 Reference Base  Parasitic muscid larvae collected from the African elepha... |
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Bequaert, J., 1916. Parasitic muscid larvae collected from the African elephant and the white rhinoceros by the Congo expeditions. Bulletin of the American Museum of Natural History 35: 377-387, figs. 1-3
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World |
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Diseases - Parasites |
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White Rhino |
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Gastric larva of Ceratotherium simum: Gyrostigma. The existence of larvae in the stomach of rhinoceroses has been known for a long time but it is only recently that we have had any definite information concerning the life history of these parasites. The first reference to the presence of Oestrid larvae in the stomachs of African rhinoceroses dates from 1839: Hope, in a paper on the parasitic larvae of man (Trans. entom. Soc. London, 2 (3): 256-271] figures incidentally (but without description) one of these parasites as 'Oestrus rhinocerontis Owen,' under which name it was classified in a museum (op.cit., p. 259, Tab. XXII, fig. 1 and 1a). In 1863, Brauer (Monogr. d'Oestrid., p. 92) briefly described, after the figure of Hope, the same larva under the name of 'Gastrophilus rhinocerontis.' As there exist many similar gastric Oestridae in the African rhinoceroses, it is impossible to refer the parasite of Hope to one of those described later.
The presence of gastric larvae in the rhinoceroses of South Africa was referred to by the explorer Delegorgue, in this way: ' Le rhinoceros simus en avait aussi quelque peu, non sous la peau, mais dans son estomac. Le rhinoceros africanus bicornis pourrait bien r?clamer le titre de p?re nourricier des oestres. On ne saurait s'imaginer la quantit? contenue dans son estomac, c'?tait ? les mesurer au boisseau, ? les prendre ? la pelle. Cette difference en nombre est constante chez les deux esp?ces et j'incline fortement ? penser que le rhinoceros africanus bicornis ne doit sa m?chancet?, la. fureur qui le distingue, qu'? la pr?sence de ces milliers de parasites, absolument comme 1'homme qu' habite le t?nia.' (Voyage, II, 1847, p. 351)
Although these parasites are abundant in their hosts, definite information concerning them is of relatively recent date. In 1885, Brauer was able, for the first time, to examine the gastric larvae from a specimen of Rhinocerog sumatrensis, which died in the Zoological Garden at Hamburg. He recognized that they were distinct from Gasterophilus and placed them in a new genus Gyrostigma, under the name of G. suntatrensis. [Verh.k.k.zool.bot.Ges Wien, 34: 269-270, tab.X] In 1892 he referred to the same genus the African larvae of Ostrus rhinocerontis Owen, figured by Hope. [SitzBer. Ak.Wiss. Wien, math.naturw. Cl., 101: 8]
A very remarkable Oestrid image was described in 1895 by Corti, from the Galla country, under the name of Spathicera paveii. [Ann.Mus.civ. Genova, ser.2, 15: 144-147] The author made the suggestion that perhaps it came from a gastric larva, probably Cobboldia or Gyrostigma. Brauer, in completing the description of this fly, showed also the great probability of the identity of Spathicera with Gyrostigma. [SitzBer. Ak.Wiss. Wien, math.naturw. Cl., 104: 582-588, 1895.] He again refers to this hypothesis in the description of Gyrogtignia rhinocerontis bicornis on larvae from an East-African rhinoceros. [Denkschriften Ak.Wiss. Wien, math.naturw. Cl., 64: 261, 1897.]
It was not until ten years later that this identity was definitely establislied by Y. Sj?stedt [Wiss. Ergebn. Schwed. Zool. Exp. Kilimandjaro, 1905-06, bd. 2, abth. 10, no. 2, 1908, pp. 11-19] who succeeded in rearing an imago from a larva collected in Rhinoceros (Diceros) bicornis from Kilimanjaro. The species which he named Spathicera, seemed to him different from the
imago Spathicera pavesii Corti and also from the larva Gyrostigma rhinocerontis bicornis Brauer. In commenting upon this discovery of Sj?stedt, Poulton [P{roc. Enbtom. Soc. London, 1908, p. xxix-xxx] refers to a curious observation by S. A. Neave: in 1908 that ento- mologist observed, in the valley of the Luangwa River (N.E. Rhodesia), three very large flies, on the carcass of a freshly killed rhinoceros. These Diptera, which were without doubt Spathicera, were unwilling to leave the carcass and allowed themselves to be picked off by hand. Neave noticed also the astonishing resemblance of these flies to certain large Hymenoptera (Salius sp.) which are bluish black with orange legs.
