The main aim of this study was to investigate and compare the patterns of male courtship behaviour in Hipparchia fagi (Woodland Grayling) and H. hermione genava (Rock Grayling) in order to determine ...if premating barriers are involved in the reproductive isolation between the two sympatric and syntopic species.Although they show a similar pattern of sexual behaviour (perching, flight pursuit, courtship), there were significant quantitative inter-specific differences in the step Bowing. During this step, the male bashes and strokes the female antennae between his forewings on the androconial scales revealing the importance of scent stimuli in mate communication. Moreover, different signals, spanning several sensory modalities (visual, chemical, tactile stimuli) and spatio-temporal scales (during the pair flight and the courtship step), might serve as premating barriers between the two species. In particular, both males and females of H. fagi (a woodland habitat specialist) seem to take less time in recognising their conspecific partner, while H. hermione males need to spend more time in courting (and identifying) the “right” females.
Fungal endophyte assemblages in leaves of Japanese beech (
Fagus crenata
Blume) trees were investigated in pure beech stands at four localities with different summer temperatures covering the natural ...distribution range of the species.
Ascochyta fagi
Woronich was dominant at every site, and the infection density (ID) of this fungus was higher at sites with low maximum air temperatures. The growth rate of A. fagi on potato dextrose agar was inhibited by temperatures above 30 °C. These results suggest that the population density of A. fagi on Japanese beech leaves is influenced by summer temperatures. However, the number of species and Shannon index of diversity (H′) of endophytic fungi increased with increasing air temperature and a negative correlation was observed between the ID of A. fagi and the diversity of other endophytes. The species composition of minor endophytes was site-specific and may reflect geographic and genetic distances between beech stands.
The conspicuous icneumonid fly Stauropoctonus bombycivorus (Gravenhorst, 1829) is recorded for the first time in Norway. Four specimens have been captured in light-traps at three different localities ...in 2007: Hvaler in Oestfold (Oe) and Arendal in Aust Agder (AAY), respectively. The biology and distribution are briefly discussed.
Using the Swiss Canopy Crane CO
2 enrichment facility, the beech weevil's host choice in a CO
2-enriched atmosphere and the
in situ effect of its infestation on the chemistry of host leaves were ...investigated. The fraction of infested leaves was larger on CO
2-enriched trees, suggesting that weevil impact on beech may increase as atmospheric CO
2 concentration keeps rising. Egg insertion in the central leaf vein partially interrupts phloem and xylem transport. Because of this separation between the source of photosynthates, the leaf tip, and the rest of the plant, the leaf tip becomes enriched in non-structural carbohydrates and depleted in nitrogen. Elevated CO
2 slightly enhanced non-structural carbohydrates in uninfested leaves, but exerted no further increase in infested leaf part, suggesting a saturation effect.
Mit Hilfe der, Swiss Canopy Crane’ CO
2-Anreicherungsanlage haben wir
in situ die Präferenzen der Buchenspringrüssler bei der Wahl ihrer Wirtsbäume nach CO
2-Exposition und den Einfluss ihres Befalls auf die Chemie von Buchenblättern untersucht. An CO
2-behandelten Bäumen war der Befall höher als an Kontrollbäumen. Mit ansteigender atmosphärischer CO
2-Konzentration könnte sich daher die Schadwirkung des Buchenspringrüsslers auf die Rotbuche verstärken.
Die Eiablage in der Hauptblattader hat zur Folge, dass Phloem- und Xylemtransport teilweise unterbrochen werden. Diese Unterbrechung zwischen einer Assimilatquelle, der Blattspitze, und dem Rest der Pflanze, führt zu einer Anreicherung nicht-strukturgebundener Kohlenhydrate (NSC) und einer Abnahme der Stickstoff Konzentration in der Blattspitze. Die NSC-Konzentration in nicht befallenen, CO
2-behandelten Blättern zeigte zwar eine leichte Zunahme, stieg aber in den befallenen, CO
2 behandelte Blattspitzen nicht weiter an, was auf einen Sättigungseffekt hindeutet.
Aphids are characterized by a specific morphology and show a high biotic potential. Most species have been described from the temperate regions of the world. The purpose of the present research was ...to investigate the biology, population dynamics and harmfulness of Phyllaphis fagi (L.) (Hemiptera: Aphididae: Phyllaphidinae) on Fagus sylvatica (L.) and its two varieties ‘Pendula’ and ‘Atropunicea’. Demographic parameters of this aphid were tested in field conditions. Trees as isolated elements of greenery in the urban environment were taken into the consideration. The highest density of overwintering eggs was observed in the bark crevices of forking shoots. The shortest prereproduction and reproduction periods and the highest fertility was exhibited in the second generation of aphids. Pre-reproduction and reproduction periods of successive aphids’ generations were extended while females’ fertility was reduced. Despite of varied number of aphids on F. sylvatica and its two varieties, no significant differences were stated. Feeding aphids caused leaves’ curling downwards on both sides of the mid-rib. Clear damage was visible even during the presence of few individuals on the leaf. Decorative values of trees were reduced as early as in June.
