INSECTICIDAL ACTIVITY AGAINST THE GREATER WAX MOTH (GALLERIA MELLONELLA L.) AND CHEMICAL COMPOSITION OF FIVE PLANT ESSENTIAL OILS

Abstract

In this study, the toxicity of four concentrations (5-10-15-20%) of five natural essential oils: Lavender (Lavandulaa ngustifolia: Labiatae) – Camphor (Eucalyptus globules: Myrtaceae) – Mint (Mentha spp.: Labiatae – Clove (Syzygiumaromaticum: Myrtaceae) - Rosemary (Rosmarinusofficinalis: Labiatae) against the third instar larvae of the greater wax worm, Galleria mellonella L. ( Lepidoptera : Pyralidae ) were evaluated as well as the mortality percentages were computed. Mortality percentages were high at rosemary oil treatments, followed by lavender, then mint, camphor and clove compared to control. In addition, LC50 were 7.11-9.45-11.45-13.61-6.45% for lavender essential oil - camphor - mint - clove - rosemary, respectively. The biochemical contents (total protein-alkaline phosphatase-acetylcholinesterase) were measured in the 3rd larvae treated with the tested essential oils. The obtained results indicated an increase in the total protein ratio in all the treatments compared with control. There was a decrease in the activity of alkaline phosphatase and acetylcholinesterase enzymes. The most effective essential oils were rosemary and lavender, compared to the control. The chemical composition of the tested essential oils was measured. The major compounds found in lavender essential oil, were linalool (38.74%) , linalool acetate (29.32%), D limonene (9.04%), triacetien(5.37%), 1.8- cineole (4.71%), camphor (2.82%), exoproneoleacetate (1.8%), a-pinene (1.79%),a- terpineole (1.43%), a-mycene (1.13%). Eucalyptus essential oil contains mainly 1.8-cineole (66.38%), 1-Limonene (16.27%). meanwhile Benzene, methyle (1-methylethyl) (7.44%), 1-phellandrene (4.25%), a-pinene (1.95%) a-terpinene (1.24%), and a-myrcene (1.16%). The major compounds in clove essential oil were trans-caryophyllene in relative concentration of 58.46%, phenol, 2-methoxy-4-(2-propenyl), humulene,1.8-cineole and eugenol were in relative concentration of 9.43%, 7.42%, 1.30%, and 1.87% respectively. the major compounds in mint essential oil were l-menthol in relative concentration (42.14%) ,1-menthone in relative concentration (27.08%) .carvone (8.90%), p-menthone (5.06%), pulegon (2.86%), 1-menthyle acetate (6.01%), and neo-menthol (2.10%). The major components in rosemary essential oil were glycerol triacetien (39.22%) ,1.8-cineole (16.82%), l-menthole (10.64%),a-camphor (8.71%), Pinene (7.16%), d-limonene (7.04%), and as for the minor compounds were p-cymene (1.17%), endobronyole acetate (0.91%), camphene (0.31%), delta 3-carene (0.39%), 1- broneole (0.13%) .