CHROMOSOME SURVEY IN THIRTY-FOUR SPECIES OF BISEXUAL AND PARTHENOGENETIC WEEVILS OF CANADA

Abstract

Introduction Since the pioneer chromosonle studies of parthenogenetic Curculionidae by Suornalainen (1940), a comparatively large number of cytological papers on the family have been published (Suomalainen, 1915, 1917, -1949, 1951, 1955, 1958; Seiler, 1917; A/Iiltulslta, 1919, 1950, 1951, 1960; AlIanna and Smith, 1959; Smith, 1952, 1953, 1956a, b, 1960; Smith and Taltenouchi, 1962; Taltenouchi, 1953, 1951, 1955, 1957a-c, 1958a, b, 1961, 1963; Sanderson, 1953). Weevil species and races with parthenogenetic reproduction show geographical parthenogenesis connected with polyploidy (Suornalainen, 1910, 1919). So far the chron~osome data on 37 parthenogenetic species from the Austrian and Eastern ,41ps, Central Europe, Finland, Switzerland, Germany, Poland, Australia, and Japan have been accumulated. Of these, 13 are triploid, with a chromosome number of 33 or thereabouts; four are tetraploid, with 41 chromosomes; two are pentaploid, having 55 chromosomes; five have both a diploid bisexual race and a triploid parthenogenetic race; one has a tetraploid parthenogenetic race besides the diploid bisexual race; two have triploid and tetraploid parthenogenetic races; one has triploid and pentaploid parthenogenetic races. In Otiorrhys7chz~s scaber L., triploid and tetraploid parthenogenetic races exist as well as a diploid bisexual race. A diploid parthenogenetic race is found in two species, namely, Polydros~~s 7?;roLLis Stroin. and Listroderes costirostris Schon., each of which also has a triploid race. The diploid chomoson~e number of the former is 22, but according to Sanderson (1956) the latter species has 2n = 30 chromoson~es. The cl~romoson~e number of the triploid race of both species is 3 3, as usual (Suomalainen, 1951; A4iltulslta, 1919; Taltenouchi, 1957a). On the other hand, in the course of a chromosome survey in search of parthenogenetic species, a total of over 130 diploid bisexual species has been studied. This paper deals with the chromoson~es of 31 species of Canadian weevils, including four parthenogenetic species. The results of the investigation are described with some remarks on the chron~osoines of the insects already reported by other cytologists.