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Cytologie und Spermapolyploidie bei Pityogenes chalcographus L. (Col., Scolytidae)
Author(s) -
Klipstein E.L.
Publication year - 1986
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.1986.tb00924.x
Subject(s) - biology , meiosis , bivalent (engine) , metaphase , orcein , chiasma , cytology , karyotype , chromosome , microbiology and biotechnology , genetics , gene , staining , chemistry , organic chemistry , metal
Cytology and spermpolyploidy in Pityogenes chalcographus L. (Col., Scolytidae) These experiments are based on the biological relationship that a partial reproductive incompatibility does exist between certain populations of Pityogenes chalcographus. Besides this and the existence of unusual spermpolyploidy in spermatogonial development four regionally distinct strains of this bark beetle were cytologically studied. Karyotypic determinations were made on orcein squashes and MEREDITH preparations of testes taken from callow adults. The karyotypic formula during the spermatogonial metaphase is 18 A + Xy and during the first meiotic metaphase 9 AA + Xy p . No diagnostic chromosome polymorphismus within the different populations was detected. In first meiotic metaphase the first bivalent is ring‐shaped in almost every nuclei. This ringform is explained as the result of obligate chiasma. In general, the spermatogonial development is normal, as is known for insects, but in some cases very large spermatids have been observed, which are the result of spermatogonial polyploidy. This genom multiplication takes place before meiosis. The parental strains differ slightly in frequency of spermpolyploidy. Examinations of six F 1 interpopular crosses provide a somewhat increased occurrence of spermpolyploidy. The origin of these remarkable cytological features and the conclusions pertaining to them are discussed. Zusammenfassung Anhand von Männchen aus 4 verschiedenen Kupferstecher‐Populationen unterschiedlicher Herkunft wurde sowohl die chromosomale Struktur der Keimzellen als auch der Spermatogenesever‐lauf untersucht. Zwischen den einzelnen Herkünften ergab sich keine diagnostische chromosomale Differenzierung. In der mitotischen Spermatogonienmetaphase liegen 20 Chromosomen mit der Karyotyp‐Formel 18 A + Xy vor. In der meiotischen Metaphase I bilden sich 10 Bivalente, welche durch die Formel 9 AA + Xy p beschrieben sind. In demselben Stadium bildet das 1. Bivalent eine auffallende Ringform aus. Neben der für Insekten als normal beschriebenen Gametenbildung kommen Riesenspermien vor, deren Entstehung polyploiden Ursprungs sind. Das Auftreten der Häufigkeit jener Spermapolyploidie scheint sich bei interpopularen Bastarden zu verstärken. Die möglichen Ursachen dieser chromosomalen und cytologischen Eigenheiten werden erörtert.