Parasites and Vectors (2016) 9 (440) - Role of different Culicoides ...

Cipriano Foxi, Gavino Delrio, Giovanni Falchi, Maria Giovanna Marche, Giuseppe Satta and Luca Ruiu (2016)
Role of different Culicoides vectors (Diptera: Ceratopogonidae) in bluetongue virus transmission and overwintering in Sardinia (Italy)
Parasites and Vectors 9 (440)
Abstract:
Background
Bluetongue (BT) epidemics have affected the Mediterranean island of Sardinia since 2000. While Culicoides imicola represents the main bluetongue virus (BTV) vector, other European Culicoides biting midges, possibly implicated in virus transmission, have been detected here. Understanding their distribution, seasonal abundance, and infection rates is necessary to predict disease incidence and spread across coastal and inland areas, and to define their role in virus overwintering.
Methods
Biting midge abundance was determined by light traps on selected farms representing diverse climatic conditions of Sardinia. Livestock-associated Culicoides species were morphologically and molecularly identified. Infection rates in prevailing midge species captured in 2013 during a BTV-1 outbreak were determined using RT-qPCR based virus detection in insect body pools, supplemented by specific body region analyses. The seasonal infection prevalence in Culicoides samples collected in 2001 in a BTV-2 affected farm was also determined.
Results
The Newsteadi complex (C. newsteadi species A and species B) prevailed among all biting midge species (47.7 %), followed by C. imicola (27.8 %) and the Obsoletus complex (C. obsoletus and C. scoticus) (17.6 %). Whilst Culicoides imicola was more abundant along the coast, the Newsteadi complex was frequently collected at higher altitude and the Obsoletus complex was notably associated to cattle farms. Culicoides pulicaris and C. punctatus abundance was found to be marginal in all farms. BTV was detected in parous female samples of all these species, and the full dissemination of the virus within the body of C. imicola, C. obsoletus, C. scoticus, and Newsteadi complex species was confirmed by analyses of thorax and head, containing salivary glands. Higher infection rates were associated with C. scoticus, C. newsteadi species A and species B, compared to C. imicola. The virus was detected in C. newsteadi species A and C. obsoletus in winter and spring, whereas it was mainly found in summer and autumn in C. imicola.
Conclusions
In Sardinia, bluetongue virus is transmitted by multiple Culicoides vectors, including C. imicola and the Newsteadi complex being the most important. The Newsteadi complex and other midge species can play an important role in internal areas and are likely to be directly involved in virus overwintering.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article
Database assignments for author(s): Luca Ruiu, Cipriano Foxi

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Culicoides imicola		Italy
	Culicoides obsoletus		Italy
	Culicoides pulicaris		Italy
	Culicoides scoticus		Italy
	Culicoides newsteadi		Italy
	Culicoides punctatus		Italy