Growth, reproduction and longevity in nematodes from sewage treatment plants

Abstract

The growth, reproduction and longevity of Diplogasteritus nudicapitatus, Paroigolaimella bernensis and Rhabditis curvicaudata were investigated under conditions of excess food within the temperature range 5°C-20°C. In all three species growth rate increased with temperature, and in D. nudicapitatus and R. curvicaudata the adult size attained varied significantly with temperature. P. bernensis did not reproduce at 5°C, but showed a progressive increase in reproductive output at higher temperatures. D. nudicaitatus showed increased egg production as temperature increased while R. curvicaudata had maximum egg output at 10°C. Longevity is temperature dependent, decreasing with higher temperatures. Virgin females survived for longer than reproducing females. The data indicate that while D. nudicapitatus and P. bernensis are thermophilic species, R. curvicaudata is adapted to lower temperatures.

Temperature Dependent Reproduction and Survival of the Soil Nematode Pristionchus maupasi In Vitro

“…Estimates of a generation time (T min ) for P. maupasi are of the same magnitude as for a range of other free-living nematodes, including its close relative P. pacificus [6]. In accordance with results on nematodes from sewage treatment plants [7], the life-span of P. maupasi decreased with increasing temperature, except when P. maupasi became 2 nd generation "dauerlarvae". In this arrested condition P. maupasi obviously survives unfavourable conditions longer, also at relatively high temperatures such as 20 o C. Arrestment may be a result of crowding in combination with reduced food supplies and increased concentration of wastes.…”

The temporal and spatial distribution of nematodes in percolating filters

“…At both sites two peaks in nematode density in the annual cycle were apparent; one in May and a second during the winter months. Lowest numbers corresponded with periods of highest temperatures, which is contrary to predictions based on laboratory studies of growth rates and reproduction (Woombs & Laybourn-Parry, 1984a;1985). The surface bacterial film, however, sloughs off during the spring months and is maintained at a low level during the summer months.…”

“…Their presence in sewage treatment processes was noted as early as 1918 by Cobb and in 1923 by Hausman. Despite the abundance of these organisms in a whole variety of habitats, both natural and man-made, we still know relatively little about their ecology and physiological functioning. We have some information on the ecological energetics of nematodes (Soyza, 1973;Marchant & Nicholas, 1974;Duncan et al, 1974;Laybourn, 1979;Woombs & Laybourn-Parry, 1984a, b, 1985, but only a few of these studies attempt to relate to field conditions, such as temperature and food availability. The majority of freeliving species appear to be bacterivores, and studies on soil microcosms indicate that the presence of bacterial grazers, such as nematodes or amoebae, has the effect of increasing the rate of nutrient cycling (Coleman et al, 1977).…”

Life History Covariation in Intestinal Nematodes of Mammals

“…Intraspecific studies have shown that there are positive correlations between developmental time, size and fecundity in invertebrates and poikilothermic vertebrates (Sibly and Calow 1986) and similar patterns have been described in populations of free-living nematodes (Schiemer 1982a,b, 1983, Woombs and Laybourn-Parry 1984. Measuring individual variation in these traits is notoriously difficult in parasitic nematodes.…”