Identification of trail pheromone of the antTetramorium caespitum L. (Hymenoptera: Myrmicinae)

The trail pheromone of the antTetramorium caespitum L. is a 7030 mixture of 2,5-dimethylpyrazine and 3-ethyl-2, 5-dimethylpyrazine. The average total amount of the two pyrazines present in the poison vesicle was found to be 3.9 ng per ant, of which 2.7 ± 0.4 ng is 2,5-dimethylpyrazine and 1.15 ±0.25 ng is 3-ethyl-2,5-dimethylpyrazine. The pyrazines constitute only 0.03% of the volume of the poison vesicle but account for the whole of the trail-following activity. A 7030 mixture of the respective pyrazines evoked the highest activity in artificial trail-following tests.     

Trail pheromone of the antTetramorium impurum and model compounds: Structure-activity comparisons

The major component of the trail pheromone ofT. impurum is methyl 2-hydroxy-6-methylbenzoate (methyl 6-methyl salicylate). The poison reservoir of each worker contains about 1.0 ng of this substance in the venom. To ascertain the degree of specificity of the substance as pheromone and to determine any correlation between structure and biological activity, 38 synthetic analogs were tested in a bioassay. Sixteen compounds showed activity at 100 ng per artificial trail. The importance of the methyl group and methyl ester were demonstrated, while the hydroxyl group has a relatively small effect.In part presented at the Fourth Annual Meeting of the International Society of Chemical Ecology, July 13–17, 1987, Hull, England.     

Mandibular Gland Secretion in Different Castes of the Leaf-Cutter Ant Atta laevigata

Gas chromatography analyses and behavioral assays showed that Atta laevigata, a highly polymorphic ant species, has a mandibular gland secretion that varies with castes. All castes contain 4-methyl-3-heptanone as the main component and its concentration is proportional to head size. Small workers and soldiers, but not medium size workers, also contain 4-methyl-3-heptanol. Queens show variations in their chemical composition after mating, as virgin males contain a secretion dominated by 4-methyl-3-heptanol, and, in a lesser proportion, 4-methyl-3-heptanone. In mated males these proportions are inverted. The compounds 4-methyl-6-hepten-3-one, 4-methyl-4-hepten-3-one, 6-methyl-tetradecene, and 2,6-dimethyl-2-dodecene are found only in queens. The behavioral response elicited by the secretion is mainly alarm, which is elicited more strongly by glands of larger workers. The results suggest that chemical castes, behavioral castes, and morphological castes overlap in this species.     

Variation with caste of the mandibular gland secretion in the leaf-cutting antAtta sexdens rubropilosa

InAtta sexdens rubropilosa, a strongly polyethic and polymorphic species of myrmicine ant, the contents of the mandibular gland vary with caste. Small workers of head width 0.5–1.8 mm, those generally engaged in duties inside the nest, contain chiefly 4-methyl-3-heptanone. Larger workers, those chiefly engaged in foraging, and the soldier caste contain a mixture dominated by neral and geranial, with very little of the ketone of the smaller workers. The soldiers have massive glands containing milligram amounts of neral and geranial. Virgin and mated females contain essentially only 4-methyl-3-heptanone, the amount increasing after mating, while virgin males have 4-methyl-3-heptanone and 4-methyl-3-heptanol in approximately equal proportions. Mated males have less secretion and lose the 4-methyl-3-heptanol.     

Novel pyrazines from the head of Australian ponerine antRhytidoponera metallica

The novel pyrazines, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2-(3-methylbut-1-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-methylbut-1-enyl) pyrazine, (E)- and (Z)-5-methyl-3-(2-methylbutyl)-2-(3-methylpent-1-enyl)pyrazine, (E)- and (Z)-5-methyl-3-isopentyl-2-(3-methylpentl-enyl) pyrazine, together with the known pyrazines, 2,5-dimethyl-3-(2-methylbutyl)pyrazine and 2,5-dimethyl-3-isopentylpyrazine, have been identified from the head of the Australian ponerine antRhytidoponera metallica. Alkanes and alkenes, in small amounts, were also detected.     

Venom chemistry of ants in the genusMonomorium

A comparative analysis of the venomous alkaloids produced by ant species in the subgenusMonomorium of the genusMonomorium has been undertaken. All species produce mixtures of unsymmetricaltrans-2,5-dialkylpyrrolidines, but the proportions of the constituents may vary considerably between species. All alkaloids contain both C₆ and C₉ side chains which are present as C₉-saturated. C₆-monounsaturated, and both C₆-and C₉-monounsaturated dialkylpyrrolidines. The structure of 2-(1-hex-5-enyl)-5-(1-non-8-enyl)pyrrolidine, a previously undescribed alkaloid, was proved by unambiguous synthesis after the location of the double bonds was established by the methoxymercuration-demercuration followed by mass spectrometry. The possible chemotaxonomic significance of the mixtures of venomous alkaloids produced by these species ofMonomorium is discussed.     

