A cascade of destabilizations: Combining Wolbachia and Allee effects to eradicate insect pests

Abstract

Abstract1. The management of insect pests has long been dominated by the use of chemical insecticides, with the aim of instantaneously killing enough individuals to limit their damage. To minimize unwanted consequences, environmentally friendly approaches have been proposed that utilize biological control and take advantage of intrinsic demographic processes to reduce pest populations.2. We address the feasibility of a novel pest management strategy based on the release of insects infected with Wolbachia, which causes cytoplasmic incompatibilities in its host population, into a population with a pre-existing Allee effect. We hypothesize that the transient decline in population size caused by a successful invasion of Wolbachia can bring the population below its Allee threshold and, consequently, trigger extinction.3. We develop a stochastic population model that accounts for Wolbachia-induced cytoplasmic incompatibilities in addition to an Allee effect arising from mating failures at low population densities. Using our model, we identify conditions under which cytoplasmic incompatibilities and Allee effects successfully interact to drive insect pest populations towards extinction. Based on our results, we delineate control strategies based on introductions of Wolbachia-infected insects.4. We extend this analysis to evaluate control strategies that implement successive introductions of two incompatible Wolbachia strains. Additionally, we consider

Editorial: Allee effects in ecology and evolution

“…The tendency for mate limitation to lead to population collapse has been often studied in the context of controlling insect invasions (Blackwood et al, 2012;Boukal & Berec, 2009;Liebhold & Bascompte, 2003), and Blackwood et al (2017)…”

“…Angulo et al (2017) provide new insight on another key Allee effect mechanism, predicting when social structure causing Allee effects in small animal groups may lead to population scale demographic Allee effects. Blackwood, Vargas, and Fauvergue (2017) then present work on how Wolbachia infection and Allee effects may interact to facilitate the extirpation of targeted insect pests, following a long tradition leveraging Allee effects to improve pest management (e.g. Blackwood et al, 2012;Liebhold & Bascompte, 2003).…”

“…add to this tradition by considering the interactive effects of a mating-related control mechanism currently being proposed for pest control. Males infected with Wolbachia bacteria tend to experience mating failure when pairing with uninfected females, reducing population growth and size while the bacteria spread Blackwood et al (2017). use models to show that while Wolbachia-induced cytoplasmic incompatibility and the mate-finding Allee effect act more or less independently, by combining these two processes, it may be possible to achieve pest population collapseeven in established populations.…”

Combining multiple tactics over time for cost‐effective eradication of invading insect populations

“…2020), release of Wolbachia bacteria (Blackwood et al . 2018), mating disruption, mass‐trapping and the sterile insect technique (Yamanaka and Liebhold 2009), but less is known about how these treatments interact with each other. Suckling et al .…”

“…Blackwood et al . (2012, 2018) used a modelling approach to evaluate interactions between different eradication tactics when applied simultaneously and to identify economically optimal combinations of tactics for eradication. Lampert and Hastings (2019) examined how to combine tactics to restore ecosystems and cross the Allee threshold.…”