Haplometra Cylindracea (Trematoda: Plagiorchiidae) in Lymnaea Truncatula: Cercarial Shedding During Single Or Dual Infections with Otherdigenean Species
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Research and Reviews in Parasitology, 53 (1·2): 57·61 (1993) Editorial Fcntalba, S.A. © 1993 Asociaci6n de Parasit61ogos Espanoles Printed in Spain HAPLOMETRA CYLINDRACEA (TREMATODA: PLAGIORCHIIDAE) IN LYMNAEA TRUNCATULA: CERCARIAL SHEDDING DURING SINGLE OR DUAL INFECTIONS WITH OTHERDIGENEAN SPECIES A. MOUKRIMI, J.A. OVIED02, Ch. VAREILLE.MoREL3, D. RONDELAUD4 & S. MAS·COMA2 1Laboratoire Eaux et Environnemenl, Departement de Biologie, Faculte des Sciences, Universite Ibnou Zohr, RP. 281S, Agadir, Morocco 2Deparlamenlo de Parasitologia, Facultad de Farmacia,Universidad de Valencia, Av. Vicenl Andres Estelles sin, 46100 Burjassot . Valencia, Spain 3Laboratoire de Malacologie Appliquee, Faculte des Sciences, Avenue Alberl Thomas 123, 87060 Limoges Cedex, France 4Laboraloire d'Histopathologie Parasitaire,Laboratoire d'Histologie, Faculte de Medecine, Rue du Docteur Marc/and 2, 87025 Limoges Cedex, France Received 10 May 1992; accepted 7 July 1992 REFERENCE: MOUKRIM (A.), OVIEDO (l.A.), VAREILLE·MoREL (Ch.), RONDELAUD (D.) & MAS·COMA (S.), 1993.- Haplometra cylindraeea (Trematoda: Plagiorchiidae) in Lymnaea truneatula: cercarial shedding during single or dual infections with other digenean species. Research and Reviews in Parasitology, 53 (1·2): 57·61. ABSTRAcr: The daily cercarial production of Haplometra eylindraeea was studied in Lymnaea truneatula naturally infected by this parasite. Observations were performed in preadult snails with developing infections and in adults shedding cercariae at the beginning of the experi- ment. In these two groups, the cercaria! production was analysed in controls and in snails subjected to a second infection with another trematode species (Fasciola gigantiea, F. hepatica, or Paramphistomum daubneyii. The cercariae of H eylindraeea were shed over a patent period of 32·47 days. Their mean numbers were maximal at days 4·6 of the patent period and regularly decreased until day 32; afterwards, they were low and irregular. No periodicity was noted in the distribution of the daily mean numbers of H cylindracea. When the infected snails were exposed to a second digenean species, a more rapid decrease in the mean daily values of H eylindraeea was noted, with cessation of shedding from days 26 to 29 of the patent period (according to the group). Metacercariae of the other trematodes were formed from day 28 or day 35 of the patent period; their production lasted from 10 to 19 days. However, the daily number of these parasites remained low (1·8 per snail). KEy WORDS: Trematoda, Haplometra cylindracea, Fasciola gigantica, F. hepatica, Paramphistomum daubneyi,Lymnaea truneatula, cer- carial production, single and dual infections. INTRODUCTION night (AUDOUSSETet al., 1989). The latter rhythm is also found in the cercaria I shedding of Fasciola gigantica As well known, the molluscan species Lymnaea trun- Cobbold, 1855 in the same snail species; however, there catula Muller, 1774 (Basommatophora: Lymnaeidae) is no daily periodicity (RAKOTONDRAVA&ORONDELAUD, plays the role of intermediate host of Fasciola hepatica 1991). Linnaeus, 1758 (Trematoda: Fasciolidae) in Europe. But Concerning dual infections, one has to bear in mind moreover this snail species also acts as intermediate host the well known antagonism between digenean species at in the life cycle of many other digenean species. This molluscan level (LIM & HEYNEMAN, 1972; COMBES, capacity to be used by trematodes pertaining to different 1982). Among the numerous aspects of the intramolluscan digenean families raises several questions concerning the inter-trematode antagonism, the aim of this paper is to cercarial shedding patterns shown by these different dige- contribute, by means of the model digeneans/ L. trun- nean species in the same snail species, not only in the cases catula, in two questions. Does dual infection of the snail in which the snail individuals are parasitized by the lar- affect the chronology of cercarial shedding in the first val stages of only one digenean species, but also in those parasite species? Are changes in cercarial shedding similar cases in which larval stages of two different digenean when the second infection is performed during the par- species coexist within the same molluscan individual. thenitae development of the first parasite or at the begin- Concerning single infections, worth mentioning are the ning of its cercarial shedding? To answer the former ques- differences found between two different species of the tion, the species Haplometra cylindracea (Zeder, 1800) same digenean genus. Thus, most cercariae of Fasciola Looss, 1899 (Trematoda: Plagiorchiidae) has been used, hepatica are shed by Lymnaea truncatula at several times since L. truncatula is a natural intermediate host in this (shedding waves) of variable length, separated by inter- trematode's life cycle (COMBES, 1968; GRABDA- vals without shedding. Two rhythmic cycles can be KAZUBSKA,1970). Cercarial shedding of this parasite was recognized in these cercarial sheddings: an infradian-type analysed in naturally infected L. truncatula, using con- rhythm with periodicity every 7 days, and a circadian trols and snails subjected to a second infection with rhythm with maximal production of parasites during the another trematode species. For this purpose, F. hepatica, 58 A. MOUKRIM et al. F. gigantica, or Paramphistomum daubneyi Dinnik, 1962 80 Number of cercariae per day (Paramphistomatidae) were used. To answer the latter H. cyllndracea question, we studied preadult L. truncatula with develop- ing infections with H cylindracea, and adult snails shed- 80 - - ding cercariae at the beginning of the experiment. 