Predator avoidance, microhabitat shift, and risk-sensitive foraging in larval dragonflies.

Area of Science:

• Ecology
• Animal Behavior
• Freshwater Biology

Background:

• Dragonfly larvae (Anisoptera) are common in freshwater but often underutilized as prey by fish.
• This suggests larvae may have behaviors to minimize predation risk when co-occurring with fish.

Purpose of the Study:

• To determine if dragonfly larvae actively avoid fish.
• To assess if microhabitat use and foraging success are affected by predation risk.
• To correlate larval vulnerability with microhabitat preferences.

Main Methods:

• Field experiments: Manipulated bluegill presence in pond patches to observe larval colonization.
• Laboratory experiments: Assessed microhabitat use and foraging success of larvae under different predation risks and diel periods.
• Vulnerability assessment: Compared predation susceptibility of different larvae species to bluegills.

Main Results:

• Dragonfly larvae Tetragoneuria cynosura and Ladona deplanata avoided areas with bluegills.
• Predation risk increased microhabitat cover use in all tested species (Tetragoneuria, Ladona, Sympetrum semicictum) and reduced foraging in Tetragoneuria and Ladona.
• Larval vulnerability to predation correlated positively with use of exposed microhabitats.

Conclusions:

• Both fixed behaviors (habitat preference, diel shifts) and reactive behaviors (predator avoidance) reduce predation risk for dragonfly larvae.
• Larval vulnerability varies significantly among species and instars.
• Predation avoidance limitations may restrict the distribution of vulnerable dragonfly larvae species.