Current immunity markers in insect ecological immunology: assumed trade-offs and methodological issues

AbstractThe field of ecological immunology currently relies on using a number of immune effectors or markers. These markers are usually used to infer ecological trade-offs (via conflicts in resource allocation), though physiological nature of these markers remains elusive. Here, we review markers frequently used in insect evolutionary ecology research: cuticle darkening, haemocyte density, nodule/capsule formation, phagocytosis and encapsulation/melanization via use of nylon filaments and beads, phenoloxidase activity, nitric oxide production, lysozyme and antimicrobial peptide production. We also provide physiologically based information that may shed light on the probable trade-offs inferred when these markers are used. In addition, we provide a number of methodological suggestions to improve immune marker assessment.

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Ecological immunology: costly parasite defences and trade-offs in evolutionary ecology

Trends in Ecology & Evolution ◽

10.1016/0169-5347(96)10039-2 ◽

1996 ◽

Vol 11 (8) ◽

pp. 317-321 ◽

Cited By ~ 1593

Author(s):

Ben C. Sheldon ◽

Simon Verhulst

Keyword(s):

Evolutionary Ecology ◽

Ecological Immunology ◽

Trade Offs

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Copulation enhances resistance against an entomopathogenic fungus in the mealworm beetle Tenebrio molitor

Parasitology ◽

10.1017/s0031182009992009 ◽

2010 ◽

Vol 137 (6) ◽

pp. 985-989 ◽

Cited By ~ 18

Author(s):

TERHI M. VALTONEN ◽

HEIDI VIITANIEMI ◽

MARKUS J. RANTALA

Keyword(s):

Fungal Infection ◽

Entomopathogenic Fungus ◽

Tenebrio Molitor ◽

Ecological Immunology ◽

Ecological Studies ◽

Phenoloxidase Activity ◽

Enhanced Resistance ◽

Trade Offs ◽

Indirect Measures ◽

Mealworm Beetle

SUMMARYEcological immunology is based upon the notion that activation and use of the immune system is costly and should thus be traded off against other energy-demanding aspects of life history. Most of the studies on insects that have examined the possibility that mating results in trade-offs with immunity have shown that mating has immunosuppressive effects. The connection between mating and immunity has traditionally been investigated using indirect measures of immunity. However, studies that have assessed the effects of mating on the resistance against real pathogens have had conflicting results. A previous study on Tenebrio molitor showed that copulation decreases phenoloxidase activity in the haemolymph, and concluded that copulation corrupts immunity in this species. In the present study we tested whether mating also affects the ability of T. molitor to resist the entomopathogenic fungus, Beauveria bassiana. Interestingly, we found that mating enhanced resistance against the fungal infection and that the effect was stronger on males than females. Furthermore, we found that male beetles were overall more susceptible to the fungal infection than were females, indicating an immunological sex difference in immunity. Our study highlights the importance of the use of real pathogens and parasites in immuno-ecological studies.

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