Persian Journal of Acarology

Abstract The yellow date palm mite, Oligonychus afrasiaticus (McGregor), commonly known as “Boufaroua” in North Africa, is one of the most destructive pests affecting date palm production in the Ziban region of southeastern Algeria. Despite its economic importance, limited information is available on the ecological role of spontaneous weed flora in maintaining mite populations and facilitating seasonal infestations of date palms. Therefore, the present study aimed to identify weed species that may serve as alternative hosts of O. afrasiaticus, to determine their contribution to the seasonal persistence of the mite, and to evaluate how seasonal plant phenology and spatial variation among palm groves influence infestation dynamics. A six-month field survey was conducted from February to July 2021 in seven representative palm groves of the Ziban oases. The occurrence of O. afrasiaticus was monitored on date palms and associated weed species in relation to seasonal dynamics and spatial variation among sites. The mite was detected in all surveyed groves, with infestation intensity varying according to microclimatic conditions and grove management practices. Among date palm cultivars, Deglet Nour exhibited the highest susceptibility. A total of 76 weed species were recorded, of which five species (Cynodon dactylon, Daucus carota, Aster squamatus, Kochia scoparia, and Salsola tetragona) were confirmed as alternative hosts capable of sustaining mite populations. Infestation patterns showed a clear seasonal progression, with early establishment on herbaceous weeds during spring followed by a shift toward date palms under hot and dry summer conditions. These findings demonstrate that weed communities play a significant ecological role in the persistence and spread of O. afrasiaticus within oasis agroecosystems and highlight the importance of integrating targeted weed management into integrated pest management strategies for sustainable date palm protection.

Abstract The data on abundance showed that the incidence of Raoiella indica and Stethorus keralicus was highest on Barhee and lowest on Anand TC variety, while moderate incidence was observed on KCCL-169. The incidence was observed throughout the year 2020–21 and 2021–22. The highest population was recorded in June and it was lowest during December. Among the four directions, maximum population was recorded from south and lowest from east throughout the year. Correlation studies revealed that S. keralicus, maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity, wind speed and evaporation showed highly significant positive correlation with incidence of R. indica, while, rainfall and rainy days showed non-significant positive correlation. However, bright sunshine hour exhibited non-significant negative correlation with incidence of R. indica. These results clearly showed that natural enemies are density-dependent and have a close association with R. indica population.

Abstract The date spider mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae) is a destructive pest on date palm trees, causing high economic losses. Here, we investigated the relationship between population density of O. afrasiaticus and the extent of its injury level as well as the relation between rate of damage and date yield losses indices on six commercial date cultivars in five date palm growing provinces including Khuzestan (Sayer and Berhee), Hormozgan (Pyarum), Kerman (Mazafati), Bushehr (Kabkab), and Sistan and Baluchestan (Rabi) of Iran. The experiment was conducted in a complete randomized block design with five treatments and three replications. To this end, in each replication, four date clusters were selected from four different geographical directions, in each of them, 25 fruits were checked randomly to unveil the number of healthy and infested fruits. The sampling was repeated at seven-day intervals from late May to early September. Finally, the Norton model was used to estimate the economic injury level (EIL) under both biological and chemical control conditions. The highest value of EIL in 2019 was estimated for Sayer in the chemical control method (1827 Mite-day) and the lowest one was estimated for Pyarum in the biological control method (25.5 mite-day). Our results also revealed that the cost of biological control was significantly lower than chemical control. The highest and lowest rate of date injury (symptoms of the pest feeding) were observed on Berhee and Mazafati cultivars, respectively. Also, the highest and lowest rate of date loss were observed on Kabkab and Sayer cultivars, respectively. On the other hand, the cost of chemical control in both years was higher than that of biological control.