The two species of the genus Stomaphis feeding on oak and birch, respectively, although morphologically similar, are considered to be separate species. However, the birch-feeding S. betulae Mamontova is considered to be a synonym of the oak and birch feeding S. quercus (L.) by some authors. The purpose of this study was to determine whether the birch feeding and oak feeding populations attributed to S. quercus belong to the same species. The mitochondrial cytochrome-c oxidase I (COXI) and II (COXII) were used to determine whether these two populations differ. There are no significant differences in these markers from oak and birch feeding individuals, indicating that these populations are conspecific. However, morphologically and ecologically distinct populations of Stomaphis were discovered feeding on oak. The molecular analysis confirmed that these populations are distinct, which resulted in the description of the new oak-feeding species, Stomaphis wojciechowskii Depa, sp. n. This new species previously remained unrecognized due to its very cryptic mode of life., Lukasz Depa, Ewa Mroz, Karol Szawaryn., and Obsahuje seznam literatury
Many aspects in the life-history of aphids are critically dependent on the quality of their host plants and prevailing temperature. Therefore, the fitness of an aphid clone will depend on these parameters and will determine its ecological and ultimately its evolutionary success. Measuring and calculating the fitness of an organism in a natural environment is an important but also a difficult task, as many parameters that code for fitness need special assumptions, e.g. a uniform environment or stable age distribution. In this study, three aspects of environmental variability were considered: (a) the nutritional supply of the host plants (high- and low-quality plants), (b) the changes in host plant quality due to the endogenic life cycle of the host and (c) constant and variable temperature regimes. For each of three successive generations of Cinara pruinosa (Hartig) feeding on Picea abies (L.) Karsten, the change in fitness was determined by calculating the intrinsic rate of increase (rm) and expected total reproductive success (ETRS) when the aphids were reared under greenhouse (constant temperature) or field (variable temperature) conditions. Nutritional supply, plant life cycle and temperature affected the fitness of aphids, with fluctuating temperatures obscuring the effects. As a consequence, differences in fitness values among treatments were most pronounced under the constant temperature regime of a greenhouse and less marked in the field. If plant quality varies but not temperature, the contribution to clonal fitness of early generations is overestimated in comparison to later generations. The limitations and consequences for the interpretation of fit ness values of aphids are discussed.