Controlling invasive ant species: a theoretical strategy for efficient monitoring in the early stage of invasion

TL;DR

This paper presents a mathematical model to optimize early-stage monitoring strategies for invasive fire ants, providing guidelines on spatial and temporal scales to effectively eradicate nests and prevent spread.

Contribution

It introduces a novel mathematical framework for determining optimal monitoring intervals and spatial coverage for invasive ant eradication efforts.

Findings

Monitoring should cover at least a 4 km radius around the source nest.

Optimal bait trap placement is every 30 meters during each monitoring session.

Monitoring duration of up to three years maximizes detection rates.

Abstract

Invasion by the red imported fire ant, Solenopsis invicta Buren, has destructive effects on native biodiversity, agriculture, and public health. This ant's aggressive foraging behaviour and high reproductive capability have enabled its establishment of wild populations in most regions into which it has been imported. An important aspect of eradication is thorough nest monitoring and destruction during early invasion to prevent range expansion. The question is: How intense must monitoring be on temporal and spatial scales to eradicate the fire ant? Assuming that the ant was introduced into a region and that monitoring was conducted immediately after nest detection in an effort to detect all other potentially established nests, we developed a mathematical model to investigate detection rates. Setting the monitoring limit to three years, the detection rate was maximized when monitoring was conducted shifting bait trap locations and setting them at intervals of 30 m for each monitoring. Monitoring should be conducted in a radius of at least 4 km around the source nest, or wider --depending on how late a nest is found. For ease of application, we also derived equations for finding the minimum bait interval required in an arbitrary ant species for thorough monitoring.