Fishless-stream mayflies express behavioral flexibility in response to predatory fish

Article Abstract:

The nymphs of the grazing mayfly, Baetis rhodani, are able to assess fish predation risks and respond fast by adopting a flexible avoidance behavior. Baetis nymphs with no prior fish experience increase their refuge use on exposure to live predatory fish but re-emerge the moment the predator disappears. The nymphs emerge from their refuges mainly during the onset of darkness in the presence of a fish model. Baetis nymphs stay unperturbed in response to chemical cues alone. The nymphs from streams without fish display more risk taking ability than those from streams with fish.

Behavior, Insects, Insect larvae, May-flies, Mayflies

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Evidence for a more effective signal in aggregated aposematic prey

Article Abstract:

Aposematic prey tend to gather together to ward off predators. Using chicks, 'Gallus gallus domesticus' as predators and the seed bug, 'Spilostethus panduras' as prey, the study reveals that aggregated prey produces greater unconditioned aversion in predators than solitary prey, indicating the effectiveness of grouping as a defense strategy. This type of aversion is like the predators' greater initial reluctance in attacking aposematic than cryptic prey.

Social behavior in animals, Animal social behavior

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Relative unpalatability of leaf beetles with either biosynthesized or sequestered chemical defence

Article Abstract:

A study of leaf beetles of the genus Oriena reveals that they use secretions of concentrated mixes of cardenolides or pyrrolizidine alkaloid-N oxides to make themselves unpalatable for consumption by predators such as red-winged birds. Predators use their olfactory nerves to smell beetles and reject those found with chemical secretions.

Analysis, Beetles, Animal defenses

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