|Crop Knowledge Master|
Steneotarsonemus pallidus (Banks)
Ronald F.L. Mau, Extension Entomologist
Jayma L. Martin, Educational Specialist
Department of Entomology
The cyclamen mite mainly attacks ornamental crops, but also infests some field crops and shrubs. Cyclamen is the most often infested ornamental plant. Other ornamental plants attacked by this mite include African violet, begonia, chrysanthemum, fuchsia, geranium, ivy, larkspur, petunia grown in greenhouses, pikake and snapdragon. Field crops attacked by the cyclamen mite are banana, field-grown strawberries and watercress.
This mite is widely distributed throughout the world including parts of Asia, Europe, Hawaii and North America (Jeppson et al, 1978). The cyclamen mite is present on Kauai, Maui and Oahu.
General damage by this mite includes irregular deformities of growth pattern, rosette type growth, irregular fruit or leaf growth, and even the total destruction of the growing tips (this symptom rarely occurs) (Jeppson et al., 1975). Buds and young tissues may become chlorotic. When the mite feeds on partially developed leaves the damaged tissues stop growing while the healthy tissues continue to grow causing distorted leaf patterns (Jeppson et al., 1975). These damage symptoms are similar to that caused by certain other mites and may also be caused by virus diseases, systemic toxins injected by mites or feeding by other plant pests (Jeppson et al., 1975). Identification of the causal agent is important.
In 1956, this mite severely infested pikake fields in Honolulu such that there was no production of flowers for leis. The mite feeds on developing shoots and flower buds causing both to be distorted and abnormally small at maturity (Haramoto and Boyle, 1958). In high infestations, the leaf bud can be completely destroyed. Infestation by this mite results in fewer flowers per cluster and often the complete abortion of the flower cluster (Jeppson et al., 1975).
On strawberries, mite feeding causes a roughened, wrinkled appearance of upper leaf surfaces, irregular folding and fluting of the leaf margins, and "blistered" veins (Jeppson et al, 1978). Mild infestations result in plants with a dense appearance because the leaf petioles fail to elongate and coppery-bronze appearance to the leaf where mild feeding has occurred (Dustan and Matthewman, 1932). Severe infestations produce plants with small, unopened leaflets and a dwarfed crown. Small leaflets have a hard, brittle texture and become pale yellowish green and turn brown or silvered when the undersides of the leaves are exposed to the sun (Jeppson et al., 1975). Infested young fruit and flowers are brown near the base and turn black and dry in severe cases (Dustan and Mattewman, 1932).
Unless African violets are examined carefully at frequent schedules, the cyclamen mite can be overlooked and result in leaf curling and leaf drying (Denmark, 1977).
Infestations on gerbera results in bronzed patches along the leaf midribs and slight curling of the leaves. Attacked flower buds develop into deformed flower rays that are unmarketable (Boyle and Haramoto, 1956).
The life cycle from egg to adult takes 2 to 21 days (Smith and Goldsmith, 1936). Optimum conditions for the development of the cyclamen mite are when the temperatures range between 60û to 80û F and the relative humidity is 80 to 90 percent (Pritchard, 1949).
The mites live and reproduce between the imbricated young leaves at the shoot apex (Haramoto and Boyle, 1958). This species commonly reproduces parthenogenetically (without male fertilization of the female), but may reproduce sexually.
In temperate regions egg laying decreases in August and stops in October. Cyclamen mites overwinter as adults (Jeppson et al., 1975). In Hawaii, where winters are mild, there is no overwintering and reproduction and generations are continuous throughout the year. Developmental rates vary with temperature.
Eggs are relatively larger than found with other tarsonemid mites. The cyclamen mite egg is about half the size of the adult female. It is elliptically shaped, opaque white, and has a smooth surface. Eggs are usually laid in clusters, or sometimes masses two or three eggs deep in the folds of the leaf bud (Jeppson et al., 1975). The immature mite may be seen through the thin egg shell. Eggs hatch in 3 to 7 days at a 77û F (25û C) (Garman, 1917).
The immature stage is opaque white, almost transparent, and has six legs. At the posterior end of the body is a triangular enlargement (Jeppson et al., 1975). The larval stage lasts 1 to 4 days (Smith and Goldsmith, 1936).
There is no molt between the larval and pupal stages. The pupa stage is characterized by a resting or quiescent stage of the larva. During this period the larvae are engorged, motionless, white and clumsy looking (Dustan and Matthewman, 1932). Adults emerge in 2 to 7 days (Smith and Goldsmith, 1936).
