بررسی خسارتزایی حشرات کامل سوسک کرگدنی(Coleop.: Scarabeaidae) elegans Prell Oryctes به خوشه‌های جوان در نخلستان‌های شهرستان دشتستان استان بوشهر

Date palm fruit stalk borer, Oryctes elegans Prell (Coleop.:Scarabeaidae) is a key pest in date palms of Bushehr province. In addition of sever larval damage, adults cause damage in the crown of trees by feeding on spathe, frond bases young leaves, and stalk of clusters and then breaking them. Field studies was conducted for investigation the damage status caused by adults of O. elegans to the spathe and young cluster stalks in date palms in two regions of Dashtestan, Bushehr province, from March 2021 to mid-June 2024, from starting of pollination activity until late cluster arrangement. The studies were 3 visits per week from at least 40 orchards and each orchard 20 fruitful trees and sampling and counting of healthy and damaged clusters of each tree. Based on the results,adults damage to young clusters was observed in both central and Bushkan(Kelemeh) regions and the average age of the damaged trees were between 25 and 40 years with 4-6m height. In addition of Kabkab and Zahedi(Qasb) cultivars, the pest damage observed on other native cultivars such as Shahabi, Berimi, Sheikh Aali, Shekar, Qandi, and Gantar. However, the most damage in Bushkan region was on the Zahedi and Kabkab cultivars and in date palms of the central region, on Kabkab, Shahabi and Zahedi cultivars respectively. On average about 15-20% of the visited trees, had one to three damaged cluster. Therefore, according to the average number of clusters in each palm (10 in Zahedi, Haj Bagheri and Berehi) and (6-8 in Kabkab, Shahabi and other cultivars), the average of yield reduction caused by only adults to the fruit or clusters in these regions was about 4-5% per tree. Also it was determined that adults prefer the early spathe and larger clusters and feeding along cluster stalk by digging a tunnel and creating sawdust and leads to breaking the cluster. In The direction of feeding and tunnel digging by adults in all cases of damaged clusters, was from the base of the cluster stalk to the outside and in some cases, its length was more than half of the stalk of the cluster. In the date palms orchards that had done continuous installation of light traps, pruning and garden cleaning, the intensity of pest infestation and damage reduced considerably than other orchards without control measures.