Effect of climate on the proportion of males in the autumn flight of the aphid Rhopalosiphum padi L. (Hom., Aphididae)

The composition of autumn flights of a cereal pest aphid, Rhopalosiphum padi, was studied in relation to climate. At 10 sites in France and at Rothamsted and Starcross (UK), evidence was sought for a relationship between winter temperature and the proportion of males. By calculating Goldwin's correlogram, significant correlations were detected between cold periods in the early winter and the proportions of males at the five mildest sites, suggesting an effect of temperature on the balance between holocyclic and non-holocyclic clones. The five sites where no significant correlations were detected are generally cold in winter, and are likely to be largely dominated by holocyclic clones. The temperature in late summer/early autumn may also have an effect on the proportion of males.