Defense of termitaria by termitophilous ants

Summary Mounds of Amitermes laurensis are frequently faided by meat ants Iridomyrmex sanguineus. Of eight ant species which often cohabit with the termites, Camponotus sp. B and C were considerably dependent on the termintaria for their nest sites and effectively protected it from the attacks by meat ants. Many termite colonies cohabiting with those two ant species were vigorous, suggesting that this ant-termite relationship is mutualistic; thus, the ants were provided nest sites and probably even food and the termites were protected from destructive natural enemies.     

Behavioral Interactions Between <Emphasis Type="Italic">Aphaenogaster rudis</Emphasis> (Hymenoptera: Formicidae) and <Emphasis Type="Italic">Reticulitermes flavipes</Emphasis> (Isoptera: Rhinotermitidae): The Importance of Physical Barriers

Predation pressure from ants is a major driving force in the adaptive evolution of termite defense strategies and termites have evolved elaborate chemical and physical defenses to protect themselves against ants. We examined predator–prey interactions between the woodland ant, Aphaenogaster rudis (Emery) and the eastern subterranean termite, Reticulitermes flavipes (Kollar), two sympatric species widely distributed throughout deciduous forests in eastern North America. To examine the behavioral interactions between A. rudis and R. flavipes we used a series of laboratory behavioral assays and predation experiments where A. rudis and R. flavipes could interact individually or in groups. One-on-one aggression tests revealed that R. flavipes are vulnerable to predation by A. rudis when individual termite workers or soldiers are exposed to ant attacks in open dishes and 100% of termite workers and soldiers died, even though the soldiers were significantly more aggressive towards the ants. The results of predation experiments where larger ant and termite colony fragments interacted provide experimental evidence for the importance of physical barriers for termite colony defense. In experiments where the termites nested within artificial nests (sand-filled containers), A. rudis was aggressive at invading termite nests and inflicted 100% mortality on the termites. In contrast, termite mortality was comparable to controls when termite colonies nested in natural nests comprised of wood blocks. Our results highlight the importance of physical barriers in termite colony defense and suggest that under natural field conditions termites may be less susceptible to attacks by ants when they nest in solid wood, which may offer more structural protection than sand alone.     

Detection of Mitochondrial COII DNA Sequences in Ant Guts as a Method for Assessing Termite Predation by Ants

Termites and ants contribute more to animal biomass in tropical rain forests than any other single group and perform vital ecosystem functions. Although ants prey on termites, at the community level the linkage between these groups is poorly understood. Thus, assessing the distribution and specificity of ant termitophagy is of considerable interest. We describe an approach for quantifying ant-termite food webs by sequencing termite DNA (cytochrome c oxidase subunit II, COII) from ant guts and apply this to a soil-dwelling ant community from tropical rain forest in Gabon. We extracted DNA from 215 ants from 15 species. Of these, 17.2 % of individuals had termite DNA in their guts, with BLAST analysis confirming the identity of 34.1 % of these termites to family level or better. Although ant species varied in detection of termite DNA, ranging from 63 % (5/7; Camponotus sp. 1) to 0 % (0/7; Ponera sp. 1), there was no evidence (with small sample sizes) for heterogeneity in termite consumption across ant taxa, and no evidence for species-specific ant-termite predation. In all three ant species with identifiable termite DNA in multiple individuals, multiple termite species were represented. Furthermore, the two termite species that were detected on multiple occasions in ant guts were in both cases found in multiple ant species, suggesting that ant-termite food webs are not strongly compartmentalised. However, two ant species were found to consume only Anoplotermes-group termites, indicating possible predatory specialisation at a higher taxonomic level. Using a laboratory feeding test, we were able to detect termite COII sequences in ant guts up to 2 h after feeding, indicating that our method only detects recent feeding events. Our data provide tentative support for the hypothesis that unspecialised termite predation by ants is widespread and highlight the use of molecular approaches for future studies of ant-termite food webs.     

