The diamondback moth, Plutella xylostella (L.), is a notorious insect pest of cruciferous plants. To examine the pattern and magnitude of genetic variation in this species in China a portion of the mitochondrial (mt) COI gene of P. xylostella, collected at six Chinese and two Korean localities, which cover ~2,151,600 km2, was sequenced. Sequence analysis of the 681-bp mt COI gene from 80 individuals resulted in 16 haplotypes, ranging in sequence divergence from 0.1% (one nucleotide) to 0.9% (six nucleotides). One nucleotide position among 16 variable sites was a transversional substitution and the remaining positions were transitional substitutions. No position resulted in amino acid substitution. Phylogenetic analysis showed that all haplotypes were highly interrelated and no discernable haplotype group was found. From a geographical perspective, most haplotypes were found singly at one or two localities, with three haplotypes widely distributed. Little genetic differentiation (FST = -0.038-0.309) and a high rate of female migration (Nm = 1.117 - infinite) between Chinese populations suggests that dispersal over long distances is a major factor in the demography of this species.
Insect genital characters are extensively used in species level taxonomy, and their value in species delimitation is great. Based on the lock-and-key hypothesis and that genital differences function as a mechanical isolation system between species, the value of genital characters has been thought to be superior to non-genital characters. Although geographical and other kind of intraspecific variation of genitalia is often assumed very moderate, its real extent is insufficiently investigated. We examined patterns of morphological variation in the male genitalia of the tortricid moth Pammene luedersiana, using geometric morphometric tools including thin-plate spline deformation grids, and found significant variation. This variation is continuous both within and between populations. No systematic shape variation was observed between populations, but genital size showed some geographic variability. The results suggest that genital morphology is not constant and should therefore be used with caution in lepidopteran taxonomy.
The ladybird Coccinella magnifica is typically considered to be myrmecophilous, and primarily associated with the Formica rufa group of wood ants. It is regularly associated with ants of the F. rufa group in north-western Europe. The very limited data on the habitat preference of C. magnifica in the southern and eastern parts of its range indicate that its ant-associations change and that it may even be non-myrmecophilous in this region. C. magnifica might consist of geographically restricted species or semispecies, on the basis of its geographical variation in ant-association. Laboratory and field observations on north-western myrmecophilous populations C. magnifica appear to indicate it is a generalist predator of aphids. Coccinella magnifica's potential dietary breadth is similar to that of its congener Coccinella septempunctata, which has been used as a model of C. magnifica's non-myrmecophilous ancestor in evolutionary studies.