Paraophioidina Scolecoides N. Sp., a New Aseptate Penaeus Vannamei
Total Page：16
File Type：pdf, Size：1020Kb
DISEASES OF AQUATIC ORGANISMS Vol. 19: 67-75,1994 Published June 9 Dis. aquat. Org. 1 l Paraophioidina scolecoides n. sp., a new aseptate gregarine from cultured Pacific white shrimp Penaeus vannamei Timothy C. Jonesl, Robin M. O~erstreet'~*,Jeffrey M. Lotzl, Paul F. Frelier2 'Gulf Coast Research Laboratory, PO Box 7000, Ocean Springs, Mississippi 39566, USA 2Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas 77843, USA ABSTRACT: The aseptate gregarine Paraophloidina scolecoides n. sp. (Eugregarinorida: Lecud- inidae) heavily infected the nlidgut of cultured larval and postlarval specimens of Penaeus vannamei from a commercial 'seed-production' facility in Texas, USA. It is morphologically similar to P korot- neffiand P vibiliae, but it can be distinguished from them and from other members of the genus by having gamonts associated exclusively by lateral syzygy. Shrimp acquired the infection at the facility; nauph did not show any evidence of infection, but protozoea, mysis, and postlarval shrimp had a prevalence and intensity of infection ranging from 56 to 80 % and 10 to >50 parasites, respectively. Infected shrimp removed from the facility to aquaria at another location lost their gamont infection within 7 d. When voided from the gut, the gregarine disintegrated in seawater. Results suggest that P vannamei is an accidental host, although a survey of representative members of the invertebrate fauna from the environment associated with the facility failed to discover other hosts. No link was established between infection and either the broodstock or the water or detritus from the nursery or broodstock tanks. KEY WORDS: Gregarine . Parasite . Paraophioidina scolecoides n. sp. Shrimp . Penaeus vannamei - Aquaculture INTRODUCTION 1977). Septate members are common intestinal para- sites of both natural and cultured shrimp (Kruse 1959, Gregarines are a diverse and successful group of Overstreet 1973, Lightner 1993).In particular, the gen- protozoan parasites belonging to the phylum Apicom- era Cephalobus Kruse, 1959 and Nematopsis Schnei- plexa. The largest order within the subclass Gregari- der, 1982 have a worldwide distribution in cultured nasina Dufour, 1828 is Eugregarinorida Leger, 1900. In penaeids (Lotz & Overstreet 1990, Lightner 1993). this order, there are 2 large suborders, the members of There is concern that heavy infection with these gre- which are distinguished morphologically by the num- garines has the potential to cause economic losses ber of body divisions (Levine 1976). Gamonts of mem- through host mortality and reduced growth of the host bers of Aseptatorina Chakravarty, 1960 are composed in ponds (Lightner 1993).In shrimp aquaculture, how- of a single compartment, but for those in Septatorina ever, gregarines are rarely seen in 'seed' (= postlarvae) Lankester, 1885 gamonts are divided into 2 distinct production. In this paper, we describe a new species of compartments. Aseptatorina that infects the midgut of larval and post- Gregarines are parasites of the intestine or body cav- larval specimens of Penaeus vannamei and report on ity of invertebrates, particularly arthropods (Manwell aspects of the protozoan's biology, factors that had eco- nomical implications for a con~mercialseed-production 'Addressee for correspondencp facility in Texas, USA. O Inter-Research 1994 Dis. aquat. Org. 19: 67-75, 1994 MATERIALS AND METHODS at 28 ppt and 27 "C. Approximately 180 gregarine-free larval shrlmp (7 d old) provided by The Oceanic Insti- Terminology. We use the term 'gamont' collectively tute, Makapuu Point, Hawaii, were added to each of to describe gregarines attached to host gut cells, free in the 4 aquaria. Shrimp were fed brine shrimp (Aquar- the lumen, in syzygy or in multiple associations and not ium Products, Glen Burnie, MD, USA) and pelleted just as paired cells in syzygy (Shrevel & Philippe 1993). commercial feed (Rangen Inc., Buhl, ID, USA). Daily Parasite observations. Infected larval and postlarval samples of 5 shrimp were removed from each tank and specimens of Penaeus vannamei were shipped live examined as fresh wet mounts for gamonts for 32 d. from the Texas production facility to the Gulf Coast We investigated broodst~ckas a potential source of Research Laboratory (GCRL) and to the Texas Agricul- infection by examining 2 male broodstock sent from the tural Experimental Station (TAES). At GCRL, the guts Texas facility. The shrimp were chilled at -4°C for of infected shrimp were removed with fine forceps and 10 min and dissected. Fresh preparations of gill, midgut, placed on glass slides in 0.85% saline for microscopic hindgut, and coelomic fluid were examined for the pres- examination of gregarines at 100 or 200x. Closer ex- ence of gamonts, gametocysts or spores. An additional 5 amination required teasing of individual gamonts from broodstock were examined by staff at the Texas facility. TATr 3ULYEyc~ .L- T --.