Abstract
Simple SummaryInvasive ants are often highly dominant competitors, having strong impacts on native species. Such invaders often exploit resources better than native species, finding them first or collecting them faster. They are also often more efficient when interfering with other species, suffering fewer losses or preventing access to resources. We assessed the competitive behavior of the invasive Argentine ant when facing another invasive species or a native dominant species. The exploratory behavior of the Argentine ant was strongly inhibited by the native dominant species. The Argentine ant brought very few prey resources to its nest and killed few opponents. Conversely, the other invasive species had low impact on the Argentine ant. Contrary to expectations, the invasive species lacked the ability to hinder resource exploitation by the Argentine ant, whereas the native dominant species did. These results suggest that a native species could impact invasive populations of the Argentine ant by interference competition, perhaps better so than some invasive species. In the northern half of Europe, it could prevent further expansion of this highly invasive species.Within ant communities, the biotic resistance of native species against invasive ones is expected to be rare, because invasive species are often highly dominant competitors. The invasive Argentine ant (Linepithema humile (Mayr)) often demonstrated numerical dominance against its opponents, increased aggressiveness, and ability to quickly recruit to food. The present study aimed to assess the behavioral mechanisms involved in the interspecific competition between L. humile, facing either an invasive species (Lasius neglectus Van Loon, Boomsma and Andrásfalvy) or a native dominant species (Lasius niger (Linnaeus)). The resource exploitation by the Argentine ant was investigated during one-hour competitive interactions using 10 dead Drosophila flies as prey. When facing La. niger, L. humile exploratory behavior was strongly inhibited, it brought very few prey resources, and killed few opponents. Conversely, La. neglectus had a low impact on L. humile. Contrarily to expectations, the invasive La. neglectus lacked the ability to hinder L. humile resource exploitation, whereas the native La. niger did. These results suggest that La. niger could impact invasive populations of L. humile by interference competition, perhaps better so than some invasive species. While L. humile has become invasive in Southern Europe, the invasion process could be slowed down in the northern latitudes by such native dominant species.
Highlights
Competition between species occurs in two ways
Results of the principal component analyses (PCAs) and linear discriminant analyses (LDAs) indicated likely differences in L. humile space occupation and ability to exploit resources according to the opponent species, but not regarding the colonizer/resident status, with more individuals in the arena and on the bait when alone in the arena than when in the presence of La. niger
La. neglectus was not so impactful, not modifying the number of L. humile in the arena or the quantity of resources brought by L. humile, L. humile engaged in more fights with La. neglectus and killed more opponents
Summary
Competition between species occurs in two ways. Exploitation competition involves the ability of species to find and exploit rapidly a resource before others, thereby making it unavailable to Animals 2020, 10, 2451; doi:10.3390/ani10122451 www.mdpi.com/journal/animalsAnimals 2020, 10, 2451 competitors. Interference competition involves the ability of species to prevent resource use by others (or to expulse them from the resource), either directly by aggression or indirectly by maintaining a territory [1,2]. Species depending on similar resources can coexist by means of a trade-off between the species’ ability to dominate resources and to discover them This discovery–dominance trade-off occurs when species’ ability to excel at interference competition results in specialized morphological, behavioral, and physiological characteristics that reduce its ability to discover resources in the first place [3]. Invasive ants especially are often highly aggressive, dominant competitors that displace many native species, through both interference and exploitative competition [7,8,9]. Because the species previously established is more familiarized with the nesting and foraging site (hereinafter called “resident effect”), such species could have an advantage during the competitive interactions [12], for instance due to local numerical dominance
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