Impacts on Nematode Pests - Climate Resilient Agriculture for Ensuring Food Security - page 181

Table 9.2 Response of herbivorous nematodes to CO 2 enrichment
Location

Cropping system Experimental arena a Nematode response b

References

New Zealand Grassland CER +/N Yeates et al. ( 1997 )

New Zealand Grassland Vent N Yeates et al. ( 1999 )

New Zealand Grassland FACE +/N Yeates et al. ( 2003 )

California, USA Grassland OTC +/N Hungate et al. ( 2000 )

California, USA Grassland OTC N Ayres et al. ( 2008 )

California, USA Grassland OTC N Ayres et al. ( 2008 )

Germany Grassland FACE +/N Sonnemann and

Wolters ( 2005 )

Germany Sugar beet and wheat

rotation

FACE + Sticht et al. ( 2009 )

Switzerland Grassland SACC N Niklaus et al. ( 2003 )
Montpellier, France Grassland CER N Ayres et al. ( 2008 )
China Rice-wheat rotation FACE +/N Li et al. ( 2007 , 2009 )
India Rice OTC N Somasekhar and
Prasad ( 2010 )
a OTC Open top chambers, SACC screen-aided CO 2 control, FA C E free air CO 2 enrichment, CER controlled environment
room, Vent natural CO 2 vent
b + Positive or increase in abundance, N neutral or not affected

range. Other potential effects of elevated temper-
ature on parasitic nematodes include altered sex
ratio, host defense responses, and interference in
their survival strategies like dauer juveniles or
egg diapauses in extreme environments.
Drier temperatures are expected to increase
symptoms of water stress in plants infected with
nematodes such as the soybean cyst nematode.
Overwintering of nematodes is not expected to be
signifi cantly affected by changes in climate,
although for some, such as the soybean cyst nem-
atode, egg viability may be reduced in mild
winters.
Plantain ( Musa spp. AAB) is both an impor-
tant staple and cash crop throughout the West/
Central African humid forest zone. Major
yield constraints are root nematodes, particu-
larly Radopholus similis . Data from lab and
field experiments demonstrate higher nema-
tode population densities and greater plantain
root damage at the projected temperature
increases. R. similis , currently absent from
cooler, higher altitude areas, is likely to
expand its range.
Climate change may also infl uence the plant
nematode interactions by interfering with host
defense mechanisms. Rebetez and Dobbertin
( 2004 ) reported that strong climate warming that

has occurred in recent years favored pine wood
nematode ( Bursaphelenchus mucronatus ) and
bark beetles and increased drought stress reduced
tree resistance against these pests. This resulted
in rapid tree mortality in pine forests in
Switzerland.

9.4.1 Breakdown of Nematode

Resistance

Genetic resistance to Meloidogyne spp. is sen-
sitive to soil temperatures above 28 °C. Tomato,
bean, and sweet potato lose resistance at
elevated soil temperatures (Dropkin 1969 ;
Fassuliotis et al. 1970 ; Jatala and Russell 1972 ).
High soil temperatures appear to be the main
reason that root-knot nematode resistance is not
effective in Florida, USA (Walter 1967 ), and in
many tropical countries. Results by Araujo
et al. ( 1983 ) indicate that race 4 of M. incognita
reproduces better on resistant tomato genotypes
than on race 1.
The resistance to root-knot nematode in
tomato (cv. 'Sanibel') has often failed as a result
of the heat instability or apparent temperature
sensitivity of the resistant Mi gene (Fig. 9.2 ). For
example, previous research has demonstrated