This is one of the smaller mites that attacks ornamental plants. The male is about 3/100 inch (0.75 mm) long and the female is about 1/25 inch (1 mm) long and have eight legs. Adult females vary from milky-white to yellowish brown and are elliptical in shape. The mouth parts consist of stout, paired palpi of indistinct segmentation inserted on the apical portion of the capitulum. It also includes the slender, styliform, paired chelicerae which are inserted into the plant cells. Detailed descriptions for microscope identification are provided by Beer (1954) and Ewing (1939).
The cyclamen mite may be confused with the broad mite, Polyphagotarsonemus latus (Banks), but the former is larger and moves slower. If misidentification is suspected the infestation should be examined for eggs or the occurrence of males that carry pupae. Only broad mite males carry pupae. The eggs are distinctly different. Broad mite eggs are flattened and have rows of opaque white tubercles on the surface of the egg.
Adult females begin laying eggs within two days after emergence (Garman, 1917). Each female may lay 1 to 3 eggs per day and a total of 12 to 16 eggs during her lifetime (Smith and Goldsmith, 1936).
These mites avoid light and require high humidity to survive, thus they live in sheltered areas of plants such as leaf and flower buds (Jepson et al., 1975). These mites are very susceptible to desiccation and will die within a few hours of exposure to direct sunlight .
Cyclamen mites are transferred from plant to plant by hand during routine cultural practices, by drafts of air, by moving between plants placed in close proximity of plants. Care should be taken when introducing new plants into the greenhouse or other areas where African violets are already located. Since cyclamen mites are parthenogenetic, one female can produce a mite colony large enough to cause damage and spread to surrounding plants (Garman, 1917).
In cases where small outbreaks occur on a few plants, the immediate removal of infested plants might prevent the spread of this pest throughout the field (Dustan and Matthewman, 1932).
Biological Control -- Predators
The phytoseiid mites, Amblyseius aurescens Athias-Henriot and A. cucumerus (Oudemans), are predators of the cyclamen mite (Jeppson et al., 1975).
Chemical control of these mites by sprays and dusts is difficult mainly because the mite is well protected within the leave bud. Fumigation may be necessary is greenhouse situations and especially in preparing new stock for transplant into a previously infested field (Boyle and Haramoto, 1956). Chemical control using endrin wettable powder was efficient in controlling this mite during the outbreak on pikake in the 1950's (Haramoto and Boyle, 1957).
Banks, N. 1901. Tarsonemus in America. Proc. Ent. Soc. Wash. 4: 294-296.
Beer, R. E. 1954. A Revision of the Tarsonemidae of the Western Hemisphere (Order Acarina), Univ. Kansas Sci. Bull. 36 Pt.2 (16): 1091-1387)
Boyle, W. W. and F.H. Haramoto. 1956. Cyclamen Mite on Pikake. Hawaii Farm Science. 5(2): 1,7,8.
Boyle, W. W. and F.H. Haramoto. 1957. Notes and Exhibitions: Steneotarsonemus pallidus. Proc Hawaiian Entomol. Soc. 16(2): 186.
Denmark, H. A. 1977. The Cyclamen Mite, Steneotarsonemus pallidus (Banks) (Acarina: Tarsonemidae), on African Violets. Fla. Dept. Agric. & Consumer Serv. Division of Plant Industry, Entomology Circular No. 177.
Dustan, A. G. and W. G. Matthewman. 1932. Some Notes on the Cyclamen Mite (Tarsonemus pallidus Banks) a Pest of Strawberry Plants. Entomol. Soc. Ontario, 62 ND Ann. Report. 931: 34-37.
Ewing, H. E. 1939. A Revision of the Mites of the Subfamily Tarsoneminae of North America, the West Indies, and the Hawaiian Islands. U.S. Agric. Tech. Bull. No. 653.
Garman, P. 1917. Notes on Tarsonemus pallidus Banks (Acarina). J. Econ. Ent. 10(5): 503.
Haramoto, F. H. and W.W. Boyle. 1958, Control of the Cyclamen Mite on Jasminum sambac (L.) Ait. in Hawaii. J. Econ. Ent. 51(4): 431-433.
Jeppson, L. R., H. H. Keifer and E.W. Baker. 1975. Mites Injurious ti Economic Plants. University of California Press; Berkeley, Los Angeles, London. 614 pages.
Pritchard, A. E. 1949. California Greenhouse Pests and Their Control. Ca. Agric. Expt. Sta. Bull. 713: 1-71.
Smith, F.F. and E. V. Goldsmith. 1936. The cyclamen mite, Tarsonemus pallidus, and its control on field strawberries. Hilgardia. 10(3): 53-54.