Natures wonders: ants quickly avoid poisoned bait (Introduction)

by David Turell , Tuesday, January 16, 2024, 17:47 (101 days ago) @ David Turell
edited by David Turell, Tuesday, January 16, 2024, 18:02

It appears to be a learned abandonment process:

https://www.nature.com/articles/s42003-023-05729-7

Abstract

"Invasive ants, such as the Argentine ant, pose a severe economic and ecological threat. Despite advancements in baiting techniques, effectively managing established ant populations remains a daunting challenge, often ending in failure. Ant colonies employ behavioural immunity against pathogens, raising the question of whether ants can collectively respond to toxic baits. This study investigates whether ant colonies actively abandon palatable but harmful food sources. We provided two sucrose feeders, each generating a new foraging trail, with one transitioning to offering toxic food. Six hours later, ant activity on that path decreases, while activity on the non-toxic food and the trunk trail remains unaffected, excluding factors like population decline or satiation as reasons for the activity decline. Laboratory experiments confirmed that ants remained alive six hours after ingesting toxic food. Ant presence remains low on the toxic food path for days, gradually decreasing along the nearest section of the trunk trail. This abandonment behaviour minimises the entry of harmful food into the nest, acting as a protective social mechanism. The evasion of toxic bait-treated areas likely contributes considerably to control failures. Understanding the behavioural response to toxic baits is essential for developing effective strategies to combat invasive ant species.

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"modern control methods predominantly rely on toxic baits, with liquid sucrose baits being especially attractive to this species43,44. However, in spite of impressive technological innovations, such as the development of hydrogel beads to broadly deploy liquid baits42,45,46,47,48, eliminating established populations of Argentine ants has proven challenging, with only limited success reported41. In field studies, baits often fail to control Argentine ants for more than 60 days, and there is often a resurgence of ant populations thereafter, or reinvasion after treatment by ants from nearby untreated areas

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"Here we ask: do invasive ants possess behavioural mechanisms, potentially similar to social immunity behaviours, which allow them to evade toxic baits? Specifically—can ants abandon otherwise palatable toxic bait?

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"We demonstrated that the presence of a toxic bait led to active abandonment of the foraging trail. This abandonment was highly spatially localized and began approximately 3 h after bait placement, resulting in a 70-80% decrease in activity on the bridge after 6 hours. Regardless of the initial population of foraging ants, the percentage decrease was consistent and persisted for several days. Activity remained high on the control sucrose bridge, indicating that the abandonment was not due to satiety or lack of motivation to forage. The trunk trail adjacent to the toxic bridge initially maintained similar activity levels, thus excluding population decline as an explanation. The abandonment gradually spread to the trunk trail but only in the vicinity of the toxic bait, not extending to areas located approximately more than 5 meters away where the sucrose bridge was placed for the period studied. The observed decrease in activity on the toxicant bridge and within the trunk trail cannot be attributed to a population decline, as the employed toxicant does not induce mortality at such a rapid rate. Taken together, these results unequivocally demonstrate a targeted behavioural abandonment of a toxic bait by this invasive ant."

Comment: the authors admitted they did not know how the ants did it. My guess relates to the fact that ants groom each other to remove fungi and other dangerous items. They nurse ill ants and isolate very ill ants. They might well recognize a poisoned ant and the colony responds. From the research author:

"This abandonment behavior is an active response strategy that minimizes the entry of dangerous foods into the nest, acting as a protective social mechanism. Our findings offer a new perspective on ant baiting strategy paradigms and a complementary interpretation of their results, shedding new light on the intriguing and complex behavioral responses of these social insects."

https://communities.springernature.com/posts/ants-evade-harmful-foods-through-active-ab...