Rigorous Morphological Studies Confirm That the Classical Object of Pest Control Chilocorus kuwanae Is the Same Species as Ch. renipustulatus (Coleoptera: Coccinellidae)

Abstract

The ladybug Chilocorus kuwanae, which was described in Japan, has been used for biological control of pests for 100 years. Chilocorus kuwanae was recently synonymized with Ch. renipustulatus described in Europe. The synonymy was based on the examination of few specimens. Our aim is to verify this synonymy. We studied all characters previously used to distinguish these taxa: eight metric and nine qualitative characters. Examination of 107 specimens from Japan and Sakhalin and 174 specimens from Europe showed that the ranges of variability in all characters in Asian and European specimens strongly overlap. There are no characters with interspecific hiatuses. Analysis with Amadon’s criteria showed that Asian and European specimens also do not represent different subspecies. Conclusions: (1) No differences between the specimens from Asia (Japan and Sakhalin) and Europe were found at specific or subspecific levels. Chilocorus kuwanae is a junior synonym of Ch. renipustulatus. (2) The releases of “Chilocorus kuwanae” in Europe and the Caucasus did not represent classical biological control since the same species was native to these regions. (3) A thorough taxonomical revision with the study of morphological variability should be conducted before the introduction of any species to new regions. (4) Taxonomical conclusions based on morphological studies should be confirmed by statistical methods.