Chemical control of leopard moth Zeuzera pyrina in walnut orchards of Oskou and Azarshahr Counties

In this study, the possibility of chemical control against 1st instar larvae of leopard moth Zeuzera pyrina  using peak flight time of adults, was assessed in walnut orchards of East Azarbaijan province. For this purpose, three areas were chosen in walnut orchards of Oskou and Azarshahr Counties. Pheromone traps were used to determine the peak flight time of leopard moth. The trees were sprayed with chlorpyrifos, imidacloprid, chlorpyrifos + imidacloprid, chlorpyrifos + indoxacarb, chlorpyrifos + fenvalerate and chlorpyrifos + cypermethrin, 12 days to two weeks after the peak of flight. Unsprayed trees were considered as controls. For damage assessment at the end of the growing season, eight to 16 trees were chosen from the control and treatment plots based on the plot area. Eight samples were taken per tree stratified as four main directions (N, E, S, and W) and two canopy levels (upper and lower half of the tree crown). Each sample was a 60 cm branch terminal. The number of larval tunnels in each sample was counted and recorded separately. Chlorpyrifos + cypermethrin had the greatest effect in reducing the number of larval tunnels (90.75 %), and imidacloprid had the lowest effect (37.5 %). Chlorpyrifos, chlorpyrifos + fenvalerate, chlorpyrifos + indoxacarb and chlorpyrifos + imidacloprid caused 51.11 %, 87.65 %, 83.33%, and 79.44 % reduction in infestation compared to control, respectively. All chemical treatments had significant difference with control at 0.05 probability level. The results of this study showed that in high populations of the pest, the use of chemical insecticide can be recommended at the peak of the emergence of first instar larvae to reduce the damage.