Life History and Host Specificity of Mediorhynchus Centurorum Nickol 1969 (Acanthocephala: Gigantorhynchidae)

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2-1977

Life History and Host Specificity of Mediorhynchus centurorum Nickol 1969 (Acanthocephala: Gigantorhynchidae)

Brent B. Nickol University of Nebraska - Lincoln, [email protected]

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Nickol, Brent B., "Life History and Host Specificity of Mediorhynchus centurorum Nickol 1969 (Acanthocephala: Gigantorhynchidae)" (1977). Faculty Publications from the Harold W. Manter Laboratory of Parasitology. 356. https://digitalcommons.unl.edu/parasitologyfacpubs/356

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LIFEHISTORY AND HOST SPECIFICITYOF MEDIORHYNCHUSCENTURORUM NICKOL 1969 (ACANTHOCEPHALA:GIGANTORHYNCHIDAE) Brent B. Nickol School of Life Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska 68588

ABSTRACT: Examination of 1905 arthropods from a swamp and surroundingpasture in southern Loui- siana revealed larval specimens of Mediorhynchus centurorum in 8 of 228 woodroaches, Parcoblatta pensylvanica, but in no other species. The life cycle was confirmed by feeding eggs of M. centurorum to laboratory-rearedwoodroaches. Cystacanths later recovered from the woodroaches developed into mature worms when pipetted into esophaguses of red-bellied woodpeckers, Centurus carolinus; red- headed woodpeckers, Melanerpes erythrocephalus;yellow-shafted flickers, Colaptes auratus; and a hairy woodpecker, Dendrocopos villosus. Infection was achieved in all woodpeckers fed cystacanths at least 47 days old and the mean prepatent period was 35 days. Cystacanths fed starlings, Sturnus vulgaris, and red-winged blackbirds, Agelaius phoeniceus, did not produce infections although cystacanths from the same pool were infective to control woodpeckers. Larval development of Mediorhynchuscenturorum in woodroachesdid not differ significantly from that of M. grandis in grasshoppers. M. centurorumis the only species of the Gigantorhynchidaefor which the life cycle has been confirmed by laboratory infections using an intermediate host species known infected in nature.

A high degree of vertebrate host specificity penetration and morphological distinctions was reported by Nickol (1969) in the original might result from parasitizing a member of descriptionof Mediorhynchuscenturorum. He the Picidae. noted that 900 birds of 68 species in 30 families To provide specimens for study of host from Louisiana were examined and that, even specificity in the laboratory, an attempt was though many of them came from the same or made to discover the life cycle of Medio- similar habitats, M. centurorumwas found in rhynchuscenturorum. Since morphologicallyM. only red-bellied woodpeckers, Centurus caro- centurorumdiffers consistentlybut only slightly linus. Further, 76 of the birds representing20 from M. papillosus Van Cleave 1916, it was of species, including 25 of four other species of particular interest whether M. centurorum Picidae, were collected from a single, small could parasitize red-winged blackbirds, Age- wooded area from which 10 of 16 red-bellied laius phoeniceus, the usual host for M. papil- woodpeckers harbored M. centurorum. Most losus, and if so whether morphologicalvariation acanthocephalanspecies, including other mem- from woodpecker specimens would be so great bers of Mediorhynchus,are not nearly so host that the two acanthocephalanspecies could not specific and infect a variety of species having be distinguished. Susceptibility of starlings, similar diets. Nickol (1969) reported also that Sturnus vulgaris, was also of interest because M. centurorumpenetrates deeply into the in- all of the frequently reported species of Medi- testinal wall of its vertebrate host causing a orhynchusin North America (M. grandis Van nodule, about 5 mm long, to bulge into the Cleave 1916, M. papillosus, and M. robustus coelom. Other species of Mediorhynchushave Van Cleave 1916) are known to occur in not been reported to cause similar