Showing papers on "Lasius published in 2010"

Aphid-ant mutualism: how honeydew sugars influence the behaviour of ant scouts.

Abstract: Honeydew is the keystone on which ant-aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a recruitment trail by scouts of the aphidtending ant Lasius niger Linnaeus, and thus may enhance collective exploitation by the ant mutualists. The feeding preferences shown by L. niger for honeydew sugars are: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose. Although feeding is a prerequisite to the launching of trail recruitment, the reverse is not necessarily true: not all ingested sugar solutions elicit a trail-laying behaviour among fed scouts. Trail mark laying is only triggered by raffinose, sucrose or melezitose, with the latter sugar being specific to honeydew. By comparing gustatory and recruitment responses of ant foragers to sugar food sources, the present study clarifies the role of honeydew composition both as a source of energy and as a mediator in ant-aphid interactions. Lasius niger feeding preferences can be related to the physiological suitability of each sugar (i.e. their detection by gustatory receptors as well as their ability to be digested and converted into energy). Regarding recruitment, the aphid-synthesized oligosaccharide (melezitose) could be used by ant scouts as a cue indicative of a long-lasting productive resource that is worthy of collective exploitation and defence against competitors or aphid predators. © 2010 The Authors. Journal compilation © 2010 The Royal Entomological Society.

Ants and sustainable agriculture. A review

Abstract: 60% of the world’s ecosystems are not used in a sustainable way. Modern agriculture is blamed for declining soil carbon and biodiversity. Climate change, habitat fragmentation and other obstacles impede the movement of many animal species, and distribution changes are projected to continue. Therefore, we need alternative management strategies. The colony organisation of social insects, especially of ants, is seen as a model to design an improved agricultural management, because ants are very experienced agriculturists. Ants represent half of the global insect biomass. Their individuals work like a super organism. This article focuses on harvester and leaf cutter ants by considering Lasius species. It reviews the organisation structure of social ant communities. Harvester and leaf cutter ants represent a high percentage of the worldwide ant societies. They collect plant saps with carbon nitrogen (C/N) ratios of about 40 for their own nourishment and leaf fragments with C/N ratios of about 100 for fungi gardens and brood nourishment. They sustain huge numbers of individuals with their low N-based organic imports and their colony commensalisms enable them to convert these polymers into lower molecular, partly volatile compounds, adenosinetriphosphate (ATP), and heat. Digging improves water infiltration, drainage and soil aeration. Ants maintain fungi as a food source for the scleroproteinous brood, carry out food preservation, infection control and waste management, and construct with endurance new nests and rebuild them after damage. All these activities move the nest sites far away from the thermodynamic equilibrium. Physical, chemical and biological gradients emerge and the growing populations, together with nest-penetrating mycorrhized plant roots, absorb the released nutrients and form biomass by lowering energy flows into potentially strong consumer-resource interactions or runaway consumptions. The plant material import of leaf cutter ants, rich in carbon but low in proteins, amounts to 85–470 kg dry weight per year. It keeps the electron donor/acceptor ratio in favour of the electron donor so that denitrifiers can reduce nitrate predominantly to N2. Ants living in highly N-polluted areas bind the pollutant in the cuticle. In their low N-input environments harvester, leaf cutter and honeydew-sucking ants furnish the N demand of adult ants with the help of N2-fixing bacteria. The low N-input management of harvester, leaf cutter and honeydew-sucking ants is therefore a resourceful concept for approaching a highly productive agriculture by avoiding soil carbon decline and N2O emissions increase.

The impact of an ant–aphid mutualism on the functional composition of the secondary parasitoid community

Abstract: 1. Mutualistic and antagonistic interactions, although often studied independently, may affect each other, and food web dynamics are likely to be determined by the two processes working in concert. 2. The structure, and hence dynamics, of food webs depends on the relative abundances of generalist and specialist feeding guilds. Secondary parasitoids of aphids can be divided into two feeding guilds: (i) the more specialised endoparasitoids, which attack the primary parasitoid larvae in the still living aphid, and (ii) the generalist ectoparasitoids, which attack the pre-pupa of the primary or secondary parasitoid in the mummified aphid. 3. We studied the effect of an ant–aphid mutualism on the relative abundance of these two functional groups of secondary parasitoids. We hypothesised that generalists will be negatively affected by the presence of ants, thus leading to a greater dominance of specialists. 4. We manipulated the access of ants (Lasius niger) to aphid colonies in which we placed parasitised aphids. Aphid mummies were collected and reared to determine the levels of endo- and ecto-secondary parasitism. 5. When aphids were attended by L. niger the proportion of secondary parasitism by ectoparasitoids dropped from 26 to 8% of the total number of parasitised aphids, with Pachyneuron aphidis most strongly affected, while endoparasitoids as a group did not respond. However, among these Syrphophagus mamitus profited from ant attendance becoming the dominant secondary parasitoid, while parasitisation rates of Alloxysta and Phaenoglyphis declined. 6. The shift to S. mamitus as dominant secondary parasitoid in ant-attended aphid colonies is likely due to the behavioural plasticity of this species in response to ant aggression, and a release from tertiary parasitism by generalist ectoparasitoids. 7. The reduction of secondary parasitism by generalist ectoparasitoids reduces the potential for apparent competition among primary parasitoids with consequences for the dynamics of the wider food web.

