Brigham Young University Science Bulletin, Biological Series Volume 20 Number 2 Article 2 10-1975 Venezuelan Macronyssidae (Acarina: Mesostigmata) Robert C. Saunders University of Idaho Branch Agricultural Experiment Station, Parma, Idaho 83660 Follow this and additional works at: https://scholarsarchive.byu.edu/byuscib Part of the Anatomy Commons, Botany Commons, Physiology Commons, and the Zoology Commons Recommended Citation Saunders, Robert C. (1975) "Venezuelan Macronyssidae (Acarina: Mesostigmata)," Brigham Young University Science Bulletin, Biological Series: Vol. 20 : No. 2 , Article 2. Available at: https://scholarsarchive.byu.edu/byuscib/vol20/iss2/2 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Brigham Young University Science Bulletin, Biological Series by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. VENEZUELAN MACRONYSSIDAE (ACARINA: MESOSTIGMATA) by Robert C. Saunders' INTRODUCTION Mites of the family Macronyssidae are prima- neric level (Till and Evans, 1964) or specific rily ectoparasites of rodents, marsupials, bats, host groups (Radovsky, 1967). and birds. Some species are of medical import- The results of a survey of macronyssid mites ance because they attack man in the absence of of vertebrates, collected by the Smithsonian their natural hosts. Some are kno\vn to harbor Venezuelan Project ( SVP ) , are presented in this or transmit causative agents of several zoonotic paper. There has been no previous comprehen- diseases such as murine typhus (Worth and sive study of the macronyssid mites of Venezu- Rickard, 1951), rickettsial pox (Philip and ela. Collecting was conducted by field teams Hughes, 1948; and Strandtmann and Wharton, under the direction of Norman E. Peterson, 1958), eastern equine encephalitis (Clark, Lutz, M. D. Tuttle, and A. L. Tuttle between July and Fadness, 1966), and coxsackie virus disease 1965 and September 1968. Hosts were collected (Schwab, Allen, and Sulkin, 1952). Not only throughout Venezuela and a variety of habitats are some species of mites involved directly in were sampled. the transmission of disease agents to man but Of the more than 5,000 specimens of mac- they may pla\' an important role in maintenance ronyssid mites that were collected, the majority cycles of arthropod-borne zoonoses as well. One will be deposited in die Smithsonian Institution, species is a proven vector of the viiois Ornithosis Washington D.C., but representatives of all taxa bedsoniae (Eddie, Meyer, Lambrecht, and Fur- will be deposited at the Universidad Central de man, 1962) and another of the filarial womi Lito- Venezuela, Caracas. mosoides carinii (Williams and Brown, 1946). Grateful appreciation is extended to many Yunker ( 1964 and 1973 ) reviewed the impor- people who have been associated with this study. tance of parasitic mites associated with labora- Special acknowledgments are given to Dr. toiy animals and indicated the species, some of Vernon J. Tipton, Director, Center for Health them macronyssids, which are potentially danger- and Environmental Studies, Brigham Young Uni- ous to man. Altliough macronyssid mites are versity, and Dr. Charles O. Handley, Jr., Smith- knoNvn vectors of some disease causing agents, sonian Institution, for logistic support. Dr. C. previous studies, for the most part, have been Selby Herrin assisted with the preparation of restricted to taxonomic discussions on the ge- the final draft of the manuscript. EVOLUTION OF THE MACRONYSSIDAE For ever\' advantage gained by a parasite in may harbor. Other characteristics which affect its relationship with a host diere is a correspond- host-parasite relationships are the host's ecologi- ing surrender of independence. Modifications in cal tolerance and whether it burrows in the morphology and life cxcles mav be advantageous ground or has no direct contact with the earth. in one situation, e.g., on a particular host, but In addition, the moi-phology of the parasite, may be disadvantageous in another. The morph- its vagility and ecological tolerance, the number olog)' of a host, its mode of life, e.g., whether it of offspring it produces, whether eggs or living is sedentaiy or wide ranging, solitars' or colonial, voung are produced, and whether all stages are nomadic or tends to return to the same place to obligate parasites or some stages are free-living build a nest, as well as ambient conditions, are are all influenced by host-parasite relationships. factors which affect the kinds of parasites a host Probabh- parasitism developed as a result of 'University of Idalm Branch .