nodules. starlings. The fact that in North America no other Except for salient features related to recog- acanthocephalan species regularly parasitizes nition of the species and its use in the labora- woodpeckers and that unlike other members tory, no attempt is made to detail Mediorhyn- of the genus Mediorhynchuscenturorum pene- chus centurorumlarval development. trates deeply into intestinal walls suggested that M. centurorummight be a usual parasite MATERIALSAND METHODS of another vertebrate species and that deep Arthropodswere collected from woodpecker foragingand nestingsites and examinedfor Medi- Receivedfor publication27 April 1976. orhynchuscenturorum larvae until naturalinfec- 104 NICKOL-LIFE HISTORYAND HOST SPECIFICITYOF MEDIORHYNCHUSCENTURORUM 105 tions were discovered in woodroaches, Parcoblatta Beginning 2 weeks postfeeding, daily fecal exam- pensylvanica. Ootheca from a laboratory colony inations were made to determine prepatent periods. of wild-caught P. pensylvanica were used to initiate After demonstratingsusceptibility of each of these a colony of laboratory-reared woodroaches. All woodpecker species, three additional red-headed woodroaches used were from the laboratory-reared woodpeckers and two additional flickers were sim- colony. ilar controls for attempts to infect other avian Woodroaches were infected with Mediorhynchus species. Fifteen cystacanths were fed to each of centurorum by 2 methods. In the first, eggs col- 15 red-winged blackbirds and 10 starlings. Acan- lected from body cavities of gravid worms were fed thocephalan eggs were sought by daily fecal ex- to woodroaches fresh or after storage in tap water aminations beginning 2 weeks postfeeding. After at 4 C. After being held 2 days without food and 60 days, blackbirds and starlings were necropsied. water, woodroaches were placed in compartments To determine when Mediorhynchus centurorum of plastic boxes the bottoms of which had been larvae become infective to woodpeckers, a group fitted with potato slices covered with a tap water of woodroaches were fed eggs and resulting larvae suspension of eggs. Woodroaches were allowed to were pipetted into esophaguses of 3 red-headed feed 48 hr on the preparationbefore being removed woodpeckers after 29, 39, and 47 days of develop- to holding boxes containing moist cotton and ment in the woodroaches. Daily examinationswere Purina Lab Chow. On one occasion woodroaches made of the birds' feces beginning 2 weeks post- were allowed to feed only 5 min and were ex- feeding of larvae and continuing for 45 days or amined 1/2 hr later. In the second infection until eggs appeared. If eggs had not appeared after method, 6 groups of woodroaches were fed eggs 45 days, birds were necropsied to determine passed naturally in woodpecker feces periodically whether nonegg-producing acanthocephalans were moistened during a 48 hr exposure period. Four present. of the groups were fed feces from a red-bellied Eggs from body cavities of Mediorhynchus woodpecker, one feces from a red-headed wood- centurorumwere fed to groups of laboratory-reared pecker, Melanerpes erythrocephalus,and one feces American cockroaches, Periplaneta americana, and from a yellow-shafted flicker, Colaptes auratus. adult grain beetles, Tenebrio molitor, to study Infections in each birds had been produced from intermediate host specificity in the laboratory. As laboratory-reared cystacanths. Except for those a control for egg viability, eggs from the same pool examined 11/2 hr after feeding, woodroaches were used to feed cockroaches and grain beetles were dissected daily and the acanthocephalans were fed to the usual intermediate host, Parcoblatta collected and prepared for microscopicstudy. pensylvanica. All measurementsare in micrometers Fifteen cystacanths resulting from feeding Medi- unless otherwise noted. orhynchus centurorum eggs to laboratory-reared woodroaches were pipetted into the esophagus of a RESULTS red-bellied woodpecker. The woodpecker was 1 of 2 removed from a nest before fledging and raised During June and July 1971, 1905 arthropods in captivity. Daily fecal examinations beginning 3 were collected from a swamp and its surround- wk before feeding of cystacanths and continuing ing pasture, 18 mi south of Baton Rouge, until insured that acanthocephalan eggs appeared Louisiana, where Mediorhynchus centurorum no acanthocephalan was initially present and per- occurred in more than of mitted determinationof the prepatent period. 