Saprolegnia sp. is an oomycete responsible for fresh water fish diseases causing great economical losses. There are a few effective treatments to combat saprolegniasis, being of great importance to have available tools to detect and prevent it. In some studies made with the homopteran Dactylopius coccus it was observed that its immune system reacted when it came into contact with some of the components of the fungi cell wall as n-acetylglucosamine and 1-3 glucans; with melanin formation by this can be used as a tool for the detection of water pathogens.
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