Taxonomy and phylogeny of European Monochamus species: first molecular and karyological data

Evaluating species boundaries using coalescent delimitation in pine-killing Monochamus (Coleoptera: Cerambycidae) sawyer beetles

Plant-feeding beetle species are diverse and often individually highly variable. Accurate classifications can be difficult to establish yet are essential for study of evolutionary patterns and processes. Molecular data are key to further characterizing morphologically difficult groups and defining genus and species boundaries. Monochamus Dejean species are ecologically and economically significant, and in coniferous forests they vector the nematode that causes Pine Wilt Disease. This study uses nuclear and mitochondrial genes to test the monophyly and relationships of Monochamus and applies coalescent methods to further delimit the conifer-feeding species. Monochamus has also included approximately 120 Old World species associated with diverse angiosperm tree species. We sample from these additional morphologically diverse species to determine their placement in the Lamiini. Through supermatrix and coalescent methods, the higher-level relationships of Monochamus show that conifer-feeders are a monophyletic group that includes the type species and has split into Nearctic and Palearctic clades. Molecular dating indicates a single dispersal of conifer-feeders to North America over the second Bering Land Bridge circa 5.3 Ma. All other Monochamus sampled fall in different parts of the Lamiini tree. Small-bodied angiosperm-feeding Monochamus group with the monotypic genus Microgoes Casey. The African Monochamus subgenera sampled are distantly related to the conifer-feeding clade. The multispecies coalescent delimitation methods BPP and STACEY delimit 17 conifer-feeding Monochamus species for a total of 18 species, and supports the retention of all current species. An interrogation with nuclear gene allele phasing reveals that unphased data can be unreliable for accurate delimitations and divergence times. The delimited species are discussed with integrative evidence, highlighting real-world challenges in recognizing the completion of speciation trajectories.

Morphological and Molecular Characterization of Diplogasteroides sp., a Cryptic Population of the Haslacheri Group (Diplogastridae), and Parasitorhabditis terebranus (Rhabditidae) from Korea

Diplogasteroides sp., a cryptic population of D. haslacheri, and Parasitorhabditis terebranus were reported from the frass of Monochamus alternatus galleries in dead Pinus thunbergii for the first time in Korea. Females and males are morphologically characterized and their linked DNA barcodes (18S-rRNA, 28S-rRNA, ITS-rRNA and COI) supplied. Females and males of the two species from Korea conform to the original species descriptions from Europe and the USA, with variations in a few details in morphometrics. Specifically, Diplogasteroides sp. is morphologically very similar to D. haslacheri. However, it cannot be designated as D. haslacheri due to the existence of cryptic species complex within the haslacheri group (D. haslacheri, D. asiaticus, D. nix, D. andrassyi, and D. carinthiacus), a condition requiring hybridization studies to test species identity within the group. Based on analysis of COI sequences, differences among these cryptic species are evident. Thus, in addition to hybridization tests, the COI might be a powerful DNA barcoding marker for the precise identification of these cryptic species within the genus. Additionally, this is the first molecular characterization of P. terebranus, and the species is herein recorded for the first time outside its type locality.

Larval Instars and Adult Flight Period of Monochamus saltuarius (Coleoptera: Cerambycidae)

Monochamus saltuarius is a vector of Bursaphelenchus xylophilus in Japan, South Korea, and the middle temperate zone of China. However, there are only a few reports on this species in China, and its biological characteristics are still unclear. In this study, we aimed to elucidate the larval development and adult flight period of M. saltuarius to provide a theoretical basis for the effective control of pine wilt disease in the middle temperate zone of China. Seven morphological variables of larvae were measured to determine the number of larval instars, and the adult specimens of M. saltuarius were collected from traps in forests to study the flight period of adults in Fushun, Liaoning, the epidemic center of pine wilt disease in the middle temperate zone of China. The results revealed that the full larval period of M. saltuarius was 279.6 d, and the larvae had five instar stages, with an average duration of 7.4, 14.3, 49.8, 83.6, and 124.5 d, respectively. Additionally, 78.4% of the overwintering larvae were fourth instar, and 21.6% were fifth instar larvae. We also found that the adults began to emerge from early May to late June, and the period was from early May to mid-August in the forest. During the investigations period from 2018 to 2020, the total number of adults captured was minimal at 744, and precipitation was highest at 291.54 mm in 2019. We characterized the larval instars and adult flight period of M. saltuarius, which is a prerequisite for developing appropriate management strategies. The results of this study will provide an important reference for the formulation of strategies to control M. saltuarius and pine wilt disease.

Phylogenetic relationships between genera Dorcadion, Lamia, Morimus, Herophila and some other Lamiinae (Coleoptera: Cerambycidae) based on chromosome and CO1 gene sequence comparison

A dual molecular and cytogenetic study was performed with the aim to improve the controversial systematic classification of some species of Lamiinae (Coleoptera: Cerambycidae). The karyotypes of species belonging to genera Morimus, Herophila, Dorcadion, Neodorcadion and Lamia share a number of characters, which differentiate them from other species, belonging to genera Phytoecia, Parmena and Monochamus. The karyotypes of the last three species comprise 20 chromosomes, mostly metacentric or sub-metacentric, as in the presumed Cerambycidae ancestors. The karyotypes of the former species share many characters derived from the Lamiinae ancestors by a number of chromosome fissions and inversions indicating their monophyly. Comparisons of the CO1 gene sequence also show the monophyly of Morimus, Lamia, Herophila and Dorcadion and their distant relationship with others. These convergent results allow us to propose a phylogenetic classification of these genera, which places the monospecific genus Lamia close to Dorcadion, clearly separates Dorcadion and Neodorcadion and places Herophila closer to Morimus than to Dorcadion/Lamia. The genus Morimus is the most derived. CO1 mutations loosely separate the forms M. asper and M. funereus, which have similar karyotypes and behaviour and copulate in captivity. The form M. ganglebaueri may have a funereus X asper hybrid origin.

