Many insects use substrate-borne vibrations to transmit information regarding species identity, mate quality, food resources, or predation threats. In some treehopper species, aggregations of nymphs produce alarm signals when threatened by a predator to evoke maternal defense. In species without maternal care, nymphal signaling may serve to warn other nymphs about potential predation threats. We tested this hypothesis with nymphs of Enchenopa binotata. We predicted that when exposed to a stimulus that mimics a predation event, nymphs would respond with a context-specific signal. Aggregations of nymphs were exposed to a crushed nymph, not from their aggregation, on filter paper to simulate a predation event. Their calling behavior and movements were then monitored for five minutes. Control groups were exposed to blank filter paper and the same measurements were recorded. In every trial, the group exposed to the crushed nymph initiated a unique calling behavior, which was less repetitive and contained variable pulse lengths compared to their common calling behavior. Control groups produced these signals in only a third of the trials. These results suggest that E. binotata nymphs have a call that is specific to predation events. Possible functions of this “alarm signal” may be to coordinate or lower the threshold for dispersal.
Species 1: Homoptera Membracidae Enchenopa binotata (two-spotted treehopper)
Keywords: vibrational communication, predation
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