Gyrinicola Batrachiensis - Hosts

Hosts

G. batrachiensis is a nematode that is a parasite of the gastrointestinal tract of herbivorous anuran species, specifically in posterior end of the small intestine and in the large intestine of the tadpole stage. It is not seen in late-stage, metamorphosing tadpoles or in adult, carnivorous frogs. It is known to occur in 8 anuran species: Bufo americanus, Hyla versicolar, Pseudacris triserata, Rana aura, R. catesbeina, R. clamitans, R. pipiens, and R. sylvatica. These hosts have been found in Eastern Canadian provinces, as well as California, Ohio, and Michigan in the United States. G. batrachiensis is of special, also, in that it is quite rare for Oxyurida to be found in aquatic hosts, so rare that only 3 such species exist. This is so because monoxeny is not a successful way of life in aquatic hosts.

Recent studies have shown that G. batrachiensis has a significant effect on the developmental rates of their tadpole hosts. They have actually been found to accelerate the development and metamorphosis. One study, Pryor and Bjorndal, 2005, found that the mean time to metamorphosis was 16 days shorter and that the range of times taken to reach metamorphosis was significantly narrower in tadpoles infected with these nematodes than the time taken in uninfected tadpoles. Some of the proposed manners by which this phenomenon may be explained are:

• An increase in the colonic width resulting from infection may allow for increased food intake, as well as longer retention of digested material in the fermentation region. Both of these could independently result in a higher energy gain, which could be directed towards the host's development.
• Altered fermentation due to infection results in higher rates of fermentation, providing higher energetic contributions to the host. Additionally, an increased production of propionate, relative to acetate, is also energetically advantageous to the tadpole host, again allowing the host to focus this additional energy towards development.

However, at the time of metamorphosis, infected bullfrogs had the same body size and appearance as uninfected bullfrogs, suggesting that the parasite has little impact on the physical morphology of its host (other than the shortening of development time).