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|Duraimurugan Ponnusamy, P S Srinivas and M Sampath Kumar|
|Tobacco caterpillar, Spodoptera litura (Noctuidae: Lepidoptera) is an economically important pest of castor throughout the crop season. The larvae damage plants by feeding on leaves at night and remain concealed during day in the soil. Regular scouting of fields and collection and destruction of skeletonized leaves along with gregarious early instar larvae is very effective management method. However, regular scouting of the larvae is laborious and expensive. Monitoring the pest activity using pheromone traps for taking up timely control measures has been evaluated in groundnut and cotton and such studies on S. litura in castor are limited. The present study was undertaken to evaluate the relative performance of sex pheromone trap and light trap to monitor the seasonal activity of S. litura in castor. Funnel trap (Fero-T) with the septa of Spodoptera litura (PCI Pvt. Ltd., Hyderabad) was used to monitor the pest activity in three locations in Hyderabad (Rajendranagar, Narkhoda and Patancheru) during kharif and rabi seasons (2012-13). In each location, four pheromone traps were installed in castor field (4000 m 2 ) and weekly observations on male moths capture in traps were recorded. Weekly observations on the number of egg masses laid by the pest were also recorded on castor foliage (randomly selected 25 plants, 5 plants in 5 places) in two locations (Rajendranagar and Narkhoda). The results revealed two peak pheromone trap catches, the first during 33 rd to 35 th MW (August second fortnight) and second during 38 th to 40 th MW (September second fortnight). The highest peak catches of S. litura in three locations ranged from 33 to 257 moths/trap/week. Trap catches declined from 46 th MW to 5 th MW (November second week to February first week). Peak egg-masses in castor was observed during 38 th MW (6.4/5 plants) at Rajendranagar and 34 th MW (5.4/5 plants) at Narkhoda and the egg-masses count declined during 51 st MW to 5 th MW (0 to 0.6/5 plants). Significant positive correlation was found between number of egg-masses and pheromone trap catches (r=0.78 to 0.95). The capture of S. litura in light trap was lower than sex pheromone trap and the correlation values between number of trapped adults and egg-masses were higher in pheromone traps (r=0.78 to 0.95) than light traps (r=0.37 to 0.45). The results suggest that sex pheromone traps could be deployed to monitor populations of S. litura in castor as a labour saving method and field scouting may be initiated a week after heavy trap catches for the collection and destruction of mesh like skeletanized leaves along with early instar gregarious larvae.|
Duraimurugan Ponnusamy has completed his Ph.D. at the age of 29 years from Tamil Nadu Agricultural University, Coimbatore. He is working as Sr. Scientist at DOR, Hyderabad. He has published more than 20 papers in reputed journals.
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