Mechanisms and Density Dependence of Benefit in an Ant-Membracid Mutualism

Abstract

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Ant-hemipteran trophobioses in a Bornean rainforest – diversity, specificity and monopolisation

“…This pattern may be widespread and was found in several systems elsewhere (Breton and Addicott, 1992;Morales, 2000;Shingleton and Foster, 2000;Blüthgen and Fiedler, 2002), although some studies showed indirect evidence for an increased intensity of ant attendance with increasing number of hemipterans (Wood, 1982;Cushman and Whitham, 1989;Itioka and Inoue, 1996). In many cases where the number of ant workers per individual hemipteran is small, owing to large numbers of the latter or to competition with neighbouring hemipteran aggregations for a limited number of ants, hemipterans suffer from an increased risk of predation or parasitism (Cushman and Whitham, 1991;Breton and Addicott, 1992;Morales, 2000;Shingleton and Foster, 2000;Fischer et al, 2001). In addition, ant partners may vary in their protective effectiveness (Buckley and Gullan, 1991;Gullan, 1997;Itioka and Inoue, 1999).…”

“…It is usually consumed by ants in direct association with the hemipterans (trophobiosis) or indirectly when harvested from excretions accumulated on foliage and other plant surfaces (Way, 1963;Delabie, 2001). Ants may protect hemipterans against predators, parasites and pathogens, and the associated plants against other herbivores, hence the tritrophic association can be often regarded as three-partner mutualism (Buckley, 1987;Cushman and Whitham, 1991;Gullan, 1997;Morales, 2000;Wimp and Whitham, 2001).…”

Use of termites, Reticulitermes virginicus, as a springboard in the invasive success of a predatory ant, Pachycondyla (=Brachyponera) chinensis

“…Hemipteran honeydew is abundant and available throughout most of the year (yearround in some climates). This food source allows ants, such as L. humile, to grow massive colonies, and expand their territories (Morales, 2000;Helms and Vinson, 2002;Lach, 2005;Grover et al, 2007;Tillberg et al, 2007;Helms and Vinson, 2008;Rowles and Silverman, 2009). It has been suggested that one of the reasons that invasive ants tend to be dietary generalists is that such generalization makes them able to take advantage of hemipteran resources (Buckley and Gullan, 1991;Helms and Vinson, 2002;Lach, 2003).…”

Differential host use in two highly specialized ant-plant associations: evidence from stable isotopes

“…Benefits to each participant may vary over space and time, however (Cushman and Whitham 1989;Thompson 1994;Hochberg et al 2000), making the precise nature of the interaction conditional upon the environment. In antcoccid associations, for example, benefits varied between years as a function of population densities (Cushman and Whitham 1989;Morales 2000), and with the availability of alternative food sources (Way 1954;Pontin 1978;Offenberg 2001). In the latter case, ants that were given a carbohydrate supplement ate the homopterans they once tended (Way 1954;Offenberg 2001).…”