Toxicity and enzymatic activity changes in rice weevil (Sitophilus oryzae) induced by basil (Ocimum basilicum) and cumin (Cuminum cyminum) essential oils

Abstract

<title>Abstract</title> Background The rice weevil <italic>Sitophilus oryzae</italic> is a common and severe pest of stored products that cause great losses of seeds. Application of essential oils from many plants is very important approach for pest control. Results In this study, the toxicity of two natural essential oils, cumin (<italic>Cuminum cyminum</italic>) and basil (<italic>Ocimum basilicum</italic>), was evaluated after three different exposure times at different doses. Gas chromatography/ mass spectrometry (GC-MS) showed that the major constituents of <italic>C. cyminum</italic> essential oil were procanal (26.07%) and ˠ- terpinene (15.78%), whereas linalool (56.7%), cadinol, epi-α (11.4%) were the major compounds in <italic>O. basilicum</italic>. Toxicity results showed that cumin essential oil was most effective with LC50 of 11.04, 8.51 and 6.61 mg/ml compared to 21.91, 15.59 and 9.94 mg/ml for basil essential oil after 24, 48 and 72 h of exposure. Additionally, the total protein content and enzymatic activity of glutamic oxaloacetic transaminase (GOT), Alkaline Phosphatase (ALP), α-amylase, and acetylcholinesterase (AChE) were measured. The results showed that the LC50 values of both tested essential oils had no significant effect on all tested enzymes, except for ALP and GOT. Conclusions cumin essential oil was most effective with LC50 of 11.04, 8.51 and 6.61 mg/ml so, it can be used to control rice weevil (<italic>Sitophilus oryzae</italic>).