Ecological consequences of interactions between ants and honeydew-producing insects

Abstract

Interactions between ants and honeydew-producing hemipteran insects are abundant and widespread in arthropod food webs, yet their ecological consequences are very poorly known. Ant–hemipteran interactions have potentially broad ecological effects, because the presence of honeydew-producing hemipterans dramatically alters the abundance and predatory behaviour of ants on plants. We review several studies that investigate the consequences of ant–hemipteran interactions as ‘keystone interactions’ on arthropod communities and their host plants. Ant–hemipteran interactions have mostly negative effects on the local abundance and species richness of several guilds of herbivores and predators. In contrast, out of the 30 studies that document the effects of ant–hemipteran interactions on plants, the majority (73%) shows that plants actually benefit indirectly from these interactions. In these studies, increased predation or harassment of other, more damaging, herbivores by hemipteran-tending ants resulted in decreased plant damage and/or increased plant growth and reproduction. The ecological consequences of mutualistic interactions between honeydew-producing hemipterans and invasive ants relative to native ants have rarely been studied, but they may be of particular importance owing to the greater abundance, aggressiveness and extreme omnivory of invasive ants. We argue that ant–hemipteran interactions are largely overlooked and underappreciated interspecific interactions that have strong and pervasive effects on the communities in which they are embedded.

The Direct and Ecological Costs of an Ant-Plant Symbiosis

“…The strong interdependence of A. octoarticulatus colonies and the scale insects they tend is surprising because the scale insects are mostly common, widely distributed, and highly generalist species. Scale insects and other hemipterans can impose substantial costs on plant fitness in both natural and agricultural ecosystems (Styrsky and Eubanks 2007), and some of the species we collected are well-known plant pests (e.g., Coccus hesperidum). Therefore, we think the scale insects probably reduced plant performance in our experiment and may be responsible for a substantial portion of the costs of defense by A. octoarticulatus to C. nodosa ( fig.…”

“…However, ants can also impose ecological costs on plants if they negatively affect the interactions between their host plants and other organisms in the environment. For example, ants can deter pollinators (Ness 2006) or increase herbivore loads on their host plants (Frederickson and Gordon 2007;Palmer et al 2008), such as by tending scale insects or aphids (Styrsky and Eubanks 2007). Direct and ecological costs are tightly linked (e.g., investing in ants instead of growth may reduce a plant's competitive ability; see also Heil 2002), but nonetheless we think the distinction is useful because of the different implications of direct and ecological costs for the evolution of cheating.…”

Ants defend coffee from berry borer colonization

“…Nonetheless, in many agroecosystems, the benefits of pest control services by ants are not recognized. Agricultural managers often view them as pests or annoyances to agricultural production because some ants tend honeydew-producing insects that can damage crops (Styrsky and Eubanks 2007). However, a review of the literature on ant-hemipteran associations suggests that even these associations benefit plants indirectly because ants remove other, more damaging herbivores Eubanks 2007, 2010).…”

“…Ants benefit plants (Styrsky and Eubanks 2007;Chamberlain and Holland 2009;Rosumek et al 2009;Trager et al 2010). Humans have known this for quite a long time.…”

Indirect effects of tending ants on holm oak volatiles and acorn quality

“…In particular, aphids feeding elicited the emission of a new monoterpene, Δ 3 -carene, and They can disperse or consume seeds, feed from specialized plant structures such as food bodies and extrafloral nectaries, act as or deter pollinitators, prey on herbivorous insects and/or develop mutualisms with honeydew-producing insects indirectly modifying plant fitness. [15][16][17] Additionally, through their nesting activities in soil, ants increase soil nutrient content available to plants, may change water infiltration and soil holding-capacity and modify biodiversity and abundance of soil organisms related to the decomposition process. 18,19 As a consequence of their activities, ants may thus change behavior, density, physiology or fitness of other species.…”