title: The caligid life cycle: new evidence from Lepeophtheirus elegans reconciles the cycles of Caligus and Lepeophtheirus (Copepoda: Caligidae).
abstract: The developmental stages of the sea louse Lepeophtheirus elegans (Copepoda: Caligidae) are described from material collected from marine ranched Korean rockfish, Sebastes schlegelii. In L. elegans, setal number on the proximal segment of the antennule increases from 3 in the copepodid to 27 in the adult. Using the number of setae as a stage marker supports the inference that the post-naupliar phase of the life cycle comprises six stages: copepodid, chalimus I, chalimus II, pre-adult I, pre-adult II, and the adult. We observed variation in body length in both of the chalimus stages which we consider represents an early expression of sexual size dimorphism. We interpret the larger specimens of chalimus I as putative females, and the smaller as putative males; similarly with chalimus II, larger specimens are putative females and the smaller are males. Two patterns of life cycle are currently recognized within the Caligidae but the evidence presented here reconciles the two. We conclude that the typical caligid life cycle comprises only eight stages: two naupliar, one copepodid, and four chalimus stages preceding the adult in Caligus, but with the four chalimus stages represented by two chalimus and two pre-adult stages in Lepeophtheirus. This is a profound change with significant implications for the aquaculture industry, given that lice monitoring protocols include counts of chalimus stages and use temperature to predict when they will moult into the more pathogenic, mobile pre-adults. Lice management strategies must be tailored to the precise life cycle of the parasite.
authors: Marine Ecosystem Research Division, Korea Institute of Ocean Science & Technology, P.O. Box 29, Seoul 425-600, Korea.
authors: Balu Alagar Venmathi
authors: BA
authors: Maran
authors: Seong Yong
authors: SY
authors: Moon
authors: Susumu
authors: S
authors: Ohtsuka
authors: Sung-Yong
authors: SY
authors: Oh
authors: Ho Young
authors: HY
authors: Soh
authors: Jung-Goo
authors: JG
authors: Myoung
authors: Anna
authors: A
authors: Iglikowska
authors: Geoffrey Allan
authors: GA
authors: Boxshall
mesh_terms: D000818:Animals; D033342:Copepoda / Q000033:anatomy & histology / Q000254:growth & development*; D004478:Ectoparasitic Infestations / Q000469:parasitology / Q000662:veterinary*; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D008018:Life Cycle Stages; D008297:Male; D008857:Microscopy, Interference; D010473:Perciformes / Q000469:parasitology*; D012727:Sex Characteristics
references: Folia Parasitol (Praha). 2005 Nov;52(4):349-58
references: 16405299
references: Folia Parasitol (Praha). 2008 Sep;55(3):231-40
references: 19202682
references: J Parasitol. 2011 Apr;97(2):221-36
references: 21506770
references: Vet Parasitol. 2012 Sep 10;188(3-4):355-61
references: 22494942