Agriculture Reference
In-Depth Information
These differences are mainly due to the high level of development of the trophic,
reproductive, excretory and response of nervous systems in phytonematodes. Com-
pared to other phytopathogens, plant nematodes exhibit a higher degree of motility
and have a more sensitive sensory system to make them safe from foreign invasion
(Zinov'eva et al.
2004
).
In general, the most widespread and economically-important phytonematodes
are root knot and cyst nematodes. These phytonematodes cause heavy losses in
some economically-important crops viz., 18-25 % loss in vegetables, 20-25 % in
pulses and 18-23 % in oil seed crops. Global annual yield loss of major crops by
nematodes damage is estimated to be 12.3 % (Sasser
1989
), causing annual losses
of nearly $ 100 billion worldwide (Nordmeyer
1992
) and considered as a serious
constraint to agricultural production, particularly in intensive cultivation of veg-
etable and cereal crops. The damage is generally not recognized at first sight be-
cause of their presence beneath the soil and plants infected by nematodes resemble
those suffering from water or nutrient stress, showing chlorosis and poor or stunted
growth.
Even judicious use of chemical nematicides is highly hazardous to human health
and the environment another disadvantage of chemical nematicides is their persis-
tence in the environment which favours development of resistance in nematodes,
leading to the use of more toxic chemicals. Because of increase in awareness and
cautious approach among people on health and environmental concerns, there has
been now a paradigm shift in the strategies towards adoption of novel ecofriendly
means. Several nematode management strategies such as nematicides, resistant vari-
eties, crop rotation, fallowing and summer ploughing, intercropping with non-hosts/
antagonistic crops, organic amendments have been used conventionally. However,
each management strategy has some limitations in its implementation. The use of
nematode-trapping fungi as potential biocontrol agent is a novel approach whose
success mainly depends upon the basic knowledge and research required for better
understanding of the ecology and biology of nematode-fungal interaction for their
successful adoption in field.
In this chapter, we have described and discussed some of the researches per-
formed by us for augmentation of mass culture of nematode-trapping fungi
Arthro-
botrys oligospora
effective in reducing root knots and inducing growth, along with
organic substrates in tomato (
Lycopersicon esculentum
), brinjal (
Solanum melon-
gena
) and rice (
Oryza sativa
) plants.
2 Overview of Nematode-Trapping Fungi
The nematophagous fungi which is also known are predaceous fungi comprises
more than 200 species (Table
12.1
), which show the characteristic of parasitism of
nematodes at different stages. They constitute endoparasitic fungi, toxin-producing
fungi, egg and female parasitic fungi and nematode-trapping fungi. As the name
implies, nematode-trapping fungi capture nematodes with the formation of various
trapping devices, i.e., adhesive hyphae, adhesive two-three dimensional networks,
