Changes in lifetime immunocompetence in male and female Gryllus texensis (formerly G. integer): trade-offs between immunity and reproduction

摘要: Abstract Determining whether males make energetic trade-offs between immunity and reproduction remains difficult, partly because of the complexity vertebrate immune system. We studied this question in an insect, which has a simpler estimated immunocompetence cricket Gryllus texensis by measuring: (1) phenoloxidase (PO) activity, (2) haemocyte number (3) susceptibility to bacterium Serratia marcescens. From last instar prereproductive adulthood, was similar that observed females. When reached age at they begin display reproductive behaviour, PO activity resistance S. marcescens declined relative females younger males. In females, increased after onset sexual female nymphs adult Both showed decline old age. Neither weight nor body length correlated with either sex. Haemocyte did not differ any age, change significantly correlate toS. marcescens , suggesting it does reflect immunocompetence. These results suggest decreased reproductively active males, supporting hypothesis trade off for reproduction. Our also may increase