The transmission and development of Paracuaria adunca (Creplin, 1846) (Nematoda: Acuarioidea) of gulls (Laridae)

Paracuaria adunca (Creplin, 1846) Anderson and Wong, 1981 of the gizzard of ring-billed gulls (Larus delawarensis Ord) developed to the infective stage in the amphipods Hyalella azteca, Crangonyx laurentianus, and Gammarus duebeni. At 18–20 °C the first moult occurred 10 days and the second 18 days postinfection. Worms developed in the proventriculus of experimentally infected gulls, the third moult occurred 2.5 days and the fourth 5 days postinfection. In 8 days immature adults were found under the gizzard lining near the proventriculus. Females found 16 days postinfection had larvated eggs. Developmental stages in amphipods and gulls are described. Prevalence and intensity of P. adunca were studied in adult and juvenile gulls at the Eastern Headland (Leslie Spit) of the Outer Toronto Harbour, Lake Ontario. The low mean intensity (1.6) in adult birds examined on April 2 suggests that there was little or no transmission of the parasite on the wintering grounds of the gulls. Intensity and prevalence increased in adult birds on the breeding grounds from April 2 to June 25 and larval stages were found in the birds. Prevalence in young-of-the-year birds increased with age of the birds. Intensity reached a high of 3.2 (1–6) in 35- to 42-day-old-birds (July 3). Infective larvae became encapsulated on the mesentery of experimentally infected goldfish (Carassius auratus). Infective larvae of P. adunca were found in the mesentery of fish (Culaea inconstans, Notropis hudsonius, Semotilus atromaculatus) collected in waters adjacent to the breeding grounds. Paracuaria adunca was transmitted experimentally to geese (Anser anser) and ducks (Anas platyrhynchos) but few worms were recovered from the few birds that became infected.