Cytogenetic analysis of Otiorhynchus bisulcatus (Fabricius, 1781) and O.(Zadrehus) atroapterus (De Geer, 1775) (Coleoptera, Curculionidae, Entiminae) using C bands, NORs, and DAPI/CMA3 staining.

The structure of the karyotypes of two Otiorhynchus species belonging to separate subgenera, viz. Otiorhynchus s.str. bisulcatus and O. (Zadrehus) atroapterus, is compared and described for the first time. Both species have the same chromosome number (2n = 22), sex chromosome system of an achiasmate parachute type (Xy(p)), symmetric karyotype with the prevalence of metacentrics, similar meiotic behaviour, localization of NORs and positive DAPI signals. The main differences involve the morphology of autosomes and the X chromosome in the C-banding pattern and DAPI/CMA3 signals as well as in the presence of additional B chromosomes.

Karyotype of the bird blowfly, Protocalliphora falcozi Séguy, 1928 (Diptera, Calliphoridae).

The karyotype structure of Protocalliphora falcozi is described for the first time. The diploid complement comprises 2n = 12, n(male) = 5+XY. Male mitotic plates include four pairs of long (metacentric) and one pair of medium-sized (submetacentric) autosomes. The submetacentric sex chromosomes X and Y are the smallest elements of the set. An achiasmatic meiosis was determined. The heterochromosomes do not form a heterovalent because they occur separately during the first meiotic division. The examined karyotype shows a pericentromeric position of constitutive heterochromatin in all autosomes. The longer arm of the X chromosome is heterochromatic, while the Y is entirely euchromatic. The NORs are active at mitotic prophase and at early meiotic stages. Small, bright signals were observed in the centromeric regions of autosomes after DAPI staining.

Karyology of parthenogenetic weevils (Coleoptera, Curculionidae): do meiotic prophase stages occur?

We investigated the cytological mechanism of parthenogenesis by analyzing the chromosomes in five weevil species. All examined species are polyploids, four of which: Otiorhynchus ovatus, Simo variegates, Cathormiocerus aristatus, and Tropiphorus elevatus possess three haploid sets of chromosomes (3n=33), whereas the fifth, Trachyphloeus parallelus, is tetraploid with 44 chromosomes (4n=44). The plates contained 27-31 chromosomes in triploid species and 38, 39, 41 and even 44 in tetraploid T. parallelus. In all species single clusters of metaphase plates with a haploid number of n=11 were visible. Some oogonial cells showed nuclei configurations resembling the stages of diplotene and diakinesis. The spiralized chromosomes in these nuclei may have been connected by chiasmata resulting in rods figures and ring-shaped bivalents. Occurrence of the remnants of meiosis could suggest some degree of recombination in parthenogenetic lineages of weevils.

Karyotype analysis of three weevil species from the Genera Brachysomus (Boheman, 1845) and Strophosoma Billberg, 1820 (Coleoptera, Curculionidae).

Karyotypes of three weevil species, viz. Brachysomus dispar (2n=22, n males = 10 + X(y(p))), Brachysomus hirtus (3n=33, n females = 10 + X) and Strophosoma faber (2n=22, n males = 10 + X(y(p))) belonging to the tribes Sciaphilini and Brachyderini, were studied using the C-banding technique. The karyotype structures of the two bisexual and one parthenogenetic species are described for the first time. Most chromosomes are meta- or submetacentric. In the two species of the genus Brachysomus, the chromosomes resemble one another in having a rather small amount of heterochromatin restricted to the pericentromeric region, visible as dark stained blocks mainly during the early stages of nuclear division. Larger bands at mitotic metaphase and diakinesis occur only in Strophosomafaber. Geographic parthenogenesis in Brachysomus hirtus is briefly discussed.

The first cytogenetic report on Laena reitteri Weise, 1877 (Coleoptera, Tenebrionidae, Lagriinae) with notes on karyotypes of darkling beetles.

