Difference between revisions of "Platyhelminthes"

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The best studied example is ''Dicrocoelium dendriticum'', the lancet liver fluke. Adults of ''Dicrocoelium dendriticum'' are found in the bile ducts of sheep, cattle, pigs, deer, cottontail rabbits, and woodchucks, while earlier life stages inhabit snails and ants. Fluke eggs are eliminated in the feces of their vertebrate hosts and are ingested by terrestrial snails. Cercaria (the free-swimming larval stage) develop in the snails, are secreted in the snail’s mucus or slime ball, and are ingested by ants. Once within the ant the parasites develop in two areas of the ant’s body, the brain and the abdomen. Those in the brain cause the ant to disperse to the tips of grass blades or other vegetation at dusk, lock their mandibles to the vegetation, and remain there until dawn. In this position they are most likely to be eaten by herbivores (the fluke's primary host) in the early morning. This behaviour will be repeated every night until the ant is eaten by a vertebrate host in which the parasite can fully mature and complete its life cycle.
 
The best studied example is ''Dicrocoelium dendriticum'', the lancet liver fluke. Adults of ''Dicrocoelium dendriticum'' are found in the bile ducts of sheep, cattle, pigs, deer, cottontail rabbits, and woodchucks, while earlier life stages inhabit snails and ants. Fluke eggs are eliminated in the feces of their vertebrate hosts and are ingested by terrestrial snails. Cercaria (the free-swimming larval stage) develop in the snails, are secreted in the snail’s mucus or slime ball, and are ingested by ants. Once within the ant the parasites develop in two areas of the ant’s body, the brain and the abdomen. Those in the brain cause the ant to disperse to the tips of grass blades or other vegetation at dusk, lock their mandibles to the vegetation, and remain there until dawn. In this position they are most likely to be eaten by herbivores (the fluke's primary host) in the early morning. This behaviour will be repeated every night until the ant is eaten by a vertebrate host in which the parasite can fully mature and complete its life cycle.
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|name1=Hehlhorn, H. 2015. The Brain Worm Story, Fig. 7.1.jpg
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|comment1=Diagrammatic representation of life cycle stages of ''Dicrocoelium dendriticum''. A Final host: chiefly sheep and cattle; humans are incidental (“accidental hosts”). 1 Sexually mature liver fluke (see under III). 1 a Egg with a fully formed miracidium. B Intermediate host: land snails (''Helicella'', ''Zebrina''). 2 Miracidium which has emerged from a snail. 3 a The youngest sprorocyst. b The oldest sporocyst stage (mother sporocyst). c Daughter sporocyst. d A single cercaria (the so-called Cercaria vitrina). e Shell of ''Helicella ericetorum''. f Shell of ''Zebrina dendrita''. C 2. Intermediate hosts: ants. 4 a Slime balls laid by the snail on grass stem. 4 b An isolated (single) slime ball laid by the snail. 5 a An ant eating slime balls. 5 b Mature metacercariae from ants. (I) A miracidium emerging. (II) “Cercaria vitrina”. (III) A sexually mature liver fluke (From: Piekarski 1963)
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|name2=Dicrocoelium LifeCycle 19.jpg
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|comment2=Typical life cycle of a ''Dicrocoelium'' spp.
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===Known Ant Hosts===
 
===Known Ant Hosts===

Revision as of 08:44, 12 October 2021

The phylum Platyhelminthes includes two classes of worms that involve ants: the cestodes (tapeworms) and the trematodes (flukes and blood flukes). These two groups have complex life-cycles, with mature stages that live as parasites in the digestive systems of fish or land vertebrates, and intermediate stages that infest secondary hosts, including ants.

Cestodes

All cestodes are parasites of vertebrates; many have complex life histories, including a stage in a definitive (main, vertebrate) host in which the adults grow and reproduce, often for years, and one or two intermediate stages in which the larvae develop in other hosts (typically arthropods or other vertebrates). The adults live in the digestive tracts of vertebrates, while the larvae often live in the bodies of other animals.

