Bryobia rubrioculus (Scheuten)
Taxonomic placing: Acari, Prostigmata, Tetranychoidea, Tetranychidae.
Common name: Brown apple mite, brown mite.
Geographic Distribution: Almost cosmopolitan.
Host plants: Various Rosaceous fruit trees and grapevines.
Morphology: The adult body is about 0.8 mm long, red-brown (and sometimes green), somewhat flattened, the anterior part being brighter. The dorsum is striated, the striations running horizontally across the dorsum, which bears paler fan-like setae. The legs are reddish, the anterior pair is very long, about twice the length of other legs. The eyes are red. The larvae are bright red.
Life history: Overwintering (hibernating) eggs are placed on the bark, twigs and main branches of host trees whereas the summer eggs are laid on the foliage, especially along the main veins. When reared on sour cherry (Prunus cerasus L.) leaves, the threshold of development was calculated to be about 9.0ºC and 360 day degrees were required to complete a generation. The females, which are parthenogenetic deposited 15-20 (up to 35) eggs each, depending on the host, a generation required about 2-3 weeks, adult longevity is 1-2 weeks and about 4 annual generations are raised.
Economic importance: Bryobia rubrioculus is a serious pest of several Rosaceous fruit trees, like apple, cherry and plum. The mite feeds on young leaves and its damage appears as whitish-grey spots on their upper surfaces. Heavily infested trees may drop their leaves prematurely, which reduces tree productivity.
Monitoring: Weekly or monthly samples for following pest population trends can be taken by marking a circle on the bark around the bases of spurs connected to a branch and counting the different mite stages on all leaves of the buds and on the bark within the circle.
Plant resistance: Mites feeding on sweet cherry (Prunus avium L.) deposited the most eggs, whereas those infesting on sour cherry, plum and on apple produced 95% fewer eggs, indicating their relative tolerance. In addition, some sweet cherry cultivars did not support the survival of the pest. Apple cultivars also differ in their susceptibility to the pest.
Chemical control: Winter oils sprayed on apples during spring (“dormant treatments”) kill many of the overwintering eggs on bark and branches.
Biological control: The stigmaeid Zetzellia pourmirzai Khanjani and Ueckermann preys on B. rubrioculus on apple trees in Iran, and their populations showed a density-dependent relationship. Another stigmaeid, Zetzellia mali (Ewing), was the most abundant predator of B. rubrioculus in sprayed apple orchards in Turkey, whereas the phytoseiid Kampimodromus aberrans (Oudemans) kept the pest at very low levels in unsprayed orchards there.
References
Darbemamieh, M., Fathipour, Y., Kamali, K. 2011: Population abundance and seasonal activity of Zetzellia pourmirzai (Acari: Stigmaeidae) and its preys Cenopalpus irani and Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae) in sprayed apple orchards of Kermanshah, Iran. Journal Agricultural Science Technology 13: 143-154.
Honarparvar, N., Khanjani, M. and Bouzari, N. 2015. A study of some physiological features of sweet-cherry cultivars regarding the biological characteristics of Bryobia rubrioculus Scheuten (Acari: Tetranychidae). Biharean Biologist 9: 15-21.
Honarparvar, N., Khanjani, M. and Forghani, S.H.R. 2011: Effect of host on egg population fluctuation of brown mite, Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae). Biharean Biologist 5: 81-85.
Honarparvar, N., Khanjani, M., Forghani, S.H.R. and Talebi, A.A. 2012. Effect of temperature on development and fecundity of the brown mite, Bryobia rubrioculus Scheuten (Acari: Tetranychidae). African Entomology 20: 69–75.
Kasap, I. 2008. Life history of the brown mite Bryobia rubrioculus Scheuten (Acari: Tetranychidae) on two apple varieties in laboratory conditions. Journal of Turkish Entomology 32: 177–184.
Kasap, I. and Çobanoĝlu, S. 2006. Population dynamics of Bryobia rubrioculus Scheuten (Acari: Tetranychidae) and its predators in sprayed and unsprayed apple orchards in Van. Turkish Journal of Entomology 30: 89-98.
Osakabe, M., Ehara, S. and Adhikari, S. 2000. Damage to young leaves of pear trees by Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae) in Nepal. Journal of Acarological Society of Japan 9: 15–22.
Soleimani, M.A., Khanjani, M., Zahiri, B. and Khederi, S.J. 2015. Demographic characteristics of Bryobia rubrioculus (Acari: Tetranychidae) reared on sour cherry leaves at different constant temperatures. Persian Journal of Acarology 2: 221–238.
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