The karyotype structure of Laena reitteri is described for the first time. The chromosome number 2n = 18+1-3B and meioformula n(male) = 8+Xy+1-3B deviates from the modal tenebrionid number. The karyotype exhibits low variation in morphology and length. The diploid set consists of four long (subtelocentric and acrocentric), twelve medium-sized acrocentric autosomes and sex heterochromosomes Xy. The X chromosome is submetacentric, while the y is acrocentric and the smallest element of the set. On mitotic and meiotic plates 1-3 small additional elements are also visible, and probably represent B-chromosomes. The NORs are very active at mitotic prophase and early meiotic stages.

New data on the cytology of parthenogenetic weevils (Coleoptera, Curculionidae).

Parthenogenesis and, in particular, polyploidy are rare in animals. A number of cases, known among weevils, represent apomictic parthenogenesis--a reproductive mode in which eggs undergo one maturation division, the chromosomes divide equationally, and no reduction takes place. Among parthenogenetic weevils there are two diploids, 48 triploids, 18 tetraploids, six pentaploids, three hexaploids and one decaploid. Eight examined parthenogenetic species are triploids with 33 chromosomes of different morphology, confirming that triploidy is the most common level of ploidy in weevils. The karyotypes are heterogeneous with the presence of meta-, submeta-, subtelo- and acrocentric chromosomes. The C-banding method showed that only two species possess a large amount of heterochromatin visible as a band around the centromere during mitotic metaphase. This agrees with observations that weevils are characterized by a small amount of heterochromatin, undetectable in metaphase plates after C-banding. In three species an atypical course of apomictic oogenesis occurs with stages similar to meiosis, in which chromosomes form bivalents and multivalent clusters. This association of chromosomes probably represents the remnants of meiosis, although these events have nothing to do with recombination. The results support the hypothesis that the evolution of apomictic parthenogenesis in weevils has proceeded through a stage of automixis.

Karyotypic characterization of three weevil species (Coleoptera: Curculionidae, Brachyderini).

Karyotypes of three species, Brachyderes incanus, Brachysomus setiger and Paophilus afflatus, belonging to the tribe Brachyderini, were studied using C-banding technique. The species share the same chromosome number 2n = 22 and meioformula n = 10+Xy(p) at all metaphase 1 plates of spermatid division. Some differences between karyotypes were observed in terms of centromere positions and C-band sizes. Most chromosomes are meta- or submetacentric and form a graded series in respect to length. The chromosomes resemble one another in having a rather small amount of heterochromatin restricted to the pericentromeric region and visible as dark stained blocks mainly during early stages of nuclear division. Only in Brachyderes incanus do larger bands occur at mitotic metaphase and diakinesis. These cytogenetic data are in agreement with karyological findings obtained in other species of Brachyderini so far examined.

Evidence of B-chromosomes in the karyotype of Barypeithes pellucidus Boheman 1834 (Coleoptera, Curculionidae, Entiminae) from Central Europe.

B-chromosomes were observed in spermatogonial mitotic metaphases, meiotic metaphases I and II of Barpeithes pellucidus from one population in Slovakia. The number of B-chromosomes ranged from one to six per cell and they paired with the sex heterochromosomes in the first meiotic metaphase and rarely with the autosomes. In metaphase I one B-chromosome was always associated with X chromosome forming a tripartite complex. The XyBp was easily recognizable as a complex of three chromosomes in a parachute association The size of the B-chromosomes was approximately the same or a little smaller than that of the y heterochromosome which was the smallest element of the regular chromosome set. Their staining intensity seems to be similar to that of the autosomes and sex chromosomes, respectively. The behaviour of B-chromosomes during mitosis and meiosis in weevils is briefly discussed.

Notes on chromosome numbers and C-banding patterns in karyotypes of some weevils from central Europe (Coleoptera, Curculionoidea: Apionidae, Nanophyidae, Curculionidae).

