Heavy and light chain homologs of ferritin are essential for blood-feeding and egg production of the ectoparasitic copepod Lepeophtheirus salmonis

The salmon louse, Lepeophtheirus salmonis, is a hematophagous ectoparasite of salmonid fish. Due to its blood-feeding activity, the louse is exposed to great amounts of iron, which is an essential, yet potentially toxic mineral. The major known iron storage protein is ferritin, which the salmon louse encodes four genes of (LsFer1-4). Two of the ferritins are predicted to be secreted. These are one of the heavy chain homologs (LsFer1) and the light chain homolog (LsFer2). Here, we perform functional studies and characterize the two secreted ferritins. Our results show that knocking down LsFer1 and LsFer2 both negatively affect the parasite's physiology, as it is not able to properly feed and reproduce. In a starvation experiment, the transcript levels of both LsFer1 and LsFer2 decrease during the starvation period. Combined, these results demonstrate the importance of these genes for the normal parasite biology, and they could thus potentially be targets for pest management.