Zusammenfassung
Long-term exposure to infections can exert serious pressure on the host's immune system and influence its capacity to react adequately when challenged by another parasite. Rather than reacting readily to the attack of a secondary pathogen the immune response might be weaker because of the costs imposed by resisting the primary infection. Rickia wasmannii is an ectoparasitic fungus, which attaches ...
Zusammenfassung
Long-term exposure to infections can exert serious pressure on the host's immune system and influence its capacity to react adequately when challenged by another parasite. Rather than reacting readily to the attack of a secondary pathogen the immune response might be weaker because of the costs imposed by resisting the primary infection. Rickia wasmannii is an ectoparasitic fungus, which attaches to the outer layer of Myrmica ants without killing the host, but causing different modifications on individual and social level. We examined the immune competence of M. scabrinodis workers of different age categories either coming from infected colonies or from healthy control colonies using encapsulation assays. Infection and age did not affect the encapsulation response separately, but their interaction had a considerable effect: the response was stronger in young, infected workers. Smaller individuals also had stronger responses. Encapsulation response was not influenced by fat content of workers. Immune facilitation might indeed work in infected colonies, although not for each worker category. This emphasizes the importance of within-colony diversity when considering colony level response to parasitic attacks.
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