Chemistry Reference
In-Depth Information
5.4.6 Nematode-destroying Fungi
Nematode-destroying fungi are a group of microfungi that are natural enemies of
plant parasitic nematodes.
76,118
They comprise fungi which parasitise nematode
eggs and other life stages.
123
Although taxonomically diverse, this group of
microorganisms is capable of destroying, by predation or parasitism, microscopic
animals such as nematodes, rotifers and protozoans. Collectively, they have the
unique ability to capture and infect nematodes in the soil and appear to be
widespread in distribution.
76
The actual mechanisms by which the fungi are
attracted to the nematodes have not been fully understood. However, it is generally
accepted that the nematode cuticle is penetrated, then the nematode is immobilised
through infection bulbs, and finally digested by the trophic hyphae produced by
the fungus.
120
In some cases, nematode-destroying fungi produce toxins that
immobilise or kill nematodes.
121
The group also includes endoparasitic species in
such genera as Harposporium (see Figure 6), Nematoctonus, Meria among others,
which spend their entire vegetative lives within infected nematodes.
122
Nematode-destroying fungi have drawn much attention due to their potential
as biological control agents of parasitic nematodes of plants and animals.
123,124
Unfortunately, there exist multi-dimensional drawbacks to the realisation of the
full potential of the nematode-destroying fungi in the management of parasitic
nematodes, especially the phytoparasitic. Lack of reliable methods to visualise
the fungi and demonstrate their activity in their natural habitats is a major
impediment. Above all, the gaps in knowledge of the ecological factors that
influence the occurrence and abundance of nematode-destroying fungi are largely
unclear. Due to these factors, this group of fungi has escaped the attention of
many scientists, especially in Africa.
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Figure 6
An example of endo-parasitic nematode-destroying fungi: Harposporium
anguillulae with the conidiaphores and conidia appearing outside the dead
nematode. (Source: Wachira
153
(Wachira et al.)).
