ADDITIONAL OBSERVATIONS ON THE DEVELOPMENT AND TRANSMISSION OF truttaedactnitis PYBUSAE
ANDERSON, 1992 (SEURATOIDEA: CUCULLANIDAE)
OF THE BROOK LAMPREY, LAMPETRA APPENDIX (DEKAY, 1842)
ANDERSON R.C.*
Summary:
Spawning brook lampreys (lampetra appendix) in a small stream in Ontario, Canada were invariably infected with Truttaedactnitis pybusae Anderson, 1992 (Seuratoidea: Cucullanidae). The gut in spawning lampreys in May degenerates and relatively few eggs of T. pybusae are passed into the spawning area. In prespawning adult lampreys collected in April, the gut was intact and eggs could readily pass into the lamprey beds containing larval lampreys (ammocoetes). It is suggested this is the source of the eggs which eventually produce larvae which infect a high percent of the older ammocoetes. Attempts to infect rainbow trout (Oncorhynchus mykiss) with third-stage larvae from the liver of ammocoetes were unsuccessful. Some adult worms intubated into the stomach of O. mykiss attached to the gut wall and persisted in diminishing numbers for about three weeks. T. pybusae is apparently an independent parasite of lampetra appendix and only an incidental parasite of trout which might consume spawning lamprey containing adult worms.
KEY WORDS : transmission, Truttaedactnitis pybusae, lampetra appendix, lamprey.
MOTS CLES : bioiogie, Truttaedactnitis, Lampetra appendix, lampraie.
Resume : OBSERVATIONS NOUVELLES SUR LA BIOLOGIE DE
TKUTTAEDACTNITIS PYBUSAE ANDERSON, 1992 (SEUFATOIDEA:
CUCULLANIDAE) PARASITE DE LA LAMPROIE, LAMPETRA APPENDIX (DEKAY, 1842).
Les lamproies (Lampetra appendix) en période de reproduction d'un petit ruisseau d'Ontario, Canada, se trouvent toutes parasitées par Truttaedactnitis pybusae Anderson, 1992 (Seuratoidea : Cucullanidae). Au mois de mai, l'intestin des lamproies en période de reproduction dégénère et relativement peu d'œufs de T. pybusae sont évacués sur les frayères. Par contre, chez les lamproies adultes récoltées en avril, avant la période de reproduction, l'intestin est intact et les œufs du parasite peuvent facilement atteindre les lits contenant les ammocètes.
Nous supposons que ce sont ces lamproies qui constituent la source des larves qui infectent un fort pourcentage des ammocètes âgées. Des tentatives d'infestation expérimentale de la truite arc-en- ciel (Oncorhynchus mykiss) avec des larves du troisième stade provenant du foie d'ammocètes ont échoué. Quelques vers adultes introduits par intubation dans l'estomac d'Oncorhynchus mykiss se sont fixés à la paroi intestinale et ont survécu en nombre de plus en plus faible pendant environ trois semaines. T. pybusae est donc vraisemblablement un parasite spécifique de Lampetra appendix et parasite seulement accidentellement la truite par suite de l'ingestion de lamproies en période de reproduction contenant des vers adultes.
INTRODUCTION
T
h e d e v e l o p m e n t a n d transmission o f the s p e - cies o f TRUTTAEDACTNITIS (Seuratoidea: Cuculla- n i d a e ) o f b r o o k lamprey, LAMPETRA APPENDIX (= L . LAMOTTENII) in North America w e r e first studied b y Pybus ET AL. ( 1 9 7 8 ) . Adults o f the n e m a t o d e w e r e found only in the intestine o f spawning adult lampreys captured t h e s e c o n d a n d third w e e k s o f May; after s p a w n i n g the lampreys die. Larvae identified as third stage w e r e c o m m o n l y found in t h e liver o f a m m o - c o e t e s a n d transformers. Pybus ET AL. ( 1 9 7 8 ) c o n c l u d e d that during transformation o f the a m m o c o e t e s to adults, third-stage larvae in the d e g e n e r a t i n g liver m o v e d t o the intestine w h e r e t h e y m a t e d a n d p r o d u c e d e g g s .* College o f Biological Science, Department o f Zoology, Univer- sity o f Guelph, Guelph, Ontario, Canada, NIG 2W1.