60% the red-bellied For study of definitive host specificity in the woodpeckers. Table I lists arthropods exam- laboratory, cystacanths produced by laboratory in- ined for larval M. centurorum. Eight of 228 fections of woodroaches were pipetted into esoph- woodroaches were of and parasitized by developing aguses woodpeckers, blackbirds, starlings. M. centurorum No other Before use, each bird had been in captivity for at (Fig. 1). arthropod least 1 month after being caught in a mist net or was found infected. removed from a nest. Daily fecal examinations Eggs from gravid Mediorhynchus centurorum beginning 2 wk before use insured absence of acan- fed in the laboratory to woodroaches hatched thocephalans. Initially cystacanths were fed to one within 11/ hr (Fig. 3). No was made each of the following species of Picidae: Colaptes attempt auratus; hairy woodpecker, Dendrocopos villosus; to determine whether hatching occurred sooner and Melanerpes erythrocephalus. In attempts to or for how long after the 11/2hr period it con- in produce infections the 3 woodpecker species, tinued. Unhatched eggs remained, however, from a of cystacanths group laboratory-infected in woodroach canals for at least 8 woodroaches were pooled in saline-filled Syracuse alimentary dishes. From the pool, 15 cystacanths were ran- days after ingestion. Forty-three percent of domly selected and fed to one Centurus carolinus, the woodroaches examined 40 or more days the host in nature and acanthocephalan's species after feeding of eggs were infected with from one previously demonstrated susceptible in the 1 to 11 (mode 1, median 2, mean laboratory. Remaining cystacanths were fed, 15 2.4) cysta- each, to the other woodpeckers. Feeding of C. canths. Student's "t" test did not indicate a carolinusprovided a control for cystacanth viability. significant difference in prevalence or intensity 106 THE JOURNAL OF PARASITOLOGY,VOL. 63, NO. 1, FEBRUARY1977

TABLE I. Arthropods examined for larval Medi- were produced in control woodroaches and in orhynchus centurorum. grain beetles. Larvae recovered from grain No. beetles 50 days postfeeding of eggs, however, No. speci- were much less than those of the Arthropod group species mens developed same age from control woodroaches simul- Chilopoda 2 5 taneously fed eggs from the same pool. Fifty- Crustacea day-old larvae recovered from grain beetles Isopoda 2 were acanthellae with recognizable proboscis Diplcpoda 1 receptacles, but without evidence of genitalia, Insecta lemnisci, or proboscis hook development. No Coleoptera cystacanth was recovered from grain beetles; Carabidae Loxandrus lucidulus 1 however, no beetle was examined after 50 days Other 1 postfeeding. Fifty-day-old larvae from wood- Cerambycidae roaches were fully formed, invaginated cysta- Prionus sp. 1 Other 1 canths. Chrysomelidae 1 During the course of study, 13 woodpeckers Curculionidae 4 red-bellied 1 wood- Bostrichidae (2 woodpeckers, hairy Adult 1 pecker, 3 flickers, and 7 red-headed wood- Larva 1 peckers), 15 red-winged blackbirds, and 10 Buprestidae (larva) 1 Elateridae starlings were fed Mediorhynchus centurorum Adult 3 cystacanths from laboratory-produced infec- Larva 3 tions. Acanthocephalans in all Lampyridae 1 produced eggs Passalidae of the woodpeckers except two red-headed Popilus disiunctus 1 woodpeckers fed young larvae to determine Adult at what Larva age cystacanths became infective. The Rhipiceridae mean prepatent period was 34 days in Zenoa picea 1 Centurus carolinus and Melanerpes erythro- Scarabaeidae 1 Staphylinidae 1 cephalus, 39 in Dendrocopos villosus, and 35 Tenebrionidae 5 in Colaptes auratus. The shortest prepatent Diptera (larva) 