PROC. ENTOMOL. SOC. WASH. 89(4), 1987, pp. 790-793 UROPODID MITES PHORETIC ON FLEAS OF GROUND SQUIRRELS IN CALIFORNIA Tom G. Schwan and Dan Corwin Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Laboratory of Patho-biology, Rocky Mountain Laboratories, Hamilton, Montana 59840. Abstract.— Uvopodid mites were found attached to two species of fleas, Diamanus montamis and Opisocwstis oregonensis, associated with ground squirrels in California. This is the first record of such mites attached to fleas in the New World. The phoretic attachment of deutonymphs of uropodid mites to insects is well known (Krantz, 1978). However, observations of such associations involving fleas as pho-rionts are uncommon. Previous records of fleas as phoretic hosts of uropodid mites are restricted to Poland (Oudemans, 1913), Russia (loff", 1926; Zasukhin et al., 1936; Popov, 1957), China (Zasukhin etal., 1936), and Sweden (Brinck-Lindroth and Smit, 1971). From September 1980 to June 1983, approximately 15,000 fleas were examined for phoretic mites during surveillance ac-tivities for plague in California. Herein we document the association of uropodid mites with two species of ground squirrel fleas, the first such records of this relationship involving fleas in the New World. Methods and Materials Fleas were collected in saline by stafl' of the Vector Biology and Control Branch, California Department of Health Services, and county health departments. Fleas were identified and those with mites attached were preserved in 70% ethanol. For scanning electron microscopy (SEM), fleas were at-tached to a stub with double stick tape, crit-ical point dried, coated with a 1 5 nm layer of a gold-palladium alloy, and viewed with a J.E.O.L. 35-CF scanning microscope. Results Of the approximately 15,000 fleas ex-amined, only 2 specimens of Diamanus montanus (Baker) and 6 of Opisocwstis or-egonensis (Good and Prince) had uropodid mites attached. Records are: 23 February 1981, 1 mite ex D. montanus 2 ex Sper-mophilus beecheyi, Santa Barbara Co., CA; 7 May 1982, 1 mite ex D. montanus 9 ex S. beecheyi, Los Angeles Co., CA; 20 April 1982, 5 mites ex 2 O. oregonensis 9 ex 2 S. beldingi, Modoc Co., CA; 13 May 1982, 6 mites ex 4 O. oregonensis (2 5, 2 2) ex S. beldingi, Modoc Co., CA. Six fleas had only 1 mite attached while 2 fleas had 3 and 4 mites attached. Phoresy provides the means for many mites, which have only limited movement of their own, to disperse greater distances by attaching in various ways to insect hosts (Binns, 1982). Uropodid deutonymphs at-tach by means of an anal pedicel (Figs. 1, 2) formed by a glandular secretion that hardens on contact with the air. The broad base of a pedicel is shown in Fig. 3. Nu-merous examples of fleas as phoretic hosts for acaridid hypopodes are known (e.g. Fain and Baker, 1983; Fain and Schwan, 1976, 1984). However, such associations between uropodid mites and fleas are rare. When
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