Integrative taxonomy of Aculus mosoniensis (Acari: Eriophyidae), a potential biological control agent for tree-of-heaven (Ailanthus altissima)

Authors: DE LILLO, ENRICO - Bari University; MARINI, FRANCESCA - Bbca-Onlus, Italy; CRISTOFARO, MASSIMO - Bbca-Onlus, Italy; VALENZANO, DOMENICO - Bari University; PETANOVIC, RADMILA - Serbian Academy Of Sciences And Arts; VIDOVIC, BILJANA - Serbian Academy Of Sciences And Arts; CVRKOVIC, TATIJANA - Institute For Plant Protection And Environment; BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL)

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2022
Publication Date: 5/23/2022
Citation: De Lillo, E., Marini, F., Cristofaro, M., Valenzano, D., Petanovic, R., Vidovic, B., Cvrkovic, T., Bon, M. 2022. Integrative taxonomy of Aculus mosoniensis (Acari: Eriophyidae), a potential biological control agent for tree-of-heaven (Ailanthus altissima). Insects. 13(5), 489. https://doi.org/10.3390/insects13050489.
DOI: https://doi.org/10.3390/insects13050489

Interpretive Summary: Tree of heaven is a tree native to both northeast and central China, as well as Taiwan. Introduced for ornamental purposes into North America and Europe, it shows a highly invasive profile in field, urban and suburban areas thus posing a serious threat to ecosystems in the introduced range. Among the herbivores attacking tree of heaven in Europe, it is a tiny mite, Aculus mosoniensis, which causes serious malformations of the growing tips. In order to determine whether this species is safe to use as a biological control agent in Europe, where the mite has already been recorded, and elsewhere within the invasive range of tree of heaven, a fully resolved taxonomy of this mite is urgently required. After investigating morphological and molecular characters of Aculus mosoniensis and comparing with those of Aculops taihangensis also attacking tree of heaven in China, it was found that this mite species has to be re-assigned to the genus Aculus and that Aculus mosoniensis can be considered junior synonym of Aculops taihangensis. Thus we conclude that the mite targeted as a potential biological control agent of Tree of heaven in Europe is one single species, Aculus mosoniensis, does not hide undistinguishable species and hence this is one more reason to consider it as a safe biological control agent for controling this highly invasive tree.

Technical Abstract: Tree of heaven (Ailanthus altissima) is a fast-growing deciduous tree native to northeast and central China, as well as Taiwan, considered a serious invasive species worldwide, with several socio-economic and ecological impacts attributed to it. Chemical and mechanical methods have limited efficacy in its management, and classical biological control may offer a suitable and sustainable option. Aculus mosoniensis (Ripka) is an eriophyid mite that has been recorded to attack tree of heaven in 13 European countries. However, the taxonomic status of Aculus mosoniensis appears to be an unresolved question and its clarification is required, owing to the potential relevance of this mite species as biological control agent of tree-of-heaven in Europe. This study aimed to resolve this question using morphology and molecular characters and giving details on a previously announced synonymization along with Aculops taihangensis. A fusiform morph of Aculus mosoniensis was distinct by a vermiform morph and this latter was recognized as deutogyne, which was herein described and illustrated. Phylogenetic relationships between Chinese Aculops taihangensis and all Aculus mosoniensis mites collected in twenty localities in Europe were investigated through the analysis of the mitochondrial cytochrome c subunit I (CO1) protein and nuclear ribosomal Internal Transcribed Spacer 1 region (ITS1). CO1 sequences of Aculops taihangensis from the Shandong province in China were 100% identical to that of mites collected in Austria and Slovenia, and the ITS1 sequence of an Aculops taihangensis paratype matched most closely (99.8%) with those obtained from protogynes and deutogynes of Aculus mosoniensis collected in Italy. The strong congruence between morphological and molecular analyses for all mites collected on tree of heaven in Europe led to confirm that Aculus mosoniensis is a junior synonym of Aculops taihangensis. Molecular analyses do not uncover cryptic species, suggesting that all European populations of Aculus mosoniensis targeted as potential biocontrol agents are one species only, making the biological control program more safe.