Insecticidal activity of ethanolic extract and essential oil of Croton hirtus L' Hér on Amitermes evuncifer Silvestri

Abstract

Pests control has historically relied on the use of synthetic pesticides. Due to the recognized hazards these pesticides pose to both human health and the environment, there is a growing demand for alternative solutions such as the use of biopesticides. This study aims to assess the termiticidal efficacy of extracts derived from the plant Croton hirtus on the termites Amitermes evuncifer. The investigation also includes a phytochemical analysis of the ethanolic extract and a Gas Chromatography/Mass Spectrometry (GC/MS) analysis of the essential oil (EO) of C. hirtus. The termiticidal activity of C. hirtus extracts was evaluated through a contact approach involving A. evuncifer workers placed in Petri dishes. Five concentrations of the ethanolic extract and 4 concentrations of the essential oil were employed. The phytochemical analysis of the ethanolic extract of C. hirtus showed the presence of terpenes, reducing sugars, flavonoids, and sterols. Furthermore, by GC/MS analysis of the EO, caryophyllene (25.48%), germacrene-D (24.19%), 𝛽𝛽-elemene (8.25%), and α-humulene (7.69%) were identified. When tested, all concentrations of the extracts led to a reduction in the survival time and life expectancy of termites. Notably, the concentration of 4.7 mg/cm 2 of the extract resulted in a complete termite mortality rate within approximately 0.83±0.26 days, while the concentration of 0.3 µL/cm 2 of the essential oil caused a total mortality in approximately 2.50±0.55 days. These findings demonstrated that Croton hirtus extracts could be promising tools in the control of termites in an integrated pest management.