Tel.: (519) 824-4120, ext. 2715. Fax: (519) 767-1656.
Eggs deposited in the intestine were excreted into the water and carried to ammocoete beds where they would embryonate to first-stage larvae in 18-20 days at 13 °C or in 8-10 days at 22 °C. The larvae would hatch from the eggs and be ingested by filter-feeding ammocoetes. The larvae invaded the liver of the ammocoetes and remained there in the third-stage until the lamprey transformed into adults. The authors concluded that the nematode was exclusively a para- site of the brook lamprey and that it used the ammo- coete as an intermediate host and the adult lamprey as a definitive host. The parasite has never been iden- tified from teleosts in North America.
Pybus ET AL. (1978) identified the worms in brook lam- preys in Ontario as T. STELMIOIDES (Vessichelli, 1910), originally described in LAMPETRA PLANERI in Italy and now regarded as a synonym of TRUTTAEDACTNITIS TRUTTAE (Fabricius, 1794) (= CUCULLANUS TRUTTAE of some Euro- pean authors), a parasite of salmonids in Europe which Article available athttp://www.parasite-journal.orgorhttp://dx.doi.org/10.1051/parasite/1996031033
A N D E R S O N R . C .
apparently uses the b r o o k lamprey (LAMPETRA PLANERI) as an intermediate host ( M o r a v e c , 1 9 7 9 , 1 9 8 0 , 1 9 9 4 ) . Third-stage larvae o f T. TRUTTAE are found e n c a p s u l a t e d o n t h e intestine o f the a m m o c o e t e w h e r e a s larvae o f the s p e c i e s in Canada o c c u r only in t h e liver. Also larvae o f T. TRUTTAE are smaller than t h o s e found in b r o o k l a m p r e y s in C a n a d a a n d w e r e r e p o r t e d t o d e v e l o p to adulthood in trout ( M o r a v e c , 1 9 7 9 , 1 9 8 0 ) . For these, a n d o t h e r reasons, Anderson ( 1 9 9 2 ) thought it prudent t o regard the form in b r o o k lampreys in O n t a r i o as a s p e c i e s distinct from that in b r o o k lam
preys in Europe a n d h e p r o p o s e d the n a m e T. PYBUSAE.
T h e current hypothesis to explain the transmission o f T. PYBUSAE is b a s e d o n the assumption that b r o o k lam
preys c a n s h e d sufficient n u m b e r s o f e g g s while spaw
ning to infect a m m o c o e t e s e l s e w h e r e in the stream.
This assumption requires further consideration b e c a u s e it is well k n o w n that the gut o f adult b r o o k lampreys d e g e n e r a t e s a n d forms constriction, a p r o c e s s w h i c h might r e d u c e the l i k e l i h o o d o f n e m a t o d e e g g s b e i n g e x c r e t e d in n u m b e r s b y s p a w n i n g lampreys. In addi
tion, the p o s s i b l e role in transmission o f trout w h i c h might c o n s u m e infected spawning lampreys n e e d e d further study as well as the infectivity to teleosts o f larvae found in the liver o f a m m o c o e t e s .
MATERIALS AND METHODS
T
h e study w a s c o n d u c t e d at B l u e Springs Creek (latitude 4 3 ° 3 6 ' N , longitude 8 0 ° 0 5 ' W ) , a tributary o f the E r a m o s a River draining eventually into Lake Ontario, Ontario, Canada. T h e site w a s u s e d by Pybus ET AL. ( 1 9 7 8 ) in the earlier study o f TRUTTAE-
DACTNITIS PYBUSAE. A m m o c o e t e s a n d p r e s p a w n i n g adults o f LAMPETRA APPENDIX w e r e c o l l e c t e d using a portable electrofishing unit at various times during the spring a n d s u m m e r . S p a w n i n g adults w e r e easily c a p tured b y dip nets the s e c o n d a n d third w e e k s o f May.
Lamprey w e r e transported in a m p l e w a t e r to the l a b o ratory at the University o f G u e l p h . S o m e w e r e main
tained alive for varying periods o f time in tanks with a constant flow o f well w a t e r at 14-15 °C a n d a m p l e air.
