Molecular identification of Culicoides (Diptera: Ceratopogonidae) species in Algeria

Molecular Identification of Culicoides Species and Host Preference Blood Meal in the African Horse Sickness Outbreak-Affected Area in Hua Hin District, Prachuap Khiri Khan Province, Thailand

African horse sickness (AHS) was reported as an outbreak in Thailand in 2020. Hematophagous insects from the genus Culicoides are the suspected vector responsible for AHS transmission. Horses in Hua Hin district, Prachuab Khiri Khan province, Thailand, were affected and died from AHS in 2020. However, the potential Culicoides species and its host preference blood meal in the affected areas are unknown. To investigate the potential vectors of AHS, Culicoides were collected using ultraviolet light traps placed near horse stables. Six horse farms, including five farms with AHS history and one farm without AHS history, were included in this study. Morphological and molecular identification of the Culicoides species was performed. Polymerase chain reaction (PCR) targeting the cytochrome b oxidase I (COXI) gene for confirmation of the Culicoides species, identification of the prepronociceptin (PNOC) gene for host preference blood meal, and bidirectional sequencing were conducted. Consequently, 1008 female Culicoides were collected, consisting of 708 and 300 samples captured at positions A and B at a distance of <2 and >5 m from the horse, respectively. Twelve Culicoides species identified by morphology were noted, including C. oxystoma (71.92%), C. imicola (20.44%), C. actoni (2.28%), C. flavipunctatus (1.98%), C. asiana (0.99%), C. peregrinus (0.60%), C. huffi (0.60%), C. brevitarsis (0.40%), C. innoxius (0.30%), C. histrio (0.30%), C. minimus (0.10%), and C. geminus (0.10%). The PCR detection of the Culicoides COXI gene confirmed Culicoides species in 23 DNA samples. PCR targeting the PNOC gene revealed that the Culicoides collected in this study fed on Equus caballus (86.25%), Canis lupus familiaris (6.25%), Sus scrofa (3.75%), and Homo sapiens (3.75%) for their blood meal. Human blood was identified from two samples of C. oxystoma and a sample of C. imicola. Three dominant species including C. oxystoma, C. imicola, and C. actoni that were reported in the Hua Hin area prefer to feed on horse blood. Moreover, C. oxystoma, C. imicola, and C. bravatarsis also feed on canine blood. This study revealed the species of Culicoides in Hua Hin district, Thailand, after the AHS outbreak.

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

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.

Detection of Dirofilaria DNA and host blood-meal identification in Culicoides paolae biting-midges

The vectorial role of blood-sucking arthropods, other than mosquitoes, has been explored for Dirofilaria immitis and Dirofilaria repens which are filarioids of increasing interest due to their zoonotic potential. Given the expansion of canine heartworm infection in southern Europe due to D. immitis and the report of the infection in Linosa Island (Sicily, Italy), we investigated and focused on the potential involvement of Culicoides spp. in Dirofilaria spp. transmission as well as the blood-meal source in Dirofilaria spp. molecularly positive biting midges. Out of 1791 specimens collected 1773 were morphologically and molecularly identified as Culicoides paolae and 18 as Culicoides obsoletus complex. Of the 1596 females, 4 (0.26%) parous C. paolae tested positive for D. immitis and D. repens (i.e. 2 Culicoides specimens for each filarial species), of which D. immitis-positive samples fed on both humans and dogs and D. repens-positive samples fed only on humans. The detection of D. immitis and D. repens DNA in Culicoides midges suggests their potential involvement in the epidemiology of the filarial nematodes, which may be of medical and veterinary importance in hyper-endemic areas. Findings of this study shed new light on the epidemiology of Dirofilaria spp. infections indicating that further investigations are needed.

From Aedes to Zeugodacus: a review of dipteran body coloration studies regarding evolutionary developmental biology, pest control, and species discovery

Over the past two decades, evo-devo (evolution of development) studies have elucidated genetic mechanisms underlying novel dipteran body color patterns. Here we review the most recent developments, which show some departure from the model organism Drosophila melanogaster, leading the field into the investigation of more complex color patterns. We also discuss how the robust application of transgenic techniques has facilitated the study of many non-model pest species. Furthermore, we see that subtle pigmentation differences guide the discovery and description of new dipterans. Therefore, we argue that the existence of new field guides and the prevalence of pigmentation studies in non-model flies will enable scientists to adopt uninvestigated species into the lab, allowing them to study novel morphologies.

Update of the Culicoides (Diptera: Ceratopogonidae) species checklist from Algeria with 10 new records

BACKGROUND

The Culicoides fauna of Algeria has been historically investigated, leading to the description of many new species by Kieffer in the 1920s, Clastrier in the 1950s or Callot in the 1960s and to a comprehensive inventory by Szadziewski in the 1980s. The emergence of bluetongue in the late 1990s enhanced Culicoides collections made in the country over the last two decades, but information remained mostly unpublished. The aim of this study is therefore to provide a comprehensive and updated checklist of Culicoides biting midge species in Algeria.

METHODS

The literature (published and grey, in French and in English) from 1920 to date on Culicoides collections in Algeria was collected and analyzed in the light of the current taxonomic and systematic knowledge and methods. Fresh Culicoides material was also analyzed using light/suction trap collections carried out from November 2015 to September 2018 in nine localities of the 'wilayah' of Tiaret (northwestern Algeria). Slide mounted specimens were identified morphologically using the interactive identification key IIKC and original descriptions. Specimens were then compared with non-type material originating from different countries and partly with type material.

RESULTS

A total of 13,709 Culicoides, belonging to at least 36 species within 10 subgenera, were examined leading to 10 new records in Algeria, including C. chiopterus, C. dewulfi, C. navaiae, C. grisescens, C. paradoxalis, C. shaklawensis, C. simulator, C. univittatus, C. achrayi and C. picturatus. These new records and all previous records provided by the literature review were discussed.

CONCLUSIONS

We propose a Culicoides checklist for the Algerian fauna of 59 valid species, including species mainly with a large Palaearctic distribution and a specific Mediterranean distribution, and only a few species from the Afrotropical region. Among them, several species, mainly of the subgenera Avaritia and Culicoides, are confirmed or probable vectors of arboviruses important in animal health.