Sex and immunity in the yellow dung fly Scathophaga stercoraria.
The immune system is of increasing interest to evolutionary biologists. Immunity may trade-off against other fitness components, with recent work suggesting reproduction in particular impinges on immune defence. There may also be sex differences in the immune system. Additionally, while life history traits typically have low heritability, little is known about additive genetic variance of immunity. An insect's major defence against multicellular pathogens is to encapsulate the invader. Phenoloxidase (PO) is a key enzyme in the cascade resulting in the melanized capsule, and is often used to estimate resistance to an immune insult. We examined the effects of copulation, egg laying, sex and age on PO in Scathophaga stercoraria. We also measured the heritability of PO activity. The sexes differed in haemolymph PO activity and PO was significantly affected by age, but not by copulation or egg laying. There was significant heritable variation for haemolymph PO.
Schwarzenbach
G A
GA
Zoology Museum, University of Zurich, Zurich, Switzerland. gioia.schwarzenbach@access.unizh.ch
Hosken
D J
DJ
Ward
P I
PI
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D004175:Diptera / Q000201:enzymology / Q000276:immunology* / Q000502:physiology; D014442:Monophenol Monooxygenase / Q000097:blood / Q000378:metabolism*; D010058:Oviposition / Q000502:physiology*; D019655:Quantitative Trait, Heritable; D012737:Sex Factors; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013053:Spectrophotometry
D014442:Monophenol Monooxygenase