Ant colonization and coarse woody debris decomposition in temperate forests

Ants are ubiquitous, abundant and have widespread impacts on ecological communities and ecosystem processes. However, ant effects on coarse woody debris decomposition are unexplored. Several ant species colonize coarse woody debris for nesting, and this puts them in contact with fauna and microbes that utilize coarse woody debris as habitat and food, potentially influencing nutrient cycling and, ultimately, forest productivity. We report results from a field experiment employing 138 artificial ant nests (routed pine blocks) across five locations in southeastern US deciduous forests. We examine the correspondence between ant, termite and wood-eating fungi colonization and variation in coarse woody debris decomposition. After 1 year, nests colonized by ants had 5% more mass than those not colonized. Ant colonization corresponded with significantly less termite- and fungal-mediated decomposition of the nests. Without ants, termites removed 11.5% and fungi removed 4% more wood biomass. Ants, termites and wood-eating fungi all colonized pine nests where temperatures were highest, and ants also preferred higher soil moisture whereas termites and fungi responded negatively to high soil moisture when temperatures were higher. Ants reduce termite colonies through predation, and may inhibit fungi through the secretion of antimicrobial compounds. Our results indicate that interactions between forest understory ants, termites and fungi may influence the rate of coarse woody debris decomposition—biotic interactions that potentially influence forest structure and function.     

Ant and termite mound coinhabitants in the wetlands of Santo Antonio da Patrulha, Rio Grande do Sul, Brazil.

This paper reports on ant and termite species inhabiting the mounds (murundus) found in three wetland sites in Santo Antonio da Patrulha. Ants and termites were found in 100% of the mounds of two sites and in 20% of those in the third site. Colonies of Camponotus fastigatus were found inhabiting all the mounds, while colonies of Brachymyrmex sp., Linepithema sp., Pheidole sp., and/or Solenopsis sp. were collected in less than 30% of the mounds. In the mounds of the three sites, colonies of Anoplotermes sp. and/or Aparatermes sp. termites were found together with the ant colonies. Another cohabiting termite species, Cortaritermes sp., was found only in the mounds of one site. The results suggest that C. fastigatus is the species building the mounds, with the other species, whether ants or termites, being the inquilines.     

Driver Ants Invading a Termite Nest: Why Do the Most Catholic Predators of All Seldom Take This Abundant Prey?

Driver ants ( i.e. , epigaeic species in the army ant genus Dorylus , subgenus Anomma ) are among the most extreme polyphagous predators, but termites appear to be conspicuously absent from their prey spectrum and attacks by driver ants on termite nests have not yet been described. Here, we report a Dorylus ( Anomma ) rubellus attack on a colony of the fungus-growing termite Macrotermes subhyalinus that was observed during the dry season in a savannah habitat in Nigeria's Gashaka National Park. It was estimated that several hundred thousand termites (probably more than 2.4 kg dry mass) were retrieved. The apparent rarity of driver ant predation on Macrotermes nests may be explained by different habitat requirements, by the fact that these ants mostly forage aboveground, by efficient termite defense behavior and nest architecture that make entry into the nest difficult, and finally by driver ant worker morphology, which differs remarkably from that of subterranean Dorylus species that regularly invade and destroy termite colonies.     

Pruning of host plant neighbours as defence against enemy ant invasions: <Emphasis Type="Italic">Crematogaster </Emphasis>ant partners of <Emphasis Type="Italic">Macaranga</Emphasis> protected by "wax barriers" prune less than their congeners

Many ant partners of tropical ant-plants prune the leaves and shoot tips of other plants growing around their hosts. According to the hypothesis proposed by Davidson et al. (Ecology 69:801-808), this specialized behaviour not only protects the host plants against overgrowth, but it also conveys a direct benefit to the ant colony as it removes contact points to the neighbouring vegetation where invasions of enemy ants could occur. Here we test this hypothesis by comparing pruning intensity in five closely related Crematogaster (subgenus Decacrema) plant-ant species (and one species of Technomyrmex) that differ in their exposure to competition by other ants. Pruning intensity was quantified by measuring the area loss of paper tape pieces wrapped around the stems of Macaranga host plants. All Crematogaster (Decacrema) ants tested but not Technomyrmex sp. pruned, but the intensity of the behaviour varied strongly between and within species. Pruning was significantly weaker in the three tested Crematogaster species inhabiting Macaranga host plants with a slippery, waxy stem surface, which functions as a mechanical barrier protecting the specific ant partners against generalist competitors. Pruning was generally stronger on more densely ant-populated trees. Even though the number of ants per twig length was lower in associations of ants with glaucous Macaranga hosts, only part of the variation of pruning activity could be explained by "ant density". When corrected for ant density, "wax-running" Crematogaster (Decacrema) ants still pruned more weakly than their congeners inhabiting non-glaucous Macaranga hosts. Pruning is obviously most important when an ant-plant is potentially accessible to intruders, but less necessary when the ant colony is isolated by a protective wax barrier. Our results support the hypothesis that "selfish" defence against invasions is the major selective pressure that has led to the development and maintenance of pruning behaviour in weakly competitive plant-ants.     

