Morphological and Molecular Identification ofCulicoides(Diptera: Ceratopogonidae) Species of the Southern California Desert

Abstract

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are vectors of important animal pathogens including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). While some Culicoides species present in the southern California desert are implicated in the transmission of these viruses to ruminant animals, these species have not been extensively studied due in part to the challenge of identifying Culicoides to species and to the lack of published gene sequences for these species to support their molecular identification. In this study, Culicoides were captured using suction traps baited with either carbon dioxide or UV light from transitional habitat between the southern California peninsular mountain ranges and the Colorado desert of southeastern California. Captured midges were initially identified using traditional morphological methods, with species identification subsequently confirmed by sequence analysis of COI and 28S rDNA genes. Phylogenetic analyses support that some Culicoides subgenera are not monophyletic. Two recognized species (C. sitiens Wirth and Hubert and C. bakeri Vargas) shared the same COI and 28S sequences. An additional cryptic species may be present within C. sitiens. Two additional recognized species (C. cacticola Wirth and Hubert and C. torridus Wirth and Hubert) may be conspecific or cryptic to each other. In total, 19 Culicoides species (or species aggregate) were collected in this study, with genetic sequences published for the first time for 16 of them. Published genetic sequences will support future research on these species, including studies on the ecology and habits of their immature stages which are often tedious to identify using morphology.

Shedding light on the controversial taxonomic status of Culicoides jamaicensis and Culicoides paolae (Diptera: Ceratopogonidae): an overseas trip among continents

“…The distribution patterns of both species varied greatly in the presence of sensilla coeloconica ; therefore, this feature does not appear to be particularly useful for drawing additional conclusions. High morphological intraspecific variability has been attributed to many Culicoides species (Talavera et al 2017, Zhang et al 2022). As a result, the existence of intraspecific variability might lead to misunderstandings in traditional species identification.…”

“…However, COI-based mitochondrial sequence analyses may not be sufficient to explore the phylogenetic relationships between closely related or disputed taxa. Combining COI with rDNA D1-D2 (28S) domains (Augot et al 2017, Zhang et al 2022), cytochrome b (Augot et al 2013), or ITS1/2 (Gomulski et al 2006, Perrin et al 2006) should be the routine approach to follow.…”

Immigration and seasonal bottlenecks: high inbreeding despite high genetic diversity in an oscillating population of Culicoides sonorensis (Diptera: Ceratopogonidae)

“…Host-seeking adult female C. sonorensis were captured from a southern California dairy (San Bernadino County) every other week from April 2018 through April 2021 (Zhang 2022). Midges were captured over a 24-h period that started at 8:45 am (9:45 am during DST) using a CDC type miniature suction trap (Model 512, J.W.…”

Large-Scale COI Gene Data Analysis for the Development of a Gel-Based Multiplex PCR Test Capable of Identifying Biting Midge Vector Species and Haplotypes (Diptera: Ceratopogonidae) of theCulicoidessubgenusAvaritiaFox, 1955

“…Adult Culicoides are commonly identified on the basis of phenotypic characteristics, such as wing pigmentation, following published identification keys [29–32]. However, this approach is time consuming, requires many years of experience and is inefficient in analyzing large quantities of midges [33]. The discovery of closely related species with similar or identical morphology further complicated traditional species identification and made it necessary to implement taxonomic categories below the subgenus level, such as ’Obsoletus Group’ [2,34,35].…”