Molecular identification of bloodmeals and species composition in Culicoides biting midges

Investigations of host preferences in haematophagous insects, including Culicoides biting midges (Diptera: Ceratopogonidae), are critical in order to assess transmission routes of vector‐borne diseases. In this study, we collected and morphologically identified 164 blood‐engorged Culicoides females caught in both light traps and permanent 12‐m high suction traps during 2008–2010 in Sweden. Molecular analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene in the biting midges was performed to verify species classification, discern phylogenetic relationships and uncover possible cryptic species. Bloodmeal analysis using universal vertebrate cytochrome b primers revealed a clear distinction in host selection between mammalophilic and ornithophilic Culicoides species. Host sequences found matches in horse (n = 59), sheep (n = 39), cattle (n = 26), Eurasian elk (n = 1) and 10 different bird species (n = 18). We identified 15 Culicoides species previously recorded in Scandinavia and four additional species haplotypes that were distinctly different from the described species. All ornithophilic individuals (n = 23) were caught exclusively in the suction traps, as were, interestingly, almost all mammalophilic species (n = 41), indicating that many biting midge species may be able to cover long distances after completing a bloodmeal. These results add new information on the composition of Culicoides species and their host preferences and their potential long‐distance dispersal while blood‐engorged.     

Influence of carbon dioxide on numbers of Culicoides midges collected with suction light traps in South Africa

To implement risk management against diseases transmitted by species of Culicoides Latreille, 1809 (Diptera: Ceratopogonidae), it is essential to identify all potential vectors. Light traps are the most commonly used tool for the collection of Culicoides midges. Given the indiscriminate artificial attraction of light, traps will collect all night‐flying insects rather than only livestock‐associated Culicoides midges. Factors that may increase the efficacy of traps, especially for livestock‐associated Culicoides midges, require investigation. In the present study, results obtained with Centers for Disease Control (CDC) and Onderstepoort light traps baited with carbon dioxide (CO₂) were compared with those of unbaited controls. Comparisons were made using two replicates of a 4 × 4 randomized Latin square design. With both trap types, the mean numbers of Culicoides midges collected in 16 baited traps were higher than those caught in 16 unbaited traps. Although exceptionally low numbers were collected with the CDC traps, the increases in the numbers and frequency of collection of Culicoides imicola Kieffer, 1913 were more pronounced in the CDC traps compared with the Onderstepoort traps. These results indicate that the addition of CO₂ may increase the efficiency of these traps for the collection of C. imicola and other livestock‐associated Culicoides species.     

Larval development and emergence sites of farm‐associated Culicoides in the United Kingdom

Culicoides biting midges (Diptera: Ceratopogonidae) are the biological vectors of internationally important arboviruses of livestock including bluetongue virus (BTV). Information on the habitats used by Culicoides for larval development is valuable for establishing targeted vector control strategies and for improving local scale models of vector abundance. This study combines emergence trap collections of adult Culicoides identified using molecular markers and physiochemical measurements of habitats to investigate larval development sites of Palaearctic Culicoides in South East England. The known range of larval habitats for several Culicoides species is extended and the potential BTV vector species C. obsoletus and C. scoticus are confirmed to co‐occur in many larval habitats. The presence of emerging C. obsoletus was favoured by increasing substrate moisture level [odds ratio (OR) 6.94 (2.30; 20.90)] and substrate pH [OR 4.80 (1.66; 13.90)] [bias‐corrected D_xy: 0.68; area under the curve (AUC): 0.86] rather than any particular larval habitat type, as expected for a species with relatively wide larval habitat preference. Of the newly emerged sub‐genus Avaritia individuals collected, 23% were observed to have a degree of abdominal pigmentation commonly inferred to indicate parity. If consistent across species and locations, this observation represents a potential source of error for age structure analyses of Culicoides populations.     

