Figure 1.

Upper: “drink-blot” experiments performed with two species of moths and two species of butterflies. The insects were allowed to drink from a sugar solution absorbed by pieces of nitrocellulose membrane. The membranes were treated, as in Western blot experiments, with the antiserum against HarmCSP4 as the first antibody, then with HRP-linked or FITC-linked second antiserum. Parallel experiments where the first antiserum was replaced with pre-immune serum did not show clear spots when treated with FITC-linked second antiserum (Supplementary Figure S3). Lower: SDS-PAGE and Western blot experiments on crude extracts from the proboscis of the species indicated. The antiserum against HarmCSP4 reacts with a band at the expected molecular mass of around 13 kDa. M: protein ladder; C: crude extract stained with Coomassie; WB: Western blot reaction.