3 was 28 (one red-headed wood- Dermaptera period days Labiidae 1 pecker), the longest 39 (one hairy wood- Hemiptera 2 pecker), and the overall mean 35. Eggs ap- Hymenoptera in feces of one red-bellied Formicidae 3 peared woodpecker Isoptera 1 for 84 days. Duration of egg production was Lepidoptera (larva) 3 not determined for worms in other birds. No Orthoptera Acrididae egg was detected in fecal examinations of red- Romalea microptera 1 10 winged blackbirds or starlings and no acantho- Blattidae was at In each Parcoblatta pensylvanica 1 228 cephalan present necropsy. Periplaneta americana 1 20 instance eggs in feces demonstrated that in- Gryllidae 1 10 fection had occurred in woodpecker controls. Phasmatidae 1 1

Salient features of development of infection between sexes of woodroaches. Woodroaches with developing acanthocephalans were maintained at room Likewise, significant differences could not be temperatures. For these from demonstrated in prevalence or intensity of in- June through September ranged 21 C to 32 C. other months the fection between woodroaches of varied age During was 18 C to 24 C. Larval groups or between groups of woodroaches fed approximate range was more summer eggs in suspension from worm body cavities development rapid during and those fed eggs in moist feces. months. Salient features of development de- Mediorhynchus centurorum eggs had not scribed here are based on development at sum- produced infections in American cockroaches mer temperatures with comparisons to similar necropsied 50 days after feeding. Infections stages at cooler temperatures. NICKOL-LIFE HISTORYAND HOST SPECIFICITYOF MEDIORHYNCHUSCENTURORUM 107

FIGURES1-3. Mediorhynchus centurorum. 1. Photograph of acanthella from naturally-infected woodroach. X 70. 2. Camera lucida drawing of empty egg shell and acanthor hatching in wet- mount. 3. Photograph of acanthor hatched in woodroach alimentary canal 112 hr postfeeding of eggs. X 460.

Egg and acanthor: Eggs passed naturally lack raphes in the fertilization membrane in woodpecker feces differed in two regards characteristic of some archiacanthocephalans, from those described and illustrated by Nickol hatching seemed to occur at a predetermined (1969) in the original species description. spot. When hatched in water no acanthor Those in feces were larger (mean 55 by 36 movement was observed, but eggs always split /um) and lacked the outer membrane. at the end of the acanthor's aclid organ. Hatched acanthors in woodroach alimentary Acanthella: Acanthellae were first detected tracts averaged 70 long by 35 wide and pos- in woodroaches 19 days postfeeding of eggs. sessed a characteristic constriction (Fig. 3). Nineteen-day-old acanthellae, along the out- Some eggs hatched artificially, probably from side of the alimentary canal, were relatively osmotic pressure, in wet-mount preparations or well developed and enclosed in clear, fluid- after storage in tap water. Acanthors arti- filled capsules. Entire capsules averaged 675 ficially hatched by these methods lacked the long and 165 wide with acanthellae proper constriction and remained enclosed in at least measuring 670 by 105. Proboscis receptacle, one egg envelope (Fig. 2). cerebral ganglion, and ligament strand were Although Mediorhynchus centurorum eggs formed. Genital nuclei were present and the 108 THE JOURNAL OF PARASITOLOGY,VOL. 63, NO. 1, FEBRUARY1977 reproductive system was partially formed. At After 47 days of development in wood- this time the proboscis was not distinct but roaches, cystacanths,about 960 long and about hook anlagen, arranged in the adult hook 450 wide, proved infective to a red-headed pattern, were discernible. Larvae developing woodpecker. Cystacanths remained infective during winter months required 40 days to de- to woodpeckers for at least 157 additional velop comparably. days. Forty-seven-day-oldcystacanths studied After 24 days acanthellae were free of the by causing proboscis evagination in tap water alimentary canal, enclosed in fluid-filled cap- differed morphologicallyonly slightly from 