Colony orientation and successful defence behaviour in the conifer aphid, Schizolachnus pineti

We studied colony structure and body orientation behaviour of Schizolachnus pineti, a specialised aphid feeding on needles of Scots pine. Aphids feeding at the margin of a colony always face towards the centre of the colony, bounding the colony with their legs. This behaviour increased the defence success aginst the specialised parasitoid (Pauesia unilachni) and the specialised predator (Scymnus nigrinus). Both enemies had less success when attacking S. pineti from the abdominal site when compared to the front. We assume that the defence orientation displayed by marginally feeding aphids has an adaptive nature and is particularly effective when feeding in a row on linear plant structures such as needles.     

Langzeit-Erfassung brutbiologischer Parameter beim KleiberSitta europaea in zwei norddeutschen Untersuchungsr?umen

Zusammenfassung Der Zusammenstellung liegen Befunde zu den brutbiologischen Parametern Gelegestärke, Schlüpftermin und Anzahl flügger Junge zugrunde, die von 1970–1995 an rund 1500 Erstbruten des Kleibers in Versuchsgebieten mit künstlichen Nisthöhlen bei Braunschweig und Essen gewonnen wurden. Die Vollgelege-Eizahl beträgt im Durchschnitt 6,8 Eier (nur Daten aus dem Braunschweiger Raum), der durchschnittliche Schlüpftermin fällt auf den 9. Mai (Braunschweig) und 6. Mai (Essen) und die Anzahl flügger Nestlinge liegt in erfolgreichen Bruten im Mittel bei 5,6 (Braunschweig) bzw. 5,2 (Essen). Im Untersuchungszeitraum kam es in beiden Gebietsregionen zu einer signifikanten Verfrühung des Bruttermins. Doch werden wohl erst die Befunde der kommenden Jahre zeigen können, ob die rezente Häufung früher Brutjahre beim Kleiber (diese Arbeit) und bei Kohl- und Blaumeisen (Winkel &Hudde unveröff.) bereits eine Folge des anthropogen bedingten global warming ist oder noch das normale Auf und Ab der Witterung widerspiegelt.

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Long-term changes of breeding parameters of NuthatchesSitta europaea in two study areas of northern Germany

Between 1970 and 1995, nestbox data about clutch size, hatching date and fledging success were collected for a total of around 1500 first broods of Nuthatches in two north German study areas (near Brunswick 52.16 N 10.32 E and near Essen 51.24 N 6.59 E). The average clutch size was 6.8 eggs (Brunswick), the average hatching date 9 May (Brunswick) and 6 May (Essen), and the mean number of fledglings per successful brood 5.6 (Brunswick) and 5.2 (Essen). Over time hatching dates significantly advanced in both areas. Data of further years are needed to clarify if the recent unusual sequence of early breeding years in the Nuthatch is already a consequence of the anthropogenic greenhouse effect or just due to normal variation of weather conditions.

     

Localization of α1-adrenoceptors in rat and human hearts by immunocytochemistry

The localization of the ai adrenoceptors (₁-AR) in the heart tissues from rat and human and in the cultured heart cells from neonatal rats was studied by indirect immunofluorescence and postembedding electronmicroscopical immuno-gold technique. With antipeptide antibodies directed against the second extracellular loop of the human ₁-AR (AS sequence 192–218), this receptor was found to be localized along the sarcolemma in both human and rat hearts. Similar localization sites were detected in cultivated rat neonatal cardiomyocytes. Beside the localization in cardiomyocytes, ₁-AR were identified in endothelial cells of capillaries and smooth muscle cells of coronary vessels, in neuronal endings, in mast cells of cultivated heart cells but not, or in less amount in fibroblasts. Interestingly, in the right atrium of rat heart the localization of ₁-AR was found to be near or on atrial natriuretic factor (ANF) granules, providing the basis for the -adrenergic influence on ANF release. The immunocytochemical studies further confirm and complete the findings known by using autoradiographic binding studies with specific ligands.     

Reduction of cardiac hypertrophy in TGR(mREN2)27 by angiotensin II receptor blockade

TGR(mREN2)27 is a transgenic rat harboring the murine Ren-2 gene and exhibit fulminant hypertension and marked heart hypertrophy. In order to study the role of angiotensin II in the increase of cardiac mass, these animals were treated with anti-hypertensive and non-antihypertensive doses of the angiotensin II receptor AT₁ antagonist Telmisartan for 9 weeks. All doses led to significant reductions of heart hypertrophy detected by the evaluation of the diameter of cardiac muscle bundles. We conclude from this study that cardiac hypertrophy in TGR(mREN2)27 is characterized by an increased volume of cardiomyocytes and an unchanged amount of fibrous tissue and that angiotensin II plays an important role in the mechanisms leading to this phenotype.     

Agglutinierte Foraminiferen aus Graptolithen-Schwarzschiefern des Llanvirnium (Ordovizium) von Plettenberg im Sauerland (Nordrhein-Westfalen,NW-Deutschland)

The Plettenberger Bänderschiefer (Ordovician, Lower Llanvirnian, Zone ofDidymograptus bifidus (Hcall) from the type locality at Plettenberg (Sauerland, NW-Germany) yielded a foraminiferal fauna consisting of primitive agglutinated species (Amphitremoida, Bathysiphon,?Raibosammina, ?Thekammina, Thurammina). Forming one of the stratigraphically oldest European foraminiferal assemblages, these taxa were washed out of an unconsolidated graptolite siltstone and represent a pelagic, oxygen-depleted environment.     

Behavioral strategies of aphid hyperparasitoids to escape aggression by honeydew-collecting ants

We analyzed the behavioral interactions between two species of honeydew-collecting ants (Lasius niger, Myrmica laevinodis) and foraging females of four species of aphid hyperparasitoids (Aphidencyrtus aphidivorus, Dendrocerus carpenteri, Pachyneuron aphidis, Asaphes vulgaris) usingAphis fabae ssp.cirsiiacanthoidis andLysiphlebus cardui on thistles as aphid and primary parasitoid, respectively. The observed interaction patterns and foraging parameters varied within hyperparasitoid species and revealed different strategies based upon behavioral and morphological constraints.D. carpenteri generally tried to avoid ant encounters. This avoidance strategy was successful in interactions withM. laevinodis but failed when encountering the more aggressiveL. niger, which caused about 26% adult mortality. In contrast,A. aphidivorus, P. aphidis, andA. vulgaris possess jumping ability and were hardly exposed to mortality risks. The escape reaction jump off was used as soon as ants made physical contact with foraging females. While the flight strategy ofP. aphidis is connected with cryptic movement patterns without avoidance behavior,A. aphidivorus first avoided ants and jumped off only as a last resort. Similar patterns, but less expressive, are displayed byA. vulgaris. We suggest that these different strategies are responsible for different foraging success in ant-attended resources in field.     

Development of insect resistance in tomato plants expressing the δ-endotoxin gene ofBacillus thuringiensis subsp.tenebrionis

A crystal -endotoxin gene ofBacillus thuringiensis subsp.tenebrionis (B.t.t.) encoding a coleopteran insect-specific toxin was used to construct a chimeric gene which expressed the toxin in plant cells. Via anAgrobacterium tumefaciens binary vector system, the toxin gene was transferred into tomato cells. From leaf disks recombinant plants were regenerated. Hybridization experiments demonstrated that these plants synthesized toxin-specific mRNA of the expected size. Transgenic tomato plants with the chimericB.t.t. toxin gene contained a 74 kDa protein which cross-reacted with toxin antibodies. The expression caused a significant insecticidal activity of the transgenic tomato plants against Colorado potato beetle larvae.