Effect of saprotrophic soil fungi <i>Penicillium frequentans</i> and <i>Stachybotrys chartarum</i> on respiratory metabolism of <i>Ascaris suum</i>, during its embryogenesis was determined using histoenzymatic methods. Based on histochemical assessment of the enzyme actvity (glycolysis-lactate dehydrogenase-LDH; tricarboxylic acid cycle-succinate dehydrogenase-SDH) changes in the energy metabolism of developing eggs of <i>A. suvm</i> were detected. Of the fungi species tested - <i>P. frequentans</i> caused the most extensive disorders in the processes of cellular oxidation, which were manifested in a decline of SDH activity during gastrulation. Incubation of eggs of Ascaris with mycelia of both fungi: <i>S. chartarum</i> and <i>P. frequentans</i> - in lesser extend affected respiratory metabolism in embryogenesis of this nematode.

The spectrum and occurrence of entomopathogenic fungi in litter beech forest. meadow soil and arable soil were evaluated using an "insect bait method". Soil and litter samples taken in autumn and spring from each stand were baited with <i>G. mellonella</i> larvae at 22°C. Six species of entomopathogenic fungi infected these larvae. In the litter <i>Beauveria bassiana</i> was the dominant species. Besides <i>B. bassiana</i>, 23% of <i>G. mellonella</i> larvae were infected by <i>Paecilomyces farinosus</i> in autumn. In the forest soil the dominant entomopathogenic fungus was not found. In this stand the number of infected larvae was the lowest. <i>Metarhizium anisopliae</i> was the dominant species in the meadow soil in both sampling periods. In the soil taken from a rye field<i> P. fumosoroseus</i> and <i>B. bassiana</i> infected <i>G. mellonella</i> larvae almost to the same degree. It was established that <i>B. bassiana</i> and <i>M. anisopliae</i> infected more <i>G. mellonella</i> larvae in spring than in autumn. In the case of <i>P. farinosus</i> and <i>P. fumosoroseus</i> an opposite tendency was observed.

The studies focused on the effect of 1-ppm ochratoxin A solution on the activity of some enzymes during successive embryogenesis stages ofAscaris suum. As a result of OTA-affected incubation ofA suum eggs, inhibition of AcP reactions was observed throughout the embryonic development, reduction in of SDH and LDH activity during cleavage and gastrulation, and enhancement of the SDH and LDH activity was found in larvae. Moreover, inhibition of the processes of cleavage, gastrulation and organogenesis was recorded. The observed morphological and metabolic embryo disorders demonstrated teratogenic properties of the studied mycotoxin, and the presence of granules of various sizes in the developing eggs may indicate that OTA penetrated into the eggs.

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