World distribution of Locustacarus trachealis (Acari: Podapolipidae), tracheal parasites of grasshoppers, and comments on the genus Locustacarus.
Two species of Locustacarus from grasshoppers (Orthoptera Acrididae) are Locustacarus trachealis Ewing, 1924 and Locustacarus masoni Husband, 1974. Distribution tables with collection localities, hosts, dates and collectors or reporters are presented. Differences in 3 genera of Podapolipidae from grasshoppers are illustrated. Explanations for the distribution of Locustacarus trachealis are suggested.
The purpose of this paper is to examine the zoogeography of Locustacarus from grasshoppers, to clarify the confusion of Locustacarus with two other podapolipid mite genera found on grasshoppers, and to consider explanations for distribution of the genus. The mite genus Locustaccrus (Acari: Podapolipidae) includes L. trachealis Ewing, 1924 and L. masoni Husband, 1974 from grasshoppers (Orthoptera: Acrididae) and Locustacarus (Bombacarus) buchneri (Stammer, 1951) from bumblebees (Hymenoptera: Apidae; Bombinae). Locustacarus buchneri was discussed in Husband and Husband (1997).
For this study, literature concerning Locustacarus was surveyed, and unpublished worldwide records sent to the authors by acarologists were examined. Unpublished records of specimens in the British Museum Natural History (BMNH),London, England; Museum National d'Historie Naturelle (MNHN), Paris, France; and the collection of Podapolipidae of the authors (RPH), Adrian, Michigan, are included. Terminology for Podapolipidae follows that of Lindquist (1986).
PRESENTATION OF DATA
A specimen of the female grasshopper, Schistocerca melanocera (Stal, 1860) had been collected by biologists aboard the U.S.S. Albatross as part of a study by the U. S. Fisheries Commission in 1888. The Albatross duplicated the voyage of Charles Darwin on the Beagle more than 50 years earlier. Grainy material was spotted near the abdominal spiracles of the grasshopper and suspected to be parasitic mites of the family Podapolipidae (Arachnida: Acari). Thus, the earliest record of the tracheal mite, Locustacarus trachealis Ewing, 1924 was found. In 1979, the late Irving Cantrell of the Museum of Zoology, University of Michigan (UMMZ), made it clear to the authors that the specimen was to be returned to the Museum in the condition it left the Museum.
One of the many puzzles in zoogeography of mites is the discovery of interesting parasitic mites followed by their apparent disappearance. In another Michigan connection, Paul Welch of the University of Michigan and Lawrence Wehrle of Cornell University published the first and last accounts of Locustacarus trachealis in grasshoppers in North America (Wehrle and Welch 1925). The initial discovery was made by a student, C. C. Hamilton, at Kansas State Agricultural College on August 13, 1914. In 1914 and continuing during the growing season of 1915, Welch and Wehrle found 19 (of about 250) Pardolophora (Hippiscus) apiculatus (Harris) and one (of a few) Xanthoptera (Arphia) carinata (Burmeister) with tracheal mites. The mites were sent to the U. S. Bureau of Entomology for identification and described as Locustacarus trachealis Ewing, 1924. Grasshoppers collected near Ann Arbor, Michigan, and Ithaca, New York, were examined by Welch and Wehrle, and no tracheal mites were found. The grasshoppers which were hosts w ere collected from a small area near the campus of Kansas State Agricultural College and are widely distributed in the Eastern United States (Otte 1984). Richard Elzinga and his students at Kansas State University, Manhattan, Kansas, examined grasshoppers from the type locality in the 1960s, 1970s and 1980s without finding tracheal mites (personal communication 1987). In 1987, the authors examined grasshoppers from the type locality and in the museum at Kansas State University and found no L. trachealis. The mite has not been reported from the western hemisphere since 1915.
The next noted appearance of L. trachealis was in Africa. In 1932, W. V. Harris collected mites from the air sacs of Locusta migratoria L. from Shinyanga, Tanganyika (Tanzania). It was described as Locustacarus locustae Ewing, 1932 and discussed by Harris (1940). Harris collected L. locustae from the same host in Morogoro, Tanganyika in 1933 but not again in Tanganyika. He mentions reports of L. locustae in Kenya. Husband and Sinha (1970) placed L. locustae in synonymy with L. trachealis.
