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-The present study standardizes a reproducible flow cytometry (FCM) protocol for DNA content measurement of bee species and applied it to Scaptotrigona and Melipona species. The mean nuclear DNA content value of male and female S. xantotricha was 0.42 pg (410.8 Mbp) and 0.44 pg (430.3 Mbp), respectively, while the mean haploid genome size was determined to be 0.93 pg (909.5 Mbp) for M. rufiventris and 0.95 pg (929.1 Mbp) for M. mondury. The variation observed in this study, albeit in a preliminary way, may be related with the variation in the heterochromatin content in the chromosomes of Scaptotrigona and Melipona species. The results provide a starting point for comparative analysis on the patterns of genome size variation in the stingless bees.flow cytometry / genome size / Hymenoptera / stingless bees

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Previous flow cytometry (FCM) analyses delivered nearly equal mean values of nuclear 2C DNA content for Eucalyptus grandis Hill ex Maiden and E. urophylla S. T. Blake (1.33 pg and 1.34 pg, respectively), whereas E. globulus Labill. presented distinct mean values (1.09, 1.13 and 1.40). These differences have been attributed to the different methodological approach, utilised plant cultivar and presence of intrinsic metabolic compounds that affect fluorochrome fluorescence. In the present study, a FCM and image cytometry (ICM) design, following international consensus criteria, were adopted to reassess the nuclear DNA contents of the above-mentioned Eucalyptus species. Statistical analyses revealed either similar or discrepant nuclear DNA contents, depending on the standard species used and whether FCM or ICM was employed. Our results demonstrated that 2C DNA values obtained by FCM and ICM were most uniform when Solanum lycopersicum was used as a standard. Moreover, the values obtained for E. grandis and E. urophylla were close, but differed as much as 24.63% in relation to previous data, and E. globulus proportionally varied up to 25%. New DNA content values are suggested for these eucalypt species.