Development of Syncuaria squamata (Linstow, 1883) (Nematoda: Acuarioidea) in ostracods (Ostracoda) and double-crested cormorants (Phalacrocorax auritus auritus)

Abstract

Syncuaria squamata (Linstow) developed to the infective third stage in two species of freshwater ostracods (Cyclocypris ovum (Jurine) and Cypridopsis vidua (Muller)). At room temperature (19–21 °C) the first moult occurred 11 d and the second moult 18 d postinfection. In experimentally infected double-crested cormorants (Phalacrocorax auritus auritus (Lesson)) larval stages of S. squamata were found between folds of the proventriculus and underwent the third moult within 3.5 d and the fourth moult within 8 d postinfection. Mature male and gravid female worms were found under the gizzard lining at 29 d postinfection; some females were embedded in the gizzard musculature with their tails protruding into the lumen. First through fourth larval stages are described. Of 14 cormorants captured at 5 weeks of age from Pigeon Island, Lake Ontario, 13 (93%) were naturally infected with S. squamata. Five of these birds, 15 weeks or older when examined, harboured only mature male S. squamata. This suggests that female worms may become senescent before males. It is estimated that S. squamata has a life-span of about 4 months in its final host.