Genome size variation within and among the sexual and asexual generations of the gall wasp Belonocnema treatae, and the putative role of tannins: Further comparisons of sexual and asexual forms

Belonocnema treatae (Cynipidae: Hymenoptera) induces galls on live oaks (Quercus; series Virentes).  Throughout its range, the insect exhibits cyclical parthenogenesis. Asexuals develop within leaf galls, emerge as adults and oviposit on shallow roots, giving rise to sexual males or females that subsequently develop in all-male or all-female root galls.  The sexual adults emerge, mate and oviposit on the leaves to produce the next generation of asexuals.  The meiotic processes associated with generating these sexual and asexual generations is poorly understood.  For example, what events cause asexuals to generate all-male or all-female producing root galls?  To examine these events in the asexuals that are male or female producing, we have developed a flow cytometric assay designed to determine if eggs from the asexuals are haploid or diploid.  This assay will help us to determine if males or females from the sexual generation are determining the sex of the asexual progeny.  Interestingly, we have observed massive differences within and among these generations that are outliers among intraspecific measures of genome size variation.  Tannins have been suggested to affect genome size variation measurement, but the distribution and concentration of tannins among B. treatae and its galls as well as the impact of tannins on the genome size of the wasp is poorly known.  Thus, we also set out to measure and link tannin concentrations within the gall with that potentially found within tissues of emerging B. treatae and separately manipulated tannin concentrations during genome size measurement, to assess the impact tannins may have.