Chemical composition and insecticidal activity of essential oil from Ziziphora clinopodioides Lam. used against the Mediterranean flour moth, Ephestia kuehniella Zeller

Abstract

The Mediterranean flour moth, Ephestia kuehniella Zeller, is a major pest of stored grain products, particularly flour. There have been major concerns over the application of conventional insecticides in stored products, which have strongly demonstrated the need for applying such alternative safe compounds as essential oils. The aim of the present study is to investigate the chemical composition and fumigant toxicity of essential oil from Ziziphora clinopodioides Lam. against the eggs, larvae, and adults of E. kuehniella. All toxicity tests were carried out under laboratory conditions set at 26±1°C and 70% relative humidity (RH). The results of gas chromatography-mass spectrometry (GC/MS) analysis indicated that the essential oil extracted from the leaves of Z. clinopodioides, is rich in pulegone (49.4%), piperitenone (10.7%), menthone (8.9%), and 1,8-cineol (6.9%). Based on the bioassay results, the LC50 value of the tested oil was estimated to be 54.61 μl·l-1 air for larvae and 1.39 μl·l-1 air for adults. Also, it is shown that increasing the oil concentration resulted in a significant increase in oviposition deterrency as well as a considerable reduction in the egg hatching percentage. These results suggest that Z. clinopodioides oil could be a potential candidate as a fumigant for managing E. kuehniella in stored products.