Catenaria anguillulae as an efficient biological control agent of Anguina tritici in vitro

During the course of our investigation on the selective isolation and pathogenicity tests of Catenaria anguillulae against plant parasitic nematodes, actively motile second stage juveniles (J(2)s) of Anguina tritici obtained from wheat galls collected from Leh, Kashmir, India were found to be severely infected by zoospores of this fungus. The motile J(2)s of A. tritici suffered nearly 82% mortality at 31 +/- 1 degrees C after 24 h of exposure while the mortality decreased to 77% at 20 +/- 1 degrees C on the 6th day. Pathogenicity trial of 13 isolates of C. anguillulae against the motile J(2)s revealed that this nematode is highly susceptible to infection. Comparative susceptibility of the plant parasitic nematodes to C. anguillulae further revealed that the fungus is more virulent to A. tritici than the other nematodes. These findings firmly established that the C. anguillulae is a highly virulent biological control agent of A. tritici which resolved the controversial issue about its virulence against a nematode belonging to order Tylenchida. Motile and non-motile J(2)s of A. tritici are equally good for the selective isolation of C. anguillulae. However, larger sporangia are produced in the motile J(2)s, hence, motile J(2)s should be preferred over the non-motile ones. Observations of the developmental stages of C. anguillulae in living J(2)s of A. tritici revealed that the development from zoospore colonization to release of zoospores from mature sporangia was completed in 22-24 h at 31 +/- 1 degrees C, whereas, at 20 +/- 1 degrees C the developmental stages were greatly delayed requiring 72-75 h for zoospore liberation. Pathogenicity and development of C. anguillulae in living J(2)s of A. tritici also proved that the fungus is a wonderful experimental tool which can be used as an example of excellent biological control in the class room. (C) 2012 Elsevier Inc. All rights reserved.