LAUSR

Abstract Elm leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae) a pest of ornamental elms. Thyme, Thymus vulgaris (Lamiaceae) is an important medicinal. In this study, effect of Thymus vulgaris L. essential oil was tested on X. luteola in laboratory. The LC 30 and LC 50 values were estimated by leaf dipping method to third instar larvae (LC30 =2.065 and LC50 =4.237% W/V). The feeding efficiency was significantly reduced in treated larvae except the approximate digestibility (94.82 in control and 98.23 in treatment). The treated larvae showed a significant reduction key biochemicals. Reduced glucose and uric acid but increased protein level was seen. Severe reduction in ovarian texture both morphologically and histologically was observed which depicts a prolonged effect of the used EO on survivors. We believe that the thyme EO has the potential to be formulated for smaller scale trial to meet the needs of an environmental friendly compound.