Host-feeding enhances stability of discrete-time host-parasitoid population dynamic models

TL;DR

This study uses a semi-discrete modeling approach to analyze how host-feeding behavior affects the stability of host-parasitoid populations, revealing that host-feeding alone does not stabilize but can enhance stability when combined with other mechanisms.

Contribution

It introduces a semi-discrete framework to incorporate mechanistic host-parasitoid interactions and examines the stabilizing effects of host-feeding within this model.

Findings

Host-feeding alone does not stabilize the system.

Combining host-feeding with density-dependent mechanisms stabilizes populations.

Host-feeding leads to higher host populations due to parasitoid inefficiency.

Abstract

Discrete-time models are the traditional approach for capturing population dynamics of a host-parasitoid system. Recent work has introduced a semi-discrete framework for obtaining model update functions that connect host-parasitoid population levels from year-to-year. In particular, this framework uses differential equations to describe the hosts-parasitoid interaction during the time of year where they come in contact, allowing specific behaviors to be mechanistically incorporated into the model. We use the semi-discrete approach to study the effects of host-feeding, which occurs when a parasitoid consumes a potential host larva without ovipositing. Our results show that host-feeding by itself cannot stabilize the system, and both the host and parasitoid populations exhibit diverging oscillations similar to the Nicholson-Bailey model. However, when combined with other stabilizing mechanisms such as density-dependent host mortality or density-dependent parasitoid attack rate, host-feeding expands the region of parameter space that allows for a stable host-parasitoid equilibrium. Finally, our results show that host-feeding causes inefficiency in the parasitoid population, which yields a higher population of hosts per generation. This suggests that host-feeding may have limited long-term impact in terms of suppressing host levels for biological control applications.