Lavoipierre (1941) discussed L. locustae and described 3 species of Podapolipidae from Durban, S. Africa: Podapolipus solitarius from Morphacris fasciatus Thunb., Podapolipus locustanus from Cyrtacantacris lineata Stoll and Podapolipus grassii from Locusta migratoria, Morphacris fasciata and Pseudochirista spp. Regenfuss (1968) moved Podapolipus solitarius Lavoipierre, 1941 to Locustacarus solitarius and Husband and Sinha (1970) placed L. solitarius in synonymy with L. trachealis. Regenfuss (1968) moved Podapolipus locustanus to Podapolipoides locustanus. Figure 2 (Lavoipierre 1941) is Podapolipoides locustanus. Figure 1 of the same paper is an unnamed Podapolipus (Husband 1995). When more than one genus of podapolipid mite exists on one grasshopper specimen, they may be misidentified. Morphological distinctions in these mites are discussed below.
In Africa in September 1944, Banzyville, Belgian Congo (Congo Republic), Cooreman (1952) found L. trachealis on Acanthacris ruficornis F. He reported it as Podapolipus solitarius. On 7 August 1970, Wintrebert collected L. trachealis in Dioura, Mali.
In Southeast Asia, Nadchatram, in 1951, and Kok in the 1960s found L. trachealis from Valenga nigricornis Burmeister in the vacinity of Kuala Lampur, Malaysia (Kok 1968).
In New Zealand, in April 1970, G. W. Ramsay collected L. trachealis from Locusta migratoria in the vacinity of Nelson, New Zealand (Husband 1974).
In Gove, Northern Territories, Australia, 4 May 1975, K. H. L. Key found L. trachealis on Valenga sp.; 5 May 1982, B. J. Loudon collected L. trachealis from Austroicetes cruciata Saussure near Boomi, New South Wales and 25 March 1987, G. L. Baker collected L. trachealis from Aiolopus tamulus (F.). Distribution records for Locustacarus trachealis are summarized in Table 1.
A second species of Locustacarus, L. masoni Husband, 1974, was described from several localities and hosts in New Zealand between May 1968 and December 1970 by P. Mason and G. W. Ramsay (Table 2).
Yoder (1997) reported Locustacarus sp. from the cockroach Nauphoeta cinerea in laboratories and mentions protonymphs and deutonymphs. We have noted the podapolipid mite, Bakerpolipus serratus Husband and Sinha, 1970, associated with the cockroach Nauphoeta cinerea but have never found Locustacarus on cockroaches. Larval instars of both genera have long [h.sub.1] setae but cheliceral stylets are very long in Bakerpolipus and short in Locustacarus. Stylets of Bakerpolipus are similar to stylets of larval Podapolipoides (Figure 1).
The genital capsule of male Locustacarus extends over the prodorsal plate but is middorsal and short in male Bakerpolipus. The surface of an adult female Locustacarus is smooth while the surface of an adult female Bakerpolipus is scaled. B. serratus and L. trachealis have a truncated development from egg to adult male and from egg to larva to adult female. We are currently looking at a variety of species of cockroaches (Blattaria) to investigate the podapolipid mite fauna.