Pheromonal basis for aggregation behavior of parasitoids of the gypsy moth:Brachymeria intermedia (Nees) andBrachymeria lasus (Walker) (Hymenoptera: Chalcididae)

The parasitoidsB. intermedia andB. lasus aggregate at sites previously frequented. Extracts from filter paper conditioned by aggregated parasitoids were chromatographed (adsorption column and gas-liquid chromatography) and bioassayed. An active component that elicited aggregation response forB. intermedia was isolated and identified as 3-hexanone. This molecule was found in trace quantities (5–10 ng/female or male) on filter paper conditioned by either male, female or a combination of the sexes.     

Building pheromones ofVespa orientalis andPolistes foederatus

Among Vespinae both the queen and the workers build cells of a typical architectural design which are suitable for rearing a brood. In the case ofVespa orientalis, but not in the speciesV. crabro, Paravespula vulgaris,P. germanica, Dolichovespula saxonica, orD. media, groups of workers of various ages which are kept in artificial breeding boxes in the absence of a queen continue to build new cells and even entire combs. Workers which are deprived of a queen build worker cells but not queen cells. The construction commences from a central point where the workers had congregated for a while. The site of construction can be preselected by intentionally directing the workers to rest in a particular spot. Once the building has been initiated, the workers will persist building in the same spot over and over again, even after any imposed limitation has been removed. In this last respect,Polistes foederatus emulatesV. orientalis. From the above results, it would seem that hornets resting in a particular spot for a length of time deposit there a substance—probably volatile—which induces assembly of hornets in that spot. Furthermore, the hornets deposit there the same or another substance which stimulates the initiation of building. It is proposed to name this substance a building initiating pheromone. A distinction should be made between the building pheromone released by the workers and usually initiating the building and similar pheromones released by the queen which are capable of either initiating or restricting the building.     

Disruption of foraging by argentine ants,Iridomyrmex humilis (mayr) (hymenoptera: Formicidae), in citrus trees through the use of semiochemicals and related chemicals

Foraging in trees by the Argentine ant,Iridomyrmex humilis (Mayr), was disrupted by a variety of synthetic chemicals, with the most effective chemical being farnesol. Testing of substrates for presentation of the disruptant chemicals gave some success with rubber or Tygon tubing, although best results were obtained through incorporation of the material into Stikem, which was then banded around tree trunks. Amounts of farnesol used for effective, long residual ant control were between 0.8 and 2 g per tree.     

Reaction of Mutualistic and Granivorous Ants to Ulex Elaiosome Chemicals

It has been proposed that chemicals on plant elaiosomes aid seed detection by seed-dispersing ants. We hypothesized that the chemical interaction between ants and elaiosomes is more intimate than a generic attraction, and that elaiosome chemicals will attract mutualistic but not granivorous ant species. We investigated this by using two gorse species, Ulex minor and U. europaeus, and two associated ant species from European heathlands, the mutualist Myrmica ruginodis and the granivore Tetramorium caespitum. Behavioral studies were conducted with laboratory nests and foraging arenas. Both ants will take Ulex seeds, but while M. ruginodis showed increased antennation toward ether extracts of elaiosome surface chemicals compared with controls, T. caespitum showed no response. Elaiosome extracts were separated into seven lipid fractions. M. ruginodis showed increased antennation only toward the diglyceride fractions of both Ulex species, whereas T. caespitum showed no consistent reaction. This indicates that M. ruginodis can detect the elaiosome by responding to its surface chemicals, but T. caespitum is unresponsive to these chemicals. Responses to surface chemicals could increase the rate of seed detection in the field, and so these results suggest that Ulex elaiosomes produce chemicals that facilitate attraction of mutualistic rather than granivorous ant species. This could reduce seed predation and increase Ulex fitness.     

Tetraponerines,toxic alkaloids in the venom of the Neo-Guinean pseudomyrmecine antTetraponera sp.

The Neo-Guinean pseudomyrmecine ant,Tetraponera sp. utilizes its modified sting to smear upon enemies a contact poison with strong deterring and toxic properties. The venom, which originates from the poison gland, contains a mixture of eight closely related, alkaloids (tetraponerine-1 to -8). The structure of tetraponerine-8 was established by an X-ray diffraction analysis and was reported previously. The structure of five other members of the series has now been determined by comparison of their spectral properties with those of tetraponerine-8 and of model compounds.King Leopold III Biological Station, Laing Island, Papua, New Guinea, Contribution No. 136.     

