Milada Holecová

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.

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.

C-banding karyotype and NORs analyse in eight species of Barypeithes Duval from Central Europe (Coleoptera, Curculionidae, Entiminae)

Abstract — Karyotypes of eight species belonging to the genus Barypeithes were studied using standard Giemsa staining, AgNOR- and C-banding techniques.The species studied share almost the same chromosome number 2n = 22 (10 + Xyp) with exception of endemic Barypeithes liptoviensis which possesses 26 chromosomes (12 + Xyp). The karyotype of Barypeithes pellucidus is characterized by the presence of one to six B chromosomes clearly distinguishable from the regular members of the complement. In all examined species heterochromatin visualized by Cbanding, is found to be limited almost to the pericentromeric region of all chromosomes with differences in their amount. The wide C-bands visible during mitotic metaphase are observed in five species whereas a small blocks of heterochromatin visible during mitotic prophase are found in three species. Also the one Ag-stained NOR situated in the sex chromosomes is visible during mitotic and meiotic prophases.

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.

Assemblage structure and altitudinal distribution of lady beetles (Coleoptera, Coccinellidae) in the mountain spruce forests of Pol’ana Mountains, the West Carpathians

In two successive years we recorded a total of 3,636 individuals and 17 species of adult lady beetles (Coleoptera, Coccinellidae) in the spruce forests of Pol’ana Mts (the West Carpathians) at altitudes ranging from 600 m to 1,300 m a.s.l. Four lady beetle species were documented as predominating (dominance of abundance > 5%) over the study period. They were the following: Aphidecta obliterata (1,828 individuals and 50.3%), Coccinella septempunctata (634 individuals and 17.4%), Adalia conglomerata (594 individuals and 16.3%) and Anatis ocellata (279 individuals and 7.7%). The assemblages of lady beetles differed among the areas and also between the years. The season revealed neglegible effect on distribution of lady beetles, whereas the effect of altitude was more pronounced. A. conglomerata preferred the areas at lower altitude (600–725 m) to those at middle (900–925 m) and/or upper altitude (1,250–1,300 m). In contrast, A. obliterata and C. septempuctata were most abundant in the area at middle altitude. The altitudinal location of area partly explained the variability in abundance of lady beetles. The first ordination axis constructed by means of correspondence analysis (CA) represented an altitudinal gradient and accounted for 19.4% of the total variance of the species data. The great proportion of lady beetle species not typically associated with spruce and/or other coniferous trees than spruce (70.6%, n = 17) may be explained by an ecotonal effect.

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.

Selective sweep of Wolbachia and parthenogenetic host genomes – the example of the weevil Eusomus ovulum

Most parthenogenetic weevil species are postulated to have originated via hybridization, but Wolbachia has also been speculated to play a role via the induction of parthenogenesis. Here, we examine the molecular diversity of Wolbachia and parthenogenetic host genomes. The host species studied here, Eusomus ovulum, is known to be exclusively parthenogenetic and triploid. The E. ovulum populations that we examined had a low genetic diversity of mitochondrial (cytochrome oxidase I gene) and nuclear markers (internal transcribed spacer 2 and elongation factor 1‐α gene), and they all were infected by only single bacteria strains (genotyped for five genes according to the multilocus sequence typing system). We found significant signs of linkage disequilibrium and a lack of recombination amongst all of the examined genomes (bacteria and host), which strongly indicates a selective sweep. The lack of heterozygosity in host nuclear genes, missing bisexual populations and selective sweep between the parthenogenetic host and bacteria genomes suggest that parthenogenesis in this species could have originated as a result of infection rather than hybridization. However, the finding that highly similar Wolbachia strains are also present in other parthenogenetic weevils from the same habitat suggests the opposite scenario: bacteria may have infected the already parthenogenetic lineage and taken advantage of the hosts unisexual reproduction.

ATTRACTTION OF BARK BEETLES (COLEOPTERA: SCOLYTIDAE) TO NORWAY SPRUCE IN TIMBERLINE FOREST IN TATRA MOUNTAINS, WEST CARPATHIANS