Opening myrmecochory’s black box: what happens inside the ant nest?

Abstract: In the process of seed dispersal by ants (myrmecochory), foragers bring diaspores back to their nest, then eat the elaiosome and usually reject viable seeds outside the nest. Here, we investigate what happens inside the nest, a barely known stage of the myrmecochory process, for two seed species (Viola odorata, Chelidonium majus) dispersed either by the insectivorous ant Myrmica rubra or by the aphid-tending ant Lasius niger. Globally, elaiosome detachment decreased ants’ interest towards seeds and increased their probability of rejecting them. However, we found marked differences in seed management by ants inside the nest. The dynamics of elaiosome detachment were ant- and plant-specific whereas the dynamic of seed rejection were mainly ant-specific. Seeds remained for a shorter period of time inside the nest of the carnivorous ant Myrmica rubra than in Lasius niger nest. Thus, elaiosome detachment and seed rejection were two competing dynamics whose relative efficiency leads to variable outcomes in terms of types of dispersed items and of nutrient benefit to the ants. This is why some seeds remained inside the nest even without an elaiosome, and conversely, some seeds were rejected with an elaiosome still attached. Fresh seeds may be deposited directly in contact with the larvae. However, the dynamics of larvae-seeds contacts were also highly variable among species. This study illustrates the complexity and variability of the ecological network of ant–seed interactions.

Zinc and cadmium regulation efficiency in three ant species originating from a metal pollution gradient.

Abstract: Highly efficient accumulation of trace metals is often reported in ants, but their metal regulation strategies are poorly understood. This study examined the relationships between Zn and Cd total (tot) and water soluble (ws) concentrations in soil and in workers of three ant species collected along a metal-pollution gradient: Formica cunicularia, Lasius flavus and Myrmica rubra. Regression line comparisons showed the body loads of metals to depend strongly on the metal and the species. M. rubra showed the most efficient regulation of Zn, as its average Zn concentration and the regression slope were several times lower than for the other species. Although the species differed in their Cd levels, the slopes of the relationships between Cd concentration in soil and in ants did not differ between species (tot: p = 0.71, ws: p = 0.31). The very weak relationship for Cd found for all species suggests at least some active Cd regulation. These results can be explained in the context of tissue-specific metal accumulation. High Zn accumulation in mandibles and ovarioles may explain its high accumulation in F. cunicularia and L. flavus.

Changes in monoterpene emission rates of Quercus ilex infested by aphids tended by native or invasive Lasius ant species.

Abstract: The emission of volatile organic compounds (VOCs) depends on temperature and light. Other factors such as insect herbivory also may modify VOC emission. In particular, aphid feeding promotes the release of new compounds and changes the composition of plant volatile blends. Given that some aphids are tended by ants, we investigated whether ants change the emission of VOCs indirectly through attendance on aphids. The effect of Lachnus roboris aphids and two different tending ant species on terpene emission rates of 4-year-old holm oak (Quercus ilex) saplings was investigated during a field experiment. There were five treatments: saplings alone (T1), saplings infested with L. roboris aphids (T2), saplings infested with aphids tended by the local ant Lasius grandis (T3), those tended by small colonies of the invasive ant Lasius neglectus (T4), and those tended by large colonies of the same invasive ant species (T5). The infestation by L. roboris elicited the emission of Δ3-carene and increased the emission of myrcene and γ-terpinene. Terpene emissions were modified depending on the tending ant species. Attendance by the local ant L. grandis increased α and β-pinene and sabinene. Attendance by the invasive ant L. neglectus only decreased significantly the emission of myrcene, one of the major compounds of the Q. ilex blend. Aphid abundance decreased with time for all treatments, but there was no difference in aphid abundance among treatments. Total terpene emission rates were not correlated with aphid abundance. These results highlight that aphids and tending ants may change terpene emission rates, depending on the ant species.

Characteristics of feeding-site selection by breeding Green Woodpeckers Picus viridis in a UK agricultural landscape

Abstract: Capsule Green Woodpeckers exhibited strong feeding‐site preference, choosing areas based on abundance of ants with additional micro‐habitat effects. Aims To identify the habitat characteristics influencing feeding‐site selection across farmland. Methods A pair of Green Woodpeckers was radiotracked during a breeding season. Habitat and prey abundance variables were compared within the birds’ combined home‐ranges. canoco was used to identify ecological gradients, and logistic regression used to predict feeding‐site use based on ant abundance with resultant residuals correlated to identify habitat features that further influenced site selection. Results Most feeding was done in sheep‐grazed pastures and garden lawns with arable and cattle‐grazed land avoided. Green Woodpecker feeding sites were associated with areas of short grassland with high plant richness and high densities of ants, especially Lasius flavus. Logistic regression correctly classified 98% of cases from ant abundance. The woodpecker pair had...

