SEX DETERMINATION IN THE HYMENOPTERAN DIADROMUS-PULCHELLUS (ICHNEUMONIDAE) - VALIDATION OF THE ONE-LOCUS MULTI-ALLELE MODEL

Males of the hymenopteran Diadromus pulchellus are normally haploid, but diploid males can be obtained by inbreeding. Inbred crosses within strains that are polymorphic at the enzymatic loci Pgm-2 and Ao-4 or that differ by a body colour mutation produce heterozygous diploid males in offspring. The genotypic distributions observed in such progeny were compared with expected results under the one-locus sex determination model or the two independent loci model. The results show that only the one-locus multi-allele model fits the data and allow a provisional estimate of approximately 15 sex alleles. These conclusions generalize the case of existence of a single locus to determine sex in Hymenoptera and are discussed at the evolutionary level.