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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The dynamics of trematode infected and uninfected Planorbella trivolvis in commercial catfish ponds

George, Barbara Ann 09 August 2008 (has links)
Planorbella trivolvis, a snail routinely found in catfish ponds, is an intermediate host in the life cycle of Bolbophorus damnificus, a digenetic trematode responsible for mortalities in catfish. This research generated information on the life cycle and the population dynamics of P. trivolvis in catfish ponds which could be implemented to control P. trivolvis. Research indicated that: P trivolvis is present year-round; survives overwintering at water temperatures of 5°C; reproduces year-round; is found in vegetation, sediment and water in ponds year-round; lays eggs two months post-hatch; and has a life span of at least one year. Planorbella trivolvis infected with Bolbophorus spp. were found in 0.8% of the snails examined; found in juvenile snails (4 mm), and could shed 3,200 cercariae/day, and shed these cercariae for up to 21 days. This data indicated that constant snail monitoring and persistent snail control is imperative to control P. trivolvis in catfish ponds.
2

Investigations into the Life Cycle of Drepanocephalus Auritus with Notes on the Discovery of a New Snail Host Biomphalaria Havanensis in Mississippi

Alberson, Neely Rae 11 August 2017 (has links)
Drepanocephalus auritus is a digenetic trematode parasitizing the double-crested cormorant, a piscivorous waterbird often found feeding on catfish aquaculture ponds in Mississippi. The aquatic snail Planorbella trivolvis was the only known intermediate host in Mississippi until a new snail host, Biomphalaria havanensis, was discovered releasing cercariae belonging to North and South American D. auritus haplotypes. In addition, previous work has reported D. auritus metacercariae begin to resolve in channel catfish 7-21 days post-infection. As a result, a 2-year study was undertaken to elucidate the life cycle of D. auritus and identify if channel catfish can serve as a true intermediate host. In year 1, the role of the channel catfish as a true intermediate host was established, as gravid adults were recovered from double-crested cormorants fed parasitized fish. In year 2, each step of the life cycle was completed, and developmental timelines for each life stage were established.

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