Chemical composition and insecticidal effects of Citrus aurantium essential oil and its powdery formulation against Tuta absoluta. Zarrad, K., Chaieb, I., Ben Hamouda, A., Bouslama, T., and Laarif, A. (Tunisia)

Abstract

The aim of this research was to investigate the chemical composition and to evaluate the insecticidal activities of the bitter orange Citrus aurantium essential oil and its major compound pure limonene against adults and larvae of the tomato miner Tuta absoluta using contact and fumigation bioassays. Results of chemical analysis of the essential oil using gas chromatography/mass spectrometry (GC-MS) revealed the presence of limonene (87.52%), β-myrcene (1.62%), α-pinene (0.56%) ß-ocimene (0.81%) and ß-pinene (0.61%) as major components. For bioassays, results indicated that both the oil and its major compound were found to be toxic to larvae and adults. In the fumigant assays, median lethal concentrations (LC50) were 10.65 and 37.36 µl/l air respectively for C. aurantium essential oil and pure limonene. In contact toxicity assay, the tomato miner adults were more susceptible to the oil than to its major compound even at the lowest concentration: LD50 values obtained after 48 h were respectively 0.21 and 0.73 µl. When insects were treated with the essential oil and its aromatized clay powder, significant differences in insect mortality were recorded depending on exposure time. The aromatized clay powder was more toxic (LT50 = 101.8 h) than the pure essential oil (LT50 = 146.32 h). Hence, bitter essential oil was found to be toxic for T. absoluta, and the clay powder could be used to stabilize the essential oil to increase its efficacy and possibly will be used as source of new eco-friendly insecticidal compounds.

Keywords

• Aromatized powder
• biopesticide
• Citrus aurantium
• essential oil
• pure limonene
• Tuta absoluta