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Gregarina hylobii and Ophryocystis hylobii n. sp. (ophryocystidae, neogregarinida) parasitizing Hylobius abietis (Curculionidae, coleoptera)
JOURNAL
OF INVERTEBRATE
Gregarina
PATHOLOGY
39, 164- 173 (1982)
hyiobii and Ophryocystis hyiobii n. sp. (Ophryocystidae, Neogregarinida) Parasitizing Hylobius abietis (Curculionidae, Coleoptera) KURTESH
Institute
of Forest
Zoology.
University Baesgenweg
PURRINI
of Goettingen, Goettingen. D-3400 3, Federal Republic of Germany
Goettingen-
Weende.
AND RENE ORMIERES’ Station
Biologiyue,
SPte. F-34200
S&e,
France
Received April 13, 1981: accepted August 5, 1981 Two sporozoan parasites, Gregarina hylobii and Ophryocystis hylobii n. sp., parasitizing the adults of natural populations ofHy/obius abietis are described. The gregarine G. hy[obii. a parasite of the gut of H. abietis. has been reexamined and its complete life cycle, including the solitary gamonts, gametocysts, and sporoducts is described. The life cycle of the neogregarine 0. hylobii infecting the Malpighian tubules of host animals examined at light and electron microscope levels is discussed. Some data on the prevalence of infections and host-parasite relationships are also discussed.
INTRODUCTION
So far, except for solitary and associated gamonts of Gregarina hylobii reported by Fuchs (1915) and Geus (1969), no sporozoan parasites of Hylobius abietis have been described. The investigations on pathogens in natural populations of adults of H. abietis collected at two outbreak zones of the pest in Lower Saxony (Federal Republic of Germany) revealed the occurrence of two so far unknown sporozoan infections of the genera Ophryocystis (Neogregarinida) and Nosema (Microsporida). The results of the examination of microsporidian infection will be published elsewhere (Purrini, 1981). The present paper reports on results of light and electron microscope examinations of the life cycle of these gregarines. An attempt has also been made to describe the prevalence of the infections caused by these parasites. Data on host-parasite relationships are also discussed. I Deceased 1981.
MATERIAL
In August 1980 Ms. Renate Hofman and Msr. Georg Vacek of the Experimental Station of Forestry in Goettingen, Federal Republic of Germany, kindly provided 806 specimens of adults of Hylobius abietis, which were brought to our laboratory and reared for 2 months in special boxes at 20°C; the animals were fed on young pine trees. The food was replenished every 2 weeks. The beetles survived for 6 weeks under these conditions without significant mortality. Later the mortality rapidly increased. Living and dead beetles were examined for pathogens at different times. An examination for pathogens in larvae has not yet been performed. The gut, Malpighian tubules, gonads, and parts of the fat body of beetles were dissected and prepared for light microscopy. Wet smears were fixed and stand stained with acetic carmine or fixed in Bouin and stained with Heidenhain’s iron hematoxylin. The gut and Malpighian tubules were fixed in Bouin’s fluid for histological sections 4-5 pm thick; sec164
0022-2011/82/020164-10$01.00/0 Copyright 0 1982 by Academic Press, Inc. All rights of reproduction in any form reserved.