Prior to dissection, lampreys w e r e a n a e s t h e t i z e d b y immersion in a 0.2 % solution o f tricaine m e t h a n e sul- p h o n a t e ( M S 2 2 2 , Kent Laboratories Ltd.). During dis
s e c t i o n s o f adult lampreys, special attention w a s paid to the structure o f the intestine, the location o f n e m a todes a n d the p r e s e n c e o f n e m a t o d e e g g s in t h e gut.
Spawning adult lampreys w e r e p l a c e d in a large funnel ( d i a m e t e r m a x i m u m 3 0 c m ) filled with well water.
R u b b e r tubing a n d a c l a m p p r e v e n t e d w a t e r from e s c a p i n g from the funnel a n d air w a s b u b b l e d into the
water. At various times the sediment was examined for
eggs of T. PYBUSAE.
Rainbow trout (ONCORHYNCHUS MYKISS) maintained at
11 °C in well water were given larvae and adult
T. PYBUSAE in the following ways:
A. THIRD-STAGE LARVAE IN LIVERS OF AMMOCOETES: portions
of lamprey containing the liver were placed in the fish tank after the fish (25-30 cm in length) had been deprived of food for several days. Alternatively, the livers of infected ammocoetes were intubated into the stomachs of trout (17-18 cm in length) anaesthetized with MS222, using a modified Pasteur pipette.
B. ADULT WORMS FROM THE INTESTINE OF SPAWNING LAM
PREYS: the worms were placed in saline, counted and
divided into four parts each of which was intubated into an anaesthetized trout (30-31 cm in length) with the modified Pasteur pipette. Fish were fed 5-GR Trout pellets (Martin Feed Mills, Elmira, Ontario) each day and were later e x a m i n e d for the p r e s e n c e o f
T. PYBUSAE.
In addition to specimens of L . APPENDIX collected in
Blue Springs Creek in 1994-1996, formalized specimens consisting of a few prespawning and spawning adults collected from Blue Springs Creek in April of 1980 were available for study.
RESULTS
EXAMINATION OF SPAWNING LAMPREYS FOR ADULTS AND EGGS OF t. pybusae IN 1994 AND 1995
I n 1994 spawning began on May 6 and ceased about May 18. On May 6 five spawning lampreys were placed in water in a large funnel and the sediment was drawn off and examined 24 hours later.
A single active male worm and some 20 eggs of
T. PYBUSAE were found in the sediment. Worms werefound in all five lampreys at necropsy. In three lam
preys, the intestine was enlarged immediately behind the liver and this region contained most of the worms and many eggs in a yellowish, mucus-like material. In one lamprey worms were distributed in all regions of the intestine and in another most worms were found in the posterior third of the intestine. The anus appeared to be patent in all five lampreys and eggs were noted in the region of the anus in two specimens.
Eleven days after spawning began (May 17) five lam
prey captured on May 8 and maintained in the labo
ratory were placed in water in a large funnel and the sediment was examined 24 hours later. A considerable amount of brownish sediment was present and about
24 eggs of T. PYBUSAE and a single male were foundin this sediment. At necropsy, all five lampreys were
3 4 Parasite, 1996, 3, 33-37
infected with 15-35 ( x = 3 5 ) w o r m s . Most w o r m s w e r e found in an enlarged part o f the gut immediately b e h i n d the liver in mucus-like material containing numerous eggs o f T. PYBUSAE. T h e gut s e e m e d to b e o p e n at the anus but it w a s generally r e d u c e d in dia
meter posteriorly.
Three additional lampreys collected while spawning o n May 6 w e r e also e x a m i n e d o n May 17. T h e mid-intes
tine in o n e lamprey w a s filamentous and the lumen c l o s e d and the anterior region immediately b e h i n d the liver w a s enlarged a n d c o n t a i n e d 25 w o r m s a n d m a n y eggs in mucus-like material. T h e lumen o f the gut a p p e a r e d to b e o p e n in the remaining t w o lampreys w h i c h c o n t a i n e d 19 a n d 4 0 w o r m s , mainly in an enlarged region o f the gut immediately b e h i n d the liver w h e r e there w e r e also large n u m b e r s o f eggs.