29- sules, elongated, and folded on themselves. day-old uninvaginated forms. Trunk dimen- Capsules averaged 1130 long and 575 wide sions of the two age classes were virtually with the acanthella proper measuring 2640 by identical. Older forms, however, had slightly 250. Proboscis hooks were well formed but longer proboscises (mean 575) and necks did not protrude from the hypodermis; well (mean 120). developed lemnisci occupied about one-half Young forms from birds: Difficulty in cap- of the trunk length, and reproductive struc- turing sufficient numbers of woodpeckers pre- tures were identifiable making discernment of vented study of developmentin definitive hosts the sex possible. by sequential sacrifice. However, the pre- Acanthellae appeared as fully formed ju- patent period ranged from 28 to 39 days and veniles after 29 days, but probosciseshad not after developing 103 days in woodpeckers, yet invaginated. Sixty days were required specimens were within the morphological during winter months for larvae to attain this ranges described by Nickol (1969). No at- stage of development. These stages were not tempt was made to study younger specimens noticeably different from that illustrated in (of known ages) from woodpeckers. Figure 1. Acanthocephalans remained enclosed in capsules which now averaged 1590 DISCUSSION long and 750 wide. Straightened parasites, Among the Gigantorhynchidae,life cycles dissected from capsules, averaged 2.7 mm long are known only for species of the genus Medi- and 500 at the widest point. About 380 be- orhynchus;M. grandis, M. micracanthus (Ru- hind the neck, a prominent constriction, 200 dolphi 1819) Van Cleave 1924, M. papillosus, across, occurred in the trunk. Average dimen- and now M. centurorum. Rizhikov and Dizer sions of proboscis and neck were 540 long by (1954) reported natural infections of tene- 285 wide and 104 by 293 respectively. Pro- brionids from the Kara Kum region of boscis armature was arranged in 21 to 25 U. S. S. R. with M. micracanthus,but did not (usually 24) approximatelylongitudinal rows confirm the life cycle by producing laboratory each with 4 to 6 (usually 5) hooks anteriorly infections in birds or beetles. Ivashkin and and 4 to 6 (usually 5) spines posteriorly. Shmytova (1969) and Kabilov (1969) dis- Thorns of hooks were 34 to 40 long and spines covered natural infections of M. papillosus in 30 to 36. Largest hook roots were 43 to 49 three species of the Tenebrionidae of Crimea (mean 46) long. On each side of the neck, an and Uzbekistan respectively, but likewise did elliptical sensory pit, about 40 by 17, was not producelaboratory infections. Moore (1962) located 5 to 9 posteriadto last proboscisspines. found that eggs of M. grandis fed to orthop- Acanthocephalansat this stage of development terans (4 species of grasshopperand 1 species did not produce infection when 15 were fed of cricket) developed into cystacanthsinfective to a red-headedwoodpecker. to definitive hosts, but found no naturally- Cystacanth: Cystacanths with proboscises infected orthopteran. Discovery of natural in- fully invaginatedwere entangled in malpighian fections of M. centurorumin the orthopteran, tubules of woodroachhemocoels after 39 days. Parcoblattapensylvanica, and occurrenceof at Infection was not achieved when 15 cysta- least partial development in Tenebrio molitor canths of this age were fed to a red-headed when the tenebrionids were fed eggs in the woodpecker. No morphologicaldifference was laboratoryis consistent with knowledge of in- discoveredbetween these and older cystacanths termediatehosts for other species of the genus. which proved infective. M. centurorumis the only species of the family NICKOL-LIFE HISTORYAND HOST SPECIFICITYOF MEDIORHYNCHUSCENTURORUM 109 for which intermediate host infections have woodroaches the number, size, and arrange- been discovered in nature and the life cycle ment of proboscishooks and spines agreed with confirmed in the laboratory. those of adult worms and after 47 days the Althoughearly embryologyof Mediorhynchus probosciswas within the