The relative importance of host characteristics and co-infection in generating variation in Heligmosomoides polygyrus fecundity

We examined the relative Importance of intrinsic host factors and microparasite co-infection in generating variation in Heligmosomoides polygyrus fecundity, a parameter that serves as a proxy for infectiousness We undertook extensive trapping of Apodemus flavicollis, the yellow-necked mouse in the woodlands of the Italian Alps and recorded eggs in utero from the dominant nematode species H polygyrus and tested for the presence of five microparasite infections The results showed that sex and bleeding status interact, such that males in breeding condition harboured more fecund nematodes than other hosts, in particular, worms from breeding males had, on average, 52% more eggs in utero than worms nom non-breeding males In contrast, we found a weak relationship between intensity and body mass, and no relationship between intensity and sex or Intensity and breeding condition We did not find any evidence to support the hypothesis that co-infection with microparasites contributed to variation in worm fecundity in this system The age-intensity profiles for mice singly-infected with H polygyrus and those co-infected with the nematode and at least one microparasite were both convex and nor statistically different from each other We concluded that intrinsic differences between hosts, specifically with regard to sex and breeding condition, contribute relatively mote to the variation in worm fecundity than parasite co-infection status