Pityogenes irkutensis irkutensis Eggers, 1910, Trypophloeus dejevi (Stark, 1936), Carphoborus cholodkovskyi Spessivtsev, 1916 and Cyclorhipidion bodoanus (Reitter, 1913) are added to the Norwegian ...part of the Palaearctic list. Ips amitinus (Eichhoff, 1872) should be listed as intercepted to Norway, since it is recorded in imported timber but not documented as established in Norway. Seven species are deleted from the Norwegian part of the Palaearctic list of bark beetles: Hylastes ater (Paykull, 1800), Hylurgus ligniperda (Fabricius, 1787), Phloeotribus rhododactylus (Marsham, 1802), Ernoporicus fagi (Fabricius, 1798), Pityogenes saalasi Eggers, 1914, Scolytus mali (Bechstein & Scharfenberg, 1805) and Scolytus multistricitus (Marsham, 1802). The conclusion of the presented work is that the number of established, outdoor-living bark beetle species documented from Norway is 71. Ips amitinus (Eichhoff, 1872) is not included in this number since it is not documented as established in Norway.
Using the Swiss Canopy Crane CO2 enrichment facility, the beech weevil's host choice in a CO2-enriched atmosphere and the in situ effect of its infestation on the chemistry of host leaves were ...investigated. The fraction of infested leaves was larger on CO2-enriched trees, suggesting that weevil impact on beech may increase as atmospheric CO2 concentration keeps rising. Egg sertion in the central leaf vein partially interrupts phloem and xylem transport. Because of this separation between the source of photosynthates, the leaf tip, and the rest of the plant, the leaf tip becomes enriched in non-structural carbohydrates and depleted in nitrogen. Elevated CO2 slightly enhanced non-structural carbohydrates in uninfested leaves, but exerted no further increase in infested leaf part, suggesting a saturation effect.Original Abstract: Mit Hilfe der, Swiss Canopy Crane' CO2-Anreicherungsanlage haben wir in situ die Praeferenzen der Buchenspringruessler bei der Wahl ihrer Wirtsbaeume nach CO2-Exposition und den Einfluss ihres Befalls auf die Chemie von Buchenblaettern untersucht. An CO2-behandelten Baeumen war der Befall hoeher als an Kontrollbaeumen. Mit ansteigender atmosphaerischer CO2-Konzentration koennte sich daher die Schadwirkung des Buchenspringruesslers auf die Rotbuche verstaerken. Die Eiablage in der Hauptblattader hat zur Folge, dass Phloem- und Xylemtransport teilweise unterbrochen werden. Diese Unterbrechung zwischen einer Assimilatquelle, der Blattspitze, und dem Rest der Pflanze, fuehrt zu einer Anreicherung nicht-strukturgebundener Kohlenhydrate (NSC) und einer Abnahme der Stickstoff Konzentration in der Blattspitze. Die NSC-Konzentration in nicht befallenen, CO2-behandelten Blaettern zeigte zwar eine leichte Zunahme, stieg aber in den befallenen, CO2 behandelte Blattspitzen nicht weiter an, was auf einen Saettigungseffekt hindeutet.
Quantitative behavioural traits associated with egg-laying, such as the level of selectivity for host-supports and the size of egg clutches, are generally thought to be of great importance for the ...subsequent survival and development of offspring. These quantitative traits, however, are often difficult to assess reliably by direct observation in the field. This is particularly the case when the insects are very tiny, which is the case for most galling and leaf mining insects. However, a new approach, the "Melba" procedure, allows the indirect inference of these quantitative traits, using easily recorded field-data only. Application of this diagnostic procedure to a large series of samples of beech leaves (Fagus silvatica), harbouring either a leaf miner, Phyllonorycter maestingella (Lepidoptera: Gracillariidae) or one or the other of two galling insects, Mikiola fagi or Hartigiola annulipes (Diptera: Cecidomyiidae) indicates that the leaf miner differs significantly from the two species of galling insect in term of combined values of host-acceptance ratio and average clutch-size, while the two gall-inducing species remain substantially undistinguishable from each other according to these traits. Thus, the galling insects (i) show stronger selectivity for a host than does the miner at any given average clutch-size and (ii) show larger average clutch-size at any given level of selectivity. That is, for at least these three species, the galling insects show a greater level of selectivity when choosing leaves to oviposit on but, then, tend to lay larger egg-clutches. These differences may be due (i) to the gall-inducing process requiring far more of leaf tissues than being simply palatable, which makes it likely that galling species will be more selective in their choice of leaves than leaf miners and (ii) to the capacity of galls to become nutrient sinks, which may help explain why the galling insects laid larger egg clutches. However, whether these trends can be regarded as general rather specific to this particular case, depends on the outcome of future studies on other groups of insects with similar life histories. PUBLICATION ABSTRACT