University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln US Fish & Wildlife Publications US Fish & Wildlife Service 1962 STUDIES ON Parorchis acanthus (TREMATODA: DIGENEA) AS A BIOLOGICAL CONTROL FOR THE SOUTHERN OYSTER DRILL, Thais haemastoma Nelson R. Cooley Fish and Wildlife Service Follow this and additional works at: https://digitalcommons.unl.edu/usfwspubs Part of the Aquaculture and Fisheries Commons Cooley, Nelson R., "STUDIES ON Parorchis acanthus (TREMATODA: DIGENEA) AS A BIOLOGICAL CONTROL FOR THE SOUTHERN OYSTER DRILL, Thais haemastoma" (1962). US Fish & Wildlife Publications. 247. https://digitalcommons.unl.edu/usfwspubs/247 This Article is brought to you for free and open access by the US Fish & Wildlife Service at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in US Fish & Wildlife Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. STUDIES ON Parorchis acanthus (TREMATODA: DIGENEA) AS A BIOLOGICAL CONTROL FOR THE SOUTHERN OYSTER DRILL, Thais haemastoma By NELSON R. COOLEY FISHERY BULLETIN 201 From Fishery Bulletin of the Fish and Wildlife Service VOLUME 62 UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE B UREAU OF COMMERCIAL FISHERIES UNITED STATES DEPARTMENT OF THE INTERIOR, Stewart Udall, Secretary FISH AND WILDLIFE SERVICE, Clarence F. Pau~'7,ke, Commissioner BUREAU OF COMMERCIAL FISHERIES, Donald L. McKernan, Director STUDIES ON Parorchis acanthus (TREMATODA: DIGENEA) AS A BIOLOGICAL CONTROL FOR THE SOUTHERN OYSTER DRILL, Thais haemastoma By NELSON R. COOLEY FISHERY BULLETIN 201 From Fishery Bulletin of the Fish and Wildlife Service VOLUME 62 Published by the U.S. Fish and Wildlife Service • Washington • 1962 Printed by the U.S. Government Printing Office, Washington For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington 25, D.C. - Price 20 cent.. Library of Congress catalog card for the series, Fishery Bulletin of the Fish and Wildlife Service: U.S. Fish and Wildlife Service. Fishery Bulletin, v. 1- Washington, U.S. Govt. Print. Off., 1881-19 v. in Illus., maps (part fOld.) 23-28 cm. Some vols. issued in the congressional series as Senate or House documents. Bulletin composing v. 47- also numbered 1- Title varies,: v. 1---49 Bulletin. Vols. 1---49 issued by Bureau of Fisheries (called Fish Commission, v. 1-23) 1. Fisheries-U.S. 2. Fish-cUlture-U.S. I. Title. SH11.A25 639.206173 9-35239* Library of Congress [59r55b1] n CONTENTS Page Materials and methods_ _ _ _ __ __ _ _ __ _ _ __ _ _ _ __ __ __ _ _ _ __ _ _ __ _ __ _ __ _ _ _ __ _ __ _ __ _ __ 78 The parasite_ _ _ _ _ _ _ __ _ __ _ _ _ __ _ _ __ _ _ __ _ _ __ _ __ __ _ _ __ _ _ __ _ __ _ __ _ _ __ _ _ __ _ __ _ __ _ 79 Taxonomy_____________________________________________________________ 79 Morphology____________________________________________________________ 79 Life-cycle______________________________________________________________ 80 Natural infections in Thais_________________________________________________ __ 85 Incidence______________________________________________________________ 85 Pathology in the snaiL _ _ _ __ _ _ __ __ _ _ __ _ _ __ __ _ _ _ __ _ _ __ _ __ _ __ _ __ _ _ __ _ __ _ __ 85 Duration of infection_ __ __ _ __ _ _ __ _ __ _ __ _ _ __ _ __ _ _ _ __ _ __ _ __ _ _ __ _ __ _ __ _ _ __ _ _ 87 Experimental infections_ __ _ _ _ __ _ _ _ _ __ _ __ _ _ __ _ __ _ __ _ _ _ __ _ __ _ __ _ _ _ __ _ __ _ _ __ _ __ _ 88 Adult hosts____________________________________________________________ 88 Larval hosts_ __ __ __ _ _ __ _ __ _ _ __ _ __ _ _ __ _ __ _ __ _ _ __ _ __ _ _ _ __ _ __ _ __ _ _ __ _ __ _ _ __ 89 Discussion and conc1usion ____ . _ __ _ _ _ __ _ _ __ _ __ _ _ __ _ __ _ _ __ _ _ __ _ _ __ _ _ __ _ _ __ _ __ _ _ 90 Literature cited_ _____ __ _ _ _ __ _ __ _ __ _ _ _ __ __ _ _ _ __ _ __ _ __ _ _ _ __ _ __ _ __ _ _ __ _ __ _ _ __ __ 91 III ABSTRACT Events in the attack on the southern oyster drill, Thais haemastoma, by miracidia of the digenetic trematode, Parorchis acanthus, are described. Infection rates in wild drill populations of various Gulf Coast localities from Florida to Texas were low, but intensity of infection in individual drills was high and caused castration. Infection rates in laboratory experiments were high, but intensities were low. Pathology of natural infections in drills is described. The infection lasts at least two years, possibly even for life. Natural infection rates of juvenile herring gulls (Larus argentatus) , ring-billed gulls (L. delawarensis), and juvenile laughing gulls (L. atricilla) are reported. Juvenile herring and ring-billed gulls were readily infected experimentally with P. acanthus, juvenile laughing gulls were less susceptible, and