Overview

The use of castor as trap plants for Spodoptera litura feeding on onions continued to be assessed during the onion-growing season. While castor plants effectively attracted S. litura, as well as another lepidopterous pest, Helicoverpa armigera (Hubner), it was not clear whether the trapping role of the castor plants is adequate to prevent these pests from entering the onion fields. So far, the larval densities within onion plots were low and did not differ significantly between plots surrounded by castor and those without castor plants.

Pheromone traps for Spodoptera confirmed the presence of S. exigua, which occurred in outbreak proportions. In the initial years of the project, the pest had not been detected despite the traps. The occurrence of S. exigua inflicted heavy damage of onions in many parts of Nueva Ecija, especially those where onions were planted late (January).