Known Ant Hosts

Ant Cestode Species Locality Source Notes
Brachyponera sennaarensis Raillietina tetragona Sudan Mohammed et al., 1988; Laciny, 2021
Harpagoxenus sublaevis Type 2 (Choanotaenia unicoronata?) South Tyrol, Italy Buschinger, 1973; Laciny, 2021
Leptothorax acervorum Choanotaenia unicoronata South Tyrol, Italy; Bavaria, Germany Buschinger, 1973; Peru et al., 1990; Laciny, 2021
Myrmica rubra Davaineidae (Raillietina urogalli??) Scotland Muir, 1954; Laciny, 2021
Myrmica scabrinodis Davaineidae (Raillietina urogalli??) Scotland Muir, 1954; Laciny, 2021
Pheidole bicarinata Raillietina georgiensis Georgia, United States Muir, 1954; Laciny, 2021 as ''Pheidole vinelandica''
Temnothorax affinis Anomotaenia brevis Germany Scharf et al., 2012; Laciny, 2021
Temnothorax affinis Dilepididae (type 1(?)) Germany Buschinger, 1973; Laciny, 2021
Temnothorax aveli Dilepididae (type 1(?)) Germany Buschinger, 1973; Laciny, 2021
Temnothorax lichtensteini Choanotaenia crateriformis Spain Espadaler & Riasol, 1983; Laciny, 2021
Temnothorax nylanderi Anomotaenia brevis France Gabrion et al., 1976; Laciny, 2021
Temnothorax nylanderi Anomotaenia brevis France (lab colony) Trabalon et al., 2000; Laciny, 2021
Temnothorax nylanderi Anomotaenia brevis Germany Scharf et al., 2012; Beros et al., 2015; Feldmeyer et al., 2016; Laciny, 2021
Temnothorax nylanderi Anomotaenia sp. Spain Espadaler et al., 2011; Laciny, 2021
Temnothorax nylanderi Choanotaenia crateriformis Spain Espadaler & Riasol, 1983; Laciny, 2021
Temnothorax nylanderi Dilepididae (type 1(?)) Germany Buschinger, 1973; Laciny, 2021
Temnothorax parvulus Dilepididae (type 1(?)) Germany Buschinger, 1973; Laciny, 2021
Temnothorax rugatulus Dilepididae unspecified (cf. Anomotaenia) Arizona/New Mexico, United States Heinze et al., 1998; Laciny, 2021
Temnothorax unifasciatus Anomotaenia sp. Spain Espadaler et al., 2011; Laciny, 2021
Temnothorax unifasciatus Choanotaenia crateriformis Spain Espadaler & Riasol, 1983; Laciny, 2021
Temnothorax unifasciatus Dilepididae (type 1(?)) Germany Buschinger, 1973; Laciny, 2021

Trematodes

Trematodes are primarily internal parasites of molluscs and vertebrates. Most trematodes have a complex life cycle with at least two hosts. The primary host, where the flukes sexually reproduce, is a vertebrate. The intermediate host, in which asexual reproduction occurs, is usually a snail, but includes several species of ants as well.

The best studied example is Dicrocoelium dendriticum, the lancet liver fluke. Adults of Dicrocoelium dendriticum are found in the bile ducts of sheep, cattle, pigs, deer, cottontail rabbits, and woodchucks, while earlier life stages inhabit snails and ants. Fluke eggs are eliminated in the feces of their vertebrate hosts and are ingested by terrestrial snails. Cercaria (the free-swimming larval stage) develop in the snails, are secreted in the snail’s mucus or slime ball, and are ingested by ants. Once within the ant the parasites develop in two areas of the ant’s body, the brain and the abdomen. Those in the brain cause the ant to disperse to the tips of grass blades or other vegetation at dusk, lock their mandibles to the vegetation, and remain there until dawn. In this position they are most likely to be eaten by herbivores (the fluke's primary host) in the early morning. This behaviour will be repeated every night until the ant is eaten by a vertebrate host in which the parasite can fully mature and complete its life cycle.


  • Diagrammatic representation of life cycle stages of Dicrocoelium dendriticum. A Final host: chiefly sheep and cattle; humans are incidental (“accidental hosts”). 1 Sexually mature liver fluke (see under III). 1 a Egg with a fully formed miracidium. B Intermediate host: land snails (Helicella, Zebrina). 2 Miracidium which has emerged from a snail. 3 a The youngest sprorocyst. b The oldest sporocyst stage (mother sporocyst). c Daughter sporocyst. d A single cercaria (the so-called Cercaria vitrina). e Shell of Helicella ericetorum. f Shell of Zebrina dendrita. C 2. Intermediate hosts: ants. 4 a Slime balls laid by the snail on grass stem. 4 b An isolated (single) slime ball laid by the snail. 5 a An ant eating slime balls. 5 b Mature metacercariae from ants. (I) A miracidium emerging. (II) “Cercaria vitrina”. (III) A sexually mature liver fluke (From: Piekarski 1963)
  • Typical life cycle of a Dicrocoelium spp.

Known Ant Hosts

Ant Cestode Species Locality Source Notes
Cataglyphis aenescens Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Cataglyphis albicans Dicrocoelium lanceatum Armenia Arakelian et al., 1997 as ''Cataglyphis albicans armenia''
Formica aserva Dicrocoelium dendriticum Canada (Alberta) van Paridon et al., 2017; Martin-Vega et al., 2018; Criscione et al., 2020
Formica cinerea Dicrocoelium lanceatum Armenia Arakelian et al., 1997 as ''Formica cinerea armeniaca''
Formica cunicularia Dicrocoelium dendriticum Germany Hohorst & Graefe, 1961
Formica cunicularia Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Formica fusca Dicrocoelium dendriticum de Bekker et al., 2018
Formica fusca Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Formica polyctena Dicrocoelium dendriticum Denmark Botnevik et al, 2016; de Bekker et al., 2018
Formica pratensis Dicrocoelium dendriticum de Bekker et al., 2018
Formica rufa Dicrocoelium dendriticum de Bekker et al., 2018
Formica rufa Dicrocoelium lanceatum Armenia Arakelian et al., 1997 Arakelian et al. (1997) note this infection is questionable
Formica rufibarbis Dicrocoelium dendriticum de Bekker et al., 2018
Formica rufibarbis Dicrocoelium dendriticum Germany Hohorst & Graefe, 1961
Formica rufibarbis Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Formica sanguinea Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Formica transkaucasica Dicrocoelium lanceatum Armenia Arakelian et al., 1997
Proformica pilosiscapa Dicrocoelium lanceatum Armenia Arakelian et al., 1997