J Parasitol. Aug;75(4) Changes in numbers and growth of Ligula intestinalis in the spottail shiner (Notropis hudsonius), and their roles in. Abstract. The tapeworm Ligula intestinalis occurs in the body cavity of its cyprinid second intermediate host, in this study the roach Rutilus rutilus, and inhibits. Since its use as a model to study metazoan parasite culture and in vitro development, the plerocercoid of the tapeworm, Ligula intestinalis, has.

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The gonads, however, are present but remain in an immature state, irrespective of fish age or season.

However, an apparently increased LH production in the eel suggested possible species differences in the action on gonadotroph activity. We have also demonstrated that infected roach have a decreased condition factor, weight, length and liguoa development with respect to their age- and season-matched uninfected counterparts. Furthermore, in vertebrate hosts, Taenia taeniaeformis appears to directly affect the testis in the rat Lin et al.

Based on increased mean somatic weight and skewness of the weight distribution for infected fish, we propose that infected spottails are subjected to size-selective mortality. Further quantification was performed in sections of the ovaries to determine the extent of oocyte development. In the roach, our data also showed that Ligula infection exerts some inhibitory effects on body growth and condition, but these effects are small and would, therefore, not account for the complete blockade of puberty noted in ligulosed fish.

WoRMS – World Register of Marine Species – Ligula intestinalis (Linnaeus, ) Gmelin,

In non-infected females, the ovaries contained large, mature eggs and several smaller, primary oocytes with only immature stages of development occurring post spawning. I, infected fish; NI, non-infected fish; F, female; M, male.


Some of the contradictions in the literature may be attributed to underestimated prevalence due to increased numbers of spawning intstinalis in the spring, mixed age-classes of Ligula in separate age-classes inetstinalis fish, and differential effects on growth due to infection in male versus female hosts.

Reproduction6; However, because of the low sample size in certain age classes of infected fish, body lengths were considered according to age class, and differences were less apparent. GSI leading up to spawning February varied between 0.

Indeed, sexual maturation will occur every year in ligila fish but not in infected ones. Ligula infection could also affect LH production by acting directly on the gonadotrophs.

Ligula intestinalis

As an internal control, 18S rRNA was amplified in an identical manner. Materials and methods Fish Ligulosed and non-ligulosed roach were collected from the Altami Angling Club, Chester, Cheshire, UK during — at three times during the reproductive year: The sample size is shown above each bar.

Comparison of body mass to condition factor of ligulosed and non-ligulosed roach. As has been noted previously by Kennedy et al.

In contrast, in infected fish, only intesstinalis immature stages of oogenesis were present throughout and no cyclical variations were recorded see Arme These studies have led to the belief that the effects of Ligula on gonadal development may be mediated through the pituitary gland.

Ligula intestinalis (Cestoda: Pseudophyllidea): an ideal fish-metazoan parasite model?

However, seasonal variations in GnRH cell activity in non-infected fish were not investigated, lntestinalis it cannot therefore be deduced that GnRH cells or GnRH release are not affected in infected fish. Previous observations have revealed that two GnRH forms salmon and chicken occurred in the brain of non-infected and infected roach Williams et al.


Ihtestinalis of fish used and effects of parasitism are shown in Table 1. Our results have confirmed previous observations made by Armeon the biometric effects of Ligula intestinalis on its roach intermediate host.

Ligula intestinalis – Wikipedia

Importantly, it also revealed that the roach—parasite interaction under investigation is typical of that found in other sampled populations. Fish exceeding 20 g were not infected with Ligula.

Further analysis of the — cohort of fish also revealed a similar trend in the association with parasitisation and growth parameters.

Ligkla Parasite burden Details of fish used and effects of parasitism are shown in Table 1. As with length, in 4 year-old fish there was no statistically significant difference between the body mass of infected and non-infected individuals infected 8.

As in other vertebrates, body growth and condition have been suggested to act as triggers for the initiation of puberty in fish, although the mechanisms by which such a trigger is initiated is still largely unknown for reviews see Peter et al.

Fish used for hormonal or molecular biological analysis were examined within 7 days of capture. However, seasonal variations in pituitary LH content observed in non-infected fish were absent in infected roach.

The majority of non-infected fish achieved sexual maturation by 2 years of age as determined by the presence of yolky oocytes and all non-infected females were mature by ligulx years of age. This abnormal behaviour may also expose roach to different light intensities, a parameter vitally important in the control of the reproductive cycle in fish Bromage et al.