Impacts on Nematode Pests - Climate Resilient Agriculture for Ensuring Food Security - page 185

Using simulated climate change, Carter et al.
( 1996 ) predicted that warming will expand distri-
bution of the potato cyst nematode ( Globodera ros-
tochiensis ) and also increase number of generations
per year by 2050 in Finland. The predicted effects
of climate change on diseases of selected major
agricultural and forestry species in Ontario showed
that the cyst nematode ( Heterodera glycines ),
root lesion nematode ( Pratylenchus spp.), and
pine wood nematode ( Bursaphelenchus xylophilus )
severity increases due to increase in rate of disease
development and potential duration of epidemic
due to climate change (Boland et al. 2004 ).
In India, rice root-knot nematode ( Meloidogyne
graminicola ), once considered to be a serious
pest only in upland rice, has made its importance
felt in almost all rice-growing areas and in all
types of rice culture including hill ecosystems in
recent years (Prasad and Somasekhar 2009 ;
Pankaj et al. 2010 ).
Neilson and Boag ( 1996 ) assessed the possi-
ble effect of climate change on the distribution of
some common virus-transmitting Xiphinema and
Longidorus species within Great Britain. They
observed that theoretically an increase in 1 °C in
mean temperature would result in the northward
extension of these nematode species by about
160-200 km. Colonization of new areas by virus-
vector nematodes has serious implications for
agriculture.

9.7 Nematode Management

Climate change will cause alterations in the spatial
and temporal distribution of nematodes, and
consequently, the control methods will have to be
altered to suit these new situations. Assessments of
the impact of climate change on nematode infesta-
tions and in crops provide a basis for revising man-
agement practices to minimize crop losses as
climate conditions change (Ghini et al. 2008 ).
Recent observations suggest that nematode
pressure on plants may increase with climate
change (Ghini et al. 2008 ). As a result, there may
be substantial rise in the use of nematicides in both
temperate and tropical regions to control them.
Nonchemical nematode management methods
(green manuring, crop rotation, mulching, applica-
tion of organic manures, etc.) assume greater
signifi cance under changing climate scenario.
Climate change-mediated changes in physiol-
ogy can alter the expression of resistance genes.
The most serious threat to genetic resistance to
nematodes may be posed by the increased selec-
tion pressure resulting from acceleration of nem-
atode developmental rate and increase in number
of generations per season due to global warming
(Ghini et al. 2008 ).
Nematode-, bacterial-, and fungal-based
biopesticides are highly vulnerable to environ-
mental stress. Increase in temperature and UV
radiation and a decrease in relative humidity may
reduce the effi cacy of these bioagents.
Therefore, there is a need to develop appropri-
ate strategies for nematode management that will
be effective under situations of global warming in
the future.

9.6 Severe Droughts

Soil nematodes are dependent on the continuity of
soil water fi lms for movement. Their activities are
largely controlled by soil biological and physical
conditions (Yeates and Bongers 1999 ). Severe
droughts resulting in a reduction of soil water will
most likely negatively affect soil nematodes.
Increased drought stress reduced pine tree resis-
tance against pine wood nematode ( Bursaphelenchus
mucronatus ) and bark beetles. This resulted in rapid
tree mortality in pine forests in Switzerland
(Robetez and Dobbertin 2004 ).
Increased water stress due to climate change
diminishes plant vigor and alters C:N ratios, low-
ering plant resistance to nematodes.

9.8 Biotechnological

Approaches to Nematode
Resistance

Biotechnology offers several benefi ts for nema-
tode control in an integrated management strat-
egy, such as reducing risks to the environment and
to human health, accessibility for food producers
in the developing world, and the possibility of