In 1 9 9 5 spawning b e g a n o n May 7 a n d c e a s e d about May 1 8 . H o w e v e r , t w o p r e s p a w n i n g adults w e r e o b t a i n e d by e l e c t r o s h o c k i n g o n May 3- B o t h lampreys w e r e infected, o n e with five males and nine females, the other with 10c? S and 1 0 2 2 o f T. PYBUSAE. T h e gut in both lampreys w a s apparently intact and eggs w e r e found along its entire length. In o n e o f the lam
preys, w o r m s e x t e n d e d throughout the gut, in the other, s o m e adult w o r m s w e r e found in the anal region but most worms occurred in an enlarged region b e h i n d the liver.
Six spawning lampreys w e r e c o l l e c t e d o n May 15 a n d kept at 14 °C in the laboratory. T h e s e six lampreys died
o n the following dates ( n u m b e r o f lamprey in paren
theses): May 19 (1), May 21 ( 2 ) , May 22 ( 1 ) , May 23 ( 2 ) . W o r m s o c c u r r e d in all t h e s e lampreys, mainly in an enlarged region b e h i n d the liver. Collectively 4 5 2 9 and 39 cT 6 w e r e r e c o v e r e d with a m e a n and range o f 17 ( 6 - 2 6 ) . In three lampreys the gut w a s c o l l a p s e d or reduced to a fine filament. Eggs were numerous around the adult w o r m s .
After death o f lampreys, the w o r m s remained alive in the carcass (at 14 °C) for about four days and s o m e e g g s e m b r y o n a t e d in the gut to the early larval stage.
Many eggs taken from the gut o f d e c o m p o s i n g lam
preys 2 and 4 days after death e m b r y o n a t e d normally at r o o m temperature giving rise to larvae 4 5 0 ( 4 1 6 - 4 9 2 ) pm in length and with lateral alae. Eggs from lam
preys d e a d for 5-6 days d e g e n e r a t e d and failed to e m b r y o n a t e .
E X A M I N A T I O N O F P R E S P A W N I N G A N D S P A W N I N G A D U L T S C O L L E C T E D IN 1 9 8 0
Eight prespawning adult lampreys w e r e c o l l e c t e d by e l e c t r o s h o c k i n g at Blue Springs Creek in April 1 9 8 0 (Table I ) . T h e s e s p e c i m e n s w e r e preserved in 10 % for
malin. All the s p e c i m e n s w e r e infected with adult T. PYBUSAE. T h e w o r m s w e r e gravid but m o r e eggs w e r e noted in the anterior uterus than in the poste
rior uterus. T h e w o r m s w e r e consistently well distri
buted along the gut, i. e. there w a s n o accumulation o f w o r m s and eggs b e h i n d the liver ( s e e a b o v e ) . Eggs w e r e o b s e r v e d in the gut o f four o f the lampreys.
Lamprey No.
Date collected
Length body (cm)
Number of worms Male Female
Eggs
in intestine Comments on female worms
1 April 11-20 14.5 14 14 + Eggs in both uteri, most in anterior. Worms distributed in intestine. Gut complete to anus.
2 April 11-20 15.5 7 14
-
Eggs in both uteri in some specimens, most in anterior.Some worms with eggs in anterior uterus. Gut complete.
3 April 11-20 16.5 1 2
-
Eggs in both uteri, most in anterior. Gut complete.4 April 11-20 16.4 14 11 + Eggs in both uteri, most in anterior.
5 April 11-20 16.0 14 12
-
Eggs in both uteri but few and mainly in anterior.6 April 28 16.0 7 9 +++ Eggs in both uteri, mainly anterior. Gut complete and ope
ning at anus. Numerous eggs in gut.
7 April 28 16.6 13 13 - Eggs rare in both uteri, mainly anterior. Gut complete and
opening at anus.
8 April 28 15.5 11 18 ++ Eggs in both uteri, mainly anterior. Eggs (12) present in
gut near anus.
