Abstract
The diploid number of 10 chromosomes has been claimed by some workers in Lipaphis erysimi, a polyphagous species of aphid while the diploid number of 8 was suggested by others. In the present study, both Giemsa-stained and Silver-nitrate stained preparations confirmed 2n=8 chromosomes in L. erysimi, and the NORs were revealed as a discrete silver-positive dot at one end of two large-sized chromosomes. It has been hypothesized that the dissociation of one or two fragments at SC sites might have led to the origin of 2n=9 or 10 chromosomes which have occasionally been observed by various workers.