Protein marking reveals predation on termites by the woodland ant, <Emphasis Type="Italic">Aphaenogaster rudis</Emphasis>

Subterranean termites provide a major potential food source for forest-dwelling ants, yet the interactions between ants and termites are seldom investigated largely due to the cryptic nature of both the predator and the prey. We used protein marking (rabbit immunoglobin protein, IgG) and double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) to examine the trophic interactions between the woodland ant, Aphaenogaster rudis (Emery) and the eastern subterranean termite, Reticulitermes flavipes (Kollar). We marked the prey by feeding the termites paper treated with a solution of rabbit immunoglobin protein (IgG). Subsequently, we offered live, IgG-fed termites to ant colonies and monitored the intracolony distribution of IgG-marked prey. Laboratory experiments on the distribution of protein-marked termite prey in colonies of A. rudis revealed that all castes and developmental stages receive termite prey within 24 h. In field experiments, live, protein-marked termites were offered to foraging ants. Following predation, the marker was recovered from the ants, demonstrating that A. rudis preys on R. flavipes under field conditions. Our results provide a unique picture of the trophic-level interactions between predatory ants and subterranean termites. Furthermore, we show that protein markers are highly suitable to track trophic interactions between predators and prey, especially when observing elusive animals with cryptic food-web ecology. Received 19 January 2007; revised 23 March 2007; accepted 26 March 2007.     

Behavioural and chemical mechanisms behind a Mediterranean ant–ant association

1. Interspecific competition among ants is common, and so is competitive exclusion among dominant ant species. In contrast, specific associations between non‐parasitic ant species are rare, especially in the temperate zones. As an exception, the subordinate ant Camponotus lateralis frequently co‐occurs with the dominant Crematogaster scutellaris but rarely with other dominant ants. 2. This association is one of various associations between Camponotus and Crematogaster species across the world. However, the mechanisms behind these co‐occurences are largely unknown. 3. In the present study, we therefore investigated the association of Ca. lateralis and Cr. scutellaris. We studied the spatial association of the nests, interspecific aggression, both species' cuticular hydrocarbon profiles, and their propensity to follow the other species' pheromone trails. 4. Crematogaster scutellaris usually attacked and displaced the generally submissive Ca. lateralis, but was significantly less aggressive at jointly used trails. Camponotus nests were always in close proximity to Crematogaster nests. 5. The cuticular hydrocarbons of both species consisted of alkanes with chain lengths between C21 and C35. The two species had 25 hydrocarbons in common, including mono‐, di‐, and tetramethyl alkanes. Despite this qualitative similarity, however, the quantitative hydrocarbon composition differed between the two species. 6. Camponotus lateralis followed artificial trails containing trail pheromones of Cr. scutellaris, but the latter did not follow Ca. lateralis trail pheromones. Interspecific trail‐following by Camponotus, but not vice versa, has been observed in another Camponotus–Crematogaster association and may be a more general mechanism that facilitates associations between the two ant genera.     

