N. Dangi1, S. Aryal1, S. Shrestha2 Y.P. Giri1 and M. Sporleder3
1Nepal Agricultural Research Council, Nepal
2Research Associate, International Potato Center (CIP), South, West & Central Asia (SWCA)
3International Potato Center (CIP), Lima, Peru
Abstract
The flight activity of two lepidopteron insect pests, Spodoptera litura and Helicoverpa armigera, (Lepidoptera: Noctuidae) was monitored using sex pheromone traps during two consecutive vegetation periods in 3 different potato field locations situated at altitudes of around 2500, 1500 and 650 masl in Sindupalchowk, Kavrepalanchowk and Dang district, respectively. Pheromone traps were installed at three locations in each site and data were recorded at 2 days interval. Populations of the two pests were observed the highest in Kavrepalanchowk during both vegetation period 2010/11 and 2011/l2. Data were pooled weekly and pheromone traps detected distinct peaks for S. litura in Sindupalchowk on 10th April (1034±219), Kavrepalanchowk on 6th April (2932±224) and Dang on 20 November (527±32) in 2010/11.Likewise, in Kavrepalanchowk and Dang, the highest peak was observed on 22nd March (950±733) and 10th November (747±468) during 2011/012, respectively. Population of H. armigera at Kavrepalanchowk peaked on 23rd March with an economically significant number (373±38 per week in Tukucha VDC and 1207±359 per week in Panauti VDC) where as Visible damage was observed on potato foliage in 2011. In Dang, H. armigera moth captured reached its peak on 30th November (32±32 adult/week). This trend clearly indicated that these pests can outbreak at tuber bulking and maturation stage of potato in all three ecological regions of Nepal. Therefore, these pests cause severe economic damage during the vegetation period of the potato crop. These dates on which the highest number of moths were trapped could be used as a benchmark to determine the occurrence and population buildup duration for these two species of moths. Understanding the pest population dynamics are useful technical knowledge needed for researchers, technicians and growers to decide more precise timing for applying appropriate management options.
Keywords: Agro-ecology, Potato, Lepidoptera, Pheromones, Trap