A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae)

Evolution, types, and distribution of flight control devices on wings and elytra in bark beetles

Gaining the ability to fly actively was a ground-breaking moment in insect evolution, providing an unprecedented advantage over other arthropods. Nevertheless, active flight was a costly innovation, requiring the development of wings and flight muscles, the provision of sufficient energetic resources, and a complex flight control system. Although wings, flight muscles, and the energetic budget of insects have been intensively studied in the last decades, almost nothing is known regarding the flight-control devices of many crucial insect groups, especially beetles (Coleoptera). Here, we conducted a phylogenetic-informed analysis of flight-related mechanosensors in 28 species of bark beetles (Curculionidae: Scolytinae, Platypodinae), an economically and ecologically important group of insects characterized by striking differences in dispersal abilities. The results indicated that beetle flight apparatus is equipped with different functional types of mechanosensors, including strain- and flow-encoding sensilla. We found a strong effect of allometry on the number of mechanosensors, while no effect of relative wing size (a proxy of flight investment) was identified. Our study constitutes the first step to understanding the drivers and constraints of the evolution of flight-control devices in Coleoptera, including bark beetles. More research, including a quantitative neuroanatomical analysis of beetle wings, should be conducted in the future.

Checklist of the subfamily Scolytinae (Coleoptera: Curculionidae) in Tucumn province, Argentina

A checklist of Scolytinae species is presented to contribute to the knowledge of the biodiversity of the subfamily in Tucumn province, Argentina. The inventory was based on collections in the field from 2016 to 2023, and a review of the material deposited in the entomological collections of the Museo de La Plata, the Museo Argentino de Ciencias Naturales Bernardino Rivadavia, and the Fundacin Miguel Lillo. Previous bibliographic records were also included. In total, 54 species belonging to 11 tribes were recorded, of which six were new reports for Argentina and nine for Tucumn province; eight species were introduced. The genus Amasa was also recorded in Argentina for the first time.

Uncharted Territories: First report of Euwallacea fornicatus (Eichhoff) in South America with new reproductive hosts records

We report the presence of the invasive ambrosia beetle, Euwallacea fornicatus (Eichhoff, 1868), for the first time in South America. The identity is established by morphological and molecular methods, although the sequences suggest that it represents a separate haplotype from the populations that have caused significant damage in South Africa, Israel, and California, and is most phylogenetically similar to specimens from Asia and greenhouses in Europe. This pest is one of the most successful invaders, causing high economic and ecological impacts in the regions where it is introduced. Our records are from the city of Buenos Aires, Argentina, one of the most populated and largest port cities in South America, where attacks by this beetle are present on a wide range of living street trees. The large number of trees attacked and the new records of reproductive host species suggest that the beetle is already established and widespread in the citys urban forest. This context implies that the beetle may pose a threat to the urban and natural environment, as well as to the forests and fruit production of the region. Informamos la presencia del escarabajo invasor de ambrosa, Euwallacea fornicatus (Eichhoff, 1868), por primera vez en Sudamrica. La identificacin se estableci mediante mtodos morfolgicos y moleculares, si bien las secuencias sugieren que representa un haplotipo distinto de las poblaciones que han causado daos significativos en Sudfrica, Israel y California, resulta filogenticamente ms similar a especmenes de Asia e invernaderos de Europa. Esta plaga es una de las especies invasoras ms exitosas, causando altos impactos econmicos y ecolgicos en las regiones donde es introducida. Nuestros registros provienen de la ciudad de Buenos Aires, Argentina, una de las ciudades portuarias ms pobladas y grandes de Sudamrica, donde los ataques de este coleptero estn presentes en una amplia diversidad de especies pertenecientes al arbolado urbano. El gran nmero de rboles atacados y los nuevos registros de especies hospedadoras reproductoras sugieren que el coleptero ya est establecido y extendido en el bosque urbano de la ciudad. Este contexto implica que el coleptero puede suponer una amenaza para el medio urbano y natural, as como para los bosques y la produccin frutcola de la regin.

A new species of Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae) from Yunnan, China

Scolytus unicornis, a new species of Scolytus Geoffroy from Yunnan, China, is described and illustrated. Three DNA barcoding sequences (COI, 28S, CAD) of this species are provided. The new species is distinguished from other Asian Scolytus species by the longitudinal wrinkles on the frons only in the area below the eyes, a large median spine situated in the middle of the ventrite 2 base, and female frons with a slightly raised blunt tubercle above the epistoma.

