title: Single-locus complementary sex determination in Diadegma chrysostictos (Gmelin) (Hymenoptera: Ichneumonidae).
abstract: Following the establishment of isofemale lines and subsequent inbreeding, the ichneumonid parasitoid wasp Diadegma chrysostictos (Gmelin) was shown by segregation of polymorphic alloenzyme loci to have single-locus complementary sex determination (sl-CSD). This and the biparental nature of diploid males was confirmed using two independent Mendelian recessive phenotypic markers. The existence of diploid males, sl-CSD, and the abrogation of diploid males following outbreeding was further confirmed by flow cytometry, a potentially general method that is independent of the maternal sex allocation or the need for genetic markers. Estimates of the number of sex alleles in several British populations demonstrated 17-19 alleles in Britain, with a decline toward the northerly limit of the parasitoid's range, varying from 16 in the south of England to 4-5 in central Scotland, in broad agreement with the rate of attainment of a male-biased sex ratio when used to establish en masse laboratory cultures. These data represent the second confirmation of the existence of sl-CSD in the Ichneumonidae (and the first in the Campopleginae subfamily), lending further support to the notion that sl-CSD was the ancestral condition in the Aculeata/Ichneumonoidea clade (Cook 1993a; Periquet et al. 1993).
authors.affiliation: Department of Biological Sciences, University of Dundee, Angus, Scotland.
authors.forename: R D
authors.initials: RD
authors.lastname: Butcher
authors.forename: W G
authors.initials: WG
authors.lastname: Whitfield
authors.forename: S F
authors.initials: SF
authors.lastname: Hubbard
mesh_terms: D000483:Alleles; D000818:Animals; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004798:Enzymes / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D005787:Gene Frequency; D005819:Genetic Markers; D006927:Hymenoptera / Q000201:enzymology / Q000235:genetics*; D008297:Male; D019849:Sex Determination Processes; D012744:Sex Ratio
chemical_list: D004798:Enzymes; D005819:Genetic Markers