Bryobia redikorzevi Reck - Brown Fruit Mite
Systematic position.Class Arachnida, order Acariformes, superfamily Tetranychoidea, family Bryobiidae, genus Bryobia. In foreign literature the Brown Fruit Mite is mainly known as Bryobia praetiosa Koch. According to Livshits (1960) Bryobia redikorzevi is a widely distributed species of the B. praetiosa species group.
Synonyms.Bryobia arborea Morg. et Anders.
Biological group.It is a pest of apple and plum mainly, and of pear, peach, blackthorn, cherry, apricot and almond to a lesser degree.
Morphology and biology.The life cycle of mites includes stages of egg, larva, protonymph, deutonymph, and adult. Phases of dormant and molt occur between post-embryonal stages. Female body is oval, flattened dorsally, convex ventrally, greenish- or reddish-brown. Body length is 0.58-0.65 mm; body width is 0.4-0.46 mm. Propodosoma has 4 prominences above gnatosoma. It has piercing and suctorial mouthparts. 32 fan-shaped setae in 7 transversal rows are located on dorsal side of body. Legs are slender, rather thin. The first pair of legs is extended forward, being approximately equal to body length. The other 3 pairs of legs are thicker and shorter. Male body is more elongated, slightly narrowed posteriad, yellowish- or reddish-brown. Body length is 0.3 mm; width is 0.22 mm. Inner propodosomal prominences are sometimes fused. 32 lanceolate and 4 narrow setae are located in 8 transversal rows on dorsal side of body. Males do not occur very often, so reproduction is mainly by parthenogenesis. Female starts to lay eggs 2-3 days after emergence, and then it lays 1-2 eggs every day for its entire life. Fertility is about 20-30, maximum to 45 eggs. Eggs spherical with smooth surface; the fresh ones are vermilion and brilliant, later they become dark-red. Diameter of egg is 0.15 mm. Larva is orange-red, round, without frontal propodosomal prominences, and with 3 pairs of legs. Body length is 0.24 mm; body width is 0.17 mm. Protonymph is larger, greenish-brown, with frontal propodosomal prominences and 4 pairs of legs. Legs thickened, shorter than body. Deutonymph has oval body with propodosomal prominences. Body length is 0.42 mm. Deutonymph differs from the adult insect by having shortened forelegs and absence of genital aperture.
Distribution.It is widely distributed throughout the northern hemisphere between latitudes 60 and 20 degrees N mainly, within the zone of cultivated and wild rosaceous fruit plants. Damage is reported in Europe, Turkey, in Northern and Southern Africa, in Canada and the USA. It is known from Argentina, Uruguay, Australia, New Zealand, absent in tropics. It inhabits all republics of the former USSR including Russia (from the western borders east to Altai Region, and locally in Primorskii Territory).
Ecology.The major host plants belong to the Rosaceae family. The pest grows up to 2000 m above sea level. The temperature threshold of its development is about 7.2°C; degree days for the development from egg to adult is about 325-352°, of which about 47% is necessary for embryonic development. One generation develops in 20-41 days. In Crimea up to 6 generations develop from the end of March until the end of the 2nd third of September. The species hibernates during the stage of egg on bark of branches and under exfoliating bark of trunks. Hibernating eggs appear during the first generation of mites. Eggs of summer generations are laid on the underside of leaves, rarely on its upper side or on leafstalk. Larva hatching coincides with the blossoming of buds. Mites aggregate mainly in the lower and central parts of tree crone. They prefer the upper sides of leaves that have weak pubescence, but hide on underside of leaf during rain. A specific feature of this pest is the absence of a web on damaged leaves. Mites are more numerous in gardens with turf-covered ground, being less numerous in gardens with plowed ground. Population density in nature depends on the activity of predators, e.g.: Typhlodromus reticulatus Oud., Phytoseius spoofi Oud., Scolothrips acariphagus Jakh., Chrysopa carnea Steph., Coccinella septempunctata L.
Economic significance.Mites pierce the epidermis of leaves by chelicerae and suck cell plasma. In the beginning the leaves are injured at base and along veins. Injured leaves become yellowish on sweet cherry, grow brown on apple, and get marble colored on plum and cherry plum. Mites cause early dropping of leaves and abscission of ovaries. Yield loss for apple trees reaches 20-50%. Early-ripening varieties of apple are more strongly injured. Cultivation of resistant varieties of fruiters, inter-row plowing and whitewashing of tree trunks are important preventive control measures against the B. redikorzevi. Control measures include ovicide treatment in spring during the hibernation of buds, or acaricide treatment during the period of bud blossoming.
Reference citations:Bagdasaryan A.T. 1957. Fauna of the Armenian SSR. Tetranychid mites (Superfamily Tetranychoidea). Yerevan: AN Armenian SSR. 163 p. (In Russian)
Batiashvili I.D. 1959. Pests of continental and subtropical fruit crops. Tbilisi: Institut sel'skogo khozyaistva. 455 p. (In Russian)
Livshits I.Z. 1960. Brown fruit mite (Bryobia redikorzevi Reck, 1947). Systematics, morphology and biology. Pests and diseases of fruiters and decorative plants. Proceedings of the Nikitsky bot. garden (Yalta), 33: 3-76. (In Russian)
Livshits I.Z., Mitrofanov V.I. 1973. A contribution to the fauna and biology of tetranychid mites of the Crimea (Acariformes, Tetranychoidea). Proceedings of the 3rd international congress of the Acarology. Prague: Academia. 229-235 p. (In English)
Livshits I.Z., Mitrofanov V.I. 1984. Order Acariformes. In: Kopaneva L.M., ed. Keys to harmful and useful insects and mites on the fruiters and berry crops in the USSR. Leningrad: Kolos. 288 p. (In Russian)
Mitrofanov V.I., Strunkova Z.I., Livshits I.Z. 1987. Keys to the tetranychid mites (Tetranychidae, Bryobiidae) fauna of the USSR and adjacent countries. Dushanbe: Donish. 224 p. (In Russian)
Prokof.ev M.A. 1987. Siberian orchards protection against pests. Moscow: Rossel.khozizdat. 239 p. (In Russian)
Reck G.F. 1959. Keys to tetranychid mites. Tbilisi: AN Georgian SSR. 151 p. (In Russian)
Reck G.F. 1976. Catalogue of Acariformes of the Georgian SSR. Tbilisi: Metsniereba. 128 p. (In Russian)
Savkovskii P.P. 1976. Atlas of pests of fruit and berry plants. Kiev: Urozhai. 207 p. (In Russian)
Sazonov A.P., Burov V.N., Sundukova N.E., Mokrousova E.P., Kolesova D.A., Zolotov L.A., Voinyak V.I., Pristavko V.P., Chernii A.M., Petrushova N.I., Medvedeva G.M., Matvievskii A.S., Maksimova V.I., Atanov N.M., Gummel R.M. 1991. Technology of practical application of biologically active compounds in the IPM on fruit and vegetable cultures against pests (recommendations). Moscow: VASKHNIL. 32 p. (In Russian)
Strunkova Z.I. 1968. Biology and ecology of the brown fruit mite (Bryobia redikorzevi Reck) in Central Tajikistan. Izvestiya AN Tadzhikskoi SSR (Dushanbe), 3(32): 42-54. (In Russian)
Vasil'ev V.P., ed. 1973. Pests of agricultural crops and forest plantations. V. 1. Kiev: Urozhai. 496 p. (In Russian)