Nest Architecture, Colony Productivity, and Duration of Immature Stages in a Social Wasp, Mischocyttarus consimilis

This study examined the nest architecture, colony productivity, and duration of the immature stages of the social wasp Mischocyttarus consimilis Zikáán (Hymenoptera: Vespidae). The study was carried out under field conditions. Nests of M. consimilis consist of a single uncovered comb, which is attached to the substratum by a single petiole. The data for the nest architecture showed a positive and significant correlation between the size of the comb and the diameter of the petiole, and also between the height and diameter of the cells. The nests were constructed on horizontal, vertical, and sloping substrata with no apparent preference for a specific orientation. The colonies produced 72.9 cells and 40.7 adults on average. The mean frequency of productive cells was 33.3%, and 19.4% of the cells were reused. The mean duration of the immature stages combined was 69.7 days and the egg, larval, and pupal stages had mean durations of 14.9, 36.0, and 18.8 days, respectively. The duration of each immature stage was significantly shorter in the warmhumid season, and the larval and pupal stages were shorter during the colony pre-emergence stage

Vermeidung von Gaszutritten aus stillgelegten Grubenfeldern

Many mines were abandoned in the Ruhr district during the past decade. Methane is still released from abandoned mines, although the termination of forced ventilation and backfilling of shafts have largely prevented it, so that only barometric gas release will take place. This project started by identifying the relevant influencing factors of gas release from abandoned mines. Knowledge of residual gas volumes and cavity volumes is of prime importance. For an exemplary coal mine in the central Ruhr district, the remaining coal and gas volumes were estimated in order to calculate residual gas emissions. Gas flow underground and to the surface is governed by available flow paths and obstacles. For this reason, the flow resistance of dams, backfilled shafts and ventilation lines was measured, and fundamental studies on permeability of the top rock were carried out. The influence of technical pressure sinks (blowers, gas removal) on underground gas flow was investigated. Finally, gas flow in different conditions was simulated by model calculations. (orig.)Der aktive Steinkohlenbergbau im Ruhrrevier hat sich sowohl durch Zusammenfuehrung von einzelnen Bergwerken zu Verbundbergwerken als auch durch Anschlussbergwerke flaechenmaessig in noerdlicher Richtung weiter ausgedehnt. Zwangslaeufig folgte eine Zunahme stillgelegter Feldesteile, in denen auch nach Beendigung des Abbaus weiterhin eine Methanabgabe des Gebirges stattfindet. Durch das Beenden der technischen Zwangsbelueftung (=Bewetterung) und Verfuellen der Schaechte wird das kontrollierte Abstroemen des Gases zur Tagesoberflaeche allerdings weitgehend unterbunden. Zu Beginn des Vorhabens stand die Erkundung und Untersuchung der fuer die Ausgasung aus stillgelegten Bereichen relevanten Einflussgroessen im Mittelpunkt. Da nach der Schliessung von Bergwerken nur noch eine barometrische Ausgasung vorhanden ist, ist die Kenntis von Restgasmengen und Hohlraumvolumina von vorrangiger Bedeutung. Daher wurden beispielhaft fuer ein Bergwerk des mittleren Ruhrreviers die verbliebenen Kohlenmengen und Restgasinhalte abgeschaetzte und damit Restgasmengen berechnet. Fuer die Gasstroemung unter Tage und zur Tagesoberflaeche sind die vorhandenen Stroemungswege und -widerstaende von massgebender Bedeutung. Es wurden daher die Stroemungswiderstaende von Daemmen, verfuellten Schaechten und Entgasungsleitungen messtechnisch erfasst sowie grundlegende Betrachtungen zur Durchlaessigkeit des ueberlagernden Gebirges angestellt. Weiterhin wurde der Einfluss von technischen Drucksenken (Luefter, Gasabsaugung) auf die untertaegige Gasstroemung betrachtet. Schliesslich wurde versucht, mit Hilfe von Modellrechnungen fuer unterschiedliche Bedingungen die Gasstroeme zu simulieren. (orig.)SIGLEAvailable from TIB Hannover: RR 1344(147) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekMinisterium fuer Wirtschaft und Mittelstand, Technologie und Verkehr des Landes Nordrhein-Westfalen, Duesseldorf (Germany)DEGerman

Observations on the Natural History and Population Ecology of the Social Wasp Ropalidia marginata (Lep.) from Peninsular India (Hymenoptera: Vespidae)

Ropalidia marginata, the most common Indian social wasp, belongs to a crucial stage of social evolution showing no obvious morphological caste differentiation but a behavioural caste differentiation and a dominance hierarchy that appears to influence division of labour. The nests consist of a single open comb that can sometimes have up to 500 cells and 10 pedicels. Nests are initiated and abandoned all round the year. Initiation is by 1-20 foundresses, 1-4 being the most common number. There is a great deal of variation in brood developmental times both within and between nests. Male progeny disappear from the nest soon after emergence while daughters stay on at the parent nest for a mean period of about a month. Small nests have a single egg layer while large nests have two or more females with well developed ovaries that presumably lay eggs. Most nests are short-lived, small nests being highly susceptible to failure. Large nests are less susceptible to failure but the emergence of multiple egg layers reduces the average relatedness of workers to the brood which presumably is the cause for large scale emigrations from these nests. An interaction of ecological and soical factors therefore appears to determine the growth of a nest