Figure 1.

The effects of ingested blood from an infected vertebrate host (large gray oval, top) on the insect midgut epithelium (large white squares, bottom). Dashed line indicates peritrophic matrix and black boxes indicate ingested factors/pathogens that are directly active or activated after reactions in the midgut lumen. Insect signaling pathways activated by these ingested factors and their downstream effects on insect immunity are indicated.