Biodiversity of Nematode Antagonistic Fungi under Vegetation of Province Khulais, Western of Saudi Arabia Kingdom

Abstract

The diversity and community structure of nematode trapping fungi (NTF) were investigated in thirteen sites located in province of Khulais, western of Kingdom of Saudi Arabia with different vegetation. NTF were isolated by using sprinkle technique. The soil pH value, soil texture and organic matters percentages of each soil sample were analyzed to investigate the relationship between these environmental factors and the occurrence of nematode trapping and parasitic fungi. Three species of nematode antagonistic fungi genera were found and identified in this study. The Hyphomycetes fungus Dactylaria brochopaga Drechsier, was isolated from 9 sites by rate 69.2% from total collected sites. The fungus was found naturally trapping of second stage juveniles (J₂s) for 3 nematode orders distributed between 6 plant species in soil samples containing organic matters more than 1.5%. The occurrence of D. brochopaga Drechsier was reduced when amount of organic matter in soil samples was less than 1%. The optimal pH value for growth of D. brochopaga Drechsier in natural habitat was ranged from 6.5 to 7.1 in sandy loamy soil texture. In addition, two species of the Chytridiomycetous fungi Catenaria were observed in 11 sites by rate 84.6% of total sites. One of them was identified as C. anguillulae Sorokin, which found parasitized on nematode body causing the breakdown of the nematode cuticle in 8 sites with different plants. While, the  another specie was identified as C. auxiliaris (Kühn) Tribe, which cause destroying nematode egg in 6 sites by rate 46.15% from total sites. The suitable pH value for the two species of Chytridiomycetous fungi was ranged from 7.0 to 8.0. C. auxiliaries (Kühn) Tribe was found in 3 soil types. While the fungus C. anguillulae Sorokin was found in 2 soil types.  On the other hand, the organic matters haven’t any effects on the growth of C. auxiliaries (Kühn) Tribe or the ability of parasitism, but they have a great effect on C. anguillulae Sorokin. The present study is considered as preliminary survey on nematode trapping fungi for the first time in province of Khulais and second study on predacious fungi in Saudi Arabian soils.

Key word: Ecology, Nematode, trapping fungi, Dactylaria, Catenaria