| interaction of b chromosomes with a or b chromosomes in segregation in insects. | additional or b chromosomes not belonging to the regular karyotype of a species are found in many animal and plant groups. they form a highly heterogeneous group with respect to their morphology and behaviour both in mitosis and meiosis. achiasmatic mechanisms that ensure the segregation of a b chromosome from another b chromosome or from an a chromosome are reviewed. an achiasmatic mechanism characterized by the "distance pairing" of segregating univalents at metaphase i was found to be respons ... | 2004 | 15292621 |
| the origin of the achiasmatic xy sex chromosome system in cacopsylla peregrina (frst.) (psylloidea, homoptera). | the status of an extra univalent, if it is a b chromosome or an achiasmatic y chromosome, associating with the x chromosome in male meiosis of cacopsylla peregrina (frst.) (homoptera, psylloidea) was analysed. one extra univalent was present in all males collected from three geographically well separated populations, it was mitotically stable, and showed precise segregation from the x chromosome. these findings led us to propose that the univalent represents in fact a y chromosome. the behaviour ... | 2003 | 14686611 |
| the influence of ant attendance on larval parasitism in hawthorn psyllids (homoptera: psyllidae). | the influence of ant attendance on parasitization of the larvae of three hawthorn psyllid species [cacopsylla peregrina förster, c. melanoneura förster, c. crataegi (schrank)] was studied over 2 years. all three psyllid species had low parasitization rates. however, the ant-attended c. crataegi was almost exclusively parasitized by prionomitus mitratus (dalman) (hymenoptera: encyrtidae) while the unattended c. peregrina and c. melanoneura were predominantly attacked by p. tiliaris (dalman). addi ... | 1994 | 28313950 |