adult size range. The centurorumwas not studied and it is therefore neck, however, apparently grows slightly with impossible to compare it to that of M. grandis the trunk after a definitive host is reached. as described by Schmidt (1973), later larval Eggs recovered from woodpecker feces during development was very similar in the two spe- this study were noticeably larger than those cies. Except for specific differences (primarily describedby Nickol (1969). Since he included proboscis hook size and number), develop- measurementsof eggs shed by living females mental stages of M. grandisdescribed by Moore in tap water, optical and chemical distortion (1962) after 20, 24 to 25, and 27 to 30 days caused by measuring eggs removed from fixed in grasshoppersare nearly identical to those of females or through body walls can only par- M. centurorum in woodroaches after 19, 24, tially account for differences. Whitfield (1970) and 29 days, respectively. demonstrated that within the body cavity of Artificial hatching of acanthocephalaneggs Polymorphus minutus fully formed eggs vary by alternate drying and wetting has been de- considerably in size but that only the larger scribed by several workers including Manter ones are passed in feces. Perhaps explusion of (1928) and Moore (1942). Uglem (1972) eggs caused by placing females in tap water described fundamental differences between results in a large number of smaller, but fully eggs artificially hatched in this manner when formed, eggs being shed. compared to those hatched in intermediate Although nearly identical morphologicallyto hosts and found that artificially hatched acan- infective forms, except that the proboscis had thors of Neoechinorhynchuscristatus were un- not yet invaginated,29-day-old Mediorhynchus infective to ostracod intermediatehosts. Some centurorumwere not infective to woodpeckers. Mediorhynchus centurorum eggs hatched in After 39 days in woodroaches,proboscises were water but freed acanthors were inactive and invaginated, but cystacanths still were unin- differed in general appearance from those fective. After 47 days, cystacanths proved in- hatched in woodroach alimentarycanals (Figs. fective to woodpeckers. No attempt was made 2, 3). Schmidt and Olsen (1964), Edmonds to infect woodpeckers with cystacanths aged (1966), King and Robinson (1967), and between 39 and 47 days. For M. centurorum, Lackie (1972) have successfully hatched eggs there was no great variation in prepatent in vitro under conditions more closely approxi- period, mean 35 days, among definitive host mating those encounteredin intermediatehosts. species. The prepatent period is unknown for Since resulting acanthors,at least of some spe- all other species of the family. cies (King and Robinson, 1967; Lackie, 1972), Because Mediorhynchuscenturorum and M. are infective when injected into intermediate papillosus are morphologicallysimilar, the pos- host hemocoels, these techniques may be more sibility was considered that some purported appropriate than drying and wetting for in differences might represent only variation in- vitro study of acanthors. The time required duced by an unusual host, Centurus carolinus. after ingestion for M. centurorumeggs to hatch Deep penetration producing a large papilla on was similarto those reportedfor other acantho- the woodpecker intestine, resulting trunk con- cephalan species by DeGiusti (1949), Schmidt striction, location of lateral sensory pits on the and Olsen (1964), and Uglem (1972), but neck, and apparent strict host specificity of was noticeably less than the 24 to 48 hr M. centurorumwere of special concern. (Moore, 1962) for eggs of M. grandis. Mediorhynchuscenturorum differs from M. With the exception of egg size, morphological papillosus in possessing lateral sensory pits on features of Mediorhynchus centurorum ob- the neck that are much closer to the last pro- served throughout this study were in agree- boscis spines than are those of M. papillosus ment with the original species descriptioneven as well as in details of proboscis armature though proboscis armature was slightly more (Nickol, 1969). The present study demon- variable than first described. After 29 days in strates that sensory pit location and proboscis 110 THEJOURNAL OF PARASITOLOGY,VOL. 63, NO. 1, FEBRUARY1977

