تاثیر زمان تکریب و هرس قاعده دمبرگ‌ها در کاهش جمعیت آفات چوبخوار خرما Oryctes spp. (Col.:Scarabaeidae) و Jebusaea hammerschmidti (Col.: Cerambycidae) در استان بوشهر

Date palms of Bushehr province with 34 thousand hectares is exposed to serious damage and threat of long horned beetle (Jebusaea hammerschmidti (Reiche)) and rhinoceros beetles (Oryctes elegans & O. agamemnoon). In IPM programs of these pests, timely and correct pruning and trimming of the dry petioles base can lead to the elimination of a part of the pest population, especially their larval stages. This study was conducted to determine the most effective time of pruning and the seasonal trimming of the petioles on pest population reduction in four orchards with similar infested conditions in Dashtestan during 2022-2023. First orchard was autumn trimming (November and December2022), second orchard was trimming winter (December and February2022-2023), third orchard was trimming spring (April and May2022), and fourth orchard was without pruning and any control measures. The number of larvae, pupae and adults of both pests removed from inside the base of the removed petioles in 1meter of long trunk of 10trees from each orchard randomly counted and recorded as an indicator of the pest population reduction. Furthermore, a light trap 10Watt LED AC installed in each orchard during June and July2022 & 2023 synchronize of the adult emergence peak and counted and recorded the number of adult/trap before and after the trimming weekly. The results showed that the mean number of pest deaths inside the removed petioles base in 1meter long trunk in autumn trimming for horned beetles and rhinoceros beetles were 7.2, 5.6 respectively, in winter trimming 9.4, 8.6 and in spring trimming 19.5, 13.7. The number of adult/trap of Oryctes spp. and J. hammersechmidti was reduced after fall trimming about 26 and 39% respectively, in winter trimming 32 and 44%, in spring trimming 41 and 58% and in the orchard without trimming 9 and 11% compared to before. Also, the studies showed that cutting the base of the petioles with a cutting angle of less than 30 degrees from the vertical surface of the tree trunk compared to the cutting angle of 60 degrees from the vertical surface of the trunk, was 15 to 20% more effective in the loss of larvae and reducing the population of these pests.Due to the removal of more volume of the petioles base as the survival and oviposition sites of these pests, more numbers of different biological stages of the pests, especially the larvae were removed and died. Based on the biology of these pests, in the spring season a large number of larvae move to the back and inside the petioles base to turn into pupae and adult. Therefore, in spring trimming, addition of mechanical removing a large population of larvae, the activity and catch rate of adults of pests decreased compared to before.