Larvicidal potential of Thuja orientalis leaves and fruits extracts against Culex pipiens (Diptera: Culicidae)

Abstract

Botanical pesticides targeted to avoid the pesticide resistance to synthetic ones that conventionally affecting ecosystems diversity. The study designed to evaluate the larvicidal potentials of leaves and fruits extracts (methanol, acetone, hexane, and aqueous) from Thuja orientalis (Pinales: Cupressaceae) against Culex pipiens 3rd instar larvae and to identify the extracts compounds by gas chromatography-mass spectrometry (GC–MS) method of analysis. Leaves and fruits extracts used in concentrations, 25, 50, 100, 200, and 400 ppm against the 3rd larval instar of Cx. pipiens in five replicates and larval mortalities recorded after 24 and 48 h post exposure. The larvicidal potentials of extracts showed concentration dependent and varied between leaves and fruits extracts. At 400 ppm concentration, leaves extracts showed 100 % larval mortality except in hexane extract exhibited 98 %. Acetone, methanol, aqueous and hexane leaves extracts recorded LC50 values, 58.04, 70.20, 77.19 and 84.25 ppm, respectively. Fruits extracts by hexane and methanol exhibited 100 % larval mortality and LC50, 68.26 and 83.21 ppm, respectively, while, acetone and aqueous fruits extracts showed 98 % and 96 % larval mortality and LC50, 92.81 and 102.97 ppm, respectively. Terpenoids and sesquiterpenoids, fatty acid esters mainly identified in both extracts.The present study showed that extracts from Thuja orientalis leaves and fruits acquired promising larvicidal potential for the control of Cx. pipiens larvae with the role of their chemical constituents.

Keywords

• Thuja orientalis
• Methanol
• Acetone
• Hexane
• Aqueous
• Culex pipiens