The Absence of Abdominal Pigmentation in Livestock Associated Culicoides following Artificial Blood Feeding and the Epidemiological Implication for Arbovirus Surveillance

Culicoides midges (Diptera: Ceratopogonidae), the vectors of economically important arboviruses such as bluetongue virus and African horse sickness virus, are of global importance. In the absence of transovarial transmission, the parity rate of a Culicoides population provides imperative information regarding the risk of virus dispersal. Abdominal pigmentation, which develops after blood feeding and ovipositioning, is used as an indicator of parity in Culicoides. During oral susceptibility trials over the last three decades, a persistent proportion of blood engorged females did not develop pigment after incubation. The present study, combining a number of feeding trials and different artificial feeding methods, reports on this phenomenon, as observed in various South African and Italian Culicoides species and populations. The absence of pigmentation in artificial blood-fed females was found in at least 23 Culicoides species, including important vectors such as C. imicola, C. bolitinos, C. obsoletus, and C. scoticus. Viruses were repeatedly detected in these unpigmented females after incubation. Blood meal size seems to play a role and this phenomenon could be present in the field and requires consideration, especially regarding the detection of virus in apparent “nulliparous” females and the identification of overwintering mechanisms and seasonally free vector zones.

Distribution of Fly Pests in a Farm in Plateau State, Nigeria

An evaluation of fly pests of cattle was conducted in Federal College of Animal Health and Production Technology (FCAH&PT) Farm, Chaha Village, Jos South Local Government Area, Plateau State, Nigeria between August and October, 2020. Samples were collected from the farm weekly for three months. A total of nine hundred and nineteen (919) adult dipterous flies comprising fifteen species in eight genera across the three sub-orders were caught and identified using aerial sweeping hand net, light trapping and aerial insecticide spray. Phlebotomus papaltasi (44.18%) was the most prevalent while Simulium damnosum (0.22%) was the least. Others were Musca domestica (17.73%), Stomoxys calcitrans (11.43%), Culicoides species (10.99%), Musca autumnalis (10.23%), mosquitoes – Anopheles gambiae/Culex quequinfasciatus (4.89%) and Tabanus species (0.33%). The haematophagous flies (72.04%) out-numbered the non-haematophagous flies (27.96%) and the number of females collected/caught 780 (84.87%) were higher than the males 139 (15.13%). The highest collections were made in October (353 representing 38.41%) while September had the lowest (263 /28.62%). The study established the presence of fly pests in the farm and recommends that appropriate control measures should be put in place to forestall any disease outbreak.

Morphological Keys for the Identification of Tunisian Culicoides Biting Midges (Diptera: Ceratopogonidae)

Culicoides biting midges are tiny blood-feeding insects of several diseases with veterinary and public health significance, including Bluetongue in ruminants, African horse sickness in equids and filarial diseases like Onchocercosis and Mansonellosis affecting various species such as humans. Their identification depends basically on the microscope examination of key morphological characters. Consequently, identification keys are important to any non experiment working with these biting midges. The Tunisian fauna of Culicoides biting midges consists of 35 species, whose morphological delineation may be troublesome for non-taxonomists. In response to this situation, and for the first time a key to the adult Culicoides species in Tunisia was prepared.

Validation of an Effective Protocol for Culicoides Latreille (Diptera: Ceratopogonidae) Detection Using eDNA Metabarcoding

eDNA metabarcoding is an effective molecular-based identification method for the biosurveillance of flighted insects. An eDNA surveillance approach maintains specimens for secondary morphological identification useful for regulatory applications. This study identified Culicoides species using eDNA metabarcoding and compared these results to morphological identifications of trapped specimens. Insects were collected using ultraviolet (UV) lighted fan traps containing a saturated salt (NaCl) solution from two locations in Guelph, Ontario, Canada. There were forty-two Culicoides specimens collected in total. Molecular identification detected four species, C. biguttatus, C. stellifer, C. obsoletus, and C. mulrennani. Using morphological identification, two out of these four taxonomic ranks were confirmed at the species level (C. biguttatus and C. stellifer) and one was confirmed at the subgenus level (Avaritia [C. obsoletus]). No molecular detection of Culicoides species occurred in traps with an abundance of less than three individuals per taxon. The inconsistency in identifying Culicoides specimens to the species level punctuates the need for curated DNA reference libraries for Culicoides. In conclusion, the saturated salt (NaCl) solution preserved the Culicoides’ morphological characteristics and the eDNA.

The Potential Significance of Biting Midge (Culicoides Latrielle) Population in Nigeria

CULICOIDES species are well-known as troublesome biters and transmitters of various diseases to man and animals. Surveys in Nigeria show Culicoides species to be well distributed throughout the vegetational zones. The possible direct and indirect effects of such a distribution on production are discussed.