Relative size matters: eyespots on large insect prey deter small arthropod predators

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Eyespots are common in nature and thought to deter predators.
• Previous research focused on avian predators, with limited understanding of arthropod predator interactions.

Purpose of the Study:

• To investigate the effectiveness of eyespots as an anti-predator defense against arthropod predators.
• To determine how prey size relative to predator size influences the protective function of eyespots.

Main Methods:

• Experiments using salticid spiders and Chinese mantids presented with mealworms with and without eyespots.
• Observed attack times of Chinese mantids on hawkmoth larvae of varying sizes and with/without eyespots.

Main Results:

• Eyespots deterred predation by arthropod predators when insect larvae were large relative to the predator.
• Eyespots promoted attacks when insect larvae were small compared to the predator.
• Arthropod predators showed aversion to large prey with eyespots.

Conclusions:

• The anti-predator efficacy of eyespots is size-dependent in arthropod-predator interactions.
• Eyespots may serve different functions depending on the predator type and relative prey size.
• Findings help explain the presence of eyespots in medium-sized caterpillars against avian predators.