The trapping fungus Dactylaria Brochopaga: induction of trap formation, attraction, trapping and the development in some phytonematodes

Abstract

All the six species of the phytonematodes induced traps directly on the spores of all the five isolates of Dactylaria brochopaga. The maximum rings induction was observed in the presence of second-stage juveniles of Meloidogyne incognita followed by Meloidogyne graminicola (J2), Xiphinema basiri, Helicotylenchus dihystera, Tylenchorynchus brassicae and Hoplolaimus indicus. Maximum number of induced traps was recorded at temperature 28°C (98.3%) and pH 7 (96.7%) in the presence of H. indicus. In attraction assay, irrespective of the isolates of the fungus, all the six phytonematodes were attracted towards the fungal discs of the different isolates of D. brochopaga. Among all the five isolates, Isolate D attracted maximum (34.7%) number of nematodes closely followed by Isolate C (31.0%), whereas, Isolate A, B and E did not differ significantly. Maximum in vitro trapping was recorded in the case of M. incognita (J2) followed by M. graminicola (J2), H. dihystera and T. brassicae. The maximum ringing (pre-capturing), trapping and killing was recorded for the second-stage juveniles of M. incognita followed by M. graminicola, T. brassicae and H. dihystera. The inflation of ring cells did not occur immediately after ringing; however, the time between ringing and inflation varied with different nematodes species. Clear hyphae were observed in the invaded nematodes body after the content of nematode body was consumed. External growth of hyphae occurred only from the inflated cells of the constricting rings, which further developed several rings. Higher number of rings was observed in mycelia developed from bigger nematodes.