Table 2.

Parameter estimates used in calculations of vectorial capacity for WNV in Culex tarsalis mosquitoes feeding on common grackles whereby MF enhancement is invoked (VC_YES) or not invoked (VC_NO)

Scenario	Biting rate (ma)a	Avian host preference (a)b	Vector competence (b)c	Daily survival (P)d	EIP (T)e
VCYES	14.1	0.176	1.00	0.80	5 d
VCNO	14.1	0.176	0.82	0.80	12 d

^aBiting rate (no. bites/bird/night)—based on the avg no. of engorged Culex tarsalis captured over 25 trap-nights by net traps baited with four species of wild birds (Anderson and Brust 1995, 1997; Lura et al. 2012).

^bAvian host preference—based a bird blood index of 0.88 during the summer months in California (Thiemann et al. 2011) divided by a gonotrophic value of 5 d (McHugh 1990).

^cVector competence—based on experimental transmission rates of WNV (Crow 397–99 strain) for orally exposed Cx. tarsalis (VC_NO; i.e., 58/71) and for disseminated infections of Cx. tarsalis (VC_YES; i.e., 6/6) (Turell et al. 2002).

^dDaily survival—based on parity rates of wild-caught Cx. tarsalis in Imperial and Coachella Valleys, CA, during the summer months (Reisen et al. 1995).

^eExtrinsic incubation period (EIP)—the `normal' EIP (i.e., VC_NO) of 12 d is based on orally exposed Cx. tarsalis held at 26°C where dissemination rate exceeded 50% (Anderson et al. 2012). The MF-enhanced EIP (i.e., VC_YES) of 5 d was calculated as 42.4% of normal EIP, based on the avg reductions of EIP observed with dengue 1 virus development within Ae. aegypti fed blood that was either dually infected (virus + Brugia malayi MF) or singly infected (virus only) (Vaughan et al. 2009).