The studies of G. Enderlein on the gastric larvae of rhinoceroses should also be noted. In 1899, he made a very complete histological examination of the respiratory organs of Gyrostigma and incidentally pointed out the existence of G. sumatrensis Br. in Rhinoceros lasiotis. [SitzBer. Ak.Wiss. Wien, math.naturw. Cl., 108 abt.1, p.235-303] He later described, under the name of Gyrogtigma conjungens, a remarkable larva from Rhinoceros bicornis from Kilimanjaro, and at the same time referred to Gyrostigma rhinocerontis bicornis Br. other larvae from East Africa (according to Sj?stedt, 1908, op. cit., the latter larvae really belong to Spathicera meruensis Sj?st. [Arch.f. Naturgesch. 67 Beigeft, 1901, p. 23-39.] Finally, more recently, Enderlein, noting that the characters of his Gyrostigma conjungens were in certain respects intermediate between Girostigma Br. (= Spathicera Corti) and Gasterophilus Leach, made his species the type of a new genus Stomachomyia. [Stettin entomol. Zeitung, 72, 1911, p. 141-144.]
The rearing of the imago of Gyrostigma meruensis by Sj?stedt (1908) has definitely proven the identity of the genera Gyrostigma Brauer (1885) founded on the larvae of a species from Sumatra, and Spathicera Corti described from an imago captured in Abyssinia. According to the rules of zoological nomenclature now in use, there is no doubt that the first of these names should have priority. As yet G. meruensis Sj?st. was the only species of the genus known both from larva and imago. Moeover, there were described three different larvw for which the corresponding imagoes had not been obtained:
G. sumatrensis Brauer 1885, from Sumatra;
G. rhinocerobtis bicornis Brauer 1897, from Africa;
G. conjungens Enderlein 1901, from Africa.
Finally G. pavesii Corti 1895 had been described from an Abyssinian imago and no larva corresponding to it was known.
In 1914 my good friend Dr J. Rodhain, who by his patient researches has contributed very largely to the progress of African parasitology, succeeded in rearing a number of imagoes from gastric larvae collected from Rhinoceros simus cottoni in the Uele district (northeastern Congo).
He was also able to clear up the mystery of oviposition and of the first larval stage of that insect. [Rodhain, Bull. Soc. Path. exot. Paris, 8, 1915: 275-279] Dr. Rodhain kindly turned over this precious material to me for study. It was, therefore, possible for me upon my return to Europe, to establish the identity of the reared imagoes with Gyrgstigma (Spathicera) pavesii Corti; on the other hand, the larvae from which these flies came could in no way be distinguished from those to which Brauer gave the name Gyrostigma rhinocerontis bicornis. This species, therefore, should bear the name of Gyrogtigma pavesii (Corti).
The Congo Expedition collected in the same region as did Dr. Rodhain numerous larve from the white rhinoceros. The label which accompanied these specimens bore the note 'Faradje, Feb. 3 and 5, 1912, from Rhinoceros; most of the stomach practically studded.' They did not differ from those which I had previously examined from the Uele district and must also be referred to Gyrostigma pavesii Corti (syn: G. rhinocerontis bicornis Brauer).
The larvae collected by Dr. Rodhain (May 1914) are in the third stage. This is true also of a large number (60 to 70) of the parasites collected by Messrs. Lang and Chapin; some of them are of very large size, measuring 3.5 mm. in greatest length and 15 mm. in greatest breadth; the others are much smaller, being not more than 16 mm. in length and 6 mm. in breadth; but the presence of three peritremes on each stigmatic plate shows that they have already moulted twice. These larvae of the third stage correspond very well to the description given by Brauer and Sj?stedt. Every stigmatic plate bears three peritremes, each of which is very strongly sinuate, like a number of S's joined end to end; the result is that the plate is completely covered by their numerous windings. The spines of the girdles are numerous, those of the anterior row on each segment are so close together that they nearly touch each other at their bases. The color of the tegument is uniform, without dark spots; it is dirty white in the small larvae and pale horny brown in the larger ones.
The material provided by the Congo Expedition contains also a number of larvae of the 2nd stage. This stage does not appear to have been recorded as yet, so that I think it worth while to describe them more in detail. (Fig. l.) They may be immediately recognized bs the peculiar structure of their posterior stigmatic plates, each of which shows omly two feebly sinuated peritremes. Some of them attain a length of 20 mm. and a greatest breadth of 6 mm.; others are much smaller, not surpassing 10.5 mm. in length and 3 mm. in breadth. Their general aspect is somewhat different from that of the full-grown larvae; they are much longer and vermicular, three to three and a half times as long as broad. The greatest breadth is not at the middle of the body but towards the posterior extremity, usually at. the eleventh segment; in front of this segment the body gradually tapers toward the cephalic extremity, which is more pointed than in the third stage. The larvae are very slightly flattened dorso-ventrally, often nearly cylindrical, especially in the posterior half.
