Global warming and climate change will trigger major changes in geographical distribution of insect pests, herbivore plant interactions and efficacy of crop protection technologies (Sharma 2014). Chemical composition of plants will change in direct response to global warming and climate change, affecting plant damage and growth and development of insect pests.

1. Effect of heat and drought stress in chickpea on expression of resistance to pod borer, Helicoverpa armigera
HC Sharma, SMD Akbar, AR War, M Pathania and SP Sharma
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, Telangana, India.
Conclusions
• Plants grown under heat and water stress were more vulnerable to damage by H.
armigera.
• Larval survival and larval weights were greater on plants grown under stress than on
the normal plants.
• Accumulation of carbohydrates increased with an increase in heat and water stress.
References
Sharma HC, Pampapathy G, Dhillon MK, and Ridsdill-Smith TJ. 2005. Detached
leaf assay to screen for host plant resistance to Helicoverpa armigera. Journal of
Economic Entomology 98: 568-576.
Sharma HC. 2014. Climate change effects on insects: Implications for Crop Protection
and Food Security. Journal of Crop Improvement 28: 229-259.
For more information, please write to: Dr HC Sharma, Principal Scientist – Entomology, ICRISAT. Email: h.sharma@cgiar.org
Effect of heat and water stress on expression of resistance to H. armigera
• Five genotypes of chickpea were grown under greenhouse (27 + 5 ℃ and 65 - 95%
RH) and under heat and water stress conditions (37 ± 5 ℃ and 25 - 65% RH)
during the summer season (April - May).
• Plants raised under greenhouse were watered on alternate days, while those raised
outside the greenhouse were exposed to heat and water stress (Plate 1).
• After 20 days of germination, the material was tested for resistance to H. armigera
using detached leaf assay (Plate 2) (Sharma et al., 2005).
• Data were recorded on leaf damage, larval survival and larval weights.
• Terminal branches of chickpea were excised after 20 days of germination for
biochemical analysis.
• Carbohydrate and protein contents in chickpea leaves were estimated by Anthrone
reagent and Lowry’s method, respectively.
• Larval survival and larval weights were greater on plants grown under stressed
conditions (larval survival 82%, larval weight 7.98 mg/larva) as compared to
the insects fed on plants grown under greenhouse conditions (larval survival
37.33%, larval weight 5.57 mg/larva) across genotypes (Fig. 1).
• Increased levels of carbohydrates were observed in plants raised under stress
conditions as compared to the plants raised under greenhouse conditions, except
in ICC 3137 and KAK 2, which showed an opposite trend (Fig. 2).
Helicoverpa armigera larva feeding on chickpea leaves and chickpea pods.
Plate 1. Chickpea plants grown under unstressed (US) and heat and water stressed (S) conditions during the summer season.
US S
July 2014ICRISAT is a member of the CGIAR Consortium
Fig. 3. Protein content of chickpea genotypes raised under stressed and unstressed conditions.
Fig. 1. Larval survival of H. armigera larvae on different genotypes of chickpea grown under greenhouse
and heat and water stressed conditions.
Plate 2. Detached leaf assay to evaluate chickpea genotypes for resistance to H. armigera (R - resistant and S -
susceptible).
SR
Fig. 2. Carbohydrate content of chickpea genotypes raised under stressed and unstressed conditions.
Results
• In plants grown under heat and water stress, the leaf damage rating ranged from
6.0 to 8.67, which was significantly higher than on plants grown under green
house conditions (DR 1.33 to 6.67).
Introduction
• Global warming and climate change will trigger major changes in geographical
distribution of insect pests, herbivore plant interactions and efficacy of crop
protection technologies (Sharma 2014).
• Chemical composition of plants will change in direct response to global warming
and climate change, affecting plant damage and growth and development of insect
pests.
• We studied the effect of heat and water stress on expression of resistance to pod
borer, Helicoverpa armigera in chickpea.
• Protein content of plants grown under stress conditions was greater in ICCL
86111 and JG 11 (Fig. 3) as compared to the plants grown under greenhouse
conditions. However, in ICC 3137, ICCV 10 and KAK 2, higher protein content
was observed in plants raised under greenhouse conditions.