MORPHOLOGICAL CHARACTERS OF PODAPOLIPID MITES FROM GRASSHOPPERS
Larval female exoskeletons adhere to adult females that expand in feeding and as ovaries develop. Thus, the concept that only 3 instars exist (i.e., egg, adult male, and adult female) in Locustacarus, as was stated by Ewing (1924) and repeated by others, is not correct. Secondly, and more important, three genera of parasites may be found on the same grasshopper (Husband 1990). Typically, Podapolipus species are near spiracles and on intersegmental membranes; Podapolipoides species are at wing bases and on intersegmental membranes; and Locustacarus species are near spiracles and in the tracheal system. However, larval females are very mobile and may be found from head to genitalia and, in severe infestations, all 3 genera may be more widely distributed on the host. This has resulted in the incorrect association of male, female, and larval stages of different genera. Males are the easiest to distinguish as their genital capsules are very distinctive. This requires careful examination as males are smaller than o ther stages and structures are sometimes obscured. Male Locustacarus have long genital capsules that extend over the prodorsal plate; male Podapolipus have genital capsules which emerge from under the prodorsal plate; and male Podapolipoides have short middorsal genital capsules (Figure 2). Larval female Locustacarus from acridid grasshoppers have idiosomal [c.sub.2] setae which are as long or longer than the width of the gnathosoma while these setae are at most 1/4 the width of the gnathosoma. Larval female Podapolipoides have distinct [h.sub.2] setae with microspines and 4 tarsi II, III setae while the other genera have at most vestigial [h.sub.2] setae and 5 tarsi II, III setae (Figure 2). Adult female Locustacarus have coxae II present and vestigial legs II are evident in some specimens. Coxae and legs II are not present in female Podapolipus or Podapolipoides. Female Podapolipoides have 2-3 tarsus I setae while only large hooklike tarsus I seta s is present in Locustacarus and Podapolipus (Figure 3). Att ention to these characters will prevent mismatching of stages of genera.
The first solution that could be proposed for the enigmatic distribution of Locustacarus is that entomologists are not focusing on finding Locustacarus on grasshoppers. Locustacarus mites are small, and all except larval females are usually internal in air sacs, hidden from view. In studies of other aspects of the biology of grasshoppers, finding or recognizing mites may not be a priority. In the latest discoveries of Locustacarus in New Zealand and Australia, entomologists were looking for potential parasitic mites. In studies by Elzinga and his students at Kansas State University, a serious search was also made although the area searched was relatively small. The main problem in finding recent records for Locustacarus may be primarily (but not singly) due to lack of looking.
A second proposal is Locustacarus trachealis became extinct in North America with the extinction of the grasshopper Melanoplus spretus (Lockwood 2001). If finding Locustacarus spp. currently in Malaysia and in similar habitats in Australia and New Zealand is characteristic of distribution of tracheal parasites of grasshoppers, Locustacarus is not likely to be extinct in America.
A third proposal is that L. trachealis came east from the Rocky Mountains with Melanoplus spretus (Walsh 1866) in mass migrations that ceased in the early 1900s. They became established temporarily in different grasshopper hosts in Eastern Kansas and elsewhere, and then died out. L. masoni exists in alpine regions in New Zealand in several host grasshoppers. Thus, meadows in the Rocky Mountains may have grasshoppers with tracheal mites. So far, no tracheal mites have been found in grasshoppers in these habitats in the U. S., but the hypothesis is not abandoned.
A final consideration is the incidence of infection or infestation by Locustacarus. In most cases, Locustacariosis is a sexually transmitted disease. An exception is the tracheal mite of bumblebees where transmission of Locustacarus buchneri may occur from bee to bee in the nest (Husband and Sinha 1970). Larval female grasshopper mites crawl from one grasshopper to another at the time of mating and when swarms rest. This short period of contact between infested and uninfested hosts lessens the opportunity for transmission and lowers the potential for infestation. If one is restricted to finding mites mostly in the mating and swarming seasons, the chance of collecting mites decreases. When single or a few mites are found on grasshoppers, they are likely to be small larval females. A common situation in looking for podapolipid mites on museum specimens is to find one insect in 100 with mites, even when that insect species is known to be an appropriate host.
The conclusion is that if many more potential hosts are examined carefully for Locustacarus, the genus is likely to be found today on every continent except Antarctica. Although Locustacarus trachealis and L. masoni may be the only recognized species at present, examination of the DNA of populations may result in recognition of more species. Knihinicki, Schicha, and Baker (personal communication 1994) tentatively identified 3 additional undescribed species in Australia based on size of structures. Differences between L. trachealis and L. masoni in New Zealand are based on differences in lengths of setae and other structures. Has L. masoni evolved in adaptation to a colder environment than the lowland L. trachealis in New Zealand? There are more questions about Locustacarus than answers. It is like trying to make decisions about a 1000-piece puzzle with only 100 pieces at hand. Studies are in progress to find more pieces.
