KARYOTYPES, SEX-CHROMOSOME SYSTEMS, AND MALE MEIOSIS IN FINNISH PSYLLIDS (HOMOPTERA, PSYLLOIDEA)

The karyotypes and structure of the testes were studied in 12 species of Psylloidea belonging to the families Aphalaridae, Psyllidae and Tri ozidae. Males of ten species, namely Aphalara avicularis Oss., A. rumi cicola Klimasz., Camaratoscena speciosa (Flor), Cacopsylla ambiqua Frs t., C. peregrina Frst., Bactericera curvatinervis Frst., B. striola Fl or., Trioza anthrisci Burckhardt, and T. apicalis Frst. have two semin al follicles per testis, this being the most typical testis structure in Psylloidea. Males of Psylla betulaenanae Oss. and P. ledi Flor. wer e found to display 4 follicles per testis. Ten species share 2n=24+X0 in males, which is the basic karyotype in Psylloidea as a whole, where as Bactericera curvatinervis Frst. and B. striola Flor. have 2n=24+neo -XY. In some karyotypes, one B-chromosome was found. Its peculiar beha viour during some stages of the first meiotic division was examined. T he karyotype of A. rumicicola was studied after Giemsa C-banding. Usin g C-band in an autosome pair as the marker of one of the telomeres it was proved that holokinetic chromosomes of psyllids are in fact dikine tic in the first meiotic division.