Mutualistic acacia ants exhibit reduced aggression and more frequent off‐tree movements near termite mounds

In many ant–plant mutualisms, ants establish colonies in hollow thorns, leaf pouches, or other specialized structures on their host plants, which they then defend from herbivores. Resource heterogeneity could affect the maintenance of these mutualisms if it leads to one or both partners altering their investment in the interaction. Such a phenomenon may be especially pertinent to the Acacia–ant mutualism found in East African savannas, where termite mounds have a profound effect on the spatial structuring of resources used by both plants and ants. Here, we examined whether the proximity to termite mounds of Acacia drepanolobium trees is associated with variation in the behavior of one of their ant associates, Crematogaster nigriceps. We found that ant colonies near termite mounds had decreased aggressive responses to simulated herbivory as well as increased off‐tree movement. We hypothesize that these changes are the result of resident ant colonies near termite mounds shifting investment from defense of their host plant to foraging for nearby resources.     

Interspecific interference for nest sites betweenLeptothorax congruus andMonomorium intrudens

Summary Interference competition for nest sites was studied in ant communities dominated byLeptothorax congruus in the suburbs of Tokyo, central Japan. At the two study plots located in a deciduous wood and in grassland,L. congruus constructed nests in dead branches or stems of dead grasses. Approximately 50% of the nests were physically broken within a year, suggesting that they were very fragile. Of totals of 67 and 91 nests ofL. congruus marked at the two sites, 12 (17.5%) and 53 (58.2%) nests, respectively, were replaced by other ant species (Monomorium intrudens,Crematogaster brunnea teranishii,Camponotus itoi andLasius sp.) which were common in both habitats. Field observation suggested that, among these ants,M. intrudens was a major competitor usurping the nests ofL. congruus by aggressive invasion.     

Influence of forest type and tree species on canopy ants (Hymenoptera: Formicidae) in Budongo Forest, Uganda

The arboreal ant fauna was investigated in Budongo Forest, a seasonal rain forest in Uganda, using the insecticidal fogging technique. Ants were collected from 61 trees, between 7 and 33 m in height, belonging to four tree species. Trees were growing in adjacent plots of forests characterized by different use and structure: an old primary forest, a primary swamp forest along a small river, and a secondary forest where selective logging was carried out for 30 years. A total number of 37,065 ants, belonging to 161 species in 30 genera were collected. Considering the high number of species found only once, the completeness of the canopy ant fauna was relatively high and of relatively similar magnitude as samples from the Neotropics or the Oriental region. Up to 37 ant species on a single tree, with an average of 18.2 species per tree, were found. Forty-four ant species (28.1%) were found only once, less than ten individuals were found for each of 88 species (54.7%), but 64.0% of all individuals belonged to one of five species. Considering the high numerical dominance of a few ant species like a Pheidole sp., Tetramorium aculeatum (Mayr) and a Crematogaster sp., there is some evidence for an ant mosaic in the lower canopy of the Budongo Forest. Individual numbers of ants were strongly correlated with nests in the fogged tree, though the ants were not homogeneously distributed in the tree crowns. Diversity measures that strongly depend on individual numbers such as the Morisita-Horn index or rarefaction methods were calculated, but results were not concordant with those of incidence-based estimates such as jack-knife calculations. Differences in ant species richness and faunal composition between tree species were low, but more significant between forest types. The ant fauna in the secondary forest was less diverse with 12.6% fewer species compared to the primary forest sites. The average number of ant species per tree was significantly lower in the secondary forest (<20% of the species; F=8.03, df=59, P<0.01) than in the undisturbed forest types. Cataulacus, Leptothorax, Tetraponera, and Polyrhachis, which are typical canopy-dwelling ant genera, had a significantly higher diversity and frequency in the two primary forest types (F=4.17, df=53, P<0.05). Secondary forest trees are often younger, lacking dead branches and epiphytes which are important requisites for ant colonization on trees.     

Settlement in the prey termite nest by the ponerine antPachycondyla caffraria (Smith), and tandem running signal analysis for the following ant

The workers ofPachycondyla caffraria attack the nests of the termiteMicrocerotermes sp. in the laboratory. The hunter workers bore into the side of the nest, enter and catch the termites, and return to their nest with the captured prey. Later in the same day, all or part of the colony moves out and settles in the termite nest. The hunter workers use tandem running for the attack of the termite nest, the capture of termite and the removal of the colony to the nest which was raided. To analyse the relevant signals for the following ant during tandem running, we offered different dummies to followers which had been separated from their leader ants. The signals which release the following behaviour are a conbination of visual and chemical signals. Seventy percent of motivated followers reacted positively to paper with methanolic extract of the leader ant, 44% of motivated followers reacted positively to an odourless paper, and 100% reacted positively to a freshly killed leader ant. The leading effect of the body surface is lost by cleaning with solvents of different polarity.     

