Light trap as a monitoring tool for common cutworm Spodoptera litura (f.) in soybean

The population dynamics of common cutworm Spodoptera litura (F.) (Lepidoptera: Noctuidae) captured by light trap in soybean was studied at the Directorate of Soybean Research, Indore during 2009–2011. In soybean, S. litura adults were not captured by light trap until 30th standard week. Two peaks of sudden increase of moth catches were observed on 38th and 41st standard week in 2009; 37th and 41st standard week in 2010 and 37th and 39th standard week in 2011. Moths caught/week usually began to decrease to <3 during post soybean season. Similarly, intensity of larval population was zero until 31st standard week, and thereafter a peak on 37th standard week was observed during 2009 and 2011 seasons, and 36th standard week in 2010; subsequently, this reduced to <2 on 41st standard week. The seasonal moth catches/light trap were significantly higher in season 2009 and 2011 compared to that in 2010. Likewise, intensity of larval population during 2010 and 2011 seasons were considerably lower than that of 2009. A significant positive correlation was observed between light trap catches vs. larval population during crop season.