nestling least terns (Sterna albifrons) appeared to be resistant. Intensity of infection was generally low. P. acanthus offers little hope of being useful as a biological control of the drill, Thais, because of difficulties in spreading the parasite or assuring a significant rise in wild drill infection rates. IV STUDIES ON Parorchis acanthus (TREMATODA: DIGENEA) AS A BIO­ LOGICAL CONTROL FOR THE SOUTHERN OYSTER DRILL, Thais haemastoma By NELSON R. COOLEY, Fishery Research Biologist, BUREAU OF COMMERCIAL FISHERIES Although the biology and control of the chief Broadly speaking, predation may be controlled Atlantic coast. oyster drill, Urosalpinm cinerea, by trapping (physical control), by poisoning has been the subject of considerable st.udy (re­ (chemical control), or by parasites or predators vie,ved by Carriker, 1955), the southern drill, (biological control). Physical control of Thais Thais haemastoma Linne,t long known as an oys­ is impractical, except in restricted areas, because ter predator, has received scant attention. of expense and inefficiency of available methods. The southern drill is widely dist.ributed in oys­ Chemical control is superficially feasible, but lack ter-producing waters along the nort.hern coast. of of specificity of most available chemicals raises t.he Gulf of Mexico, exists in incredible numbers fear of damage to oysters and other economically in coastal bays and est.uaries, and is extremely . important species. Biological control by means prolific. Its reproductive cycle has been studied of predators or parasites specific for the drill ap­ in some detail by Butler (1953). Females deposit pears to be least likely to damage other species egg capsules regularly from March to August. and, for that reason, was selected for investiga­ Each capsule contains from several hundred to tion. 4,000 eggs, and there is almost no mortality wit.hin Few natural enemies of Thais are known. But­ the capsule. In a growth experiment. performed ler's (1953) laboratory observations that hermit by Butler, 250 females deposited an estimat.ed 100 crabs attack drills to gain possession of their million eggs during 1 month. Hatching occurs shells and that stone crabs, if sufficiently hungry, in 12 to 16 days at 25° C, and after a planktonic crack and eat drills are the only known proved life that may be as much as 7 weeks, the veliger reports of predators. The drill larva, a free­ larvae metamorphose into tiny snails. Sexual swimming veliger, may be eaten by pelagic fishes. maturity is usually attained during the second Thus, although normal predation on larval stages summer, i.e., at 1 year of age, but. normal egg may, probably does, cause enormous losses to drill and capsule deposition by snails not more than populations, there appears to be no immediate 8 weeks old has been observed. prospect of further popUlation reduction by this Thais is probably the most important oyster means. predator in this area (Butler, 1953). In 1956 Only a few parasites are known from Thai8. drill predation was so severe on depleted reefs in The commensal polyclad, H oplopZana inquilina, Mississippi waters -(about one-half of the reef and larvae of Parorchis acanthus, a digenetic bottoms of the State) that much of the annual trematode, were reported by Shechter (1943). spat£all in the area was destroyed. In addition, Larval stages of at least two unidentified trema­ drills destroyed a half of the oysters on the pro­ tode species which caused considerable gonad ducing natural reefs in Mississippi that year damage were noted by Butler (1953). (Chapman, 1958). During this study, examination of abont 7,600 If such severe losses in the Gulf oyster industry snails since the snmmer of 1956 revealed: one, are to be reduced, control measures must be in­ possibly two, unidentified protozoans that invade stituted against the drill. and slightly damage digestive gland follicular cells; isolated instances of larval nematode infec­ 1 Clench (1947) considers this marine snail to be two sub­ RPf'cies. T. haemastoma jloridana Conrad, 1837, and T. h. haysae tions and a few cestode infections (almost cer­ Clench. 1,92,7, but because of ecological similarities, they are tainly larval tetraphyllideans) which appeared to trea ted here as the same animal. be encysted single individuals, rather than repro­ NOTE.-Approved for publication May 25, 1961. Fishery Bul­ letin 201. ducing populations; a single infection by sporo- 77 78 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE cysts of an unidentified small furcocercaria; and .Juvenile herring gulls (Laru8 argentatu8) , ring­ many instances of heavy, severely damaging billed gulls (L.