Worker aggression of ant Lasius japonicus enhanced by termite soldier–specific secretion as an alarm pheromone of Reticulitermes speratus

The subterranean termite Reticulitermes speratus usually nests in rotten wood trunks, which may also be occupied by the Japanese garden ant Lasius japonicus. Few battles were observed between them under ordinary circumstances because they inhabit separate nesting sites. However, once the termite nesting sites were artificially broken, the ant workers invaded and hunted the termites, although the termite soldiers fought against the ants. This study aims to confirm intra‐ and inter‐specific chemical interactions between the termite and ant. Solid phase microextraction–gas chromatograph (SPME‐GC) analyses revealed that R. speratus soldiers secreted caste‐specific sesquiterpene hydrocarbon when they were irritated. Both the hexane extract of the soldiers and its hydrocarbon fraction, as well as the crushed soldier bodies, attracted the soldiers but dispersed the workers when presented on the trails. We also confirmed that the soldier chemicals enhanced aggressiveness of L. japonicus, which rushed around the odor sources and hunted any termites that were present. These findings suggest that: (i) the soldier–specific secretion might serve as an alarm pheromone in termite chemical communication, in which components recruit soldiers and also warn the other colony members away; and (ii) termite communication is eavesdropped on by L. japonicus workers to locate and hunt the termites.     

Behavioural Interactions Between <Emphasis Type="Italic">Crematogaster brevispinosa rochai</Emphasis> Forel (Hymenoptera: Formicidae) and Two <Emphasis Type="Italic">Nasutitermes</Emphasis> Species (Isoptera: Termitidae)

In the savanna-like Brazilian biome caatinga, the arboreal and polydomous ant Crematogaster brevispinosa rochai can be found cohabiting with two closely related Nasutitermes species (N. corniger and N. ephratae). This ant occupies variably sized portions of the termite nests and maintains a physical separation with its hosts by plugging the cells of the boundary areas with fibrous material. Although all the analysed cohabiting C. b. rochai nests were queenless, they always contained brood, especially from male and female reproductive castes. Interaction experiments between workers of C. b. rochai and workers or soldiers of N. ephratae revealed a low level of aggressiveness between the two species that contrasts with the aggressiveness of both C. b. rochai and N. ephratae in encounters with other ant (Azteca cf. chartifex, Cephalotes pusillus) or termite (M. cf. indistinctus) species. The association could benefit both ants (additional nesting sites, brood rearing places) and termites (protection against predators, dead ants or ant refuses as source of nitrogen).     

Let them eat termites—prey‐baiting provides effective control of Argentine ants,Linepithema humile,in a biodiversity hotspot

Invasive ants threaten biodiversity, ecosystem services and agricultural systems. This study evaluated a prey‐baiting approach for managing Argentine ants in natural habitat invaded by Argentine ants. Blackmound termites (Amitermes hastatus) were topically exposed to fipronil and presented to Argentine ants (Linepithema humile). In laboratory assays, L. humile colonies were offered fipronil‐treated termites within experimental arenas. The termites were readily consumed, and results demonstrate that a single termite topically treated with 590 ng fipronil is capable of killing at least 500 L. humile workers in 4 days. Field studies were conducted in natural areas invaded by L. humile. Fipronil‐treated termites scattered within experimental plots provided rapid control of L. humile and ant densities throughout the treated plots declined by 98 ± 5% within 21 days. Results demonstrate that the prey‐baiting approach is highly effective against L. humile and may offer an effective alternative to traditional bait treatments. Furthermore, prey‐baiting offers environmental benefits by delivering substantially less toxicant to the environment relative to current control methods which rely on commercial bait formulations and may offer greater target specificity.     