--c- .::1: the rr.idgu! fcr phctcgrapk; and cccasionsl fixatior; iii LIIC I exa3 ICICI~I~~er~vi~ uameai [or oilier Davidson's fixative (Humason 1972). Fixed specimens potential hosts and sources of infection. Water and of whole larval and postlarval shrimp stored in 70% detritus samples were taken from the broodstock hold- ethanol were embedded in paraffin blocks, sectioned ing raceway, nursery tanks, maturation tanks, biofil- at 4 klm, and stained in Gill's hematoxylin and eosin- ters from both the nursery and broodstock systems, phloxine. At TAES, similarly fixed nauplii were em- main storage tank and external holding pond. Each bedded in epon and stained with toluidine blue. sample was examined for parasitic life-stages, and Life history studies. A total of 15 to 20 shrimp from invertebrates were removed for additional observation each consignment of nauplii (3 and 5 d old), protozoea under the compound microscope; large organisms (8 d old), mysis (10 d old), and postlarvae (15, 16 and were teased apart using forceps, and small specimens 21 d old) of Penaeus vannamei were received at GCRL were examined whole. and immediately processed for histological assessment Coccidiostat experiments. At TAES, the efficacies of as described above. Shrimp were maintained with 4 coccidiostats for treatment of infections with Para- minimal water changes in 38 l aquaria at 28 ppt salin- ophioidina scolecoides were tested with infected post- ity and 26 "C. A sample of 25 larval or postlarval shrimp larvae of Penaeus vannamei. The 4 coccidiostats were was examined as wet mounts for gregarines daily for administered orally in poultry feed to 5 groups of post- the first 10 d postreceipt and weekly thereafter. Nau- larvae (16 to 21 d old). Each group had 2 replicates so plii, protozoea, and mysis were observed over a 31 d that 2 control replicates received feed without drugs, 2 period while postlarval shrimp 15, 16 and 21 d old were replicates each received either Elancoban-100@ or examined up to 86 d. The intensity and prevalence of Bovateca at a dose of 1.66 g kg-' of feed, and 2 groups infection was determined for each shrimp group. each received either Rofenaidm or ~onteban@at 92 O/o Immediately on receipt at TAES, approximately of the high poultry dose. After 6 d, selected shrimp 100 nauplii (4 d old) and 1131 postlarvae (21 d old) were removed from each group and examined histo- from the Texas facility were processed similarly for his- logically for evidence of infection. tological assessment. We followed in detail the loss of gregarine infections from 6 heavily infected postlarvae (21 d old) which DESCRIPTION were isolated in a 40 mm glass petri dish filled with 27 ppt seawater. Gamonts observed under a dissecting Paraophioidina scolecoides n. sp. (Figs. 1 to 6) microscope were monitored for their movements at 12, 22, 25, 27 and 28.5 h. Diagnosis: Apicomplexa, Eugregarinorida, Asepta- Source of gregarine infection. Broodstock feces and torina, Lecudinidae Kamm, 1922, with elongate, asep- detritus taken from the maturation and larval rearing tate gamont. Gamont with truncated anterior mucron. systems were tested to determine if either was the Nucleus spherical to ovoid with central nucleolus; source of infection by exposing uninfected shrimp to nucleus located in anterior third of the body. Syzygy the material. Two 600 m1 plastic bottles containing lateral, often involving multiple associations. Move- detritus and a plastic bag filled with 600 m1 of seawater ment by gliding. Parasitic in Crustacea. and broodstock feces were shipped to GCRL. The sam- Description: Two forms of gregarine gamonts were ples were shaken for 30 s and individually dispensed recovered from the rnidgut and hindgut (Figs. 1 & 2): into 3 of 4 (fourth tank served as a control) 38 l aquaria (1) The immature gamont was aseptate, translucent, urd OS = ieq aIess 'rysieuroN dq 'uor~eledaldysaq .lnBprur ur luoureB alnleu jo wioj papunoa m ~rl001 = ieq a.[ess 'rysieuroN hq 'uogeiedaid qsaig uauIn1 ur aaij pue IIeM 01 paqselle sluoure6 ~IIMenie~lsod JO lnbp!~ ,urrl OS = ieq apss 'ssrldo rysieruo~'paurelsun ,uorleiedaid qsaq lapmeas ur luoure6 Buqe.~Balu~s~a.p;fjrj ,urrl 0~ = leq aress '3'8~,snapnu urylr~(~oiie) snIoa1snu al~seiedpup 'iapioq qsniq lselu! 'urnr~aqlrdaaql jo uo!lrpuos p006 alou :(peau[~oiie) [[PM lnljprur 01 payselle d[.[ersrjladns s1uoure6 auras .sluowe6 qlr~palsajur h[raeay e~ie1lsodjo ~nBp~y\l.E wrt OS = ieq aless '3%~.sluomeB aln~eunurpue (U) ainleur 'sauue6a16 6urure1uo~e~e.[lsod jo ~nBprm.Z;Blfl ,urd OS = ieq aless '!ysieuro~ Aq 'uorleiedaid qsaq .sluomeB ain~eunur pue (m) sluou1e6 alnleur z Bur~oqsea~e~lsod papaju~ JO ln6p~UI sluoure6 Dis. aquat. Org. 19: 67-75, 1994 and elongate, measuring up to 200x 10 pm (N = 10). Taxonomic remarks: Levine (1977) established The posterior end was bluntly rounded. The anterior Paraophioidina Levine, 1977 to accommodate elongate end was truncated and possessed a flattened mucron. gregarines that were both parasitic in crustaceans and The single nucleus was spherical to ovoid (3.4 to lacked a ball and socket association in syzygy.