Spatio-temporal distribution and mass-trapping of leopard moth, Zeuzera pyrina in walnut orchards

Abstract

Leopard moth Zeuzera pyrina L. (Lepidoptera: Cossidae) is a serious pest of walnut orchards in Iran. This study was conducted during two growing seasons, 2019 and 2020 in walnut orchards located in Ajabshir County, East Azarbaijan Province of Iran. At the beginning of the growing season, pheromone delta sticky traps (baited with female sex pheromone) were placed in the canopy of the treatment trees at 6 m above the ground (16 traps per hectare). The traps were checked weekly and the captured insects were counted and removed. Geostatistics was used to determine the spatial distribution pattern of male adults captured by pheromone traps. At the end of the growing season, damage of leopard moth larvae was assessed in 60 trees chosen from the control and treatment plots. Eight terminal branches were taken from each tree stratified in four cardinal directions (N, E, S, and W) and two canopy levels (upper and lower halves of the tree crown). The number of larval galleries in each sample was counted. The male trapping effect was not significant in the first year of the study, but it reduced leopard moth damage significantly in the second year (p < 0.01). Effects of cardinal direction, canopy level and their interactions were not significant on leopard moth damage (p > 0.05). The geostatistical analysis indicated that leopard moth male adults had random distribution at low populations, and were aggregated during flight peak with moderate to strong spatial autocorrelation. It can be concluded that distribution maps, prepared for spatially autocorrelated datasets, can be used for precision mass-trapping during the flight peak of leopard moth, as a safe method for the environment and natural enemies.