AND METHODS
Grqarina
AND
Ophryocystis
tions were stained with Heidenhain’s iron hematoxylin. Distribution of pathogens in the organs was recorded by light microscopy. For electron microscopy, infected Malpighian tubules were fixed with glutaraldehyde and osmium tetroxyde, and embedded in Spurr’s low-viscosity medium. Ultrathin sections were cut with an LKB ultramicrotome, poststained with uranyl acetate and lead citrate, and examined with a Philips 301 electron microscope. RESULTS Description
of the Parasites
Gregarina hylobii. The earliest stages of gregarines observed were young gamonts 55 pm long consisting of a deutomerite (35 pm), a protomerite (10 pm), and an epimerite (10 pm) (Figs. 1, 16). Some epimerites preserved in their old form, a “vacuolized sphere-like” structure measuring lo-15 pm in diameter, were also observed in maturating gamonts (Fig. 2). The existence of such stages is an exceptional morphological feature of the epimerites of species belonging to the genus Gregarina. It was observed that two mature individuals (gamonts) unify, thus producing associations of different sizes, ranging from 800 to 1000 pm long (Figs. 3, 17). Figure 3 represents an association where the primite was 470 pm long, while the satellite, being more or less curved, measured 500 pm. In preparations which were fixed and stained with acetic carmine all gregarines showed a slight striation, particularly visible at their sides. From some dissected guts of heavily infected adults of H. abietis a large number of gametocysts could be collected. They were nearly spherical in shape, measuring 300-400 pm in diameter (Fig. 4). After a cultivation of 4 to 5 days in humid microchambers, several birth holes, appearing as dark “ring-like” zones of the future sporoducts, could be observed. But only two or three of them produced sporoduct channels, liberating long chains of doliform spores (Figs. 4, 5). After liberation, these chains disintegrated, and spores 7 pm long and 5 pm wide
PARASITIZING
Hylobius
16.5
were free (Fig. 18). They represent resistent stages of the parasite which can be considered the beginning of a new infection if they are swallowed by a host. Ophryocystis hylobii n. sp. The earliest stages observed in the life cycle of neogregarine were large mycetotic schizonts, measuring 20 x 10 pm. They were found either as free-floating stages in the cavity of Malpighian tubules (Fig. 15), or in close contact with the cell wall of the host tissue (Figs. 6, 21). The radicells, stages known to occur in the life cycle of some parasites of the genus Ophryocystis as reported by Leger (1907), were absent. The young gamonts which has developed from schizonts were spherical in shape, measuring 7 pm in diameter (Figs. 7, 8). After fusion of two gamonts, the produced copula was round, but later became elliptical, measuring 8-11 x 5-7 pm. Growth of these stages continued during pairing (syzygy). At the initial stage of copulation, both copulated gamonts contained a single nucleus (Figs. 9, 19); later on, the nucleus multiplied. Stages with two nuclei in each of the gamonts were formed (Fig. 10). Only one of the filial nuclei gave rise to a second division, and six nuclei were produced (Fig. 11). Four of the six nuclei in the copula degenerated. The other two were isolated at the place of their fusion, each of them producing a single gamete (Figs. 11, 20). Copulation of two gametes created a zygote which developed into spherical sporoblast containing one nucleus (Fig. 12). Gradually, the sporoblast stretched out, and was transformed to give the sporocyst. The multiplying nucleus in the sporocyst produced eight sporozoites (Fig. 13). The cytoplasm of the exospore disappeared, and the sporocyst became free. The sporocysts were spindle shaped with a thick, “button-like” structure at each pole, measuring 8 x 2.5-3.5 Frn, (Fig. 14). The sporocysts represent resistent stages of the parasite which can become the beginning of a new infection if they are swallowed by a host. Some developmental stages of 0. hyZobii were also examined at the electron micro-
166
PURRINI
0
AND
ORMIERES
lOOF
figs.28,4 0
,
,‘fr
figs. 1,5 FIGS. I-5. Grrgurina hylobii. (1). Young gamonts (5.5 wrn long) with spherically shaped epimerite; (2) maturating gamont (240 pm long), with an exceptional epimerite showing a “vacuolized spherelike” structure: (3) association of two mature gamonts; (4) gametocyst with 12 birth holes of “ringlike” form, two of them producing a sporoduct channels; (5) a chain of doliform spores.
scope level (Figs. 23-28). Unfortunately, these studies did not reveal, either in solitary or in associated gamonts, any clear features of their ultrastructure. In our mate-
rial, the investigated stages always appeared as very electron-dense bodies filled with masses of paraglycogen granules (Fig. 23). Similar difficulties were encountered
Gregarina
AND
Ophryocystis
PARASITIZING
Hylobirrs
167
FIGS. 6- 15. Ophryxystis h.dobii n. sp. (6) Mycetotic schizonts in close contact with the inner cell wall of the host tissue (Malpighian tubules); (7, 8) uninucleate gamonts; (9, IO) uni- and binucleate copula of pairing gamonts; (11) formation of gametes: (12) formation of uninucleate sporoblast; (13) single sporocyst in gametocyst: (14) free mature sporocyst containing eight sporozoites: (15) free mycetotic schizont.
during investigations of sporocysts (Figs. 25 - 28). Therefore we could determine only few features of their inner structure. The sporocyst in Figure 24 showed membraneous residues of the formerly paired gamonts. The membrane surrounding the sporocyst being thin as shown in Figure 24, at the initial stages of maturation, later became thicker (Fig. 25). The thick parts were “buttonlike” structures at each of the poles of the sporocysts, resulting from the thickening process of the surrounding membrane.
