A cascade of destabilizations: Combining <em>Wolbachia</em> and Allee effects to eradicate insect pests

1. 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 <em>Wolbachia</em>, 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 <em>Wolbachia</em> can bring the population below its Allee threshold and, consequently, trigger extinction. 3. We develop a stochastic population model that accounts for <em>Wolbachia</em>-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 <em>Wolbachia</em>-infected insects. 4. We extend this analysis to evaluate control strategies that implement successive introductions of two incompatible <em>Wolbachia</em> strains. Additionally, we consider methods that combine <em>Wolbachia</em> invasion with mating disruption tactics to enhance the pre-existing Allee effect. 5. We demonstrate that <em>Wolbachia</em>-induced cytoplasmic incompatibility and the Allee effect act independently from one another: the Allee effect does not modify the <em>Wolbachia</em> invasion threshold, and cytoplasmic incompatibilities only have a marginal effect on the Allee threshold. However, the interaction of these two processes can drive even large populations to extinction. The success of this method can be amplified by the introduction of multiple <em>Wolbachia</em> cytotypes as well as the addition of mating disruption. 6. Our study extends the existing literature by proposing the use of <em>Wolbachia</em> introductions to capitalize on pre-existing Allee effects and consequently eradicate insect pests. More generally, it highlights the importance of transient dynamics, and the relevance of manipulating a cascade of destabilizatons for pest management.