Abstract
Two clones originally collected from tobacco (=tobacco form) and three clones from radish or Chinese cabbage (=non-tobacco form) of Myzus persicae (SULZER) were reared on tobacco and potato in the laboratory (15L-9D, 20°C) to evaluate their adaptation to tobacco. On potato there were no significant differences between the tobacco and non-tobacco forms in the developmental period (8-10 days) or in the survival rate in the larval stage (96-100%). On tobacco, however, remarkable differences were observed between the two forms: the developmental period was slightly longer than that on potato in the tobacco form (9-14 days), and much longer in the non-tobacco form (10-20 days); the survival rate in the larval stage was 98% in the former, and only 10% in the latter. On tobacco, alate virginoparae of the tobacco form lived for 15-29 days and produced 19-63 larvae per female, although those of the non-tobacco form lived for a shorter period of time (3-8 days) and produced fewer larvae (0-17). These results suggest that the susceptible forms to tobacco are eliminated from tobacco within a few generations even if alate forms settle on the plant and only the resistant forms survive there. Some characters of the aphid, which may possibly contribute to the resistance to tobacco, are discussed.
