The field of Quaternary entomology has focused primarily on the study of beetles (Coleoptera) and, to a lesser degree, nonbiting midges (Diptera: Chironomidae). Beetles typically predominate because they have heavily sclerotised exoskeletons, and they are abundant in a great variety of habitats. Because of taphonomy and scarcity, other Quaternary invertebrates have been less studied. Only a few records of fleas (Siphonaptera) and mites (Acari) are reported from Pleistocene deposits that span the Seward Peninsula in Alaska, United States of America, to the Klondike goldfields in central Yukon Territory, Canada. Grasshoppers (Orthoptera) and thrips (Thysanoptera) have not been reported previously from Quaternary deposits across the Arctic’s Beringia region. However, recent extensive sampling of Arctic ground squirrel, Urocitellus parryii Richardson (Rodentia: Sciuridae), middens from permafrost deposits of the Klondike goldfields has yielded specimens from each of these underrepresented invertebrate groups. Here, we present records of fleas (Oropsylla alaskensis Baker (Ceratophyllidae)), mites (including Fusacarus Michael (Astigmata: Glycyphagidae) and cf. Haemogamasus Berlese (Mesostigmata: Laelapidae)), and the first records of grasshoppers (Acrididae: Gomphocerinae) and thrips (Thysanoptera: Thripidae) from Beringia from six middens spanning approximately 80 000–13 500 years BP. We also provide brief reviews of the fossil history of each major taxon.

Nonnative earthworm species are invading the boreal forest in North America. Oribatid mites are key detritivores in boreal forest soils, initiating litter decomposition and maintaining forest floor structure. Earthworms are also detritivores and are considered ecosystem engineers. When introduced into nonendemic environments, earthworms may alter soil biogeochemical cycling and adversely affect oribatid mite communities. However, to our knowledge, no field studies in boreal forests have investigated invasive earthworms and their impacts on oribatid mites. The present study was conducted in a boreal trembling aspen, Populus tremuloides Michaux (Salicaceae), stand near Wolf Lake, Alberta, Canada. After assessing the current state of earthworm invasion, we identified an area with a lower density of earthworms that was invaded by one species, Dendrobaena octaedra Savigny (Crassiclitellata: Lumbricidae), and an area with a higher density of earthworms that was invaded by multiple species, D. octaedra (Crassiclitellata: Lumbricidae) and Aporrectodea spp. (Crassiclitellata: Lumbricidae). The higher-density area was associated with lower understorey vegetation species richness and with thinner forest floors characterised by higher bulk density but lower total organic carbon and nitrogen stocks. Oribatid mite community composition differed between the two areas, and their richness significantly decreased with higher earthworm density. Our findings suggest that earthworm invasion is substantially disrupting habitat for oribatid mites and might affect the overall boreal ecosystem equilibrium in the long term.

Metarhizium guizhouense (Clavicipitaceae) is an insect pathogen employed as a mycoinsecticide against many insect pests worldwide. In this study, for the first time in a laboratory setting, the pathogenicity of the M. guizhouense isolate PSUM04 was evaluated against the coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae). Following the exposure (1 × 109 spores/mL) of H. hampei to M. guizhouense PSUM04, morpho-histopathological changes and numbers of apoptotic cells via the TUNEL (terminal deoxynucleotidyl transferase (TdT), dUTP (deoxyuridine triphosphate) nick-end labelling) assay in H. hampei were evaluated at 12-hour intervals until 144 hours after exposure. The external morphology of H. hampei underwent drastic changes from 24 to 144 hours post-exposure accompanied by the degeneration of integument and adipose tissues. The semi-quantitative analytical score of TUNEL-positive cells showed a slight increase at 12 hours after exposure and a significant increase in TUNEL-positive apoptotic cells at 48 hours after exposure. These results suggest a series of tissue alterations of H. hampei during its process of infection with a strain of M. guizhouense, highlighting the pathogen’s potential as a biological control agent in natural settings.