The twelve segments are very distinctly separated and they increase in length from the first to the eleventh; the latter segment is very well developed, especially on the dorsum; the twelfth is cut much shorter than the eleventh and slightly larger on the ventral than on the dorsal face.
On the ventral side there are sometimes traces of median, intermediate fields between segments five and eight; and there are even broad transverse elevations on each side of the median line, which perhaps may be used as ambulatory pseudopodes. On the sides the longitudinal superposed pads and the transversse intermediate pads have the same arrangement as in the third stage.
The concavity on the posterior face of the anal segment (twelfth) is usually deeper and inclosed by better developed lips than is the case in the full-grown larva, so that the small stigmatic plates are not usually seen. However, each of these anal lips bears four superficial papillae, as in the third stage.
The cephalic (first) segment bears two antennal pads constricted at the base, very broad and flattened at the apex, relatively, much nearer the median line than in the third stage. Each of these shows two very pale (sometimes almost invisible) ocellary spots; I was not able to make out a chitinous basal ring. There are two pairs of buccal hooks which are practically of the same shape and arrangement as in the full-grown larva. The external pair are claw-shaped, dark brown, and their bases inclose the internal pair which are much shorter, often retracted, conical stiletto-shaped, pale, slightly brownish.
The larvae are amphipneustic. The anterior stigmata have the same structure as in the third stage. Their external aperture is situated on the side in the fold between the second and the third segments, but it is very small and difficult to see. The posterior stigmatic plates are small (about 0.8 mm long and 0.52 mm in greatest breadth) and occupy. only a small area of the posterior face of the twelfth segment. They are oriented as in the full-grown larvae, but their shape is somewhat different: they are oval, much broader toward the ventral third; their inner margin is only slightly emarginate toward the dorsal third, and it is at this level that one sees between the two plates the scar of the stigmatic orifice of the first stage.
In each plate are two marinate peritremes each forming a single irregular S, so that two well marked curved angles are present; their general aspect then is nearly that noticed in the third stage of Gyrostigma sumatrensis Br. (according to the figures of Brauer and Enderlein, for I have never seen specimens of this species). Each peritreme attains a length of about 1.12 mm and shows on the outside a series of transverse chitinous ridges numbering sixty to sixty-five and placed about 0.018 mm. from each other; every one of these ridges corresponds to an internal curved supporting plate. (Fig.2)
The spinulation has a somewhat different appearance from that of the third stage larva: the spines are scarcely visible, nearly colorless, only the points slightly brownish; they are very small, quite numerous and close together. The first segment (protocephalon) bears a complete girdle of minute spines which cover the inferior labial pad and extend even back of the antennae; the second (postcephalon) is unarmed. Segments three to nine are furnished on the anterior border with a continuous girdle of spines, very close together in three or four rows, covering about the anterior quarter of the segments, the spines of the anterior row being slightly stronger than the others. On the tenth segment the spinous girdle is continuous on the ventral face and slightly interrupted along the median line on the dorsal face; the eleventh segment seems to be unarmed on the dorsal face and on the ventral face bears one or two feeble lateral rows of spines; the twelfth segment is unarmed. The intermediate lateral pads between segments five to nine also have three or four minute spines; the one between the ninth and tenth segment is unarmed.
Behind the spiny girdles there are often on the dorsal and ventral faces of each segment a transverse series of minute elongated brownish spots: in some larvae they are quite visible to the naked eve and they then somewhat resemble spines. These spots seem to be sub-epidermal and, moreover, they are not always very distinct; their significance is unknown, but perhaps they are nerve-endings.
It should be noted that the rhinoceros from which Messrs. Lang and Chapin collected both the second and third stages was shot early in February, a date which corresponds to the height of the dry season in the savannah of the Uele district. Mr. Chapin informs me that the dry season in this region is very pronounced from December to April. At the beginning of the rainy season (May) Dr. Rodhain found only larvae of the third stage in the rhinoceros. Therefore, there must be a period of the year (probably corresponding to the last half of the dry season) during which no adult flies emerge. But here again it is desirable to have further observations made on the spot before we can establish the different periods in the seasonal development of this parasite.
Thanks to the kindness of Dr. Rodhain, 1I am able to figure for the first time the puparium of Gyrostigma pavesii (Corti) from a photograph taken in the Congo by Mr. Lebrun (Fig. 3).
In the material collected by the Congo Expedition there are a certain number of larvae attached to other parasites of the alimentary tract; e. g. Scoleces of Taeniids. But according to the verbal explanation given by Mr Lang, this attachment certainly happened after the parasites left the stomach, since there they are always attached to the walls. This seems to be indicated furthermore by the fact that larvae of Gyrostigma sometimes are found attached to true intestinal worms. Mr. Lang also observed that when placed on the hand, the larvae of Gyrostigma are able to attack the human skin by their powerful hooks and thus produce a sharp pain.
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