TABLE 1 Distribution, host, collector or reporter and date for Locustacarus trachealis Ewing, 1924. LOCALITY HOST COLLECTOR/REPORTER, DATE Galapagos Islands Schistocerca melanocera U. S. Fish. Comm. Study Indefatigable Islands 1888 Manhattan, Kansas Xanthoptera carinata C.C. Hamilton, L.P. U.S.A. Pardolophora apiculatus Wehrle and P.S. Welch 1914-1915 Shinyanga, Morogora, Locusta migratoria W. V. Harris, 1932, 1933 Tanzania Kenya L. migratoria H. Wilkerson, 1930s Durban, S. Africa Morphacris fasciatus M. Lavoipierre, 1939 Banzyville, Congo Acanthacris ruficornis J. Cooreman, 1944 Republic Kuala Lampur, Valanga nigricornis M. Nadchatram, 1951 Malaysia M. L. Kok, 1960s Nelson, New Zealand Locusta migratoria G. W. Ramsay. 1970 Dioura, Mali Gastrimargus amplus D. Wintrebert, 1970 G. aficanus Gove, N. T., Valanga sp. K. H. L. Key, 1975 Australia New Haven, near Austroicetes cruciata B. J. Loudon, 1982 Boomi, Australia Scone, N.S.W. Aiolopus tamulus G. L. Baker, 1987 TABLE 2 Distribution, Host, Collector or Reporter and Date for Locustacarus masoni Husband, 1974 in New Zealand LOCALITY HOST Potter Heights Paprides nitidus Hutton Amuri Ski Field P. nitidus Waiau River, W. of Hammer P. nitidus Porter Heights Brachaspis nivalis (Hutton) Sigaus australis (Hutton) Armstrong Saddle In tube with Sigaus piliferus Hutton and Zealandosandras sp. Mt. Patriarch Brachaspis collinus Hutton Mt. Robert B. collinus LOCALITY COLLECTOR/DATE Potter Heights P. Mason, 1968-1969 Amuri Ski Field P. Mason, 1968 Waiau River, W. of Hammer G. W. Ramsay, 1969 Porter Heights P. Mason, 1970 P. Mason, 1970 Armstrong Saddle G. W. Ramsay, 1970 Mt. Patriarch G. W. Ramsay, 1970 Mt. Robert G. W. Ramsay, 1970
The authors are appreciative of the cooperation of the following persons for providing specimens, comments and advice: the late Irving Cantrell, Barry M. O'Connor, Mark O'Brien and staff of the Museum of Zoology, University of Michigan, Ann Arbor, Michigan; Evert Lindquist, Agriculture Canada, Ottawa, Canada; R. N. Sinha, Agriculture Canada, Winnipeg, Canada; Richard Elzinga of Kansas State University, Kansas; J. A. Lockwood, University of Wyoming, Laramie; T. J. Cohn, San Diego State University, California; the late Michel Lavoipierre and R. Schuster of the University of California, Davis; D. Macfarlane, the Museum of Natural History, London, England; M. Naudo, Museum National d'Histoire Naturelle, Paris, France; the late J. Cooreman, Inst. Roy. Sci. Nat. Belg., Bruxelles, Belgium; the late D. C. Lee, South Australian Museum; Adelaide, R. B. Halliday, CSIRO, Canberra, Australia; G. L. Baker, D. Knihinicki, and E. Schicha, BCRI, Rydalmere, NSW, Australia; K. H. L. Key, Cove, N.T., Australia; B. J. Loudon, Boo mi, NSW, Australia; G. W. Ramsay and P. Mason, DSIR, Nelson, New Zealand; and M. Nadchatram and M. L. Kok, Kuala Lampur, Malaysia.
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0026-2005/02. Copyright (C) 2002 by the Michigan Academy of Science, Arts, and Letters. All rights of reproduction in any form reserved.
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|Author:||Husband, Robert W.; Husband, Patricia S.|
|Date:||Jan 1, 2002|
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