Table I. — Results of examining prespawning adult brook lampreys collected April 11-20 and April 28, 1980 at Blue Springs Creek.
S p a w n i n g in 1 9 8 0 at B l u e Springs C r e e k started o n May 7-8 and five spawning lampreys w e r e c o l l e c t e d a n d preserved. T h e following w o r m s w e r e found in t h e s e lampreys: 1) 1 2 ? 2 , l l c T c ? ; 2 ) 4 2 2 , 666; 3 ) 15 2 2 , HcTcT; 4 ) 8 2 2 , 76 6; 5 ) 6 ? 2 , 5 c ? 6 \ All the female w o r m s w e r e gravid. Careful dissection revealed that the anus w a s patent a n d that n e m a t o d e e g g s w e r e found o n the rectal m u c o s a n e a r the anus in t w o o f the lampreys. In s o m e female w o r m s , e g g s w e r e e q u a l l y n u m e r o u s in b o t h uteri. In t w o l a m p r e y s w o r m s w e r e in a dilation b e h i n d the liver.
A T T E M P T S T O I N F E C T T R O U T W I T H T H I R D - S T A G E LARVAE F R O M T H E LIVER O F A M M O C O E T E S
Thirty-three a m m o c o e t e s (length X = 9.5, range 6.9- 16.2 c m ) w e r e c o l l e c t e d . T h e livers o f 18 w e r e e x a m i n e d for larvae and 5 0 % w e r e infected. T e n larvae, fixed in hot g l y c e r i n e - a l c o h o l and c l e a r e d gradually in pure glycerine w e r e 1.2 (0.9-1.4) m m in length and had p r o m i n e n t lateral alae e x t e n d i n g from the c e p h a l i c region to the tail. B e c a u s e o f their d e l i c a c y and ten
d e n c y to b e c o m e d a m a g e d during dissection it w a s d e c i d e d to give s e c t i o n s o f the b o d y containing the liver o f the remaining 15 lampreys to four trout ( 3 0 c m in length) from w h i c h food had b e e n withheld for o n e w e e k . T h e fish, kept at 10-11 °C, ingested the sections o f lamprey and w e r e then fed regularly with trout food, but w h e n e x a m i n e d 2 0 , 3 0 , 4 0 a n d 5 6 days later n o w o r m s w e r e found.
T h e livers from six large ( 1 1 . 5 - 1 7 . 5 c m ) a m m o c o e t e s w e r e intubated intact into the s t o m a c h o f six r a i n b o w trout ( 1 7 - 1 8 c m in length) kept at 10-11 °C. T h e fish w e r e fed regularly with trout food. No w o r m s w e r e found at n e c r o p s y 3 0 days later.
A T T E M P T S T O I N F E C T T R O U T W I T H A D U L T T. PYBUSAE
Eight lampreys c o l l e c t e d 11 days after spawning b e g a n in 1 9 9 4 c o n t a i n e d a total o f 199 adult m a l e and female w o r m s . T h e w o r m s w e r e p l a c e d in saline a n d as rapidly as p o s s i b l e divided into four portions e a c h o f w h i c h w a s intubated into the s t o m a c h o f an a n a e s thetized trout 3 0 - 3 1 c m in length kept at 10-11 °C.
At n e c r o p s y the following w a s found:
1. 6 days post-infection, 6 2 2 a n d 46 6 w e r e found attached to the posterior e n d o f the intestine. T h e n e m a t o d e s w e r e active in saline and females p a s s e d eggs. In three females, e g g s w e r e approximately equal in n u m b e r in b o t h uteri. In t w o females, e g g s w e r e m o r e n u m e r o u s in the anterior uterus than in the p o s terior uterus.
2. 14 days post-infection, 4 2 2 a n d 26*0* w e r e found attached to the anterior half o f the intestine. T h e y w e r e
active in saline and d e p o s i t e d e g g s . In t w o o f the w o r m s , eggs w e r e present in equal n u m b e r s in b o t h uteri. In t w o w o r m s , e g g s w e r e m o r e n u m e r o u s in the anterior uterus than the posterior uterus.
3. 22 days post-infection, a single 6 w a s a t t a c h e d to the posterior quarter o f the intestine.
