Figure 4.

The impact of Wolbachia infection and larval competition on WNV infection in Culex quinquefasciatus. Prevalence of WNV infection was measured in the bodies (A), legs (B), and saliva (C) of female Cx. quinquefasciatus mosquitoes at 14 days post-oral challenge. Significant increases in the prevalence of infection were associated with increased competition stress in legs (dissemination), and saliva (transmission) specimens, but not in mosquito bodies (Logistic Regression: p < 0.05). Filled areas on donut charts and central numbers represent the percentage of specimens positive for WNV via plaque-forming assay. WNV load in bodies (D), legs (E), and saliva (F) was also determined via plaque-forming assay. Overall, increased competition stress led to increased WNV load in mosquito bodies and legs (Two-way ANOVA; p < 0.05). However, Wolbachia infection reduced WNV loads in mosquito bodies at low and medium competition stress treatments (Two-way ANOVA: p < 0.01). No effects of competition or Wolbachia were seen in saliva samples. Dots represent WNV load values from individual mosquito tissues/saliva samples. Horizontal lines indicate treatment means ± s.e.m. Different lower-case letters above data sets indicate statistically significant differences between treatment groups determined via pairwise comparisons.