They are well visible in Figures 25 and 26. Eight transversally cut sporozoites inside of the sporocyst represent another important ultrastructural feature observed in 0. hylobii (Figs. 27, 28). Prevalence of Infection and Host-Parasite Relationships
The gregarine infections did not produce any apparent external symptom; however, it could be noted that some adults were not as active as healthy ones, and finally stopped
FIGS. 16-18. Grr,vuitlu hvlobii (light microscopy, fresh). (16) Young and mature gamonts (200x ); (17) two associations of mature gamonts (500x): (18) doliform mature spores (2000x).
Gregarina
AND
Ophryocystis
PARASITIZING
Hylobius
169
FIGS. 23-26. Ophryocystis hylobii n. sp. (electron microscopy). (23) Some solitary gamonts and some gamonts pairing in copula: their cytoplasm filled with masses of paraglycogen granules (4700x); (24) young sporocyst, with residues of pairing gamonts still visible (22,000~); (25) maturating sporocyst with a thick surrounding membrane: two thick “button-like” structures at each of the poles of the sporocyst are well recognizable (14,000~): (26) A thickened membrane forming a “button-like” structure in a sporocyst shown at high magnification (75,000~).
is
Gregarinn
AND
Ophryocystis
PARASITIZING
H.vIobius
171
FIGS. 27-28. Ophryocystis hybbii n. sp. (electron microscopy). Paralongitudinal(27), 22,000~) and transveral (28), 27,000x, ultrathin sections of sporozoites in mature sporocysts. In Fig. 28, eight sporozoites are well visible. 172
Gregnrina
AND
Ophryocystis
feeding. After dissection the degraded gut and Malpighian tubules of infected beetles could be observed under the light microscope. Prevalence of infection by the gregarine G. hylobii was 14% in single infections, and 16% in triple infections with 0. hylobii and N. hylobii. In some cases (6% of examined specimens) more than 600 gamonts and more than 15 gametocysts (maximal 21) were observed in the gut lumen of infected animals. The infection by the neogregarine 0. hylobii has only been observed in dual infections with G. hyfobii (18%) or in triple infections (16%) with G. hyfobii and N. hylobii. Usually the gregarine (G. hylobii) and the microsporidian (N. hylobii) dominate; some specimens of diseased adults showed that occasionally 0. hylobii predominated. In these cases the Malpighian tubules as principal sites of infection by the parasite were completely degenerated. They appeared hypertrophied, transparent, thin walled, and yellow. Large areas tilled with vegetative stages (gametes and gametocysts) and sporocysts of the parasite could be observed under the light microscope (Fig. 22). DISCUSSION
Fuchs (1915) and Geus (1969) described a gregarine found in the gut of adults of H. abietis. The name Gregarina hylobii was proposed by Fuchs. Only solitary and associated gamonts of the gregarine were described. Our investigations, started in 1980 with a large number of infected adults of H. abietis, allowed us the reexamination of this parasite. The development of the gregarine was followed and its complete life cycle can now be described. There are actually 11 known neogregarines of the genus Ophryocystis, all of them parasites of different species of the Coleopteran families Tenebrionidae, Alleculidae, and Scolytidae; Ophryocystis dubosqui Leger 1907 is an exception. It is associated with three species of weevils: Otiorrhynchus ligustici, 0. meridionalis, and 0. fuscipes (Curculionidae, Col.). All
PARASITIZING
Hylobius
173
