Insecticidal effects of some selected plant extracts against Anopheles stephensi Liston (Culicidae: Diptera)

Abstract

Background: The use of synthetic insecticides against mosquitoes may lead to resistance development and potential health hazards in humans and the environment. In connection to these adverse effects, a paradigm needs to shift towards the alternative use of botanical insecticides that could strengthen an insecticide resistance management program. This study aimed to assess the insecticidal effects of crude leaf solvent extracts of Calpurnia aurea, Momordica foetida, and Zehneria scabra on an insectary colony of Anopheles stephensi larvae and adults. Methods: Fresh leaves were collected and dried, then separately ground to powder. Powdered leaves of test plants were extracted using sonication with aqueous, hexane, and methanol solvents. The extracts were concentrated, and a stock solution was prepared. For comparison, temephos (Synthetic larvicide) and control solutions (a mixture of water and emulsifier) were used as the positive and negative controls, respectively. A range of test concentrations for the larvae and the adults were prepared and tested according to WHO (2005) and CDC (2010) guidelines to determine lethal concentration (LC) values. Mortality was observed after 24 hrs exposure. The statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) software (Kruskal-Wallis test) and R software (a generalized linear model was used to determine LC50 and LC90 values of the extracts). Results: The lowest LC50 values were observed in aqueous M. foetida extract, followed by Z. scabra and C. aurea at 34.61, 35.85, and 38.69 ppm, respectively, against the larvae. Larval mortality was not observed from the hexane and negative control, while the standard larvicide (temephos) achieved 100% mortality. In addition, the adulticidal efficacy was greatest for aqueous Z. scabra extract with LC50 = 176.20 ppm followed by aqueous C. aurea (LC50 = 297.75 ppm). Conclusions: The results suggest that the leaf extracts of the three test plants have the potential of being used for the control of vector An. stephensi larvae and adult instead of synthetic mosquitocides. Further studies need to be conducted to identify the active ingredients and their mode of action.

Evaluating the insecticidal potential of ethanol extracts from Melia azedarach Linn. against Bactrocera cucurbitae - a pest inflicting damage on Momordica charantia Linn.

“…Flavonoids, tannins, and polyphenols, major components in MAFS, are known for their antioxidant properties, reducing damage from free radicals, and antibacterial effects. Polyphenols contribute to antioxidant activity and cellular damage to insect structures, tannins create hindrance and affect digestive functions, while flavonoids inhibit biological processes in insect bodies, disrupting energy metabolism or reproductive processes Muhammed et al (2022). These results highlight the potential of MAFS to provide antioxidant defenses and inhibit the development of B. cucurbitae, contributing to the protection of bitter melon plants.…”

Insecticidal Efficacy of Selected Botanicals on three species of Adult Mosquitoes in Osogbo, Osun State, Nigeria

“…Ocimum gratissimum and O. basilicum have also been shown to have more repellant properties than plants such as Azadirachta indica, Citrus lemon and Jatropha curcas (Kazembe and Chaibva, 2012). Other botanicals whose insecticidal properties have been studied include Calpurnia aurea, Momordica foetida, Zehneria scabra etc (Muhammed et al, 2022).…”