Table Of ContentActa arachnol., 45 (1): 43-46, September 30, 1996
Further Report on Nematode-pseudoscorpion
Associations
Bozidar P. M. CURCIC, Rajko N. DIMITRIJEVIC, Slobodan
E. MAKAROV, Luka R. LUCK and Srecko B. CURCIC1~
Abstract Nematode-pseudoscorpion associations were studied in Neobisium bernar-
di VACHON, N, carpaticum BEIER, N simoni (L. KocH), N. sylvaticum (C. L. KOCH),
and Roncus jarilo CURCIC, all from Yugoslavia. Mermithid parasitism of pseudoscor-
pions was re-established for N. carpaticum and R. pannonius CURCIC, DIMITRIJEVIC, et
KARAMATA (Neobisiidae). Phoretic associations of rhabditid nematodes and false
scorpions were found in R. jarilo and re-established in N. carpaticum. The possible
origin of such associations, their characteristics, frequency, and significance are briefly
discussed. The total number of pseudoscorpion species associated with nematodes, is at
present 15; of these, the majority belong to the family Neobisiidae (11 species), while 3
species belong to the Chthoniidae, and one to the Sternophoridae.
Records of nematode parasites and associates of pseudoscorpions are rare and
consist of brief reports by VACHON (1949), HARVEY (1982), JUDSON (1993), and
POINAR and CURCIC (1992, 1994) who cite unidentified mermithid and rhabditid
nematodes in European, Asian, and Australian pseudoscorpions, respectively. In
addition, POINAR and CURCIC (1994) summarized earlier records of pseudoscorpion
parasitism by nematodes.
An examination of the pseudoscorpion collection of the senior author revealed
additional hosts of nematodes, bringing the total number of pseudoscorpion species
associated with nematodes to 15 (Table 1). The present paper reports these records and
summerizes our knowledge of nematode-pseudoscorpion associations.
Mermithid parasitism was re-established for Neobisium carpaticum BEIER in the
following individuals, all collected in Topcider Park, Belgrade, Yugoslavia: two females
collected in August 1981, and a tritonymph collected in June 1981. A mermithid-
parasitized female of Roncus pannonius CURCIC, DIMITRIJEVIC et KARAMATA
(CURCIC, 1992) was also recovered from the same locality; additionally, a parasitized
tritonymph of R. pannonius was collected in the village of Obrez, near Belgrade,
Yugoslavia, on July 10, 1992. Furthermore, a female of N. simoni (L. KoCH), and one
female and one tritonymph of N bernardi VACHON, collected from Passerole, near
Moulis-St. Girons, France, during June and July 1987, were also associated with
mermithid nematodes. Furthermore, mermithids were found in the body cavities of two
females and one male of R. jarilo CURCIC, collected during 1992 from near Zitoradja,
Yugoslavia.
Samples of infected pseudoscorpions were obtained by sifting leaf litter, humus and
soil. Three individuals of N carpaticum from a total of 1,614, and two individuals of
R. pannonius, from a total of 746 specimens were infected with representatives of the
family Mermithidae. This results in overall infection rates of 0.185% and 0.27%, respec-
t) Institute of Zoology, Faculty of Biology, University of Belgrade, Studentski Trg 16, 11000
Belgrade, Yugoslavia
Accepted July 2, 1996
44 B. P. M. CURCIC et al.
tively. In addition, the overall infection rates for other studied species were as follows:
0.05% (N. simoni), 0.14% (N. bernardi), and 0.25% (R, jarilo). It is evident that all these
values are lower if compared to those obtained for R, pannonius (CURCIC and POINAR,
1992). This low incidence of occurrence suggests that parasitism of pseudoscorpions by
Mermithidae, while apparently successful, may be accidental. Since both pseudoscor-
pions and mermithid nematodes inhabit leaf litter, humus, and soil, these arachnids are
placed close to the source of infection.
Two mermithid-parasitized individuals of N carpaticum, one of N sylvaticum (C.
L. KocH), and one of N bernardi were dissected and the nematodes removed. In all
four hosts, the internal tissues, including the reproductive organs, were atrophied and the
body cavity was almost completely occupied by the parasites. One of the four hosts (N
sylvaticum) contained two parasites while the other three contained a single mermithid
each. It is probable that a pair of nematodes, found in N sylvaticum, would represent
a male and a female, since such ratio favours continuation of the life cycle and reproduc-
tion. Nematodes removed from parasitized N carpaticum and N bernardi were in their
parasitic and late-parasitic stages, respectively (the latter stage had already developed the
anlage of the male genitalia). The individual size of these nematode juveniles was
different (KAISER to CURCIC, 2 October 1995). Although the identification of mermith-
ids is made only for adults, it is already known that pseudoscorpions may be infected
with different species of nematodes (POINAR and CURCIC, 1994); some of these use
pseudoscorpions either as intermediate or paratenic hosts. All other mermithids exhibit
direct development (POINAR and CURCIC, 1994).
VACHON (1949) mentioned that the ovary of the parasitized female of Roncus sp.,
from France, was atrophied, while JUDSON (1993) assumed that the testes in the infected
male of Bisetocreagris ussuriensis (REDIKORZEV), from Russia, had been probably
reduced or absent, similar to the conditions found in the present study. However,
JUDSON (1993) also assumed that the presence of a nematode in a pseudoscorpion host
may inhibit the development of the secondary (male) sexual characters, or cause different
anomalies in the setation of the appendages (walking leg IV).
Three dauer-stage juveniles of an unknown species of the Rhabditida were attached
to the abdominal pleura, leg I, and leg III of a female of R. jarilo, respectively; this
specimen was collected in Asanovac, near Zitoradja, Yugoslavia, on April 3, 1992.
Additionally, 24 adult and subadult specimens of N carpaticum (out of 1,406), from the
Botanical Garden "Jevremovac", Belgrade, Yugoslavia, collected in 1986, were associat-
ed with rhabditid nematodes; this resulted in an overall infection rate of 1.71%. It is
interesting to note that the dauer stages of rhabditids were attached to the different
regions of the pseudoscorpion body: the chelicerae, the pedipalps, the abdominal
pleurae, and the walking legs I-IV. Their frequency varied from 1-6 rhabditids per
each individual pseudoscorpion. Both phenomena represent phoresy; here, the rhab-
ditid nematodes use pseudoscorpions for dispersal.
With the new associations reported in the present study, the total number of
pseudoscorpion species associated with nematodes is now 15, with the majority of
records pertaining to mermithids (13 cases) and less to rhabditids (3 cases) (Table 1).
Acknowledgements
We acknowledge the financial help, in the form of travelling expenses, of the Serbian
Nematode-pseudoscorpion Associations 45
46 B. P. M. CURCIC et al.
Ministry of Science and Technology (Grant 03E03), the Serbian Academy of Sciences
and Arts, and the "Beobanka"-Belgrade. Our gratitude is also due to Dr. H. KAISER
(Graz) for his useful information on some aspects of nematode-pseudoscorpion associa-
tions.
References
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