بررسی کارایی جدایه بومی نماتد بیماری‌زای حشرات Steinernema carpocapsae IRMoghan1(Rhabditida; Steinernematidae) روی سرخرطومی حنایی خرما Rhynchophorus ferrugineus

Red palm weevil (RPW) Rhynchophorus ferrugineus Olivier (Coleoptera: Dryophthoridae) is one of the most important and dangerous pests of date palms. In Iran, due to the spread of this quarantine pest in different regions of the country in the recent years, the groves have faced a serious problem and the risk of destruction. Entomopathogenic nematodes are valuable agents of biological control that have shown high efficiency in controlling various pests, especially pests that operate in soil or hidden habitats. These nematodes are successfully used in different parts of the world against RPW. In this study, the efficacy of S. carpocapsae IRMoghan1 against late instar larvae of RPW was evaluated in the laboratory. The bioassay was performed with a concentration of 720 infective juveniles (IJ) Larva-1 using filter paper contamination method and the control received distilled water instead of nematode suspension. In a separate experiment, one kilogram of pest-infested palm tissue (containing five last instar larvae of R. ferrugineus) was treated with the nematode. In both experiments, 72 hours after treatment, mortality was recorded. To investigate the possibility of survival of the nematode IJs within the plant tissue, two two-year-old date palms (100 cm in height and 50 cm in diameter) infested with the pest were selected in the Manujan region and the nematode was injected into the trunks of the palms through four holes. After 10 days, the trunks were removed and the trunk tissues were washed and examined for the presence of live IJs. The results of the filter paper contamination method bioassay showed 70% mortality of the RPW larvae. The treatment of infested palm tissue resulted in 40% mortality of the insect larvae. The examination of the trunks showed the presence of live nematodes in both trunks 10 days after the injection. Emphasizing the foraging behavior of S. carpocapsae (benefits from both ambusher and cruiser strategies), the results of the study showed that the native entomopathogenic nematode isolate is promising in controlling R. ferrugineus, however, more and detailed investigations are needed.