General Biology of the Rhinonyssidae

The nasal mite family Rhinonyssidae is a group of blood feeding respiratory endoparasites that have not been shown to transmit disease, but they have been shown to precipitate lesions, rhinitis, sinusitis, and lung congestion in caged birds (Baker et al., 1956).  However, related taxa Macronyssidae, Laelapidae, and Dermanyssidae are proven transmitters of disease (Krantz, 1978), so it is probable that the rhinonyssids do as well.  The family is currently classified into eight genera and has over 500 described species.  During the evolution of the group, the rhinonyssids have undergone a major regression of chaetotaxy, with the genus Sternostoma not only being intranasal parasites but tending to infect the lungs as well having the most extreme diminution of setae (Fain, 1969).  The reduction in chelicerae, loss of opisthosomal plate, fragmentation of podosomal plates, and loss of peritremes from the stigmata has also been noted (Bregetova, 1964; Pence, 1979), relative to their macronyssid sister group.  These mites are found in most non-ratite orders of birds and based on morphology appear to have a fairly high degree of host specificity, which is almost always to order, usually to family, and often to genus and species (Pence, 1979).  They can remain in the nasal cavity by using their ambulacral claws or suckers (Mitchell, 1963), but the nasal mucus that they are embedded in also probably contributes (Fain, 1969).  Although parasitic mites are usually larviparous (Krantz, 1978), most nasal mites appear to be ovoviviparous (Mitchell, 1963), and this has been confirmed in laboratory studies for Sternostoma tracheacolum (Bell, 1996b) and Ptilonyssus mimi (Spicer cited in Bell, 1996b).  However, Fain (1969) has noted that in at least two species (Tinaminyssus clani and Ptilonyssus ploceanus) the female produces a completely developed nymph instead of a larva, inferring that they are viviparous.  Observations by Bell (1996b) suggest that the development from egg to adult in Sternostoma tracheacolum takes only about 6 days; adult mites probably live about 3-4 months (Spicer, unpublished). Prevalence of these mites seems to vary from one host taxonomic group to another, and from one geographic region to another (Spicer, 1987).  In general, the rate of infestation of the birds varies from 16-18% as reported by the major published studies (Maa and Kuo, 1965; Pence 1973c; Spicer 1987). Mode of transmission among these mites is currently unknown.  This is problematic because it makes it difficult to explain host specificity when the means of transfer from one host to another is not fully understood.  A number of authors have suggested that different genera may have separate modes of transfer.  For example, Porter and Strandtmann (1952) found that House Sparrow nestlings were infected with Ptilonyssus nudus and P. hirsti at about a 40% infection rate, while their adult parents were infected at a rate of about 70%.  Murray (1966) and Bell (1995a) also noted that young Gouldian Finches were infected with Sternostoma tracheacolum nasal mites.  However, others have noted a different pattern of infection.  TerBush (1963) showed that in gulls, which could be aged by plumage patterns, first year birds were only infected with Larinyssus orbicularis at about 1%, while second year birds were at 40%, and adult birds showed a rate of about 55%.  Amerson (1967) showed a similar result for the Sternostoma and Larinyssus that infect Sooty Terns, and suggested that the mites were transferred during courtship billing.  The extensive laboratory studies of Bell (1996b) suggest that transmission of the mite Sternostoma tracheacolum occurs by adult non-gravid females that migrate out of the nares onto the head plumage, and eventually into a new host.

Greg Spicer
Department of Biology
Last Modified: Sat, Sep 3, 2005