author(s)
Gürkan Semiz

abstract
Pine processionary moth (Thaumetopoea wilkinsoni Tams.) is the most important defoliator in the Meditterrenean Basin. Larval defoliation of this pest results in decreasing the annual diameter increment of host trees. Defoliated trees can become highly prone to the incidence of secondary insects. Plant natural products have received a great attention from scientific world as they serve as a rich source for novel compounds possessing insecticidal properties. In this study, the crude aqueous extracts of Nerium oleander leaves were reported for larvicidal activity against the Thaumetopoea wilkinsoni. Third and fourth instar mortality from eight concentrations (62.5, 125, 250, 500, 1000, 2000, 4000 and 8000 ppm) of plant extract were recorded and mortality was observed in 0, 24, 48, 72 and 96 hours. Aqueous leaf extract exhibited highest larvicidal activity with a LD50 value of 322.50 ppm and 190.00 ppm after 24 and 48 hours respectively. Further detailed investigations are needed to clarify this activity against pest species and also the active ingredient(s) should be identified. This study is the first to report on the larvicidal activity of leaf extracts of N. oleander against T. pityocampa.