Chemical Profile, Antifeedant, Insecticidal Activities, and Some Biochemical Properties of Two Essential Oils, Cyperus and Jojoba, Against the Rice Weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

Abstract

This study aimed to evaluate the antifeedant and insecticidal activities of two essential oils, Jojoba and Cyperus, against the adults of the rice weevil Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and their impact on the activities of α-amylase and lipase enzymes, in addition to characterizing their chemical profile using GC-MS. The GC-MS analysis revealed that the major components found in Cyperus oil are alpha-linoleic acid (17.67%), linalool formate (12.30%), á- Ocimene (11.6%), and oleic acid (8.08%). whereas the major components found among 21 components in Jojoba oil are citronellol (17.95%), lemonol (9.88%), and (S)-citronellol acetate (7.40%). The insecticidal activity of Jojoba oil was significantly higher than that of Cyperus oil, with LC50 values of 485.0 and 1700.73 mg/g for Jojoba and Cyperus oil, respectively. The results of antifeedant activity generally showed that the antifeedant activity of Cyperus oil was higer than that of Jojoba oil, and these results clearly appeared in the activities of both tested enzymes, α-amylase, and lipase, in treated insects with LC50s of both oils, as the activities of them inhibited significantly compared to control, and this inhibition was more significant in the case of Cyperus oil.