armature of M. centurorum cystacanths from strated for corresponding stages of M. papil- woodroaches agree with those of adults from losus by Ivashkin and Shmytova (1969) and woodpeckers. M. grandis by Moore (1962) and these species Large nodules, approximately 5 mm by 2 lack trunk constrictions as adults. It appears mm, such as those produced on host intestines as if deep penetration by M. centurorum early by Mediorhynchus centurorum are not known in the course of infection may prohibit trunk to be caused by other species of the genus. growth typical of other species rather than Personal observation confirmed that M. grandis, actually inducing a constriction. M. papillosus, and M. robustus do not produce Eight species of Mediorhynchus have been them in any of a large number of host species, reported from North America, but only four, including M. grandis from a red-bellied wood- M. centurorum, M. grandis, M. papillosus, and pecker. M. centurorum produced nodules in M. robustus, are known to occur regularly. each of the avian hosts infected in the labora- Two, M. bakeri Byrd and Kellogg 1971 and tory. The earliest any woodpecker was ne- M. colini Webster 1948, both known only from cropsied after being fed cystacanths was 103 a few specimens from quail, Colinus virgin- days. In that instance each of four M. centuro- ianus, have not been reported since their orig- rum was removed from an intestinal nodule of inal descriptions. M. sipocotensis Tubangui a flicker. Nodules were like those of older 1935 is known only from the Philippines ex- laboratory and natural infections. On one oc- cept for a surprising report from Indiana robins casion a red-headed woodpecker died 111 days by Baker and Hamon (1967). M. emberizae after being fed cystacanths. Five M. centuro- (Rudolphi 1819) Travassos 1923, reported rum (3 females, 2 males) were embedded in once from Puerto Rico (Whittaker, Schmidt, intestinal nodules and the intestine was filled and Diaz, 1970), is known to occur in at least with blood. Each nodule was equal in size to 16 different host species. M. grandis, M. papil- those of older laboratory and natural infections losus, and M. robustus have been reported from but differed from them in being thin-walled 18, 43, and 11 host species, respectively. The and transparent rather than tough and fibrotic. degree of host specificity exhibited in nature Intestinal hemorrhage was not observed in any by M. centurorum is therefore surprising. Feed- other bird infected with M. centurorum. ing experiments of this study indicate that M. A long, prominent constricted region of the centurorum is capable of maturation in at least trunk, corresponding to that portion of the three species of Picidae other than Centurus worm inside the nodule, is a distinguishing carolinus. These were all included in the orig- feature of Mediorhynchus centurorum. Nickol inal survey and one, Colaptes auratus, was (1969) believed the constriction resulted from among those examined from the site at which compression by host intestinal muscles even approximately 2/3 of the C. carolinus, but no though it was unaffected when the acantho- other species, were infected (Nickol, 1969). cephalan was placed in tap water to force pro- Infection and subsequent maturity in hosts boscis evagination. After study of development other than C. carolinus does not seem to result in intermediate hosts, that opinion is uncon- in loss of infectivity for woodroaches or other firmed. Upon hatching in woodroach alimen- woodpeckers. In one series of feeding experi- tary canals, M. centurorum acanthors possess a ments, eggs collected from a red-bellied wood- peculiar constriction (Fig. 3) not found, so far pecker were used to infect woodroaches and as has been determined, in acanthors of other resulting cystacanths produced infection in a