A triploid race of the parthenogenetic Japanese weevil Blosyrus japonicus Sharp (Coleoptera: Curculionidae).

Abstract

The chromosomes of the weevil, Blosyrus japonicus Sharp, have been investigated in Hokkaido. A triploid parthenogenetic race (3x=33) was found in Ishiyama-rikkyo, Sapporo.The species is now known to have four parthenogenetic races, 3x, 4x, 5x, 6x, as well as a diploid bisexual race. All these races have been found in Japan. This represents the highest number of different polyploid races observed in any parthenogenetic weevil.Previously, I reported that Blosyrus japonicus Sharp had three parthenonogenetic races, tetraploid (4x = 44), pentaploid (5x = 55) and hexaploid (6x = 66-68), and further that the species had a diploid bisexual race (n =10 + Xyp in ', n =10 + XX in ) (Takenouchi 1975(Takenouchi , 1976. Both tetraploid and pentaploid races coexist at Bihoro Pass and the latter was also found in Jugoshima Park near Sapporo. A hexaploid race was also found in Oshidomari, Rishiri Island, and Misumai, Sapporo. A diploid bisexual race was found in Esashi, Wannai, Himenuma, Hakodate and Kojima.

Genetic polymorphism and evolution in parthenogenetic animals. XIII. Changes in the degree of polyploidy in Curculionidae.

“…There are 4 diploid, 42 triploid, 18 tetraploid, 6 pentaploid, three hexaploid and one decaploid parthenogenetic species or races of Curculionidae (Takenouchi et al 1983;Takenouchi 1983b and1983c). That makes a total of 74 cytologically studied different parthenogenetic forms.…”