4. 3 0 days post-infection, n o w o r m s w e r e present.
DISCUSSION
T
h e results confirm the findings o f P y b u s ET AL.( 1 9 7 8 ) that eggs o f TRUTTAEDACTNITIS PYBUSAE are p a s s e d into the stream b y s p a w n i n g b r o o k lampreys. It is difficult, h o w e v e r , to a c c o u n t for the small n u m b e r s o f n e m a t o d e e g g s b e i n g p a s s e d s i n c e large n u m b e r s o f e g g s w e r e often p r e s e n t in the gut o f the spawning lampreys. T h e s e eggs, h o w e v e r , w e r e f o u n d m a i n l y a r o u n d adult w o r m s in a m a r k e d l y dilated region o f the gut immediately b e h i n d the liver;
in s o m e individuals this dilation e x t e n d e d t o a b o u t a quarter o f the length o f the gut. Eggs a n d w o r m s in these dilations w e r e in a yellowish, mucus-like mate
rial not present in posterior regions o f the gut. T h e gut o f lampreys is ciliated (Hardisty, 1 9 7 9 ) a n d p o s s i b l y cilia activity is largely a b s e n t in the d e g e n e r a t i n g gut o f most spawning lamprey and this w o u l d a c c o u n t for the relatively small n u m b e r s o f e g g s p a s s e d a n d their a c c u m u l a t i o n around parent w o r m s . In addition, in s o m e lampreys the central o r posterior regions o f the gut h a d c o l l a p s e d and this w o u l d h a v e p r e v e n t e d the p a s s a g e o f e g g s to the anal region. A few adult w o r m s w e r e p a s s e d b y the s p a w n i n g l a m p r e y s but t h e s e w o u l d h a v e b e e n the result o f m o v e m e n t s o f the w o r m s t h e m s e l v e s .
T h e fate o f the few e g g s p a s s e d into the riffle area w h e r e spawning takes p l a c e is uncertain although o n e might s p e c u l a t e that they w o u l d b e carried along with sediment to a m m o c o e t e b e d s d o w n s t r e a m s i n c e they are s m o o t h shelled and d o not a d h e r e to o b j e c t s in the environment.
Pybus ET AL. ( 1 9 7 8 ) did not e x a m i n e prespawning adult lampreys in B l u e Spring Creek. B e c a u s e o f w e a t h e r conditions, ice a n d high w a t e r levels, they are difficult or impossible to collect in March and April in the creek.
Pybus ET AL. ( 1 9 7 8 ) noted that 9 o f 14 transformers from B i g C r e e k , O n t a r i o ( l a t i t u d e 4 2 ° 5 0 ' N ; l o n g i t u d e 8 0 ° 3 0 ' W ) f l o w i n g i n t o L a k e Erie c o n t a i n e d adult T. PYBUSAE. T h e y did not give the date o f c o l l e c t i o n although it w a s p r o b a b l y in March or April during the spring thaw. T h e y also did not report if t h e s e trans
formers w e r e passing eggs o f T. PYBUSAE o r if the latter w e r e gravid. T h e information indicates, h o w e v e r , that
3 6 Parasite, 1996, 3, 33-37
the n e m a t o d e r e a c h e s adulthood well b e f o r e lampreys are ready to spawn.
In the present study, t w o p r e s p a w n i n g adult lampreys w e r e c o l l e c t e d four days before s p a w n i n g c o m m e n c e d (May 7 ) in Blue Springs Creek. B o t h c o n t a i n e d mature T. PYBUSAE a n d in o n e the w o r m s w e r e distributed along t h e length o f the gut w h i c h w a s o f uniform dia
meter w h e r e a s in the other most w o r m s w e r e in a dila
tion b e h i n d the liver. Eggs w e r e present along the entire length o f the gut o f b o t h s p e c i m e n s .
