Keeping cool: Kissing bugs avoid cannibalism by thermoregulating
2018
Lazzari, Claudio R. | Fauquet, Aurélie | Lahondère, Chloé
Kissing bugs possess a highly developed thermal sense and when starved, they attempt to bite any object which temperature is close to that of a warm-blooded host. At each feeding event, these insects take massive meals in just a few minutes. One could then expect fed-bugs being heated-up by the ingested warm blood and so becoming attractive to starved conspecifics. This is not however the case, arising the question about why cannibalism is very rare among these insects. Recently, the ability of thermoregulating during feeding has been demonstrated in Rhodnius prolixus. These bugs possess a countercurrent heat-exchanger that cools down the ingested blood, before it reaches the abdomen. We hypothesise that avoiding thermal stress is not the only adaptive advantages of this mechanism, but could also help avoiding cannibalism. We tested this hypothesis by quantifying cannibalism by never-fed first-instar larvae on: (1) just-fed 5th instar bugs, (2) artificially heated just-fed bugs, (3) heated or (4) non-heated objects of the same size. In line with our hypothesis, non-heated just-fed bugs were not attacked by the 1st instar larvae, whereas heated bugs and object triggered biting behaviour in starved bugs, which performed either cleptohaematophagy or haemolymphagy on heated bugs. We conclude that cannibalism triggered by thermal stimuli has been one of the selection pressures that gave origin to thermoregulation during feeding on kissing bugs.
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