Comparative Karyotypic Analysis of Four Aphid Species Infesting Economically Important Horticultural Plants

Abstract

Chromosomes of four aphid species infesting different horticultural crops were investigated from the North-Western Himalayas. The aphid species studied included Aphis pomi de Geer, a destructive pest of apple plants, Brachycaudus helichrysi (Kaltenbach), associated with peach Chromaphis juglandicola (Kaltenbach), infesting walnut and Eriosoma lanigerum (Hausmann), a well-known pest of apple orchards.  The karyotypic studies deduced the diploid chromosome number (2n) of 8 in A. pomi and C. juglandicola , and 12 in E. lanigerum  and B. helichrysi. . The chromosomes in all studied species were holocentric in nature. Comprehensive measurements of metaphase chromosomes were made to determine the mean actual length, total complement length, and relative length of individual chromosomes. Based on relative length data, idiograms were constructed for each species to illustrate their chromosomal organization and facilitate comparative cytogenetic analysis.