Prey preference in stoneflies: a comparative analysis of prey vulnerability

Area of Science:

• Ecology
• Predator-prey dynamics
• Aquatic entomology

Background:

• Predator size and prey morphology are critical factors influencing predation success.
• Understanding these interactions is key to comprehending aquatic food web dynamics.

Purpose of the Study:

• To investigate how predator size, prey size, and prey morphology affect the feeding success of the stonefly Hesperoperla pacifica.
• To quantify encounter rate (E/min), attack propensity (A/E), capture success (C/A), and handling time (HT).

Main Methods:

• Laboratory feeding trials using Hesperoperla pacifica and various mayfly and dipteran prey.
• Observations under dim red light to record predation event parameters.
• Analysis of prey dry weight relative to predator dry weight.

Main Results:

• Handling time (HT) decreased with increasing predator size and increased with the ratio of prey to predator dry weight.
• Capture success (C/A) was higher for dipterans than mayflies, particularly with larger stoneflies.
• Predator size influenced C/A within a specific prey size range.

Conclusions:

• Predator size and prey type significantly impact predation efficiency and reward.
• While predators did not consistently target the most profitable prey, size and morphology remain crucial factors in predator-prey interactions.
• Findings offer insights into predation dynamics in natural aquatic environments.