Abstract
In Japan tobacco plants generally harbour red forms of Myzus persicae (SULZER) with yellow and green forms being occasionally recorded. Breeding trials were carried out to examine the association between the hypothetic gene(s) conferring resistance to tobacco and the gene for body color. Two crosses (I and II) between red clones belonging to the “tobacco form” (female)×yellow clones of the “non-tobacco form” (male) yielded 68 healthy F1 clones, of which 49 were red (cross I: 22, II: 27) and 19 yellow or green (cross I: 0; II: 19). Survival rates on the 10th day of nymphs, that were transferred from radish to tobacco plants immediately after birth, in 21 F1 clones examined (12-84%) were distributed between those of the parent clones (cross I: “tobacco form” 90% and “non-tobacco form” 0%; II: 98% and 6%, respectively). The survival rates of nymphs of 2 green F1 clones examined (52% and 74%) were comparable to those of 2 green clones originally collected from tobacco plants cultivated on Miyako-jima and Ishigaki-jima, Ryûkyû (44% and 64%, respectively). These results indicate that the gene(s) for resistance to tobacco is not closely linked to the red gene and that the inheritance of resistance to tobacco may depend on a polygenic system.
