Meeting Abstract

4.2  Sunday, Jan. 4  Innate immunocompetence in Polistes dominulus: A critical test of the haploid susceptibility hypothesis WILSON-RICH, N.*; HESTER, F.; STARKS, P.T.; Tufts University; Tufts University; Tufts University noah.wilson_rich@tufts.edu

The order hymenoptera is characterized by a haplodiploid mode of genetic inheritance, whereby males are typically haploid and females are typically diploid. The ‘haploid susceptibility hypothesis’ assumes that since male haploids have only one allele at any given locus, they will be more susceptible to disease than female heterozygous diploids. We critically tested this hypothesis by examining multiple metrics of innate immunocompetence (IC) in the paper wasp, Polistes dominulus, an invasive species to North America which produces mutant, diploid males. The inclusion of haploid and diploid males controls for sex effects (i.e., the effects of being male) and allows for a critical test of the haploid susceptibility hypothesis without confounding ploidy with gender. Haploid susceptibility predicts that haploid individuals (reproductively-viable, haploid males) will possess low IC, while diploid individuals (reproductively-viable females and sterile diploid males) will possess high IC. The encapsulation response and phenoloxidase activity did not differ between haploid and diploid males, contradicting the haploid susceptibility hypothesis. Surprisingly, differences in IC were found across female castes — non-reproductive workers had low IC and reproductive gynes had high IC, while males fell in between. These differences may be driven by caste dissimilarities with regards to reproductive viability and/or lifespan.