Complex Insect-Pathogen Interactions in Tree Pandemics

Tree pandemics are a major cause of economic and ecological loss in forest and urban ecosystems. They often depend on the introduction of a non-native pathogen, which is occupying the niche of a native, non-aggressive organism. Complex interactions with native insects carrying fungi and nematodes can be established based on the proximity of the aggressive pathogenic agents. Here we review three major pandemics of forest and urban trees in temperate ecosystems at world scale, i.e., the Dutch elm disease, the cypress canker, and the pine wilt disease. For each system, the relationships between aggressive and non-aggressive fungi and nematodes with the native insect vectors are presented. Hidden players such as insects, microorganisms or plants, which may have the role of facilitating or contrasting the performance of the agents, are also considered. Results suggest that pandemics rely on the introduction of a non-native pathogen that exploits well-developed interactions between native non-aggressive organisms and insects associated with trees. The success of the invaders depends on the morpho-physiological proximity of the players and on the mutual benefits resulting from the associations. Deciphering such interactions in native systems may help to predict the outcome of the introduction of new pathogens and the development of new tree pandemics.

Pest categorisation of non-EU Monochamus spp

The Panel on Plant Health performed a pest categorisation of non-EU Monochamus spp., a well-defined insect genus in the family Cerambycidae (Insecta: Coleoptera). Species can be identified using taxonomic keys at national and regional level, and DNA barcoding. Two online world catalogues exist for the genus. The genus includes about one hundred species and many subspecies colonising conifers and non-conifer trees in many areas in the world. The non-EU species are listed in Annex IAI of Council Directive 2000/29/EC. Although Monochamus spp. colonise weakened or dead trees and have therefore no direct impact, some species vector the pine wood nematode, Bursaphelenchus xylophilus, which they inoculate to healthy trees when they proceed to maturation feeding on twigs, causing high mortality among pines in Asia and the EU (Portugal). Sixteen species in Asia and America attack conifers. The main pathways for entry are raw untreated wood and wood products, wood packaging material, particle wood and waste wood, finished wood products and hitchhiking. Monochamus species were categorised in two groups. The first group includes 16 species colonising conifers and absent in the EU known or likely to vector the pine wood nematode. The species in this group satisfy all the criteria to be considered as Union quarantine pests. Measures are in place to prevent the introduction of Monochamus with coniferous wood. The second group gathers all the remaining species, all non-EU species colonising non-conifers. These do not satisfy all the criteria to be considered as Union quarantine pests. As plants for planting are not a pathway for Monochamus spp., and as most of the species within these groups are absent from the EU territory, the two groups do not meet the criteria to be considered as regulated non-quarantine pests.

New data on the longhorn beetles of Mongolia with particular emphasis on the genus Eodorcadion Breuning, 1947 (Coleoptera, Cerambycidae)

New data on the distribution, biology, and ecology of the longhorn beetles occurring in Mongolia are presented together with a list of 35 species that were collected during a one-month entomological expedition in August 2015. New localities of some rare taxa endemic to Mongolia, such as Eodorcadiondorcasdorcas (Jakovlev, 1901), E.humeraleimpluviatum (Faldermann, 1833), and E.intermediumintermedium (Jakovlev, 1889) are given. High-quality photographs of several rather unique species, i.e., Pachytodeslongipes (Gebler, 1832), Eodorcadionmaurumaustrale Danilevsky, 2014, E.oryx (Jakovlev, 1895), Monochamusimpluviatusimpluviatus (Motschulsky, 1859), and M.sutorlongulus (Pic, 1898) along with images of their habitats or feeding grounds are also presented. Furthermore, the ecological role of the fireweed Chamaenerionangustifolium (L.) Scop. in the case of boreal anthophilous cerambycid species is highlighted for the first time.

Within- and Between-Species Variation of Wing Venation in Genus Monochamus (Coleoptera: Cerambycidae)

We have described the morphological variation of five Western Palaearctic species of Monochamus Dejean, 1821. The variation was assessed using wing measurements. Special emphasis was placed on the differences between Monochamus sartor (F., 1787) and Monochamus urussovii (Fischer-Waldheim, 1805). There was an interesting pattern of variation between the two species. Individuals of M. sartor from the Carpathians differed markedly from individuals of M. urussovii from Siberia, but individuals from north-eastern Poland were intermediate between those two populations. The intermediate individuals were more similar to the Siberian M. urussovii than to the Carpathian M. sartor despite the relatively large geographic distance between north-eastern Poland and Siberia. The occurrence of the intermediate individuals in north-eastern Poland may be the effect of hybridization between M. urussovii and M. sartor, which might have occurred after secondary contact between the two species in the Holocene.