Vector competence of pre-alpine Culicoides (Diptera: Ceratopogonidae) for bluetongue virus serotypes 1, 4 and 8

Parasites & Vectors

Table 3 Description of Culicoides populations from different areas screened for virus presence in the head (dissemination) after exposure to blood spiked with bluetongue virus (BTV-1, BTV-4 or BTV-8)^a

Area	BTV strain	No. Culicoides: blood-fed/examined for BTV/positive for BTV^b (infection rate, %)	Species^c
Area	BTV strain		RT-qPCR positive species (% of all specimens tested)	C_q range	RT-qPCR negative species (% all specimens tested)
Swiss Plateau (650 masl)	BTV-1	160/61/27 (44)	24 C. scoticus (39)	33.2–41.3	16 C. scoticus (26)
			2 C. obsoletus (3)	35.7–39.6	16 C. obsoletus (26)
			1 C. pallidicornis (2)	39.6	2 unknown (3)^d
	BTV-4	242/104/2 (2)	2 C. scoticus (3)	45.4–48.9	46 C. obsoletus (75)
					7 unknown (11)
					5 C. scoticus (8)
					1 C. chiopterus (2)^d
	BTV-8	407/145/3 (2)	2 C. obsoletus (7)	40.2–40.9	20 C. obsoletus (67)
			1 C. pallidicornis (3)	39.9	6 C. scoticus (20)
					1 C. punctatus (3)^d
Pre-alpine I`(≈1550 masl)	BTV-1	239/64/1 (1.5)	1 C. reconditus-like^e (1.5)	40.3	28 C. grisescens II (44)
					23 C. obsoletus (36)
					4 C. grisescens I (6)
					4 unknown (6)
					2 C. scoticus (3)
					1 C. pulicaris (1.5)
					1 C. deltus (1.5)
	BTV-4	107/35/0 (0)			nd
	BTV-8	24/18/0 (0)			nd
Pre-alpine II (2030 masl)	BTV-1	2/1/0 (0)			1 C. grisescens II (100)
	BTV-4	168/17/0 (0)			nd
	BTV-8	202/103/0 (0)			nd

Abbreviations: unknown, species not included in database; nd, not done
^aTitres (log₁₀TCID₅₀/ml) of the blood meals were 5.50 (BTV-1) or 6.25 (BTV-4, BTV-8). Engorged females were incubated for eight days under a fluctuating temperature regime (13–25 °C, average 19 °C)
^bC_q values < 50
^cSpecies identified by MALDI-TOF MS analyses
^dAll specimens examined for BTV dissemination identified to species level (experiments with BTV-1, collected in September-October) or proportions with randomly selected specimens (biting midges from experiments with BTV-4, collected in July-August, and BTV-8, collected in June)
^eIdentified by PCR/sequencing (96% identity with GenBank entry of C. reconditus)

ISSN: 1756-3305