Attracttion of bark beetles (Coleoptera: Scolytidae) to Norway spruce in timberline forest in Tatra Mountains, West Carpathians Attraction of bark beetles (Coleoptera: Scolytidae) to Norway spruce was studied in the timberline forest in Tatra Mountains, West Carpathians, Central Europe, by trapping bark beetles in flight interception traps fixed to the lower parts of the 18 trunks of spruce trees, and by recording colonizations of bark beetles on those trees in 2004. The trees were devoid of needles in the upper crown (1/4 up to 1/3 of the tree top dead) and were growing in three distant sample plots. Each plot was representing three different situations (biotopes) in the timberline spruce forest - forest, forest line and tree line, in altitudes between 1,280-1,560 m. A total of 18 traps yielded a total of 5,015 individuals and 19 bark beetle species associated with spruce, the five of which, Phtorophloeus spinulosus, Xyloterus lineatus, Pityophthorus pityographus, Pityogenes chalcographus, Ips typographus, were also documented to be developing in the the studied trees. Traps in the forest line yielded more individuals of bark beetles (all species considered together) than those in the forest and the tree line, although this was not significant (P>0.05, K-W Anova). The bark beetle assemblages showed very low dissimilarity in their structure between the forest and forest line, however, the assemblages in these two situations, aparently, differed from the assemblage in the tree line. Over the period 2004 - 2008 three (16.7%) of the 18 studied trees died. All documented cases of the tree mortality were associated with colonization by I. typographus. Atraktivita smreka pre podkôrnikovité chrobáky (Coleoptera: Scolytidae) na hornej hranici lesa v Tatrách, Západné Karpaty Príspevok sumarizuje výsledky výskumu atraktivity 18 chradnúcich dospelých jedincov smreka (Picea abies) pre podkôrnikovité chrobáky (Coleoptera: Scolytidae) v oblasti hornej hranice lesa v Tatrách v roku 2004 a zároveň hodnotí prežívanie týchto smrekov v rokoch 2004-2008. Do chemicky nevnadených nárazových lapačov umiestnených na kmeňoch predmetných smrekov bolo odchytených spolu 5 015 jedincov a 19 druhov podkôrnikovitých vývinom viazaných na smrek. Najviac jedincov podkôrnikovitých (všetky druhy hodnotené spolu) bolo získaných z lapačov na smrekoch rastúcich na hranici, resp. v okraji súvislého smrekového lesa, menej z lapačov v smrekovom lese pod touto hranicou a najmenej z lapačov v oblasti jednotlivého výskytu smreka v pásme vysokohorských lúk a kosodreviny. Dva sledované jedince smreka odumreli v roku 2004, jeden jedinec odumrel v roku 2007. Všetky tri prípady odumretia smreka (16,7 %, n = 18) súviseli s úspešnou kolonizáciou smrekov lykožrútom smrekovým.

Arthropods in the nests of the Common Kestrel (Falco tinnunculus)

Arthropods in the nests of the Common Kestrel (Falco tinnunculus) In 2008 we analyzed nest material from 25 nests of the Common Kestrel nesting in the residential and rural areas of Bratislava. 4486 arthropod individuals were determined, belonging to the orders Coleoptera, Mesostigmata, Prostigmata, Astigmata, Oribatida, Diptera and Siphonaptera. The arthropod fauna in the nests of the Common Kestrel can be classified into 4 groups: mites, dipteran larvae, adult beetles and dipterans. Three families of avian ectoparasites were present, comprising 26% of the total arthropod abundance. The remaining 74% of arthropod abundance in the nests comprised coprophagous and nidicolous species. Článkonožce v hniezdach sokola myšiara (Falco tinnunculus) Počas roku 2008 sme analyzovali hniezdny materiál z 25 hniezd sokola myšiara hniezdiaceho v intraviláne a extraviláne Bratislavy. Determinovaných bolo 4486 jedincov článkonožcov z radov Coleoptera, Mesostigmata, Prostigmata, Astigmata, Oribatida, Diptera a Siphonaptera. Faunu článkonožcov v hniezdach sokola myšiara môžeme rozdeliť na 4 skupiny: roztoče, larvy dvojkrídlovcov, imága chrobákov a dvojkrídlovcov. Ektoparazity vtákov boli zastúpené 3 čeľaďami a predstavujú 26 % abundancie článkonožcov v hniezdach, zvyšných 74 % tvoria koprofágne a nidikolné druhy.

Caterpillar (Lepidoptera) communities on European Turkey oak (Quercus cerris) in Malé Karpaty Mts (SW Slovakia)

Between 2000–2002, the structure of communities of lepidopteran larvae was studied in leaf bearing crowns of Quercus cerris in the central and northern part of the Malé Karpaty Mts (SW Slovakia). Caterpillars were collected using the beating method in four study plots. In total, 58 species were found. The families Geometridae, Noctuidae and Tortricidae comprised the highest number of species found. The family Geometridae comprised the highest number of pests. The most abundant species for individual plots were Lymantria dispar, Operophtera brumata, Ypsolopha alpella and Cyclophora ruficiliaria. Most of the recorded species belonged to the trophic group of generalists (39 species). Shannon-Wiener’s diversity index and Pielou’s equitability (evenness) value indicated there were marked differences between the Horný háj study plot (an insular forest with ants as the predators of caterpillars) and other plots. The main ecological gradient along DCA-1 related to the host specificity of caterpillars and consisted of three groups: (a) polyphagous species; (b) specialist species feeding chiefly on oaks or exclusively on oaks and (c) species preferring some oak species, mainly Q. cerris. The fragmentation of growth was identified along DCA-2.