Abstract
Variation in karyotype of Sitobion rosaeiformis (Das) collected from two different hosts Rosa sp. and Rubus ellipticus has been reported in this paper. Surprisingly, the populations of this aphid species collected during rainy season on two different hosts possess 2n=18, whereas a population collected in summer on the former host shows 2n=14. These findings suggest that the host plant and the season possibly affect the genome size in aphids.
