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

Abstract

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 (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.

On the explosive instability in a three‐species food chain model with modified Holling type IV functional response

“…This is achieved via Theorem . Although versions similar to this were simulated in , no rigorous proof was given. To this end, it would be interesting to explore the spatially explicit version, with the inclusion of time delay.…”

The Effects of Invasive Epibionts on Crab–mussel Communities: A Theoretical Approach to Understand Mussel Population Decline

“…As a future direction in modelling the crab-mussel-epibiont interaction, we would also like to examine interference effects [19,21,20]. This effect has often seen to be stabilising [34], and thus modeling interference among the crab population, at high epibiont density is also realistic.…”

Appearance of Temporal and Spatial Chaos in an Ecological System: A Mathematical Modeling Study

“…Zhang et al ( 2005 ) studied the dynamical behavior of a Holling I prey-predator model with mutual interference in the case of pest-free periodic solutions. Parshad et al ( 2016 ) stated that mutual interference between species can cause population explosion and mathematically termed this as finite time blow up.…”

“…Also, the study complied with self and cross-diffusion patterns. Upadhyay et al ( 2013 ) studied dynamics induced by the predator interference with generalist predator and Parsad et al ( 2016 ) extended this model and pointed out some other properties of predator interference. They also showed the spatial chaos and Turing instability for the model.…”