Action of the nematophagous fungusPochonia chlamydosporiaonDioctophyma renaleeggs

Abstract

The ovicidal action of the nematophagous fungus Pochonia chlamydosporia (VC4) was evaluated on Dioctophyma renale eggs under laboratory conditions (Assay A). Next, the enzymatic action of proteases and chitinases produced by P. chlamydosporia (VC4) was evaluated on D. renale eggs, under laboratory conditions (Assay B). At the end of the experiment, there was difference (p < 0.01) in the destruction of eggs in the four concentrations tested in relation to control group at each interval studied. On the other hand, no difference was observed (p > 0.01) among the concentrations in the destruction of eggs. However, there was a trend of increasing mortality with increased concentration. Then (Assay B), it was observed that in the 24-hour interval, the proteases and chitinases of P. chlamydosporia (VC4), either individually or together, caused a significant percentage reduction (p < 0.01) on the number of viable eggs of D. renale, compared to control, with the following reduction values: 27.8% (proteases), 29.4% (chitinases) and 43.4% (proteases + chitinases). Thus, the constant search for alternatives that may help combat the various infectious forms (or eggs and larvae) of potentially zoonotic nematodes is important, as in the use of fungi destroyers of eggs. Therefore, it is suggested that the application of P. chlamydosporia would be an approach in the biological control of nematodes.

Predacious Strategies of Nematophagous Fungi as Bio-Control Agents

“…The shells of nematode eggs contain high levels of chitin and proteins, which are hydrolyzed by endochitinases and exochitinases, catalyzing the glycosidic bonds between chitin N-acetylglucosamine groups [21]. The nematode-trapping fungus M. thaumasium produces chitinases and exhibits nematicidal activity against the nematode Panagrellus redivivus [103]. Furthermore, chitinases have demonstrated nematicidal activity when used without the presence of fungi [104].…”