Predator interference effects on biological control: The "paradox" of the generalist predator revisited

TL;DR

This paper investigates how predator interference can lead to population explosions of generalist predators, explaining their effectiveness in biological control despite traditional theory suggesting they should be ineffective.

Contribution

It demonstrates that predator interference alone can cause finite-time blow-up in predator populations, providing a new explanation for the success of generalist predators in biological control.

Findings

Interference can cause predator population explosion.

Model exhibits Turing instability and chaos.

Time delay effects influence predator-prey dynamics.

Abstract

An interesting conundrum in biological control questions the efficiency of generalist predators as biological control agents. Theory suggests, generalist predators are poor agents for biological control, primarily due to mutual interference. However field evidence shows they are actually quite effective in regulating pest densities. In this work we provide a plausible answer to this paradox. We analyze a three species model, where a generalist top predator is introduced into an ecosystem as a biological control, to check the population of a middle predator, that in turn is depredating on a prey species. We show that the inclusion of predator interference alone, can cause the solution of the top predator equation to blow-up in finite time, while there is global existence in the no interference case. This result shows that interference could actually cause a population explosion of the top predator, enabling it to control the target species, thus corroborating recent field evidence. Our results might also partially explain the population explosion of certain species, introduced originally for biological control purposes, such as the cane toad (\emph{Bufo marinus}) in Australia, which now functions as a generalist top predator. We also show both Turing instability and spatio-temporal chaos in the model. Lastly we investigate time delay effects.