species. This constriction cannot correspond to red-headed woodpecker. Eggs from this wood- that of adults, however, since it occurs in the pecker were used to produce cystacanths which body wall of the acanthor and the body wall were in turn fed to a flicker and another red- of subsequent stages arises from the acanthor's bellied woodpecker. In each case infection oc- central nuclear mass. M. centurorum juveniles, curred and resulting eggs produced cystacanths before invagination, possess constrictions of the in woodroaches. trunk (Fig. 1), as do invaginated forms. These All species of Mediorhynchus of North Amer- constrictions could correspond to those of ica, except M. centurorum and those known adults, but similar constrictions have been illu- only from a single report, are recorded from NICKOL-LIFEHISTORY AND HOSTSPECIFICITY OF MEDIORHYNCHUSCENTURORUM 111

Agelaius phoeniceus, the usual host of M. papil- KING, D., AND E. S. ROBINSON. 1967. Aspects losus, and Sturnus vulgaris. Failure of M. of the development of Moniliformisdubius. J Parasitol 53: 142-149. centurorum to infect red-winged blackbirds or LACKIE, J. M. 1972. The course of infection and of this acantho- starlings suggests inability growth of Moniliformis dubius (Acantho- cephalan species to survive in those avian spe- cephala) in the intermediate host Periplaneta cies in nature and augments morphological and americana. Parasitology64: 95-106. behavioral differences between M. centurorum MANTER,H. W. 1928. Notes on the eggs and larvae of the worm and other of the thorny-headed of hogs. species genus. Trans Am Microsc Soc 47: 342-347. MooRE,D. V. 1942. An improved technique for ACKNOWLEDGMENTS the study of the ancanthor stage in certain The author is indebted to Dr. A. acanthocephalanlife histories. J Parasitol 28: Jerome 495. State for in- Jackson, Mississippi University, 1962. Morphology, life history, and de- dispensable aid in capturing red-bellied wood- velopment of the acanthocephalanMediorhyn- peckers. Mrs. Shareen Cook Buckner, Univer- chus grandis Van Cleave 1916. J Parasitol 48: 76-86. sity of Nebraska, provided much appreciated NICKOL, B. B. 1969. Acanthocephalaof Louisiana assistance in caring for very young birds and Picidae with description of a new species of Dr. J. Harvey Roberts, Louisiana State Univer- Mediorhynchus. J Parasitol 55: 324-328. K. AND Y. B. DrZER. assisted in identification. Much RIZHIKOV, M., 1954. Biology sity, arthropod of Macracanthorhynchuscatulinus and Medi- of the fieldwork was supported by the Univer- orchynchus micracanthus. Dokl Akad Nauk sity of Nebraska Research Council. SSSR 95: 1367-1369 (In Russian.) SCHMIDT, G. D. 1973. Early embryology of the LITERATURECITED acanthocephalan Mediorhynchus grandis Van Cleave 1916. Trans Am Micros Soc 92: 512- BAKER, J. B., AND J. H. HAMON. 1967. Some 516. intestinal parasites of robins from Marion , AND O. W. OLSEN. 1964. Life cycle and County, Indiana. Proc Indiana Acad Sci 77: development of Prosthorhynchus formosus 417-419. (Van Cleave 1918) Travassos 1926, an acan- DEGIUSTI, D. L. 1949. The life cycle of Lep- thocephalan parasite of birds. J Parasitol 50: torhynchoides thecatus (Linton), an acantho- 721-730. cephalan of fish. J Parasitol 35: 437-460. UGLEM, G. L. 1972. The life cycle of Neoechi- EDMONDS, S. J. 1966. Hatching of eggs of norhynchus cristatus Lynch 1936 (Acantho- Moniliformis dubius. Exp Parasitol 19: 216- cephala) with notes on the hatching of eggs. 226. J Parasitol50: 721-730. IVASHKIN,V. M., AND G. YA. SHMYTOVA. 1969. WHITFIELD, P. J. 1970. The egg sorting function The life cycle of Mediorhynchus papillosus. of the uterine bell of Polymorphus minutus Tr Gel'mintol Lab 20: 62-63 (In Russian.) (Acanthocephala). Parasitology 61: 111-126. KABILOV,T. 1969. On detection of the acanthella WHITTAKER, F. H., G. D. SCHMIDT, AND J. G. DIAZ. Mediorhynchuspapillosus Van Cleave 1916 in 1970. Helminth parasites of some birds in beetles. Mater Nauk Konf Vses Obshch Gel'- Puerto Rico. Proc Helminthol Soc Wash 37: mintol for 1969, Pt 1: 105-107 (In Russian.) 123-124.