Fig. 3.

Effect of antibiotic treatment on susceptibility of biting midges and mosquitoes for arthropod-borne viruses. a Mean infection rates of Schmallenberg virus (SBV) in biting midges (N_nubeculosus = 196, N_sonorensis = 44; untreated: white bars) fed on glucose solution and glucose solution with antibiotics (N_nubeculosus = 275, N_sonorensis = 47; antibiotic-treated: gray bars). Culicoides nubeculosus and C. sonorensis were blood-fed 3 to 6 days after emergence and tested for virus infection after an incubation period of 10 days. Error bars indicate the SEM. b Average titers of SBV in infected biting midges (C. nubeculosus and C. sonorensis) for both treatments (untreated: white dots and antibiotic-treated: gray dots). Each dot represents the titer for one individual biting midge and horizontal bars indicate the median. c Mean infection rates of Zika virus (ZIKV) and chikungunya virus (CHIKV) in Aedes aegypti mosquitoes (N = 100 for each group) fed on glucose solution (untreated: white bars) and glucose solution with antibiotics (antibiotic-treated: gray bars). Mosquitoes were blood-fed 4 to 8 days after emergence and tested for virus infection after an incubation period of 10 days. Error bars indicate the SEM. d Average titer of ZIKV and CHIKV in infected mosquitoes for both treatments (untreated: white dots and antibiotic-treated: gray dots). Each dot represents the titer for one individual mosquito and horizontal bars indicate the median. e Percentage positive saliva samples (transmission efficiency) for untreated (white bars) and antibiotic-treated (gray bars) Ae. aegypti mosquitoes exposed to ZIKV or CHIKV (N = 100 for each group). Error bars indicate the SEM. f Average titer of ZIKV- and CHIKV-positive saliva samples of untreated (white dots) and antibiotic-treated (gray dots) Ae. aegypti mosquitoes. No positive saliva samples were found for ZIKV-infected mosquitoes. Each dot represents the titer for one individual mosquito and horizontal bars indicate the median