Serious outbreak of Helicoverpa armigera in China
Serious outbreaks of Helicoverpa armigera (EPPO A2 quarantine pest) were reported from Hebei Province in China. In 1992 explosions of first and second generations of the cotton bollworm were recorded not only on nearly 800 000 ha cotton fields but also in nearly 600 000 ha of wheat crops. Densities of larvae of the pest reached up to 195 larvae/mý. Reasons for this outbreak was thought to be favourable climatic conditions during the preceding winter and spring, satifactory abundance of food sources and an increased insecticide resistance in H. armigera populations.
Sources
Wei, C.; Riu, C.; Fan, Z.; Zhao, Y.; Meng, X.; Wei, Y.; Wang, H.; Zhang, G. (1993) Serious explosions of the first and second generations of cotton bollworm in Hebei Province, China in 1992 and the observation of its resistance level.
Resistant Pest Management Vol 5 (2); 14-17.