Patterns of the <Emphasis Type="Italic">Crematogaster-Macaranga</Emphasis> association: The ant partner makes the difference

Summary. One of the most species-rich ant-plant mutualisms worldwide is the palaeotropical Crematogaster-Macaranga system. Although the biogeography and ecology of both partners have been extensively studied, little is known about the temporal structuring and the dynamics of the association. In this study we compared life-history traits of the specific Crematogaster (Decacrema) partner-ants and followed the development of ant colonies on eight different Macaranga host plant species, from colony founding on saplings to adult trees in a snapshot fashion. We found differences in the onset of alate production, queen number and mode of colony founding in the ant species and examined the consequences of these differences for the mutualism with the host plant. The lifespan of some host plants and their specific ant partners seemed to be well matched whereas on others we found an ontogenetic succession of specific partner ants. The partner ants of saplings or young plants often differed from specific partner ants found on larger trees of the same species. Not all specific Crematogaster species can re-colonize the crown region of adult trees, thus facilitating a change of ant species. Therefore lifespan of the ant colony as well as colony founding behaviour of the different partner ant species are important for these ontogenetic changes. The lifespan of a colony of two species can be prolonged via secondary polygyny. For the first time, also primary polygyny (pleometrosis) is reported from this myrmecophytic system.     

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

Invasive ant species have general diet and nest requirements, which facilitate their establishment in novel habitats and their dominance over many native ants. The Asian needle ant, Pachycondyla chinensis, native throughout Australasia was introduced to the southeastern US where it has become established in woodland habitats, nests in close proximity to and consumes subterranean termites (Rhinotermitidae). P. chinensis do not occur in habitats lacking Rhinotermitidae. We suggest that subterranean termites are critical for P. chinensis success in new habitats. We demonstrate that P. chinensis is a general termite feeder, retrieving Reticulitermes virginicus five times more often than other potential prey near P. chinensis colonies. Odors produced by R. virginicus workers, as well as other potential prey, attract P. chinensis. Furthermore, P. chinensis occupy R. virginicus nests in the lab and field and display behaviors that facilitate capture of R. virginicus workers and soldiers. Termites are an abundant, high quality, renewable food supply, in many ways similar to the hemipteran honeydew exploited by most other invasive ant species. We conclude that the behavior of P. chinensis in the presence of termites increases their competitive abilities in natural areas where they have been introduced.     

Predation by ants controls swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) infestations

The swallow bug (Oeciacus vicarius) is the only known vector for Buggy Creek virus (BCRV), an alphavirus that circulates in cliff swallows (Petrochelidon pyrrhonota) and house sparrows (Passer domesticus) in North America. We discovered ants (Crematogaster lineolata and Formica spp.) preying on swallow bugs at cliff swallow colonies in western Nebraska, U.S.A. Ants reduced the numbers of visible bugs on active swallow nests by 74‐90%, relative to nests in the same colony without ants. Ant predation on bugs had no effect on the reproductive success of cliff swallows inhabiting the nests where ants foraged. Ants represent an effective and presumably benign way of controlling swallow bugs at nests in some colonies. They may constitute an alternative to insecticide use at sites where ecologists wish to remove the effects of swallow bugs on cliff swallows or house sparrows. By reducing bug numbers, ant presence may also lessen BCRV transmission at the spatial foci (bird colony sites) where epizootics occur. The effect of ants on swallow bugs should be accounted for in studying variation among sites in vector abundance.     

The effects of interspecific interactions on resource use and behavior in a desert ant

We examined how interspecific competition in ants affects resource use and behavior. To test how neighboring Myrmecocystus colonies influence the desert ant Aphaenogaster cockerelli, we placed temporary enclosures around Myrmecocystus spp. colonies and recorded the resources collected by A. cockerelli and the numbers of A. cockerelli ants engaged in various tasks outside the nest. When neighbors were enclosed, A. cockerelli colonies collected a significantly higher proportion of termites and significantly less plant matter than when neighbors were active. The numbers of A. cockerelli ants engaged in foraging behavior and nest maintenance work increased when Myrmecocystus colonies were enclosed. Interspecific interactions thus can affect the behavior and resource use of A. cockerelli colonies and may influence colony fitness.