The influence of environmental factors on the respiration of plant parasitic nematodes
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Respiration of selected nematode species was measured relative to CO₂ level, temperature, osmotic pressure, humidity, glucose utilization and high ionic concentrations of sodium and potassium. In general, respiration was stimulated most by the dominant environmental factors at levels near those expected in the nematode's "natural" habitat. Soil-inhabiting nematodes utilized O₂, most rapidly with high (1-2%) CO₂ whereas a foliar nematode (Aphelenchoides ritzemabosi) did so with 0.03% CO₂, the concentration typically found in air. Temperature optima for respiration corresponded closely to those for other activities. Ditylenchus dipsaci and Pratylenchus penetrans adults and Anguina tritici and A. agrostis second-stage larvae respired within the range of osmotic pressures from 0 to 44.8 arm and respiration of their drought-resistant stages was stimulated by increasing osmotic pressure which accompanies the onset of drought. Rehydration of A. tritici and A. agrostis larvae with RH as low as 5% stimulated measurable respiration. Glucose utilization from liquid medium by A. tritici larvae or A. ritzembosi was not detectable. Supplemental Na⁺ stimulated respiration of Anguina tritici, K⁺ did not.