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Effect of climatic factors on the incidence of Helicoverpa armigera and Spodoptera exigua on chickpea
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Effect of climatic factors on the incidence of Helicoverpa armigera and Spodoptera exigua on chickpea

  1. Effect of climatic factors on the incidence of Helicoverpa armigera and Spodoptera exigua on chickpea T Pavani, RS Munghate and HC Sharma International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, Telangana, India. References Sharma HC. 2005. Heliothis/Helicoverpa management: Emerging Trends and Strategies for Future Research. New Delhi, India: Oxford and IBBH Publishing Co. 469 pp. 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 Materials and methods • Five chickpea genotypes (ICCL 86111, ICCV 10, JG 11, KAK 2 and ICC 3137) were evaluated for studying the effect of climate change on the incidence and severity of H. armigera and S. exigua during the 2012/13 rainy seasons under field conditions. • The genotypes were sown at monthly intervals from Oct - Jan. Data were recorded on numbers of insects/plant or pod damage at fortnightly intervals in each planting. • The abundance of H. armigera and S. exigua was correlated with temperature and RH during the observation period. Helicoverpa armigera larvae feeding on chickpea. Spodoptera exigua larvae feeding on chickpea. a b c July 2014ICRISAT is a member of the CGIAR Consortium Plate 1. Reaction of chickpea genotypes in response to damage by pod borers. Conclusion • Temperature and RH showed a significant effect on incidence and damage by H. armigera and S. exigua on different genotypes of chickpea. • Abundance of H. armigera and S. exigua larvae increased with increase in temperature across the sowing dates. • Activity of natural enemies also decreased with rise in temperature. Fig.1. Incidence of pod borers in chickpea across different sowings under natural infestation in the field a) H. armigera larvae and b) S. exigua larvae. a b Fig. 2. Number of Campoletis chlorideae cocoons on different chickpea genotypes across sowings under natural infestation. Plate 2. Campoletis chlorideae female parasitizing H.armigera larvae. • Incidence of H. armigera was highest in ICC 3137 and lowest on ICCL 86111 across sowing dates (Plate 1). • ICCL 86111 recorded highest numbers of S. exigua eggs (4.31 egg masses/5 plants) in 3rd sowing, corresponding to Tmax 30.41 ºC and RHmax 86.27%. However, the larval density was highest (5.75 - 9.67 larvae/5 plants) in the 4th sowing (Fig. 1b). • Numbers of H. armigera larval parasitoid, Campoletis chlorideae cocoons decreased with an increase in temperature from first to fourth sowing (Fig. 2, Plate 2). Results • Egg laying by H. armigera decreased (8.12 to 5.09 eggs/5 plants in sowings 1 - 4), while larval density increased (11.59 to 17.87 larvae/5 plants in sowings 1 - 4) (Fig. 1a), corresponding to Tmax 28.49 ºC and RHmax 94.33% in first planting to Tmax 33.4 ºC and RHmax 76.73% in the 4th planting. Introduction • Pod borers Helicoverpa armigera and Spodoptera exigua are the major pests of chickpea. H. armigera alone causes an estimated loss of $2 billion, despite application of insecticides costing over $500 million annually (Sharma, 2005). • Climate change will have a major impact on the distribution and abundance of insect pests (Sharma, 2014). • Therefore, we studied the effect of climatic factors on the incidence of pod borers in chickpea.
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