Myzus persicae ssp. nicotianae Blackman, 2005

Victor, Eastop, F. & Blackman, Roger L., 2005, Some new synonyms in Aphididae (Hemiptera: Sternorrhyncha), Zootaxa 1089, pp. 1-36 : 29

Myzus persicae ssp. nicotianae Blackman new status

Myzus nicotianae was distinguished from M. persicae because samples collected from many parts of the world on tobacco ( Nicotiana tabacum ) and in different years showed consistent differences in morphology and biology associated with this host ( Blackman 1987). Most of the samples analysed were from regions where populations are permanently parthenogenetic, but Margaritopoulos et al. (2000) found that holocyclic populations of tobacco aphids in Greece could also be discriminated morphometrically from those collected on other crops, and from peach away from tobacco­growing regions. It has been suggested ( Clements et al. 2000a) that these morphological differences could be due to phenotypic plasticity associated with feeding on a particular host plant. However, it is clear that the differences are genetically­based, as all the samples analyzed by Margaritopoulos et al. were clones reared under controlled conditions on the same host plant; the clones originating from peach in tobacco­growing regions and conforming to the morphology of nicotianae had never fed on tobacco. Relative preference for tobacco by nicotianae has been demonstrated in the laboratory ( Margaritopoulos et al., 2005; Troncoso et al., 2005). Genetic isolation between nicotianae and persicae cannot be complete, as amplified esterase genes conferring resistance to insecticides are identical in the two forms ( Field et al. 1994). Absence of complete reproductive isolation, perhaps in conjunction with a very recent origin of nicotianae , may explain the failure to find consistent diagnostic genetic markers ( Margaritopoulos et al. 1998, Fenton et al. 1998, Clements et al. 2000a, b), or the divergence of gene sequence that one might normally expect to find between separate taxa ( Clements et al. 2000a). However, the degree of isolation must have been sufficient to preserve the integrity of the tobacco­adapted genome for at least 15–20 years, and it would be unwise to regard this form simply as synonymous with M. persicae , as suggested by Clements et al. (2000a, b), as this would hide important information. The tobacco aphid conforms to the broader definition of the subspecies category advocated by Müller (1986) and Rakauskas (2004), which aims to ensure that indexable names are available for intraspecific variants of economically important species. We therefore propose that the tobacco aphid should be called M. persicae ssp. nicotianae .