described species of the genus Ophyryocystis, except 0. duboscqui, differ in shape and size of developmental stages and in the host-parasite relationships from the neogregarine presented here. Only 0. duboscqui can be compared with the parasite found in H. abietis. These two parasites have host-species of the family Curculionidae. The gamonts, although similar in shape, differed in size, being 5 (0. duboscqui) and 7 pm (0. hylobii) in diameter. The copula of 0. hylobii, measuring 8- 11 x 5-7 pm, was nearly of the size of that of 0. duboscqui, being 8 pm long and 5 pm wide. The sporocysts were identical in shape, but they differed in size, being 8 pm long and 2.5-3.5 pm wide in case of 0. hylobii, and 9 pm long and 4 pm wide in case of 0. duboscqui. The radicells, known as common stages occurring in the life cycle of 0. duboscqui, were not observed in 0. hylobii. The finding that the neogregarine described in the present investigation is the parasite of H. abietis, a species so far not described as a host for a neogregarine, as compared to the known species of the genus Ophryocystis, gave us cause to describe it as a new speices. The name Ophryocystis hylobii n. sp. is proposed. ACKNOWLEDGMENTS The authors wish to thank Professor Institute of Microbiology, University for his help during examinations with croscope. We are grateful also to Mss. and Mr. Georg Vacek, Experimental try, Goettingen, for supplying insect
Dr. F. Mayer, of Goettingen, the electron miRenate Hofman Station of Foresmaterials.
REFERENCES FUCHS, G. 1915. Die Naturgeschichte der Nematoden und einiger anderer Parasiten des Ips typographus L. und Hylohius uhietis L. Zool. Jahrb. 38, 109-222. GEUS, A. 1969. Sporentierchen, Sporozoa. Die Gregarinida. Tierwelt Deutschlands, Vol. 57, pp. l-608. Fischer, Jena. LUGER, L. 1907. Les Schizogregarines des Tracheates. I-Le genre Ophryocystis. Arch. Protistenk., 8, 159-202. PURRINI, K. 1981. Nosema hylobii n. sp. (Nosematidae, Microsporida) a new microsporidian parasite of Hylobius abietis L. (Curculionidae, Coleoptera) .I. Appl. Entomol.. 92, 1-8.
OF INVERTEBRATE
Gregarina
PATHOLOGY
39, 164- 173 (1982)
hyiobii and Ophryocystis hyiobii n. sp. (Ophryocystidae, Neogregarinida) Parasitizing Hylobius abietis (Curculionidae, Coleoptera) KURTESH
Institute
of Forest
Zoology.
University Baesgenweg
PURRINI
of Goettingen, Goettingen. D-3400 3, Federal Republic of Germany
Goettingen-
Weende.
AND RENE ORMIERES’ Station
Biologiyue,
SPte. F-34200
S&e,
France
Received April 13, 1981: accepted August 5, 1981 Two sporozoan parasites, Gregarina hylobii and Ophryocystis hylobii n. sp., parasitizing the adults of natural populations ofHy/obius abietis are described. The gregarine G. hy[obii. a parasite of the gut of H. abietis. has been reexamined and its complete life cycle, including the solitary gamonts, gametocysts, and sporoducts is described. The life cycle of the neogregarine 0. hylobii infecting the Malpighian tubules of host animals examined at light and electron microscope levels is discussed. Some data on the prevalence of infections and host-parasite relationships are also discussed.
INTRODUCTION
So far, except for solitary and associated gamonts of Gregarina hylobii reported by Fuchs (1915) and Geus (1969), no sporozoan parasites of Hylobius abietis have been described. The investigations on pathogens in natural populations of adults of H. abietis collected at two outbreak zones of the pest in Lower Saxony (Federal Republic of Germany) revealed the occurrence of two so far unknown sporozoan infections of the genera Ophryocystis (Neogregarinida) and Nosema (Microsporida). The results of the examination of microsporidian infection will be published elsewhere (Purrini, 1981). The present paper reports on results of light and electron microscope examinations of the life cycle of these gregarines. An attempt has also been made to describe the prevalence of the infections caused by these parasites. Data on host-parasite relationships are also discussed. I Deceased 1981.
