Morphological and Molecular Analysis of Australian Earwigs (Dermaptera) Points to Unique Species and Regional Endemism in the Anisolabididae Family

Abstract

Dermaptera (earwigs) from the Anisolabididae family may be important for pest control but their taxonomy and status in Australia is poorly studied. Here we used taxonomic information to assess the diversity of southern Australian Anisolabididae and then applied cox1 barcodes as well as additional gene fragments (mitochondrial and nuclear) to corroborate classification and assess the monophyly of the putative genera. Anisolabididae morphospecies fell into two genera, Anisolabis Fieber and Gonolabis Burr, based on paramere morphology. Combinations of paramere and forceps morphology distinguished seven morphospecies, which were further supported by morphometric analyses. The morphospecies were corroborated by barcode data; all showed within-species genetic distance < 4% and between-species genetic distance > 10%. Molecular phylogenies did not support monophyly of putative genera nor clades based on paramere shape, instead pointing to regional clades distinguishable by forceps morphology. This apparent endemism needs to be further tested by sampling of earwig diversity outside of agricultural production regions but points to a unique regional insect fauna potentially important in pest control.

Lifecycle of the invasive omnivore, Forficula auricularia, in Australian grain growing environments

“…Victoria accounted for 60% of all samples, with 98% identified as F. auricularia while 96% of individuals from South Australia were F. auricularia (Table 1). This supports previous studies that have found F. auricularia to be the most abundant earwig species in grain crops in southern Australia 10,50 . We found head capsule width to be the most consistent trait in determining life stage, as occasionally the antennae of earwigs were damaged and missing segments.…”

“…This supports previous studies that have found F. auricularia to be the most abundant earwig species in grain crops in southern Australia. 10,50 We found head capsule width to be the most consistent trait in determining life stage, as occasionally the antennae of earwigs were damaged and missing segments. Across all sites, the average head capsule width measured across more than 2500 individuals was 0.92 (± 0.01) mm for first instars (n = 215), 1.29 (± 0.02) mm for second instars (n = 505), 1.53 (± 0.01) mm for third instars (n = 892), and 1.84 (± 0.01) mm for fourth instars (n = 908) (Supporting information Fig.…”

“…All F. auricularia individuals were separated from the other Dermapteran species that were captured. This was achieved using morphological characteristics under ×40 magnification as described in Crumb, 4 with species determinations verified by molecular methods as needed (results presented in Stuart et al 50 ). Individual adult and nymphal stages were categorized using head width, the number of antennal segments and wing bud development 4 (Supporting information, Figs.…”

The dual role of earwigs (Dermaptera) in winter grain crops in Australia

“…There are at least 80 species of earwigs present in Australia (Haas, 2018). Recent work using a combination of morphological and molecular data has indicated that at least ten different species of earwigs occur in southern Australian grain crops (Stuart et al., 2019), of which there is not a lot known (Macfadyen et al., 2019). The most widespread species in grain crops within Australia is the European earwig ( Forficula auricularia Linnaeus) (Hill et al., 2019), which was introduced over a century ago (Quarrell et al., 2018).…”

“…Forficula auricularia is considered a complex of at least four cryptic species with different climatic niches (González‐Miguéns et al., 2020), with two subclades (B 1 and B 2 ) occurring on mainland Australia (Quarrell et al., 2018). The two most common native earwig species in Australian grain crops appear to be the common brown earwig ( Labidura truncata Kirby) and the black field earwig ( Nala lividipes Dufour) (Stuart et al., 2019). Nala lividipes is reported as a pest of Queensland cereals (Hargreaves, 1970), although it is unclear whether this is also the case in southern Australia or whether it feeds on canola.…”