INFLUENCE OF BACTERIAL TYPE AND DENSITY ON POPULATION-GROWTH OF BACTERIAL-FEEDING NEMATODES

The contribution of bacterial-feeding nematodes to litter decompositio n and nutrient mineralization depends, in part, on the abundance of pa rticular nematode species Population dynamics will be constrained by e daphic factors, food availability and food quality. We report the popu lation growth rates for six nematode species as affected by different bacterial isolates and by changes in food supply. Populations of Caeno rhabditis elegans grew faster than any other nematode-bacterium combin ation when Bacillus polymyxa was supplied as food (lambda = 12.26 d(-1 )). Caenorhabditis elegans also exhibited the greatest variation in po pulation growth rate across the set of bacteria investigated. Acrobelo ides bolenheimeri, A. buetschlii, Bursilla labiata, C. elegans, Cephal obus persegnis, and Rhabditis cucumeris did not develop or reproduce w hen fed Streptomyces halstedii scabies. Within the range of food conce ntrations considered, the six nematode species approached their respec tive maximal population growth rate between 10(4) and 10(5) colony for ming-units (CFUs) per nematode. Populations stopped growing when food concentrations declined to 10(3)-10(4) CFUs per nematode. Between 10(3 ) and 10(6) CFUs per nematode, variation in population growth rate due to changes in food supply was greatest for C. elegans and was least f or A. buetschlii. (C) 1998 Elsevier Science Ltd. All rights reserved.