Insects feeding on desert bighorn sheep, domestic rabbits, and Japanese quail in the Santa Rosa mountains of southern California.

Desert bighorn sheep (Ovis canadensis cremnobates), a domestic rabbit (Oryctolagus cuniculus), and Japanese quail (Coturnix japonica) were used as bait animals to collect blood-feeding flies in an area of active blue-tongue and epizootic hemorrhagic disease virus transmission. Precipitin tests were used to confirm the blood source where feasible. Eight species of Culicoides, members of the Leptoconops kerteszi group, Simulium spp., Anopheles franciscanus, and Stomoxys calcitrans were collected from the bighorn sheep. Feeding on the bighorn sheep by Culicoides brookmani (n = 25), C. variipennis (n = 6), C. cacticola (n = 1), and Simulium spp. (n = 3) was confirmed by precipitin testing. Primary species attacking the rabbit were C. brookmani, C. variipennis, and the L. kerteszi group. The quail were attacked primarily by members of the C. copiosus group and the L. kerteszi group.

Spatial and seasonal distribution of potential vectors of hemorrhagic disease viruses to peninsular bighorn sheep in the Santa Rosa Mountains of southern California.

Blood-feeding midges (Culicoides sp. and Leptoconops sp.) were sampled in the Santa Rosa Mountains, Riverside County, California (USA), to determine which species might be involved in the transmission of bluetongue and epizootic hemorrhagic disease viruses to peninsular bighorn sheep (Ovis canadensis cremnobates). Host-seeking midges were sampled with CO2-baited suction traps over a period of 30 mo. Nineteen species of Culicoides and seven of Leptoconops were collected. Five of the Culicoides sp. recovered are previously undescribed. The most abundant and widely distributed Culicoides sp. during spring (presumed virus transmission period to lambs) were C. (Selfia) brookmani, C. variipennis, C. (Avaritia) sp. (a new species near C. pusillus), and C. lahontan. Of these, C. brookmani (all elevations) and C. (Avaritia) sp. (elevations greater than 750 m) were common in the mountainous terrain inhabited by bighorn sheep. Culicoides variipennis, a vector of bluetongue virus in agricultural settings, and C. lahontan were numerous in sandy washes but were much less common in the mountains themselves. Leptoconops belkini and L. foulki were occasionally common in upper Deep Canyon in spring (April-June), while L. torrens was very abundant in the same area for 2 wk following heavy summer rains. Parity (an indicator of longevity and success in finding hosts and oviposition sites) in mountain areas was very low in C. variipennis (5%), low-moderate in C. (Avaritia) sp. (13%) and C. lahontan (21%), and relatively high in C. brookmani (40%). Vectorial capacity of Culicoides spp. for these hemorrhagic disease viruses is discussed, and it is suggested that species in addition to C. variipennis be considered as potential vectors of hemorrhagic disease viruses to desert bighorn sheep.