Agriculture Reference
In-Depth Information
physiographic features of the landscape and hence
can best be utilized in area-wide pest management
programs. How climatic changes will affect devel-
opment, incidence, and population dynamics of
insect pests can be studied through GIS by predict-
ing and mapping trends of potential changes in
geographical distribution (Sharma et al.
2010
) and
delineation of agroecological hot spots and future
areas of pest risk (Yadav et al.
2010
).
likely to see a substantial increase in the use of
genetically engineered plants. Genetically engi-
neered plants have been designed to resist pests
such as stem borers and nematodes without the
need for pesticides. Others are expected to com-
bine both herbicide resistance and insect resis-
tance in one seed.
Environmental factors such as soil moisture,
soil fertility, and temperature have strong infl u-
ence on the expression of
Bacillus thuringiensis
(Bt) toxin proteins deployed in transgenic plants
(Sachs et al.
1998
). Cotton bollworm,
Heliothis
virescens
, destroyed Bt-transgenic cottons due to
high temperatures in Texas, USA (Kaiser
1996
).
Similarly,
Helicoverpa armigera
and
H. punctig-
era
destroyed the Bt-transgenic cotton in the sec-
ond half of the growing season in Australia
because of reduced production of Bt toxins
(Hilder and Boulter
1999
). Cry1Ac levels in
transgenic plants decrease with the plant age,
resulting in greater susceptibility of the crop to
insect pests during the later stages of crop growth
(Sachs et al.
1998
; Kranti et al.
2005
). Possible
causes for the failure of insect control in trans-
genic crops may be due to inadequate production
of the toxin protein, effect of environment on
transgene expression, Bt-resistant insect popula-
tions, and development of resistance due to inad-
equate management (Sharma and Ortiz
2000
). It
is therefore important to understand the effects of
climate change on the effi cacy of transgenic
plants for pest management.
Colorado potato beetle (CPB) resistance in
potato has been achieved through the incorpora-
tion of a gene from the
B. thuringiensis
(Bt) pro-
tein into potatoes (Russet Burbank, Atlantic).
Several developing-country potato varieties
have been transformed with the Bt gene to
express resistance to the potato tuber moth:
• In Central Africa (Rwanda, Burundi, Uganda,
Congo), resistant varieties include Mabondo,
Sangema, Murca, and Cruza.
• For the Andean region (Peru, Bolivia,
Ecuador), tuber moth resistance is now in
Tomasa Condemayta, Costanera, Achirana
INTA, María Tambeña, and Revolución.
• In Colombia, Pardo Pastusa has been
transformed.
7.20.4 Screening of Pesticides
with Novel Modes of Action
It has been reported by some researchers that the
application of neonicotinoid insecticides for con-
trolling sucking pests induces salicylic acid-
associated plant defense responses which enhance
plant vigor and abiotic stress tolerance, indepen-
dent of their insecticidal action (Ford et al.
2010
).
This gives an insight into investigating the role of
insecticides in enhancing stress tolerance in
plants. Such compounds need to be identifi ed for
use in future crop pest management.
7.20.5 Improved Pest Control
Because insects destroy potential crop produc-
tion worldwide, use of appropriate technologies
to reduce pest losses would increase crop yields.
In addition to the prudent application of pesti-
cides, increased use of nonchemical pest controls
would help minimize crop losses (Pimentel et al.
1993
). Nonchemical controls include crop rota-
tions, biological controls, altering planting dates
and fertilizer and irrigation applications, and soil
management and tillage. These technologies
could help minimize projected pest losses and
thereby help maintain crop yields.
7.20.6 Transgenic Crops for Pest
Management
Another important issue regarding pest manage-
ment in the future centers on the role of biotech-
nology in crop protection. The next 20 years will
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