Extended Data Fig. 1: M. robertsii-colonized G. mellonella larval cadavers attract healthy insects to become infected.

(a) G. mellonella larva mycosed by the GFP-expressing M. robertsii strain WT-GFP visualized with bright field (BF, Left, scale bar: 0.5 cm), and epifluorescence using filters set to detect GFP fluorescence (GFP, Middle). WT-GFP spores on the cadaver (Right, scale bar: 10 μm). Healthy larvae used as controls for autofluorescence. (b) Healthy 3^rd instar D. melanogaster larvae were infected after attraction to M. robertsii-colonized G. mellonella cadavers. Left panel: WT-GFP CFUs per larval surface after 10 min exposure to cadavers. Right panel: insects after exposure to cadavers (top: healthy larvae as a control for autofluorescence; middle: dark green spores (arrowed) in guts just post-exposure; bottom: a WT-GFP-colonized D. melanogaster cadaver five days post-exposure). Scale bar: 0.1 cm. N: the number of insects assayed. (c) Spores attached to the cuticle of healthy G. mellonella larvae after 30 min exposure to M. robertsii-colonized G. mellonella cadavers. Left: WT-GFP CFUs per larval surface. Right: spores and fungal growth on larval cuticle [top: spores attached to intersegmental membranes after body surface sterilization (scale bar: 50 μm); middle: excised cuticle from sterilized insect placed on Metarhizium-selective medium (note: no fungal growth); bottom: fungal growth on excised cuticle from unwashed insects (scale bar: 1 cm)]. (d) Ingested spores in the alimentary canals of healthy G. mellonella larvae at different time points after 30 min exposure to WT-GFP-colonized G. mellonella cadavers. This figure supplement Fig. 1d. Note: ingested spores can infect healthy larvae by penetrating foreguts. S: spores; GL: fungal germlings; HP: fungal hyphae; H: insect hemocytes. ID: intima dentation in foregut crops; Hb: yeast-like hyphal bodies (blastospores) of the fungus. Scale bar: 50 μm. Images are representative of at least three independent experiments.