Complete Mitochondrial Genome of Scolytoplatypodini Species (Coleoptera: Curculionidae: Scolytinae) and Phylogenetic Implications

The complete mitochondrial genomes (mitogenomes) of beetles in the tribe Scolytoplatypodini (genus Scolytoplatypus) were sequenced and annotated. These included Scolytoplatypus raja (15,324 bp), Scolytoplatypus sinensis (15,394 bp), Scolytoplatypus skyliuae (15,167 bp), and Scolytoplatypus wugongshanensis (15,267 bp). The four mitogenomes contained 37 typical genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The gene orientation and arrangement of the four mitogenomes were similar to other Coleoptera mitogenomes. PCGs mostly started with ATN and terminated with TAA. The Ka/Ks ratio of 13 PCGs in the four species revealed that cox1 had the slowest evolutionary rate and atp8 and nad6 had a higher evolutionary rate. All tRNAs had typical cloverleaf secondary structures, but trnS1 lacked dihydrouridine arm. Partial tRNAs lost the discriminator nucleotide. The trnY did not possess the discriminator nucleotide and also lost three bases, showing a special amino-acyl arm. Bayesian inference (BI) and maximum likelihood (ML) methods were conducted for phylogenetic analyses using 13 PCGs. Scolytoplatypodini was clustered with Hylurgini and Hylastini, and the monophyly of Scolytoplatypodini was supported. The four newly sequenced mitogenomes increase understanding of the evolutionary relationships of Scolytoplatypodini and other Scolytinae species.

New Canadian and Provincial Records of Coleoptera Resulting from Annual Canadian Food Inspection Agency Surveillance for Detection of Non-Native, Potentially Invasive Forest Insects

The arrival and establishment of adventive, invasive forest insects are a threat to the health, diversity, and productivity of forests in Canada and the world at large, and their early detection is essential for successful eradication and management. For that reason, the Canadian Food Inspection Agency (CFIA) conducts annual surveys at high risk sites such as international ports and freight terminals, industrial zones, and disposal sites for solid wood packaging material using two methods: (1) semiochemical-baited traps deployed in a total of about 63-80 sites per year in British Columbia (BC), Ontario (ON), Quebec (QC), New Brunswick (NB), Nova Scotia (NS), and Newfoundland and Labrador (NL); and (2) rearing of insects from bolts collected from stressed trees and incubated in modified shipping containers in four cities (Vancouver, Toronto, Montreal, and Halifax). We report 31 new Canadian provincial records of Coleoptera from surveys conducted in 2011-2021, including 13 new records for Canada and 9 species adventive to North America (indicated by †). Nine of the new Canadian records were native North American species previously detected only south of the border. All but three species belong to the Curculionidae family and most of these were in the subfamily Scolytinae. The records include: Xenomelanophila miranda (LeConte) (Canada, BC) (Buprestidae: Buprestinae); Neoclytus mucronatus mucronatus (Fabricius) (BC) (Cerambycidae: Cerambycinae); Amphicerus cornutus (Pallas) (Canada, BC) (Bostrichidae: Bostrichinae); Mecinus janthinus (Germar)† (ON) (Curculionidae: Curculioninae); Aulacobaris lepidii (Germar)† (Canada, ON); Buchananius striatus (LeConte) (ON) (Curculionidae: Baridinae); Cylindrocopturus binotatus LeConte (Canada, ON) (Curculionidae: Conoderinae); Himatium errans LeConte (ON); Phloeophagus canadensis Van Dyke (ON); Rhyncolus spretus Casey (Canada, BC); Stenomimus pallidus (Boheman) (Canada, ON); Tomolips quercicola (Boheman) (Canada, ON) (Curculionidae: Cossoninae); Strophosoma melanogrammum (Forster)† (NB) (Curculionidae: Entiminae); Conotrachelus aratus (Germar) (ON) (Curculionidae: Molytinae); Anisandrus maiche Stark† (Canada, ON, QC); Cnesinus strigicollis LeConte (Canada, ON); Cyclorhipidion pelliculosum (Eichhoff)† (Canada, ON, QC); Hylesinus fasciatus LeConte (QC); Hylesinus pruinosus Eichhoff (QC); Hypothenemus interstitialis (Hopkins) (Canada, ON); Lymantor alaskanus Wood (BC); Pityogenes bidentatus (Herbst)† (Canada, ON); Scolytus mali (Bechstein)† (BC); Scolytus schevyrewi Semenov† (QC); Trypodendron scabricollis (LeConte) (Canada, ON); Trypophloeus populi Hopkins (QC); Xylechinus americanus Blackman (NFLB); and Xylosandrus crassiusculus (Motschulsky)† (BC, QC) (Curculionidae: Scolytinae). We also provide additional data confirming the presence of the adventive Hylastes opacus Erichson† in NS. Rearing of insects from bolts accounted for two new records (H. pruinosus, R. spretus) and trapping accounted for the remainder. These surveys not only assist our efforts to manage forest insects by documenting new species introductions and apparent range expansions but also increase our knowledge of biodiversity.

