Changes in the site specificity of Gyrodactylus turnbulli Harris, 1986 (Monogenea) during infections of individual guppies (Poecilia reticulata Peters, 1859)

Abstract

Gyrodactylus turnbulli Harris, 1986 infected the caudal peduncle (42% of all flukes) and caudal fin (40%), of guppies (Poecilia reticulata Peters, 1859), occurring less frequently on the pectoral (8%), dorsal (5%), pelvic (2%), and anal (1%) fins. This distribution of parasites on the fish and their crowding varied with infection age. On newly infected guppies, G. turnbulli occurred less frequently on the peduncle, and mean nearest-neighbour distance was not correlated with population size. Over the first 4 days of the infection the proportion of parasites on the peduncle increased to 60%, and mean nearest-neighbour distance became correlated with population size. In declining infections (day 6 onwards) the proportion on the peduncle declined, and mean nearest-neighbour distance increased independent of population size. This pattern suggests random colonization of the fins followed by migration to the peduncle, from which dispersal occurred during the declining phase of the infection.

Identification of Gyrodactylus ectoparasites in Polish salmonid farms by PCR-RFLP of the nuclear ITS segment of ribosomal DNA (Monogenea, Gyrodactylidae)

“…In particular, the shape of the tiny marginal hook sickles is species specific, but unfortunately it is known that the morphology of the attachment organ is variable. Factors like temperature, host and geographical location influence the intraspecific phenotypic variation of the haptors (Malmberg 1970;Ergens 1976;Mo 1991Mo , 1993Harris 1988). In addition, the large number of species and small size (<1 mm) make the identification very difficult and uncertain.…”

Les interactions entre la reproduction et la biologie des populations chez les Monogènes Gyrodactylidae : revue

“…Infestations peak 10-12 days post-infection and disappear after 20d (Fig. 1E) following a host reaction (Scott & Anderson, 1984;Harris, 1988b). At 25 °C the parasites expérience high, exponentially increasing mortality throughout their life time.…”

“…The most thoroughiy studied species are Gyrodactylus turnbulli on guppies (Scott, 1982;Scott & Anderson, 1984;Harris, 1988bHarris, , 1989Harris & Lyles, 1992) and Gyrodactylus salaris on salmon (Bakke et al, 1990(Bakke et al, , 1992aHarris et al, 1993). For both of thèse species population behaviour can be combined with observations on population structure and reproductive biology.…”

“…During the course of infections the parasite population shows characteristic changes in distribution on the fish (Harris, 1988b). Initially parasites are widely spaced on the pectoral and caudal fins, the resuit of chance contacts with transmitting parasites.…”

“…They move slowly onto the peduncle, where a dense population builds up 6-7d after infection. A reverse migration takes place as the infection déclines (Harris, 1988b). Copulation takes place in G. turnbulli infections and is associated primarily with the peak phase when parasites are crowded onto the peduncle (Harris, 1989).…”