MATERIAL
In August 1980 Ms. Renate Hofman and Msr. Georg Vacek of the Experimental Station of Forestry in Goettingen, Federal Republic of Germany, kindly provided 806 specimens of adults of Hylobius abietis, which were brought to our laboratory and reared for 2 months in special boxes at 20°C; the animals were fed on young pine trees. The food was replenished every 2 weeks. The beetles survived for 6 weeks under these conditions without significant mortality. Later the mortality rapidly increased. Living and dead beetles were examined for pathogens at different times. An examination for pathogens in larvae has not yet been performed. The gut, Malpighian tubules, gonads, and parts of the fat body of beetles were dissected and prepared for light microscopy. Wet smears were fixed and stand stained with acetic carmine or fixed in Bouin and stained with Heidenhain’s iron hematoxylin. The gut and Malpighian tubules were fixed in Bouin’s fluid for histological sections 4-5 pm thick; sec164
0022-2011/82/020164-10$01.00/0 Copyright 0 1982 by Academic Press, Inc. All rights of reproduction in any form reserved.
AND METHODS
Grqarina
AND
Ophryocystis
tions were stained with Heidenhain’s iron hematoxylin. Distribution of pathogens in the organs was recorded by light microscopy. For electron microscopy, infected Malpighian tubules were fixed with glutaraldehyde and osmium tetroxyde, and embedded in Spurr’s low-viscosity medium. Ultrathin sections were cut with an LKB ultramicrotome, poststained with uranyl acetate and lead citrate, and examined with a Philips 301 electron microscope. RESULTS Description
of the Parasites
Gregarina hylobii. The earliest stages of gregarines observed were young gamonts 55 pm long consisting of a deutomerite (35 pm), a protomerite (10 pm), and an epimerite (10 pm) (Figs. 1, 16). Some epimerites preserved in their old form, a “vacuolized sphere-like” structure measuring lo-15 pm in diameter, were also observed in maturating gamonts (Fig. 2). The existence of such stages is an exceptional morphological feature of the epimerites of species belonging to the genus Gregarina. It was observed that two mature individuals (gamonts) unify, thus producing associations of different sizes, ranging from 800 to 1000 pm long (Figs. 3, 17). Figure 3 represents an association where the primite was 470 pm long, while the satellite, being more or less curved, measured 500 pm. In preparations which were fixed and stained with acetic carmine all gregarines showed a slight striation, particularly visible at their sides. From some dissected guts of heavily infected adults of H. abietis a large number of gametocysts could be collected. They were nearly spherical in shape, measuring 300-400 pm in diameter (Fig. 4). After a cultivation of 4 to 5 days in humid microchambers, several birth holes, appearing as dark “ring-like” zones of the future sporoducts, could be observed. But only two or three of them produced sporoduct channels, liberating long chains of doliform spores (Figs. 4, 5). After liberation, these chains disintegrated, and spores 7 pm long and 5 pm wide
PARASITIZING
Hylobius
16.5
were free (Fig. 18). They represent resistent stages of the parasite which can be considered the beginning of a new infection if they are swallowed by a host. Ophryocystis hylobii n. sp. The earliest stages observed in the life cycle of neogregarine were large mycetotic schizonts, measuring 20 x 10 pm. They were found either as free-floating stages in the cavity of Malpighian tubules (Fig. 15), or in close contact with the cell wall of the host tissue (Figs. 6, 21). The radicells, stages known to occur in the life cycle of some parasites of the genus Ophryocystis as reported by Leger (1907), were absent. The young gamonts which has developed from schizonts were spherical in shape, measuring 7 pm in diameter (Figs. 7, 8). After fusion of two gamonts, the produced copula was round, but later became elliptical, measuring 8-11 x 5-7 pm. Growth of these stages continued during pairing (syzygy). At the initial stage of copulation, both copulated gamonts