All e i g h t p r e s p a w n e r s c o l l e c t e d April 1 1 - 2 8 , 1 9 8 0 c o n t a i n e d gravid n e m a t o d e s a n d h a d a c o m p l e t e gut with n o dilations or constrictions. Relatively few e g g s w e r e n o t e d in the gut o f t w o p r e s p a w n e r s suggesting that e g g s w e r e p a s s i n g t h r o u g h t h e gut p o s s i b l y b e c a u s e o f residual ciliary activity. T h e s e e g g s w o u l d be deposited directly o n b e d s containing a m m o c o e t e s , a p r o c e s s w h i c h p r o b a b l y t a k e s p l a c e for at least 2-3 w e e k s during t h e maturation o f the lampreys.
Thus, the s o u r c e o f the e g g s r e s p o n s i b l e for the high p e r c e n t a g e o f larval T. PYBUSAE in a m m o c o e t e s in B l u e Springs C r e e k ( s e e Pybus ET AL, 1 9 7 8 ) c o u l d b e from late transformers a n d certainly p r e s p a w n i n g adults living in c l o s e association with a m m o c o e t e s , rather than s p a w n i n g adults depositing a few e g g s in a riffle area in the stream.
Attempts t o infect trout with third-stage larvae o f T. PYBUSAE w e r e unsuccessful. M o r a v e c ( 1 9 7 9 , 1 9 8 0 , 1994) reported that larvae o f T. TRUTTAE found e n c a p sulated o n the intestine o f E u r o p e a n b r o o k lamprey (LAMPETRA PLANERI) d e v e l o p e d to adulthood w h e n fed to b r o w n trout (SALMO TRUTTA). T h e infective larva o f T. PYBUSAE o c c u r s only in t h e liver o f a m m o c o e t e s o f LAMPETRA APPENDIX a n d is l o n g e r than that o f T. TRUTTAE (i. e. 1.1-1.4 um, Pybus ET AL. 1 9 7 8 ; 1.2-1.4 um, this study VERSUS 8 4 0 - 9 2 4 um, M o r a v e c , 1 9 7 9 ) .
S o m e adult T. PYBUSAE intubated into r a i n b o w trout persisted for s o m e two-three w e e k s a n d r e m a i n e d gravid for at least 2 w e e k s . T. PYBUSAE has n e v e r b e e n reported in teleosts in North America and a p p e a r s to b e essentially a parasite o f the b r o o k lamprey. T e l e o s t s which might predate infected spawning lampreys could acquire transient infections w h i c h might h e l p to dis
perse eggs in the environment but this has not yet b e e n demonstrated.
throughout the study w a s m u c h appreciated. Dr. Cheryl M. Bartlett kindly r e v i e w e d the manuscript.
REFERENCES
ANDERSON R.C. Nematode parasites of vertebrates: their deve
lopment and transmission. CABI, Wallingford, U.K. 1992, i-xii, 5 7 8 p.
HARDISTY M.W. Biology of Cyclostomes. Chapman Hall, London, 1979, i-xii, 4 2 8 p.
MORAVEC F. Observations on the development of Cucul- lanus (Truttaedactnitis) truttae (Fabricius, 1794) (Nema- toda: Cucullanidae). Folia Parasitológica (Praha), 1979, 26, 2 9 5 - 3 0 7 .
MORAVEC F. Biology of Cucullanus truttae (Nematoda) in a trout stream. Folia Parasitológica (Praha), 1980, 27, 2 1 7 - 226.
MORAVEC F. Parasitic nematodes of freshwater fishes of Europe. Academia, Praha, 1994, 4 7 3 p.
PYBUS M.J., UHAZY L.S. & ANDERSON R.C. Life cycle of Trut
taedactnitis stelmioides (Vessichelli, 1 9 1 0 ) (Nematoda:
Cucullanidae) in American brook lamprey (Lampetra lamottenii). Canadian Journal of Zoology, 1978, 56, 1420- 1429.
Reçu le 7 novembre 1 9 9 5 Accepté le 1 6 novembre 1 9 9 5
ACKNOWLEDGEMENTS
I
a m grateful for t h e h e l p o f Dr. F.W.H. B e a m i s h , Dr. S. Li, B r u c e Morrison a n d J o h n Witt in c o l l e c ting lampreys. Prof. B e a m i s h kindly w e n t through his e x t e n s i v e c o l l e c t i o n a n d found p r e s e r v e d presp a w n i n g lampreys o f value to this study. His advice
