Fig. 1

Usutu virus spreads within the Culex pipiens s.l. population through vertical transmission. Bubble plot representing the number of adult Cx. pipiens s.l. (red) and the number of adult Cx. pipiens s.l. reared from larvae collected in the field (blue) between January 2023 and January 2024 inclusive. Arrows mark detections of USUV RNA by RT-qPCR (n = 6 adults, n = 1 reared from larvae).