Oligonychus afrasiaticus (McGregor)
Taxonomic placing: Acari, Prostigmata, Tetranychoidea, Tetranychidae.
Common name: Old world date mite. The date palm dust mite.
Geographical distribution: North Africa, Middle East to Iran and Saudi Arabia.
Host plants: Date palms, various grasses, and in Tunis, eggplants (Solanum melongena L.) and melons (Cucumis melo L.).
Morphology: The female is about 0.3 mm in length, pale-green and bears 13 pairs of simple setae.
Life history: The pest occurs on green dates only from around May to September, when the fruit begins to yellow and the the water content of the fruit is >84%. During that period they reproduce rapidly, raise very large populations and the sex ratio is strongly female biased (0.85). Their populations on the fruit decline as the water content decreases to below 75% and total soluble solids comprise 15%. The variety “Medjool” is infested almost two months earlier than “Deglet Noor”, with “Barhi” being intermediate. During the rest of the year the mites occur on various Poaceae {especially Bermuda grass, Cynodon dactylon (L.), sorghum and sugar cane} or, in very low numbers, on the palm fronds. The mite prefers hot, dry weather and may raise 10-12 annual generations in summer each within less than a fortnight. A female deposits 30-50 eggs, lives about 3-4 weeks in summer, several months in winter. The pest is dispersed by winds and possibly by insects and by fruit-eating birds.
Economic importance: The mites feed on the green date fruit, covering the bunches with dense webbing that hinders photosynthesis and accumulates much dust. Infested fruit become reddish, produce gum-like exudations, shrivel and may split, greatly reducing their market value. Heavy infestations can lead to partial or total yield loss..
Management
Horticultural control: Intercropping, weed control, bunch covering, irrigation, tillage and the removal of infested bunches decreases pest infestations in Iran. Water sprays provided almost total mite control in Iran.
Chemical control: Dustings with sulphur and sprays with the carbamate fenbutatin oxide and with abamectin kill the pest, as do sprayes of organophosphates. By killing the natural enemies of other date palm pests, these pesticides should be avoided as much as possible. Various plant extracts also provided good pest control.
Biological control: A few predators of the families (Phytoseiidae (especially Cydnoseiusand negevi) and Coccinellidae are associated with the pest, but only few during the critical mid-summer period.
References
Arbabi, M. (and 6 co-authors) 2017. Evaluation of different treatments in control of Oligonychus afrasiaticus in date palm orchards of Iran. Persian Journal of Acarology 6: 125-135.
Ben Chaaban, S. and Chermiti, B. 2009. Characteristics of date fruit and its influence on population dynamics of Oligonychus afrasiaticus in the southern of Tunisia. Acarologia 49: 29-37.
Ben Chaaban, S., Chermiti, B. and Kreiter, S. 2011. Oligonychus afrasiaticus and phytoseiid predators’ seasonal occurrence on date palm Phoenix dactylifera (Deglet Noor cultivar) in Tunisian oases. Bulletin of Insectology 64: 15-21.
El-Shafie, H.A.F. 2019. An upsurge of the Old World date mite (Oligonychus afrasiaticus) in date palm plantations: possible causes and management options. Outlooks on Pest Management 30: 13-17.
Fetoh, B.E.-S, and Kholoud A. Al-Shammery, K.A. 2011. Acaricidal ovicial and repellent activities of some plant extracts on the date palm dust mite, Oligonychus afrasiaticus Mcg. (Acari: Tetranychidae). International Journal of Environmental Science and Engineering 2: 45-52.
Gharib, A. 1967. Paratetranychus (Oligonychus) afrasiaticus (McGregor) (Tetranychidae). Entomologie et Phytopathologie Appliquees 26: 27-30, 44-53 (in Persian with a French summary).
Hussain, A.A. 1969. Biology of Paratetranychus afrasiaticus McGr., infesting date palms in Iraq. Bulletin de la Societe Entomologique d’Egypte 53: 221-225.
Latifian, M., Rahnam, A.A. and M. Amani, A. 2014. The effects of cultural management on the date spider mite (Oligonychus afrasiaticus McG) infestation. International Journal of Farming and Allied Sciences_ 3: 1009-1014.
Nasser H. Al-Dosary, N.H. 2010. Evaluate efficiency of some insecticides and sticker color traps to protect date palm fruits infested by date mite Oligonychus afrasiaticus (McGregor) and the lesser moth Batrachedra amydraula (Merck). Basrah Journal of Agricultral Sciences 23: 1-22.
Palevsky, E., Borochov-Neori, H. and Gerson, U. 2005. Population dynamics of Oligonychus afrasiaticus in the southern Arava Valley of Israel in relation to date fruit characteristics and climatic conditions. _Agriculture and Forest Entomology _7: 283-290.
Palevsky, E., Ucko, O., Peles, S., Yablonski, S. and Gerson, U. 2004. Evaluation of control measures for Oligonychus afrasiaticus infesting date palm cultivars in the Southern Arava Valley of Israel. Crop Protection 23: 387-392.
Websites
http://www.iraqi-datepalms.net/uploaded/file/magazinedatepalms115.pdf