Mites (Acari) Associated with the Ants (Formicidae) of Ohio and the Harvester Ant, Messor pergandei , of Arizona

Abstract: Ants (Formicidae) have long been an insect group of great interest to the scientific world, whether for their ecological roles, feeding strategies, or social behaviors. They form complex colonies, harboring resources that can potentially be exploited by myrmecophiles (organisms living in association with ants). Myrmecophily has been studied in detail for Coleoptera, but mites (Acari), the most frequent of ant guests, remain largely unstudied. Previous work has focused primarily on descriptions and has provided little ecological information. The first study is an effort to provide a more robust list of the often overlooked inhabitants of ant nests focusing on Ohio, a state that has yet to be mentioned in any myrmecophilous mite studies. A general survey of common Ohio ants was conducted from April 2008-March 2010. Phoretic mites were individually removed from ants and debris in 273 colonies. Mite collections totaled 198 species: 151 species phoretic and at least 47 mite species in non-phoretic relationships within the ant nests. Phoretic mites consisted of representatives of the cohort Astigmata (Histiostomatidae and Acaridae), the cohort Heterostigmatina (Scutacaridae, Pygmephoridae, and Microdispidae), and the suborder Mesostigmata (Laelapidae, Antennophoridae, and Uropodina). Many mite species were host specific and attachment site specific. An unusually large number of mite species was found to be associated with the ant genus Lasius , possibly the result of social parasitism. Post hoc statistical analyses show significantly greater mite diversity in colonies when 1) in the ant subfamily Formicinae, 2) the colony is in the woods, 3) the nest substrate is wood, 4) the colony is populous, 5) the ants are large, and 6) the ant species establishes its nest parasitically. A second study focused on the seed harvester ant Messor pergandei and its acarine associates. At least seven mite species are phoretically associated with M. pergandei : Armacarus sp., Lemanniella sp., Petalomium sp., Forcellinia sp., Histiostoma sp., Unguidispus sp., and Cosmoglyphus sp. Most of these species show preference for specific phoretic attachment sites and most preferentially board female alates rather than male alates. Five mite species were found in low numbers inhabiting the chaff piles: Tydeidae sp., Procaeculus sp., Anystidae sp., Bakerdania sp., and Tetranychidae sp. The phoretic Petalomium sp. was observed consuming fungus on a dead dealate, but the roles of the other species are still unclear.

A simple method to differentially exclude ants from tree canopies based on ant body size

Abstract: Summary1. Antsareubiquitouscomponentsofmostterrestrial communities.Antexclusionfromtreecano-pies using sticky barriers is frequently used to ascertain the ant’s role in the community. Thismethodisveryeffectivebutcannotdifferentiatebetweenantspecies,andexcludesthemallfromthecanopy.2. Here we describe a simple method which permits free access of small ants to the canopy, andexcludes ants larger than a defined size. This method is flexible in the sense that can be adapted todecidetosomedegreewhichspeciesofantsineachparticularcommunityareallowedaccesstotreecanopies.Key-words: ant exclusion, Camponotus, Formica, Lasius grandisIntroduction Since the pioneering work of Paine (1966), the experimentalexclusion of predators has been used as a major tool to revealspecies interactions in ecological communities. One majordrawbackofthismethodologyisthatawiderangeoforganismsis normally excluded. In terrestrial communities, the most fre-quentlyexcludedpredatorsarea nts.Inthemeta-analyticstudyofSchmitz,Hamba¨ck,&Beckerman(2000)oftrophiccascadesin terrestrial systems, 58% of the reported studies were antexclusion experiments. Ants are normally excluded from treesby placing sticky barriers (Samways & Tate 1985) or slipperysubstances(Lenoir2003)onthetrunk.Theseexclusionsystemsdo not discriminate among ant species but exclude them all.Occasionally, for some experiments it could be necessary toselectively exclude a group of ants rather than the entire antcommunity. The reason might be, for example, that some antspecies are mainly arthropod predators, whereas others arehemipteranmutualistsorleaf-cuttingspecies(Beattie1985).Here, we describe a method intended to exclude only someant species from tree canopies. The method is based on thebodysizeoftheantspecies.Weusedtheclassicalstickybarrieron the trunk, but underneath we placed two plastic tubes of acertaindiameterwhichgrante daccesstothecanopiestoasub-setofsmallantspecies.Theinternal diameter of the plastictube is clearly the key criterion. To decide the appropriatediameter, an a priori knowledge of the ant community of thestudysiteisneeded,withanaccurateestimateofantsizewithinthecommunity.Wedemonstratethemethodwiththeantcom-munityofanorganiccitrusgroveintheMediterranean.

Lasius cinereus seifert, une espèce nouvelle pour la france, sa distribution en espagne et en france et remarques sur sa biologie [hymenoptera, formicidae]

Abstract: The distribution of Lasius cinereus Seifert, 1992 in France and Spain is updated, and comments on its biology are given. The species, under a different name ―Lasius niger― was already detected by the late Paul Du Merle in the 1980es, from the Diois and Mont Ventoux regions in France. By careful quantitative field studies he had already hinted at its specific novelty.