•Agricultural Experiment Staliun. Par 75 76 Bricham Young University Science Bulletin continued close association of predatory mites sclerotization and generally a full complement with potential vertebrate hosts. The abundance of setae. The more specialized forms (e.g., the of necessary elements for survi\^al afforded b\' Macronyssidae) tend to have less heavily sclero- a vertebrate host, e.g., food and shelter, gradual!}' tized bodies and a general reduction in setation. replaced the less dependable survival elements Tlie Macronyssidae apparently are derived associated with a predatory mode of life. With from the Laclapidae. The macronyssid genera an increase in host specificity and development retaining the most characteristics indicating a of intimate host-parasite relationships, adaptive laelapine origin are Ichoromjssiis, Beivsiella, and morphological changes occurred in parasitic Synaspomjssus, which are found on bats ( Rad- mites. ovslcs' and Furman, 1969) and which are similar The transition from free-living to parasitic to the laelapid bat parasites Neolaelaps and No- states can be observed by examining the existing tolaelaps. Apparently this group of genera forms mite faunas within various groups of parasitic the stem from which the remainder of the fam- mites. Free-living, predate r\' mites are charac- ily Macronyssidae evolved. Important facts that terized by heavy sclerotization and massive give credence to this hypothesis are that the chelae. The closely related nest-dwelling facul- laelapid bat parasites are restricted to bats of tative parasites, which are one step removed the primiti\e suborder Megachiroptera, while from free-living forms, generally have a less the Macronyssidae are restricted to the more re- heavily sclerotized idiosoma and the chelae are cent Microchiroptera. These facts have led to somewhat smaller, as seen in many of the mites the conclusion that the Macronyssidae first of the subfamily Laelapinae. At this juncture evolved and radiated on bats and secondarily in the evolutionary process, true host specificity acquired other hosts (Radovsky, 1969). Support- has not developed and a more appropriate term ing evidence is provided by the host relation- would be "nest specificity," as proposed by ships of the two subfamilies of Macronyssidae. Wharton ( 1957 ) . The host-parasite relationship The more primitive Macronyssinae, which are at this point may be said to be generalized. found almost exclusively on bats, exhibit the As host-parasite relationships become more greatest morphological diversity and the greatest intimate and specificity increases, changes in degree of host specificit)', indications of long the morphology of parasitic mites occur which association with particular hosts. The Omith- allow them to benefit from specific characteris- onyssinae, on the other hand, have a low degree tics of the host. Tlie first and more conspicuous of host specificitv and many species of this sub- changes often involve reduction in sclerotization family have nonchiropteran hosts. Furtliermore, of the idiosoma and a decrease in the number of they are more uniform moiphologically, and setae. Also, as the parasites become more spec- probably biologicalh', and there are more spec- ialized, the moutlrparts become better fitted for ies, all indications of recent evolution. piercing and sucking, thus aiding in the blood- The Macronyssidae appear to have gone feeding process; they may also be modified for through several phases of adaptive radiation, attachment to prevent removal when the host some of which have taken place largely or en- moves or preens. Tliere are changes in body tirely in the Neotropics. That the Neotropics are structure that aid the mite in either adhering to particularly rich in the number of macronyssid its host or moving rapidly through the pelage species is demonstrated b\' the species diversity or plumage, e.g., flattening of the body, uni- in Venezuela. One phase involved macronyssine directional orientation of the setae, develop- evolution on bats, apparently beginning at an ment of caudally directed spines and spurs on early stage in the history of the Neotropical the coxae, and large tarsal claws. In some in- chiropteran fauna. Several endemic genera stances, parasites with very intimate host-para- arose, including Parichownyssus, Radfordiella, site relarionships have developed morphological and Macront/ssoides, particularly on bats of the characterisrics which almost enrirely limit their superfamily Ph\ llostomoidea. Even though existence to one host or a closely related group phyllostomoid bats were apparently the hosts of hosts. Such characteristics as size and strength during earh' radiation, there has been consider- of tarsal claws, number and size of setae, and able mo\'enient to other