Emergence of Culicoides obsoletus group species from farm‐associated habitats in Germany

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) may transmit several arboviruses to ruminant livestock. The species of the Obsoletus group are considered to be among the most important vectors of bluetongue virus (BTV) in northern Europe. As agricultural environments offer suitable habitats for the development of their immature stages, the emergence of adult Culicoides from potential breeding sites was investigated at 20 cattle farms throughout Germany in 2012 and 2013. In analyses of species‐specific habitat preferences and relationships between Culicoides abundance in breeding substrates and their physicochemical characteristics, dungheaps emerged as the most important substrate for the development of Culicoides obsoletus sensu stricto (s.s.) (Meigen), whereas Culicoides chiopterus (Meigen) and Culicoides dewulfi Goetghebuer were generally restricted to cowpats. A decreasing pH value was associated with a higher abundance or a higher probability of observing these three species. Furthermore, the abundance of C. obsoletus s.s. was positively related to increasing moisture. Dungheaps were very productive breeding sites for this species and are therefore suggested as a target for potential control measures.     

Studies on the possible role of cattle nuisance flies, especially Hydrotaea irritans, in the transmission of summer mastitis in Denmark

The summer mastitis pathogens Actinomyces pyogenes, Peptococcus indolicus, Bacteroides melaninogenicus ss. levii, Fusobacterium necrophorum and Streptococcus dysgalactiae were isolated from the polyphagous symbovine dipterans Hydrotaea irritans (Fallén) and Morellia sp. caught around dairy heifers on pasture, but not from the haematophagous species Haematobia irritans (L.), Haematobosca stimulans (Meigen), Culicoides sp. and Simulium sp. Secretions from clinical cases of summer mastitis proved to be sources of summer mastitis bacteria for more than 3 weeks despite antibiotic treatment and teat amputation. Taking into account the seasonal activity pattern of Hydrotaea irritans and its topographical distribution on grazing cattle, it appears evident that this fly may play a central role in the establishment and maintenance of the bacterial contamination with summer mastitis pathogens on the teats of healthy cattle. In the present study the survival of A.pyogenes and P.indolicus for 7 days in experimentally infected Hydrotaea irritans, as demonstrated by the recovery of these microorganisms from agar plates exposed to live infected flies, is described. However, experimental transmission of summer mastitis from sick to healthy heifers by Hydrotaea irritans proved unsuccessful.     

A quantitative analysis of wing pattern in the Culicoides pulicaris species group (Diptera: Ceratopogonidae)

Wing pattern is very important in the taxonomy of the genus Culicoides. To date no quantitative method has been described permitting the inclusion of wing pattern characters with traditional morphometric characters in multivariate studies.
Two alternative methods for quantifying wing pattern are developed here. The first superimposes a grid onto a wing and the 420 'characters' generated are scanned for pigmentation. A second method recognizes 13 pattern elements from a sequentially arranged series of wings. The latter method was considered superior for several reasons: it uses logically acceptable characters, reduces character redundancy and allows easier and faster coding.
Empirical multivariate studies show the pattern element method to be of taxonomic value in the difficult C. pulicaris group, and to have considerable potential for use in this and other groups of Diptera with patterned wings.     

Species Diversity and Seasonal Distribution of Culicoides spp. (Diptera: Ceratopogonidae) in Jeju-do,Republic of Korea

Biting midges belonging to the genus Culicoides (Diptera: Ceratopogonidae) were collected by Mosquito Magnet^® and black light traps at 5 sites on Jeju-do, Republic of Korea (Korea), from May-November 2013 to determine species diversity and seasonal distribution. A total of 4,267 specimens were collected, of which 99.9% were female. The most common species was Culicoides tainanus (91.8%), followed by C. lungchiensis (7.2%) and C. punctatus (0.6%), while the remaining 4 species accounted for <0.5% of all Culicoides spp. that were collected. High numbers of C. tainanus were collected in May, followed by decreasing numbers through August, and then increasing numbers through November when surveillance was terminated. Peak numbers of C. lungchiensis were collected during September, with low numbers collected from May-August and October-November. The presence of C. lungchiensis in Korea was confirmed by morphological and molecular analyses.     

海南霸王岭发现库蠓属二新种(双翅目:蠓科)

2009年在海南霸王岭(19.0°N,109.0°E)的昆虫调查采集中,采获许多蠓类,经分类研究,发现其中有二种库蠓新种,分别命名为霸王岭库蠓Culicoides bawanglingensis Yu,Wang and Chen,sp.nov.和曲囊库蠓Culicoides reduncutheca Yu,Wang and Tan,sp.nov.。这2种库蠓属新种的模式标本珍藏于医学昆虫标本馆(北京丰台东大街20号,100071)。