Social defences of ant colonies against bacterial infection

Bračić, Marko (2016) Social defences of ant colonies against bacterial infection. Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

In response to pathogen pressure, social insects evolved specific organisational, physiological and behavioural adaptations resulting in avoidance, control or elimination of parasites. Such collective action of individuals at the level of the whole colony is called social immunity; established primary on fungal “external” infections. However, orally infecting parasites are poorly investigated. Therefore, I here used an entomopathogenic bacterium Bacillus thuringiensis and ants, to test the influence of bacterial spore ingestion on ant survival, in order to establish a novel model system for exploring social immunity. However, spores from three different B. thuringiensis strains did not consistently induce mortality under used experimental setup. Given that mechanisms of social immunity may act before the parasite had established an infection, I further tested whether behavioural changes in Linepithema humile ants are observed after exposure to B. thuringiensis. Indeed, B. thuringiensis-exposed ants self-groomed their gaster tip longer then the control-exposed ants. L. humile have different gaster glands, which secretions consumed after spore ingestion might inhibit bacterial growth. Indeed, I found that the gaster secretions inhibit B. thuringiensis growth, indicating gaster tip self-grooming may serve as the first line of defence against orally induced parasite invasion of the colony, before the infection was even established within the host body.

Item Type: Thesis (Diploma thesis)
Keywords: social immunity, host-parasite interaction, gaster glands, orally infecting parasites, Bt
Supervisor: Cremer, Sylvia and Lisičić, Duje
Date: 2016
Number of Pages: 49
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Grozdana Sirotic
Date Deposited: 28 Nov 2016 09:32
Last Modified: 28 Nov 2016 09:32
URI: http://digre.pmf.unizg.hr/id/eprint/5347

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