Chromosome numbers and C-banding patterns of sixteen weevil species are presented. The obtained results confirm the existence of two groups of species with either a small or large amount of heterochromatin in the karyotype. The first group comprises twelve species (Apionidae: Oxystoma cerdo, Eutrichapion melancholicum, Ceratapion penetrans, Ceratapion austriacum, Squamapion flavimanum, Rhopalapion longirostre; Nanophyidae: Nanophyes marmoratus; Curculionidae: Centricnemus (=Peritelus) leucogrammus, Sitona humeralis, Sitona lineatus, Sitona macularis, Sitona suturalis). In weevils with a small amount of heterochromatin, tiny grains on the nucleus during interphase are visible, afterwards appearing as dark dots during mitotic and meiotic prophase. The second group comprises four species from the curculionid subfamily Cryptorhynchinae (Acalles camelus, Acalles commutatus, Acalles echinatus, Ruteria hypocrita) which possess much larger heteropycnotic chromosome parts visible during all nuclear divisions. The species examined have pericentromeric C-bands on autosomes and on the X chromosome.

C-banded chromosomes of the genus Bembidion Latr. (Coleoptera, Carabidae).

The C-banding pattern of Bembidion punctulatum, B. varium, B. varicolor, B. ascedens, B. tibiale, B. ustulatum, B. decorum, and B. modestum are presented. All examined species have a symmetrical karyotype with meta- and submentacentric chromosomes and meioformula n=11+XY. All of them have an achiasmatic spermatogenesis in common. The present data confirm earlier studies indicating a considerable morphological and numerical stability of the Bembidiini karyotype. The C-banding showed the existence of heterochromatin in the paracentric regions of chromosomes, and also 2-3 intercalar C-positive segments were observed. The Y chromosome is entrely euchromatic. The C-banded karyotype of the analysed species in genus Bembidion has large heterochromatin segments on chromosomes, an exception in Coleoptera.

Chromosome numbers, C-banding patterns and sperm of some ladybird species from Central Europe (Coleoptera, Coccinellidae).

C-banded karyotypes were studied in the males of seven ladybird species from the subfamily Coccinellinae, viz. Adonia variegata (Goeze), Tythaspis sedecimpunctata (L.), Coccinella septempunctata (L.), Calvia decemguttata (L.), Calvia quatuordecimguttata (L.), Propylea quatuordecimpunctata (L.), Phyllobora vigintiduopunctata (L.). All the species, with the exception of Tythaspis sedecimpunctata (L.), possess 2n = 20, n(male) = 9 + Xy(p). Tythaspis sedecimpunctata (L.), however, has 2n = 24, n(male) = 11+Xy. The examined karyotypes show only a paracentromeric position of constitutive heterochromatin in all autosomes and the sex chromosome X, while the y heterochromosome is dot-like and wholly euchromatic. Successive stages of spermiogenesis were analysed.

Heterochromatic banding patterns on chromosomes of twelve weevil species (Insecta, Coleoptera, Curculionoidea: Apionidae, Curculionidae).

The C-banding patterns of twelve weevil species are presented. The obtained results confirm the existence of two groups of species: with a small or large amount of heterochromatin in the karyotype. The first group comprises seven species (Apionidae: Holotrichapion pisi; Curculionidae: Phyllobius urticae, Ph. pyri, Ph. maculicornis, Tanymecus palliatus, Larinodontes turbinatus, Cionus tuberculosus). In weevils with a small amount of heterochromatin, tiny grains on the nucleus in interphase are visible, afterwards in mitotic and meiotic prophase appearing as dark dots. The absence of C-bands does not indicate a lack of heterochromatin but heterochromatic regions are sometimes so small that the condensation is not visible during the cell cycle. The second group comprises five species (Otiorhynchus niger, O. morio, Polydrusus corruscus, Barypeithes chevrolati, Nedyus quadrimaculatus) which possess much larger heteropicnotic parts of chromosomes visible during all nuclear divisions. The species examined have paracentromeric C-bands on autosomes and the sex chromosome X, except for Otiorhynchus niger, which also has an intercalary bands on one pair of autososomes. All the species examined differ in the size of segments of constitutive heterochromatin. The y heterochromosome is dot-like and wholly euchromatic in all the studied species.