Avian Predators Avoid Attacking Fly-Mimicking Beetles: A Field Experiment on Evasive Mimicry Using Artificial Prey

Area of Science:

• Ecology
• Evolutionary Biology
• Behavioral Ecology

Background:

• Neotropical beetles often mimic red-eyed flies, presumed to be evasive mimicry models.
• The role of predators in selecting for these evasive mimicry patterns in natural settings is not well understood.

Purpose of the Study:

• To experimentally test the role of predators in selecting for evasive mimicry in beetles.
• To investigate specific traits, such as coloration and size, that influence predation rates on mimic beetles.

Main Methods:

• A field experiment using non-toxic plasticine replicas of a fly-mimicking beetle species.
• Replicas were manipulated in coloration (reddish eye spots vs. control) and size, and exposed on host plants.
• Predation signs (beak marks) were analyzed to identify predator type and selective pressures.

Main Results:

• Replicas with reddish eye spots simulating flies had significantly lower predation rates than controls.
• Bird beak marks were the most common sign of attack, indicating avian predation pressure.
• Predation rates were higher for replicas matching the beetle's size and during warmer, wetter seasons.

Conclusions:

• Predator-mediated selection significantly influences the evolution of evasive mimicry in beetles.
• Reddish eye spots mimicking flies are a crucial trait for reducing avian predation.
• Beetle size and seasonal activity also play roles in predation dynamics.