Impact of Endocrine Disruption on Host-Parasite Interaction: A Digest from a Cosmopolitan Cestode Model Ligula intestinalis

Abstract

Endocrine disruption of different host species by their parasites is an oft-neglected topic in the field of ecotoxicology. Several endocrine disrupting chemicals, both synthetic and natural, are reported to influence hostparasite interactions in various ways. This review highlights different aspects of endocrine disruption by a diphyllobothriidean (previously pseudophyllidean) cestode Ligula intestinalis and its effect on its wide range of fish hosts. Although this cosmopolitan cestode with a three-host life cycle can damage the host physiology by reproductive, phenotypic, behavioural, haematological, growth and mortality related alterations, the most significant of these effects is parasitic castration, i.e., reducing the fecundity by damaging the reproductive system. The effects of endocrine disruption by other helminth infections and interactions with polluting agents are also discussed. It is concluded that the potential bioaccumulation of the effects in the hosts at higher trophic levels and consequent threat towards human, especially in Indian context, need to be studied in depth to control or reduce the detrimental effects of parasite-induced endocrine disruption in the hosts.

First Reports of Ligula intestinalis and a Schistocephalus sp. Infecting Small-Bodied Fish in New Brunswick, Canada

“…It remains to be determined whether these parasites are recent introductions or result from environmental change promoting their emergence. Despite outstanding species-level identification of the Schistocephalus sp., plerocercoids from species in both genera raise ecological concerns because they can induce sterility of host fishes ( Heins and Baker, 2010 ; Heins, 2017 ; Biswas and Ash, 2021 ). Their influence on local fish populations remains to be determined, but epizootics induced by plerocercoids of both parasites are reported ( Kennedy et al, 2001 ; Heins and Ecke, 2012 ).…”

“…Plerocercoids of Ligula and Schistocephalus can alter the behavior of their intermediate host fish to increase the odds of fish predation by their bird definitive host ( Loot et al, 2001 ; Barber et al, 2004 ), a phenomenon known as Parasite Increased Trophic Transmission (PITT; Lafferty, 1999 ). Plerocercoids of both species can also induce sterility of host fishes ( Heins and Baker, 2010 ; Heins, 2017 ; Biswas and Ash, 2021 ), and epizootics caused by both parasites are reported ( Kennedy et al, 2001 ; Heins and Ecke, 2012 ).…”