: Mosquito-borne diseases have become increasingly severe due to rapid urbanisation and population growth. Although chemical insecticides have been widely used for mosquito control, their extensive application has led to problems such as insecticide resistance and environmental pollution. Therefore, there is growing interest in plant-based alternatives as eco-friendly and effective mosquito control agents.
Objective: The current research aimed to determine the effects of aqueous and alcoholic extracts of Eucalyptus globulus and Myrtus communis on adult mosquito emergence inhibition and the mortality rate of fourth-instar larvae.
Material and Methods: This study was conducted in Karbala Governorate, Iraq, in March 2021, to control the Culex molestus (Diptera: Culicidae) mosquito, calculate the mortality rate of the fourth larval stage, and inhibit the emergence of the adult insect. Concentrations of the aqueous and hexane extracts were (0.2, 0.4, 0.6, 0.8, and 1.0) mg/ml each, while the concentrations of the cold aqueous extract of M. communis were (0.5, 1, 1.5, 2, and 2.5) mg/ml. The concentrations were (0.5, 1, 2, 4, 8) (mg/ml) for the boiled and cold water extracts, while the concentrations were (0.1, 0.2, 0.3, 0.4 and 0.5) mg/ml for the hexane extract of E. globulus plants. In addition, FTIR spectroscopy was used to identify the functional groups present in the plant extracts.
Results: The results of this study showed that the effect of the extracts varied depending on the concentrations, extraction method, and solvent used. This confirmed an increase in the mortality rate of the fourth larval stage and inhibition of adult emergence, as the extracts of the plants had the greatest effect in eliminating the fourth larval stage and inhibiting the emergence of adults by 100%, as these extracts outperformed the effect of eucalyptus extracts in the percentage of fourth larval stage mortality and inhibition of adult emergence when treated with cold and boiled water extracts and hexane, and eucalyptus extracts had an effect on the mortality of fourth instar larvae and inhibition of adult emergence compared to the control group treatments.
Conclusion: The results of the study showed that the extracts of the Myrtle and Eucalyptus plants are of great importance in controlling mosquitoes, which are medical insects that transmit many diseases. These extracts are natural, environmentally safe, harmless to non-target organisms, and quickly decompose. FTIR analysis confirmed the presence of bioactive functional groups responsible for their activity. The results provide evidence supporting the potential use of Eucalyptus globulus and Myrtle communis as natural pest control agents. These studies contribute to the broader scientific community by exploring environmentally friendly tools for mosquito control.
Keywords: Culex molestus, plant extracts, Eucalyptus globulus, Myrtus communis