Patterns of host tree use within a lineage of saproxlic snout-less weevils (Coleoptera: Curculionidae: Scolytinae: Scolytini)

The influence of plants in the diversification of herbivorous insects, specifically those that utilize moribund and dead hosts, is little explored. Host shifts are expected because the effectiveness of toxic secondary chemicals is lessened by decay of dead plants. Feeding on dead plants also releases herbivorous insect lineages from diversifying within a particular plant lineage. Thus, phylogenetic constraints on the herbivorous insect lineage imposed by the host plants are diminished and repeated patterns of species diversification in an association with unrelated host trees is hypothesized (i.e., taxon cycle). Scolytini, a diverse weevil tribe, specialize on many different dead and moribund plant taxa as a source of food. These species and their hosts offer an opportunity to examine the association between dead host plants and the extent of phylogenetic constraints. A phylogeny of the Scolytini was reconstructed with likelihood and Bayesian analyses of DNA sequence data from nuclear (28S, CAD, ArgK) and mitochondrial (COI) genes. Ancestral host usage and geography was reconstructed using likelihood criteria and conservation of host use was tested. Results supported a monophyletic Scolytini, Ceratolepis, Loganius, and a paraphyletic Scolytus, Camptocerus and Cnemonyx. Diversification of the Scolytini generally occurred well after their host taxa diversified and suggests a sequential evolution of host use. In this scenario the beetle imposes little selection pressure on the tree but the tree provides a platform for beetle evolution. Major changes in host tree use occurred during periods of global cooling associated with changes in beetle biogeography. Diversification of beetles occurred on common and widespread hosts and there was likely a single origination of conifer-feeding from angiosperm-feeding species during the early Pliocene and a radiation of beetle species from the Palearctic to the Nearctic. Overall, the observed patterns of Scolytini host use are conserved and are similar to those expected in a taxon pulse diversification. That is, after a host switch to an unrelated tree, the beetles diversify within the host plant lineage. The need to locate an ephemeral food resource, i.e., a dying tree, likely maintains host specificity once a host shift occurs. These findings suggest that characteristics of dead and moribund host plants (e.g. secondary chemicals) influence the diversification of these saproxlic weevils despite the reduction of selection pressures.

Genetic Variability Among Xyleborus glabratus Populations Native to Southeast Asia (Coleoptera: Curculionidae: Scolytinae: Xyleborini) and the Description of Two Related Species

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is native to Southeast Asia, where it specializes on Lauraceae trees. It forms a symbiosis with the ambrosia fungus Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, which can act as a pathogen in living host trees. The beetle and fungus were recently introduced into the United States, where they have killed millions of native Lauraceae trees and threaten the avocado industry. These introduced populations have limited genetic variation. In the native range, the fungi are genetically variable, but the native genetic variability of the beetles is unknown. It is important to assess the beetle's native genetic variation because different lineages may vary in the capacity to vector this fungus, which may affect disease etiology. Here, we analyzed genetic variation in several Chinese, Taiwanese, and Vietnamese populations of X. glabratus using mitochondrial (COI) and nuclear DNA (CAD) markers. Phylogenetic analysis revealed nine COI haplotypes and four CAD genotypes. Uncorrected 'p' distance for intrapopulation comparisons ranged from 0 to 0.1 and 0 to 0.013 and interpopulation comparisons ranged from 0.137 to 0.168 and 0.015 to 0.032 for COI and CAD, respectively. Two populations exceeded the range of intraspecific nucleotide differences for both genes. Given that individuals from these populations also exhibited consistent morphological differences, they are described as two new species: Xyleborus insidiosus Cognato & Smith, n. sp. and Xyleborus mysticulus Cognato & Smith, n. sp. Xyleborus glabratus was redescribed and a lectotype was designated to facilitate its recognition in light of these new species. These results indicate that X. glabratus is genetically variable and is related to two morphologically similar species. Whether these new species and X. glabratus lineages associate with different fungal strains is unknown. Given that the biology and host colonization of these new species are unknown, preventing their introduction to other regions is prudent.

