Effects of Certain Solutes, Osmotic Potential, and Soil Solutions on Parasitism ofCriconemella xenoplaxbyHirsutella rhossiliensis

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Abstract
Adult C. xenoplax nematodes were inoculated with spores of the fungus, H. rhossiliensis, and incubated for 5 days in distilled water or in solutions adjusted to osmotic potentials of -0.3, -3 or -6 bars with KCl. Almost all nematodes in KCl solutions became infected; those in distilled water did not. The effect of KCl was not due to the osmotic potential of the incubation solution because little or no infection occurred in solutions adjusted to -0.3, -3 or -6 bars with sucrose or polyethylene glycol 8000. All inoculated nematodes incubated in solutions adjusted to -6 bars with KCl, KNO3, KH2PO4, CaCl2, Ca(NO3)2 and MgCl2 became infected: much less infection occurred in solutions containing either Na+ or SO4-2 (NaCl, NaNO3, Na2SO4, K2SO4, and MgSO4). Infection in extracts of saturated soil from 5 [peach] orchards was correlated with salt concentration as measured by electrical conductivity. Concentration or dilution of the soil extracts increased or decreased infection, respectively. Parasitism of C. xenoplax by H. rhossiliensis is greatly influenced by the kind and concentration of ionic solutes in the ambient solution.