Biology subjects

Werneke, C.

Publications and source records attributed to Werneke, C..

2 recordsLinked to original sources

bioRxiv2024

Palatability of Insecticides and Protein in Sugar Solutions to Argentine Ants

Invasive ant species like Linepithema humile cause significant ecological and economic harm, making effective control strategies essential. Insecticide baits are currently the most effective approach for controlling ants. Therefore, quantifying how palatable or unpalatable baits, bait additives, or toxicants are, is critical for developing effective control methods. It has recently been demonstrated that in the comparative evaluation of foods, animals that are aware of both a test food and a comparator food exhibit greatly increased sensitivity when detecting the unpalatability of liquid baits. Here, we deploy a newly developed comparative evaluation methodology to examine the palatability to L. humile workers of three toxicants used in invasive ant control: Fipronil, spinosad, and imidacloprid, as well as egg white protein. Ants showed no significant preference between pure sucrose and sucrose-toxicant solutions, indicating that they either cannot detect the toxicants or that they do not find them distasteful. Survival tests confirmed that the toxicant concentrations used were lethal, with a survival rate of 50% or below after 72 hours. However, ants found egg protein additive unpalatable, significantly preferring pure sucrose to a sucrose-egg protein mix. These findings confirm that three major toxicants are suitable for use in baits, and that reported abandonment or avoidance of toxic baits is not due to the unpalatability of these toxicants. However, the addition of egg protein to sucrose baits, even at ratios which optimise colony growth, is likely counterproductive. Future research should investigate the relative preference of invasive ants for various bait matrixes over naturally available food, ensuring more effective pest management strategies.

animal behavior and cognition↗

bioRxiv2024

Invasive ants fed spinosad collectively recruit to known food faster yet individually abandon food earlier

Current management strategies applied to invasive ants rely on slow-acting insecticides which aim to delay the ants ability to detect the poison until its effects are noticeable. Despite this, most control efforts are unsuccessful, likely due to bait abandonment and insufficient sustained consumption. Conditioned taste aversion, a learned avoidance of a particular taste, is a crucial survival mechanism which prevents animals from repeatedly ingesting toxic substances. However, whether ants are capable of this delayed association between food taste and subsequent illness remains largely unexplored. Here, we exposed colonies of the highly invasive Argentine ant, Linepithema humile, to a sublethal dose of the slow-acting insecticide spinosad. We combined measurements of individual-level feeding patterns with quantification of collective preferences and foraging dynamics to investigate the potential effects of the toxicant on behaviour. Collectively, ants preferred an odour associated with a previously experienced food, even if this contained spinosad, over a novel one. However, at the individual-level, previous exposure to spinosad resulted in reduced food consumption, as a consequence of earlier food abandonment. Moreover, while control-treated colonies recruited slower to a food source which tasted like a previously experienced one, spinosad-exposed colonies recruited equally fast to both novel and familiar foods. Although it appears that ants are unable to develop a conditioned taste aversion to sublethal doses of spinosad, ingestion of even small amounts of the toxicant strongly influences foraging behaviour. Understanding the subtle effects of slow-acting pesticides on ant cognition and behaviour can ultimately inspire the development of more efficient control methodologies.

animal behavior and cognition↗