Behavioural response of Lucilia sericata to a decaying body infested by necrophagous insects

Numerous insect species are necrophagous, with Dipterans and Coleopterans
being themost abundant on a corpse. Whether the presence of necrophageous species
on a corpse affects the attraction of adult blowflies to the corpse is sparsely studied.
We test the hypothesis that Lucilia sericata can discriminate the odour of a noncolonized
cadaver from the odour of a cadaver on which conspecific and/or heterospecific
necrophagous insects are feeding. The volatile organic compounds are collected from
decomposing rats under four modalities: (i) in the absence of insects; (ii) in the presence
of L. sericata adults; (iii) in the presence of Dermestes frischii adults; (iv) and in
the presence of both D. frischii adults and L. sericata adults. During a multiple-choice
bioassay, blowflies are exposed to the four odour samples, and are shown to prefer the
odour of a corpse where conspecific larvae are present.We also expect blowflies to avoid
cadavers on which predators where present, although L. sericata are not repulsed by the
odour of a cadaver colonized by hide beetles. We then compare the average quantities
of all 61 volatile molecules identified, finding that the presence of necrophagous insects
impacts some of them. However, none of the volatile organic compounds previously
reported in the literature as being attractive for L. sericata adults are impacted by the
presence of necrophagous insects. The results of the present study suggest that blowfly
larvae modify the volatilome of a corpse, enabling adults to discriminate a colonized
from a noncolonized corpse.