Gut cancer increases the risk forDrosophilato be preyed upon by hunting spiders

Abstract

<jats:title>Abstract</jats:title><jats:p>Predators are thought to prey on individuals that are in poor physical condition, although the evidence supporting this is ambiguous. We tested if sick individuals where more predated using <jats:italic>Drosophila melanogaster</jats:italic> flies as manipulable preys. We asked if hunting spiders, trapped from the wild, would selectively prey upon flies with compromised health (i.e. chronically infected or cancerous) versus healthy flies under laboratory conditions. Flies chronically infected with the bacterium <jats:italic>Providencia rettgeri</jats:italic>, a natural <jats:italic>Drosophila</jats:italic> pathogen, were not selectively preyed upon by neither jumping spiders, nor small wolf spiders. We suggest that this result support the hypothesis that chronic infection is associated with reduced symptoms to avoid the predation of their host. We then induced colon cancer in some of the flies and asked if the presence of cancer led to selective predation; there is little evidence for this, even in vertebrates. As the cancer developed, the incidence of predation by jumping spiders on the afflicted flies increased. We conclude that predation can impact disease lethality even in invertebrate species and that cancer is a factor in selective predation. Our results may explain why early tumors, but not metastasized cancers, are commonly detected in organisms in the wild, as cancer bearing individuals are rapidly eliminated due to the strong selective pressure against them.</jats:p>

A review of the methods used to induce cancer in invertebrates to study its effects on the evolution of species and ecosystem functioning

“…), predicted to be quickly eliminated by predators, or to become preferential hosts for parasitic species. Similarly, predators unable to sustain tumour burdens have enhanced risk of death (Boutry, Tissot, et al, 2022; Duneau & Buchon, 2021; Perret et al, 2020). However, not all cancers die with their host.…”