Epidemiology of cereal aphids on winter wheat in Norfolk, 1979-1981.
Abstract
The cereal aphid outbreaks of 1979 (Metopolophium dirhodum) and 1980 (Sitobion avenae) and their lower populations in 1981, in Norfolk, eastern England, are described. The high incidence of outbreaks is probably due to a combination of factors, including the large area devoted to cereals, the low numbers of aphid-specific and polyphagous predators early in the season and the dry conditions during the immigration period. It is suggested that monitoring for M. dirhodum could be carried out on Rosa spp., while a forecasting scheme for S. avenae can only be developed when a greater understanding of its life cycle is obtained.