Laboratory Rearing of Culicoides stellifer (Diptera: Ceratopogonidae), a Suspected Vector of Orbiviruses in the United States

Laboratory rearing procedures of Culicoides stellifer Coquillett (Diptera: Ceratopogonidae) were evaluated with an aim towards colonization of this species. Eggs collected from field-collected gravid females were placed on 0.25% agar slants and given a diet of 1) nematodes (Panagrellus redivivus Linnaeus), 2) nematodes + lactalbumin and yeast (LY), 3) microbes from nematode medium, and 4) tap water (autoclaved). Complete larval development to adult stage occurred only in two treatments: 1) nematodes and 2) nematodes + LY. Culicoides stellifer larvae could not survive beyond 1 wk on a diet of microbes alone or in the sterile water treatment. Larval survival rates were high using nematode diet (79.2 +/- 11.3% [mean +/- SE]) but were slightly lower in the nematode + LY group (66.5 +/- 19.6%). Larval stage lasted ~21 d in both treatments. Sex ratio of F1 adults was ~1:1 (M:F) using nematode diet but was male biased (~2:1) with nematode + LY diet. These findings collectively suggest that a microbial community is required for midge larvae, either to support invertebrate prey base or as a potential food source. But in the present study, the supplied microbes alone were not sufficient to support midge survival/development. It appears that other nutritional components may also be essential to support the larval survival/development of C. stellifer. Overall, a simple diet of bacterial feeding nematodes and their associated microorganisms can be used to rear C. stellifer larvae under laboratory conditions. However, captive mating in F1 adults poses a major obstacle for successful colonization of this species currently.