Overwintering strategy and the timing of the spring migration of the cereal aphids Sitobion avenae and Sitobion fragariae.
There is a linear relationship between the timing of the spring migration of both Sitobion avenae and S. fragariae and latitude, due to the effect of winter weather on both the aphids and their host-plants. Higher temperatures in more southerly latitudes result in an earlier migration. Differences between the timing of the migrations of the 2 species were compared, and it was concluded that they can be explained by the different overwintering strategies of the aphids. In southern England, there was a linear relationship between the timing of the spring migration of S. avenae and winter temperatures, particularly temperatures in January and February. In northern England, a different linear relationship was found, and in Scotland the timing of migration was not related to temperatures from this period of the winter. The timing of the spring migration of S. fragariae was not significantly related to winter temperatures. The relationships from the southern sites were used to forecast the time of the spring migrations of S. avenae.