Meeting Abstract
P2.54 Jan. 5 The effects of larval age on sex ratios of Heligmosomoides bakeri BOYD, Carrean*; KRISTAN, Deborah M.; California State University, San Marcos boyd009@csusm.edu
For many species, males and females have different life spans. However, it is unknown if this occurs for male and female parasites at the free-living infective larval (L3) stage. We examined this question by experimentally infecting male Swiss Webster laboratory mice (Mus musculus) with the intestinal nematode Heligmosomoides bakeri using oral inoculation. Sex of the L3 is not readily determined; therefore, we investigated the sex ratio of fourth stage larvae and adult worms for ten mice infected with 390-400 day old L3. We removed fourth stage larvae and adult worms from the small intestine after 6 days or 24 days, respectively. Upon removal, worms were counted and each worm was sexed using morphology of the posterior region. The average (± 1 standard deviation) sex ratio of males to females for fourth stage larvae was 0.84 ± 0.1 and for adult worms was 0.49 ± 0.2. Our data show that fourth stage larvae have nearly equal numbers of males and females, which indicates that the lifespan may be similar for male and female L3 as well. However, there were more female than male adults which implies differential survival between the sexes for worms that develop from chronologically old L3. This is the first study to examine sex ratio of multiple parasite stages in the context of aging in male and female infective stage larvae.
