Biology of Euwallacea interjectus, an emerging poplar pest, reared on an ambrosia beetle artificial diet and medium of fungal symbiont.

Euwallacea interjectus, a recently discovered pest in poplar plantations, poses a significant economic threat due to its role in causing widespread tree mortality. This pest's cryptic behaviour has hindered research and control efforts, making laboratory rearing a valuable tool for studying its development and biology. We investigated the development period and biological characteristics of E. interjectus using artificial diets and fungal medium. Our findings revealed that the development time for eggs, larvae, and pupae averages approximately 6, 18, and 6 days, respectively. Notably, first and second instar larvae displayed peak moulting periods at 3.45 ± 0.64 SD and 7.92 ± 1.77 SD days, respectively. Furthermore, we measured head capsule widths of postmolt larvae, yielding values of 318.02 ± 7.38 SD µm for first-instar larvae, 403.01 ± 11.08 SD µm for second-instar larvae, and 549.54 ± 20.74 SD µm for third-instar larvae. Our research also uncovered a positive correlation between the number of progeny (eggs, larvae, pupae, and adults) and the mean length of the gallery system. Interestingly, the haplodiploid reproductive strategy did not significantly affect the number of offspring produced by the foundress. Additionally, we observed that foundresses displayed higher fecundity when subjected to nutrient-rich diets as compared to nutrient-poor diets. Our results will deepen our understanding of the biology of E. interjectus and provide criteria for larval instar classification. Additionally, managing nutrient availability within the colony could be considered a viable approach to regulating population size.

The tribal placement of Urocorthylus Petrov, Mandelshtam & Beaver, with a description of the male of U. hirtellus Petrov et al., and notes on its biology (Coleoptera: Curculionidae: Scolytinae).

We show, using molecular data, that the enigmatic genus Urocorthylus Petrov, Mandelshtam & Beaver from Southeast Asia belongs in the scolytine tribe, Dryocoetini, and not in the almost wholly American tribe Corthylini, where it was originally placed. The male of Urocorthylus hirtellus Petrov, Mandelshtam & Beaver is described and figured for the first time, and new records from China are presented. Urocorthylus hirtellus is a bark beetle, and not an ambrosia beetle as originally hypothesised. Keys are provided to the genus within the Dryocoetini, and to the two species included in the genus.

Transcriptome analysis of Euwallacea interjectus reveals differentially expressed unigenes related to developmental stages and egg laying.

Euwallacea interjectus (Curculionidae: Scolytinae) is an ambrosia beetle species in its early stages of research. Therefore, studying the related molecular mechanism associated with the development and egg laid is essential. Transcriptome sequencing was used in this study to compare the gene expression of the beetles at different developmental stages and female adults before and after oviposition. A total of 40,047 annotated unigenes were obtained. There were 4225 differentially expressed unigenes (DEUs) from larva to prepupa stage, 3651 DEUs between prepupa and pupa, 1675 DEUs generated from pupa to adult, and 4762 DEUs between females before and after oviposition. The most significant pathway differences between different development stages and before and after oviposition were selected through functional annotation of DEUs between different stages. Among them, there were many pathways related to protein metabolism including: neuroactive ligand-receptor interaction, endoplasmic reticulum and RNA transport. This study provides valuable information on the molecular regulation mechanism of development and the egg laid of E. interjectus.

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 species and new records of Scolytoplatypus Schaufuss (Curculionidae, Scolytinae) from China, and resurrection of Scolytoplatypussinensis (Tsai & Huang, 1965) as a distinct species.

This study describes two new species, Scolytoplatypuswugongshanensis Liao, Lai & Beaver, sp. nov. and S.skyliuae Liao, Lai & Beaver, sp. nov., reinstates S.sinensis (Tsai & Huang, 1965) from synonymy with S.mikado (Blandford, 1893), and records five species for the first time from China, S.brahma Blandford, 1898, S.curviciliosus Gebhardt, 2006, S.minimus Hagedorn, 1904, S.ruficauda Eggers, 1939, S.samsinghensis Maiti & Saha, 2009, and three from mainland China, S.blandfordi Gebhardt, 2006, S.calvus Beaver & Liu, 2007, S.pubescens Hagedorn, 1904. A key to the males of Scolytoplatypus species in China is given. Genetic data from four genes indicate a rather isolated position for both new species, although their genetic relationship to each other was close.

A new species, a new combination, and a new record of Crossotarsus Chapuis, 1865 (Coleoptera, Curculionidae, Platypodinae) from China.

This study describes a new species, Crossotarsus beaveri Lai & Wang, sp. nov., designates a new combination, C. brevis (Browne, 1975, comb. nov. from Platypus Herbst, 1793), and notes a new record, C. emorsus Beeson, 1937, from China. Genetic data from four genes indicate that the new species and C. brevis form a clade clustered with other Crossotarsus species. Molecular phylogeny and morphological characters support their taxonomic placement.