Amphitetranychus viennensis (Zacher)
(Formerly known as Tetranychus viennensis Zacher).
(More than a single species, one infesting apples and the other oaks (Quercus spp.), may be “hiding” under this name).
Taxonomic placing: Acari, Prostigmata, Tetranychoidea, Tetranychidae.
Common name: Hawthorn spider mite.
Geographical distribution: Europe, Middle East, Russia, India, China, Japan.
Host plants: Around 50 species, especially pome and stone fruits (Rosaceae).
Morphology: The females are dark red with white legs and a white gnathosoma,the body about 0,5-0.6 mm long. The peritremes anastamose distally. The aedeagus is bent sharply upwards.
Life cycle: Generation development usually requires about a fortnight. Each female lives for around 3 weeks, produces about 100 eggs that are placed on leaf surfaces and covered by thin webs. The females usually overwinter under the tree bark. The calculated threshold of development was estimated to be at 9.1°C and 185 day degrees were calculated to complete a generation. These data may differ on various host plants. In Iran the pest annually completes 3 generations.
Economic importance: An important pest of Rosaceaous fruit trees and ornamentals, and of concern to quarantine authorities in the USA. In Turkey it is one of the most important pests of apple and is widely distributed in all its growing areas. The mite often feeds on the terminal shoots, which results in leaf flecking, turning yellowish-grey and dropping. Fewer fruit buds are formed and the fruit is smaller in the same season, followed by fewer flowers and fruits in the next. Yield losses may reach up to 40% of the crop, especially in dry years.
Management
Modified atmospheres: Exposing mite-infested Apricots to elevated CO2 atmosheres (15%) at 46ºC killed all mites.
Chemical control: Various acaricides have been used against this mite. The economic threshold for applying acaricides to apples is when 4-5 individuals/leaf are seen during the first half of the vegetative period. During the second half of the growth period, the threshold is at about 7-8 mites/leaf.
Biological control: In various regions the pest is attacked by phytoseiids and stigmaeids. In Turkey they controlled the pest only in unsprayed orchard, but not in a sprayed orchard, presumably due to the excessive use of pesticides. The trombidiid Allothrombium pulvinum Ewing attacks the hawthorn spider mite in Iran.
References
Golpayegani, A. Z., Saboori, A., Nowzari, J. and Kamali, K. 2004. Biology of Amphitetranychus viennensis Zacher (Acari: Tetranychidae) in Baraghan region of Karaj, Iran. Acarologia 44: 69–71.
Goksu, M.E. 1968. Research on the biology and control of Tetranychus viennensis Zacher (Acarina: Tetranychidae) in the Region of Marmara. Plant Protection Bulletin 8: 194–213 (in Turkish with an English summary).
Gotoh, T. and Takayama, K. 1992. Developmental characteristics, genetic compatibility and esterase zymograms in three strains of the hawthorn spider mite, Tetranychus viennensis Zacher (Acari: Tetranychidae). Journal of The Acarological Society of Japan 1: 45-60.
Hosseini, M., Hatami, B., Saboori, A., Allahyari, H. and Ashouri A. 2005. Predation by Allothrombium pulvinum on the spider mites Tetranychus urticae and Amphitetranychus viennensis: predation rate, prey preference and functional response. Experimental and Applied Acarology 37: 173–181.
Kafil M., Allahyari, H. and Saboori, A. 2007. Effect of host plants on developmental time and life table parameters of Amphitetranychus viennensis (Acari: Tetranychidae). Experimental and Applied Acarology 42: 273–281.
Kasap, I. 2003. Life history of hawthorn spider mite Amphitetranychus viennensis (Acarina: Tetranychidae) on various apple cultivars and at different temperatures. Experimental and Applied Acarology 31: 79-91.
Son, Y.-R., Lee, J.-H., and Kim, Y.-G. 2012. Control efficacy of controlled atmosphere and temperature treatment system against the hawthorn spider mite, Tetranychus viennensis. Korean Journal of Applied Entomology 51: 131-140.
Yanar, D. and Ecevit, O. 2008. Species composition and seasonal-occurrence of spider mites and their predators in sprayed and unsprayed apple orchards in Tokat,Turkey. Phytoparasitica 36: 491-501.