10 Pages

Adult longevity – A factor stabilizing the abundance of a Laemostenus schreibersi population (Coleoptera, Carabidae)

WithEvelyn Rusdea

A population of the microphthalmic carabid Laemostenus schreibersi (Küster 1846) was studied in a cave near Yillach in Carinthia/Austria during 15 seasons of investigation between 1986 and 1995. The beetles were trapped in pitfalls, individually marked and released in the cave near the trapping site. The following aspects of population structure and dynamics are investigated: seasonal and spatial distribution of the beetles in the cave, patterns of movement between the different cave-compartments and between the cave and the surrounding fissure-system, seasonality of breeeding and development, reproduction rate, mortality, age-structure, sex-ratio and population size. Obviously, in some seasons all individuals living inside the explored cave-compartments were marked. The size of the population was small, but rather constant (50 – 100 individuals). Some beetles attained the remarkable age of 7.5 and >8 years. Longevity of the individuals is discussed as one factor stabilizing population size. Measurements of climatic parameters complemented the biological investigations.