Attack by a common parasitoid stabilizes population dynamics of multi-host communities

Area of Science:

• Ecology
• Population Dynamics
• Theoretical Ecology

Background:

• Host-parasitoid interactions are fundamental to community dynamics.
• Constant parasitoid attack rates (Type I) often lead to unstable population dynamics.
• Non-linear functional responses, like Type III, can alter interaction stability.

Purpose of the Study:

• To model the population dynamics of two host species and a shared parasitoid.
• To investigate the stabilizing effect of a Type III functional response in a generalist parasitoid.
• To explore how host species asymmetry and different functional responses influence community stability.

Main Methods:

• Utilized a discrete-time mathematical model to simulate year-to-year population densities.
• Analyzed scenarios with two hosts sharing a Type III response parasitoid.
• Examined cases where one host experienced a Type I response and the other a Type III response.

Main Results:

• Sufficiently rapid acceleration in parasitoid attack rate (Type III) stabilizes three-species dynamics.
• Host species asymmetry can lead to destabilization when one host is removed.
• A Type III response to even a single host species can stabilize the entire three-species interaction.

Conclusions:

• Generalist parasitoids employing a Type III functional response are crucial for stabilizing host-parasitoid communities.
• This stabilizing effect is observed even in complex apparent competition scenarios.
• The functional response type is a key factor in determining the stability of multi-species ecological interactions.