Cannibalism and the stage-dependent transmission of a viral pathogen of the Indian meal moth, Plodia interpunctella

1. The transmission of an insect pathogen by cannibalism was studied by a series of choice and no-choice experiments. 2. Infection of Plodia interpunctella larvae with a granulosis virus occurred through cannibalism of infected larvae. 3. Depending on the larval instars of the cannibal and the victim relative to each other, preferential cannibalism of both infected and healthy larvae was observed. 4. Larvae cannibalise healthy, less vulnerable larvae preferentially, but it is argued that there is no evidence that they are avoiding infection. 5. The victim cannibalised can be explained as a balance between the reduced risk of injury and the ease of cannibalism of moribund infected individuals on the one hand and the greater food resource value of healthy individuals on the other. 6. The implications for the insect population dynamics of the transmission of the pathogen via cannibalism and the effective removal of infective particles through cannibalism by immune stages are discussed.