contained a single nucleus (Figs. 9, 19); later on, the nucleus multiplied. Stages with two nuclei in each of the gamonts were formed (Fig. 10). Only one of the filial nuclei gave rise to a second division, and six nuclei were produced (Fig. 11). Four of the six nuclei in the copula degenerated. The other two were isolated at the place of their fusion, each of them producing a single gamete (Figs. 11, 20). Copulation of two gametes created a zygote which developed into spherical sporoblast containing one nucleus (Fig. 12). Gradually, the sporoblast stretched out, and was transformed to give the sporocyst. The multiplying nucleus in the sporocyst produced eight sporozoites (Fig. 13). The cytoplasm of the exospore disappeared, and the sporocyst became free. The sporocysts were spindle shaped with a thick, “button-like” structure at each pole, measuring 8 x 2.5-3.5 Frn, (Fig. 14). The sporocysts represent resistent stages of the parasite which can become the beginning of a new infection if they are swallowed by a host. Some developmental stages of 0. hyZobii were also examined at the electron micro-
166
PURRINI
0
AND
ORMIERES
lOOF
figs.28,4 0
,
,‘fr
figs. 1,5 FIGS. I-5. Grrgurina hylobii. (1). Young gamonts (5.5 wrn long) with spherically shaped epimerite; (2) maturating gamont (240 pm long), with an exceptional epimerite showing a “vacuolized spherelike” structure: (3) association of two mature gamonts; (4) gametocyst with 12 birth holes of “ringlike” form, two of them producing a sporoduct channels; (5) a chain of doliform spores.
scope level (Figs. 23-28). Unfortunately, these studies did not reveal, either in solitary or in associated gamonts, any clear features of their ultrastructure. In our mate-
rial, the investigated stages always appeared as very electron-dense bodies filled with masses of paraglycogen granules (Fig. 23). Similar difficulties were encountered
Gregarina
AND
Ophryocystis
PARASITIZING
Hylobirrs
167
FIGS. 6- 15. Ophryxystis h.dobii n. sp. (6) Mycetotic schizonts in close contact with the inner cell wall of the host tissue (Malpighian tubules); (7, 8) uninucleate gamonts; (9, IO) uni- and binucleate copula of pairing gamonts; (11) formation of gametes: (12) formation of uninucleate sporoblast; (13) single sporocyst in gametocyst: (14) free mature sporocyst containing eight sporozoites: (15) free mycetotic schizont.
during investigations of sporocysts (Figs. 25 - 28). Therefore we could determine only few features of their inner structure. The sporocyst in Figure 24 showed membraneous residues of the formerly paired gamonts. The membrane surrounding the sporocyst being thin as shown in Figure 24, at the initial stages of maturation, later became thicker (Fig. 25). The thick parts were “buttonlike” structures at each of the poles of the sporocysts, resulting from the thickening process of the surrounding membrane.
They are well visible in Figures 25 and 26. Eight transversally cut sporozoites inside of the sporocyst represent another important ultrastructural feature observed in 0. hylobii (Figs. 27, 28). Prevalence of Infection and Host-Parasite Relationships
The gregarine infections did not produce any apparent external symptom; however, it could be noted that some adults were not as active as healthy ones, and finally stopped
FIGS. 16-18. Grr,vuitlu hvlobii (light microscopy, fresh). (16) Young and mature gamonts (200x ); (17) two associations of mature gamonts (500x): (18) doliform mature spores (2000x).
Gregarina
AND
Ophryocystis
PARASITIZING
Hylobius
169
FIGS. 23-26. Ophryocystis hylobii n. sp. (electron microscopy). (23) Some solitary gamonts and some gamonts pairing in copula: their cytoplasm filled with masses of paraglycogen granules (4700x); (24) young sporocyst, with residues of pairing gamonts still visible (22,000~); (25) maturating sporocyst with a thick surrounding membrane: two thick “button-like” structures at each of the poles of the sporocyst are well recognizable (14,000~): (26) A thickened membrane forming a “button-like” structure in a sporocyst shown at high magnification (75,000~).
