Identification of the oak seed insects and determination of its damage on Persian oak (Quercus brantii Lindl) at different altitudes of Ilam oak forests

The acorn (oak nut) is attacked by Coleoptera and Hymenoptera and another insects before and after falling from trees to ground surface because of large food capacity. This study has been done to investigate the effect of pests of acorn damages on regeneration of Persian oak (Quercus brantii Lindl) in Arghavan valley oak forests of Ilam city in west of Iran. For this purpose, acorns from south direction at different elevation classes in six oak forest sites were collected. The collected acorns transferred to the laboratory and their weights were measured with digital scale and they were placed in some special plastic containers in order to overwinter the acorn-eating pests. Also a number of infected and infested acorns were planted in the nursery in order to study the effect of pests on their germination potential. The results of study showed that in the study area, two oak nut pests, Curculio glandium Marsham and Cydia fagiglandana Zeller caused damages to acorns. The precent of C. glandium damages was higher than C. fagiglandana. Percentage of C. glandium damage was 71.9% and C. fagiglandana damage was 28.1%. The highest infestation rate was on algae pests at 1900 m above sea level elevation, and the lowest at 1700 meter altitude. The falling acorns have highest percent of infection than the acorns which still remain on tree branches. Germination percentage of healthy seeds was 74.8% and germination percentage of infected seeds was 25.2%. The results of planted nuts showed that infected seed had much lower germination potential than healthy nuts. The percentage of contaminated seeds under the trees was 60.4% and the infected seeds on the crown of trees were 39.6%. Also, healthy seeds had more weighted mean (α=5%) than contaminated seeds. So in planting oak seeds we could avoid the seeds with any sign of pests that collected from high altitudes.