Chemical Defense by the Native Winter Ant (Prenolepis imparis) against the Invasive Argentine Ant (Linepithema humile)

Abstract

The invasive Argentine ant (Linepithema humile) is established worldwide and displaces native ant species. In northern California, however, the native winter ant (Prenolepis imparis) persists in invaded areas. We found that in aggressive interactions between the two species, P. imparis employs a potent defensive secretion. Field observations were conducted at P. imparis nest sites both in the presence and absence of L. humile. These observations suggested and laboratory assays confirmed that P. imparis workers are more likely to secrete when outnumbered by L. humile. Workers of P. imparis were also more likely to secrete near their nest entrances than when foraging on trees. One-on-one laboratory trials showed that the P. imparis secretion is highly lethal to L. humile, causing 79% mortality. The nonpolar fraction of the secretion was chemically analyzed with gas chromatography/mass spectrometry, and found to be composed of long-chain and cyclic hydrocarbons. Chemical analysis of dissected P. imparis workers showed that the nonpolar fraction is derived from the Dufour's gland. Based on these conclusions, we hypothesize that this chemical defense may help P. imparis to resist displacement by L. humile.

Toxicity and utilization of chemical weapons: does toxicity and venom utilization contribute to the formation of species communities?

“…Previous studies have shown that venom plays an important role in ant community composition (Andersen and Patel 1994; Holway 1999; Sorrells et al. 2011). The underlying mechanisms for the co-occurrence patterns cannot, however, be explained by venom toxicity alone, although there is some evidence in M. antipodum that venom behavior might influence survival chances.…”

“…2011). One study reported venom of Monomorium rothsteini (Forel) to be highly repellent against three Iridomyrmex species, and the authors concluded that venom alkaloids may be a potent yet poorly appreciated force in interference competition and possibly play an important role in the structure of ant communities (Andersen et al.…”

Effects of Vegetation Cover, Presence of a Native Ant Species, and Human Disturbance on Colonization by Argentine Ants

“…Similarly, appearance of winter ants at sites with Argentine ants varied with season, vegetation cover, and development. In most survey periods, winter ants persisted at sites regardless of Argentine ant presence or absence (Table 2), possibly because, like several other ant species that coexist with Argentine ants (Holway 1999; Holway et al 2002; Sagata & Lester 2009), they produce chemicals to defend nests (Sorrells et al 2011). Winter ant appearance, however, was negatively associated with Argentine ant presence in sites where Argentine ants were most persistent: near development or without thick vegetation cover (Figs.…”

Density of Antennal Sensilla Influences Efficacy of Communication in a Social Insect

“…The primary focus is how ecological and social factors might modify workers' response to nonnestmates, including seasonal changes (Mabelis 1979;Ichinose 1991;Katzerke et al 2006), territoriality (Whitehouse and Jaffe 1995;Wenseleers et al 2002), experimental design , and the number (Gordon et al 1993;Roulston et al 2003;Sorrells et al 2011), age (Nowbahari and Lenoir 1989;van Wilgenburg et al 2005), and size (Nowbahari et al 1999) of the workers. In contrast, Newey et al (2010) propose that the variation in worker response may derive from differences in signal perception, which they suggest is the result of adaptive differences in individual odor templates.…”