ESTIMATES OF HETEROZYGOSITY IN 2 SOCIAL INSECTS USING A LARGE NUMBER OF ELECTROPHORETIC MARKERS

An extensive electrophoretic survey of enzyme and protein markers was conducted for a haplodiploid eusocial insect, the red imported fire ant (Solenopsis invicta), and for a diploid communal insect, the eastern tent caterpillar (Malacosoma americanum). This survey resulted in the discovery of 110 electrophoretic loci for S. invicta (15 of which were polymorphic at the 95 per cent level) and 37 electrophoretic loci for M. americanum (seven polymorphic). Expected heterozygosities (mean H(exp) +/- S.E.) were 0.051 +/- 0.013 and 0.092 +/- 0.030 for S. invicta and M. americanum, respectively. Although these values do not differ significantly, they are consistent with the frequently reported pattern of low gene diversity in the eusocial Hymenoptera relative to non-eusocial diploid insects. This pattern persists when a large number of markers is scored in different life stages and castes, as in S. invicta in this study, and when a direct comparison is made using data generated in a single laboratory.