Some Physiological Observations on Date Palm Fruits during its infestation by the date palm dust mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae)

Abstract

The current study aimed to survey the phytophagous tetranychid mite, Oligonychus afrasiaticus (McGregor) Tetranychidae in different regions of Egypt. Also, the effect of O. afrasiaticus infestation on the different components of date palm fruits was determined after one month of filed infestation. The results showed that the O. afrasiaticus appeared infested the date palm fruits in New -Valley, Giza, and Marsa Matruh Governorates only and disappeared from the other tested locations of Egypt. It was observed from the study that O. afrasiaticus infested Barhi Variety (Fresh) with a rare number in Sharq El-Ewinate region (New –Valley) only. On the other hand, Siwi variety (Semi-dry) infested with O. afrasiaticus on date palm fruits in Baharia Oasis (Giza Governorate), Siwa Oasis region (Marsa Matruh), El-Kharga Oasis and Dakhla Oasis region (New -Valley ). However, it was noticed that Samani and Zaghloul (Fresh varieties) did not infest with O. afrasiaticus during this study. The current study indicated that the protein contents were decreased when the fruits exposed to the infestation by O. afrasiaticus where it was recorded 18.6 mg/gm of fruits in infested fruits compared to 26.37 mg/gm in non-infested fruits. The highest level of carbohydrate content was (445.0 mg/gm) in non-infested date palm fruits. While the lowest carbohydrates level (308.0 mg/gm) was found when the date fruits exposed to mite's infestation. The obtained data showed that the nitrogen content of infested date palm fruits was 3.33 ug/gm of fruits but the recorded level of nitrogen in non-infested fruits was 4.37 ug/gm of fruits.The lowest content of phosphorus (3.1 µg/gm) was observed with infested fruits compared with 7.43µg/gm in the case of non-infested fruits. There were slight differences in potassium contents(7.16 and 7.83 µg/gm ) between infested and non-infested date fruits respectively,.The biochemical data revealed that the level of calcium contents was slightly differed (16.4 and 16.67 µg/gm) in date palm fruits infested and non-infested with mite individuals of O. afrasiaticus, respectively.