New Curculionoidea (Coleoptera) records for Quebec, Canada

The following species of Curculionoidea are newly recorded from the Canadian province of Quebec: Coelocephalapionemaciipes (Fall, 1898); Ischnopterapionvirens (Herbst, 1797); Omphalapionhookerorum (Kirby, 1808); Perapionpunctinasum (J.B. Smith, 1884) (all Brentidae); Anthonomusrobustulus LeConte, 1876; Pseudanthonomushelvolus (Boheman, 1843); Bagousmagister LeConte, 1876; Bagoustanneri O’Brien, 1979; Buchananiusstriatus (LeConte, 1876); Ceutorhynchusbolteri Dietz, 1896; Ceutorhynchuspallidactylus (Marsham, 1802); Ceutorhynchuspauxillus Dietz, 1896; Conotrachelusbuchanani Schoof, 1942; Conotracheluspusillus LeConte, 1878; Conotrachelusrecessus (Casey, 1910); Curculiorubidus (Gyllenhal, 1835); Cylindrocopturuslongulus (LeConte, 1876); Hadroplontuslitura (Fabricius, 1775); Hyperarumicis (Linnaeus, 1758); Lixusterminalis LeConte, 1876; Myosidesseriehispidus Roelofs, 1873; Phloeotribusdentifrons (Blackman, 1921); Plocamusechidna (LeConte, 1876); Scolytusmuticus Say, 1824; Sirocalodessericans (LeConte, 1876); Smicronyxsculpticollis Casey, 1892 (all Curculionidae). Among these, Buchananiusstriatus, Conotrachelusbuchanani, Conotracheluspusillus, and Curculiorubidus (all Curculionidae) are also recorded from Canada for the first time. The latter is also newly reported from Ontario. Collecting data are provided for Lixuspunctinasus LeConte, 1876, previously reported to occur in Canada without any further information, and for Choragussayi LeConte, 1876 (Anthribidae) and Rhyssomatusaequalis Horn, 1873 (Curculionidae), both previously recorded from Quebec, also without further details.

Biology of Scolytus piceae (Coleoptera: Curculionidae: Scolytinae) in Northern Idaho and Notes on Comparative Anatomical Features of the Larva

The forests of the northern Rocky Mountains are hosts of nine species of Nearctic conifer-infesting bark beetles of the genus Scolytus Geoffroy. One of these, Scolytus piceae Swaine (Coleoptera: Curculionidae), infests spruces across the continent including Picea engelmannii Parry (Pinaceae) in Idaho. Mature larvae overwintered before transforming to adults, which infested new hosts in early June. Scolytus piceae most commonly infested shaded out lower branches of mature live spruce. In sporadic wind-felled spruce, the beetle infested the terminal portion of branches throughout the crown, whereas another Scolytinae, Polygraphus rufipennis (Kirby), infested the thicker bark basal portion of the same branches. This niche separation resulted from difference in time of their dispersal flight and ability of S. piceae to colonize thin bark by engraving the underlying sapwood. Population recruitment of S. piceae was low in shaded out lower branches, in balance with this limited host resource. Features of the head of S. piceae larvae differed from that reported in literature, including the mandible dentition, antennal field, and pattern of setae on the postlabium.

History of the Exotic Ambrosia Beetles Euwallacea interjectus and Euwallacea validus (Coleoptera: Curculionidae: Xyleborini) in the United States

Exotic insects are constantly intercepted at U.S. ports-of-entry. Of these, wood-boring beetles, particularly xyleborine ambrosia beetles, are sometimes missed during port inspections and become established in the United States. Euwallacea validus (Eichhoff) and Euwallacea interjectus (Blandford) are morphologically similar Asian ambrosia beetle species that vary by their fungal associates and their potential to cause economic damage. Euwallacea validus and E. interjectus were first discovered in New York (1975) and Hawaii (1976), respectively. Euwallacea validus was collected multiple times from widely separated localities and is assumed to have spread throughout the eastern United States. The discovery of E. interjectus in Florida (2011) and Texas (2011) prompted our review of the E. validus specimens because of the potential misidentification of the species. In addition, using mitochondrial cytochrome oxidase I (COI) DNA data and phylogenetic analysis, we tested the hypothesis that multiple introductions account for the U.S. populations of E. interjectus and E. validus. Our review of 7,184 specimens revealed an earlier introduction to the mainland for E. interjectus, which was first collected from Louisiana in 1984. This species is distributed in the South while E. validus occurs in the North with a known area of syntopy in northeastern Georgia. The extent of the syntopy within the United States is unknown and further investigation is required. Phylogenetic analysis of 24 E. interjectus and 20 E. validus individuals resolved clades that associated with each species and gross geographic provenance. Four well-supported clades represented E. interjectus which included the following localities: 1) Hawaii and Thailand; 2) Vietnam, Taiwan, and Texas; 3) Okinawa (Japan); and 4) Japan and several southern U.S. states. One clade comprised all E. validus specimens from Japan and the mainland United States. Four and two haplotypes were found for the E. interjectus and E. validus specimens, respectively, in mainland United States. Except for the Texas specimen, the haplotypes differed by one nucleotide. The relationship of the haplotypes and their sequence similarity suggested that the provenance of E. validus and the majority of E. interjectus haplotypes was Japan while the Texas haplotype originated later and from a location near Taiwan. Given the high nucleotide sequence difference between the Hawaiian and Thai haplotypes, the exact origin of the Hawaiian E. interjectus is unknown but likely Southeast Asia. A broader investigation including more SE Asian individuals will help to further explain the introduction of E. interjectus into Hawaii and Texas.