is
Gregarinn
AND
Ophryocystis
PARASITIZING
H.vIobius
171
FIGS. 27-28. Ophryocystis hybbii n. sp. (electron microscopy). Paralongitudinal(27), 22,000~) and transveral (28), 27,000x, ultrathin sections of sporozoites in mature sporocysts. In Fig. 28, eight sporozoites are well visible. 172
Gregnrina
AND
Ophryocystis
feeding. After dissection the degraded gut and Malpighian tubules of infected beetles could be observed under the light microscope. Prevalence of infection by the gregarine G. hylobii was 14% in single infections, and 16% in triple infections with 0. hylobii and N. hylobii. In some cases (6% of examined specimens) more than 600 gamonts and more than 15 gametocysts (maximal 21) were observed in the gut lumen of infected animals. The infection by the neogregarine 0. hylobii has only been observed in dual infections with G. hyfobii (18%) or in triple infections (16%) with G. hyfobii and N. hylobii. Usually the gregarine (G. hylobii) and the microsporidian (N. hylobii) dominate; some specimens of diseased adults showed that occasionally 0. hylobii predominated. In these cases the Malpighian tubules as principal sites of infection by the parasite were completely degenerated. They appeared hypertrophied, transparent, thin walled, and yellow. Large areas tilled with vegetative stages (gametes and gametocysts) and sporocysts of the parasite could be observed under the light microscope (Fig. 22). DISCUSSION
Fuchs (1915) and Geus (1969) described a gregarine found in the gut of adults of H. abietis. The name Gregarina hylobii was proposed by Fuchs. Only solitary and associated gamonts of the gregarine were described. Our investigations, started in 1980 with a large number of infected adults of H. abietis, allowed us the reexamination of this parasite. The development of the gregarine was followed and its complete life cycle can now be described. There are actually 11 known neogregarines of the genus Ophryocystis, all of them parasites of different species of the Coleopteran families Tenebrionidae, Alleculidae, and Scolytidae; Ophryocystis dubosqui Leger 1907 is an exception. It is associated with three species of weevils: Otiorrhynchus ligustici, 0. meridionalis, and 0. fuscipes (Curculionidae, Col.). All
PARASITIZING
Hylobius
173
described species of the genus Ophyryocystis, except 0. duboscqui, differ in shape and size of developmental stages and in the host-parasite relationships from the neogregarine presented here. Only 0. duboscqui can be compared with the parasite found in H. abietis. These two parasites have host-species of the family Curculionidae. The gamonts, although similar in shape, differed in size, being 5 (0. duboscqui) and 7 pm (0. hylobii) in diameter. The copula of 0. hylobii, measuring 8- 11 x 5-7 pm, was nearly of the size of that of 0. duboscqui, being 8 pm long and 5 pm wide. The sporocysts were identical in shape, but they differed in size, being 8 pm long and 2.5-3.5 pm wide in case of 0. hylobii, and 9 pm long and 4 pm wide in case of 0. duboscqui. The radicells, known as common stages occurring in the life cycle of 0. duboscqui, were not observed in 0. hylobii. The finding that the neogregarine described in the present investigation is the parasite of H. abietis, a species so far not described as a host for a neogregarine, as compared to the known species of the genus Ophryocystis, gave us cause to describe it as a new speices. The name Ophryocystis hylobii n. sp. is proposed. ACKNOWLEDGMENTS The authors wish to thank Professor Institute of Microbiology, University for his help during examinations with croscope. We are grateful also to Mss. and Mr. Georg Vacek, Experimental try, Goettingen, for supplying insect
Dr. F. Mayer, of Goettingen, the electron miRenate Hofman Station of Foresmaterials.
REFERENCES FUCHS, G. 1915. Die Naturgeschichte der Nematoden und einiger anderer Parasiten des Ips typographus L. und Hylohius uhietis L. Zool. Jahrb. 38, 109-222. GEUS, A. 1969. Sporentierchen, Sporozoa. Die Gregarinida. Tierwelt Deutschlands, Vol. 57, pp. l-608. Fischer, Jena. LUGER, L. 1907. Les Schizogregarines des Tracheates. I-Le genre Ophryocystis. Arch. Protistenk., 8, 159-202. PURRINI, K. 1981. Nosema hylobii n. sp. (Nosematidae, Microsporida) a new microsporidian parasite of Hylobius abietis L. (Curculionidae, Coleoptera) .I. Appl. Entomol.. 92, 1-8.