40" . MATERIAL AND METHODS Snails 20 L. truncatula specimens were collected at La Basse-Mazelle, bet- ween the communes of Limoges and Rilhac-Rancon, department of Haute-Vienne, France. They were living in a stream that runs lr 1r throughout the year from the exit point of a subterranean drainage O~~illill~~WW~illill~~WW~illill~~ system collecting water of several springs. This colony was widely 5 10 15 20 25 30 32 infected by H. cylindracea, with prevalences from 37070 to 78% Duration of the patent period (days) (HOURDIN, MOUKRIM & RONDELAUD, 1991). The superficial sedi- ment of the habitat was siliceous (water pH: 6,5). Preadult snails Fig. 1.- The number of cercariae shed by preadult controls in rela- (4 mm in height) and adults (5 to 5,5 mm) were used in these ex- tion with the days of the patent period. periments. One hundred and thirty preadults were collected in June, and were part of the second annual generation. They harboured to F. giganlica according to the same protocol. Miracidial exposure natural infection by H. cylindracea. Histological examination of 35 occurred the day that the first H. cylindracea cercariae were shed. other preadult snails gathered in the same conditions, bred in From the beginning of the experiment, the snails were isolated in laboratory, and killed from day 3 to day 42 after collection 35-mm diameter Petri dishes. Daily observations and cercarial counts demonstrated that natural infection by H. cylindracea had occur- were performed identically as with the preadults. red 15 days before snail collection in their habitat (MOUKRIM, HOUR. H. cylindracea cercariae were «active cercariae» and did not en- DIN & RONDELAUD, 1991). Three hundred and seventy-five adults cyst on container walls. Those from other trematodes formed were collected in April and were part of the first annual generation. metacercariae after several minutes. They were infected by H. cylindracea and were shedding cercariae at the time of their collection. Histological examination of 35 adults Processing of data using the same protocol revealed that the span of haplometrid snail infection was 30-35 days at the time of their collection (MOUKRIM Figures concerning cercarial counts were all averaged and s.d. deter- & RONDELAUD, 1992). Snails were transported to the laboratory mined, taking into account the numerical order of the days of the under isothermal conditions and kept in standard breeding containers patent period. Daily results were processed using an autocorrelation for 48 h (at 20° C) before being subjected to experimentation. analysis (BRooM, 1979) to determine whether there was periodicity in the production of cercariae. Parasites Three trematode species were used: F. hepatica, F. giganlica, and RESULTS p. daubneyi. Eggs of F. hepalica were collected at the Limoges slaughterhouse (Haute-Vienne, France) and were collected in heavily- infected bovine gallbladders. Eggs of F. gigantica originated from Preadult controls gallbladders of Malagasy infected cattle. Eggs of P. daubneyi were collected in faeces of French cattle only infected with this helmin- There were 31 survivors on day 42, with a mean shell thosis. All eggs were maintained for 16 days at 23° C in total darkness, height of 8,2 mm. Cercarial shedding occurred in 28 in accordance with the reports of OLLERENSHAW(1971) concerning snails. The beginning of the patent period occurred from F. hepalica. days 35 to 38 of the experiment for 27 snails, and at day 51 for the last snail; its maximum duration was 32 days. Experimental protocol The number of snails decreased rather slowly until day The first 45 preadults served as controls. The 85 others were each 27 of the patent period, with seven deaths during this exposed to 2 miracidia of P. daubneyi for 4 h in 35-mm diameter phase; a sudden numerical decrease then occurred until Petri dishes containing 2 ml of water from their original habitat. day 32 (data not shown). One shedding wave was noted The snails were bred in closed-circuit aquaria in an air-conditioned only in eight snails. Sheddings occurred 2, 3, 4, and 5 room at constant temperature (20° C), with a 12-h photophase and times respectively in 6, 3, 9, and 2 snails. Wave duration light intensity of 4000 lux at the container's surface. The snails were fed lettuce ad libitum. On day 35, the survivors were isolated in was 13,7 ± 10,4 days for the first wave, 6 ± 5,4 days for 35-mm Petri dishes with 2 or 3 ml of water and a piece of lettuce. the second wave, and 3 to 3,5 days for the last three waves.