Assessment of in vitro growth and predation of Arthrobotrys oligospora to Haemonchus contortus under the influence of media type and age of mycelium

Corn meal agar followed by potato dextrose agar was found the best medium for supporting in vitro growth of Chhattisgarh isolate of Arthrobotrys oligospora. Media type clearly affected the ring structure and trophic hyphal development, though attachment of Haemonchus contortus larvae to adhesive hyphae of A. oligospora was not affected. Initially a part of active thirds stage larvae of H. contortus was attached to hyphae within a period of 4 days in all media types except in nutrient agar at 26°C. However, the capture and immobility of the infective larvae were very sluggish. Growth, capture and development of trophic hyphae inside the H. contortus larval body in water agar indicated that development of trapping devices increased when few energy sources are available. Age of mycelium of A. oligospora isolate had significant influence on deployment of all the trapping structures, where maximum predatory effect was found in one month-old fungal mycelium. In colonies in which nematodes mainly encountered aged hyphae, significant reduction in attachment, capture and development of trophic hyphae was found.