Phenylalkenals in ponerine(Leptogenys sp.) and myrmicine (Pogonomyrmex sp.) ants

Cephalic extracts of two unrelated species of ants,Leptogenys processionalis andPogonomyrmex rugosus, have been found to contain 2-phenylpropenal and 2-phenyl-2-butenal, while two other species related to the first,L. chinensis andL. kitteli, lacked either.L. kitteli also produced a tetrasubstituted pyrazine found previously only in two New Zealand ants in the genusMesoponera. The chemical reactivity of the phenylalkenals suggests their function in repelling attack by predators.     

Propaganda substances in the cuckoo antLeptothorax kutteri and the slave-makerHarpagoxenus sublaevis

This paper reports the first discovery of propaganda substances in a workerless inquiline ant, the European myrmicineLeptothorax kutteri Buschinger. These substances are used by the parasite queen as a chemical weapon for defense against hostile workers of the host speciesL. acervorum. The substances also have an unusual behavioral effect: they cause host workers to attack each other, and they therefore appear to override nestmate recognition in host colonies. Laboratory experiments show that the source of these substances is the Dufour's gland of theL. kutteri queen. Our experiments also confirm the hypothesis that the closely related slave-making antHarpagoxenus sublaevis uses its Dufour's gland secretions as a chemical weapon during slave raids and colony foundation. The behavioral effect of these slave-maker secretions is identical to that ofL. kutteri queens.     

Exocrine glands ofPolyrhachis simplex: Chemistry and function

The mandibular glands of the Israeli weaver ant,Polyrhachis simplex, contain a mixture of 4-heptanone, 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol;its Dufour's gland secretion consists mainly ofn-tridecane. The significance of these glandular secretions in the biology of the weaver ant is discussed.     

Trail pheromone of the leaf-cutting ant,Acromyrmex octospinosus (Reich), (Formicidae: Myrmicinae)

The most active component of the trail pheromone of the leafcutting ant,Acromyrmex octospinosus, is methyl 4-methylpyrrole-2-carboxylate (I). Two pyrazine isomers (II) and (III) are present but inactive.     

Chemotaxonomic implications of the venom chemistry of someMonomorium “antarcticum” populations

A comparative analysis of the venom alkaloids produced by ants in the genusMonomorium (= Chelaner) collected on North Island and South Island, New Zealand, has been undertaken. All of the ants producetrans-2, 5-dialkylpyrrolidines along with 3,5-dialkylpyrrolizidines. The structures and sterochemistry of the novel alkaloidstrans-2-butyl-5-(8-nonenyl) pyrrolidine, (5E,8Z)-3,5-di(5-hexenyl)pyrrolizidine, and (5Z,8E)-3-methyl-5-(8-nonenyl)pyrrolizidine were established by unambiguous synthesis. The geographic distribution and the chemotaxonomic significance of the alkaloids produced by these ants are discussed.     

Secondary amines isolated from venom gland of dolichoderine antTechnomyrmex albipes

A series of unsaturated secondary amines have been isolated from the dolichoderine antTechnomyrmex albipes (F. Smith). The major components of the mixture have been shown by spectroscopic procedures to be dinon-8-enylamine, andN-hept-6-enylnon-8-enamine, and these structural assignments have been confirmed by synthesis. Mass spectrometry indicates the presence of trace amounts of the bis C₁₁ amine and the C₉-C₁₁ amine. The four amines, present in total at approximately 2.8g/ant, are located in the gaster of the insect in a gland that is considered to be the venom gland although it is atypical from a morphological standpoint.     

Sex Pheromone of Queens of the Slave-Making Ant, Polyergus breviceps

The sex attractant pheromone produced in mandibular glands of queens of the slave-making ant Polyergus breviceps has been identified as a blend of methyl 6-methylsalicylate and 3-ethyl-4-methylpentanol. In field trials, each compound alone was completely unattractive to males, whereas blends of the two compounds attracted hundreds of males within a couple of hours.     

Evidence for diglycerides as attractants in an ant-seed interaction

The chemical basis of an ant-seed interaction was investigated for the antAphaenogaster rudis and the ant-dispersed violetViola odorata. A laboratory behavioral bioassay was developed to chemically identify the attractant responsible for the interaction. The ant attractant, localized in the elaiosome, was classified as a lipid by both field and laboratory bioassays. Assays of partially purified lipid extracts revealed that the principal attractant may be a diglyceride. Gas-liquid chromatography analysis of the hydrolyzed diglyceride fraction revealed oleic acid as the major fatty acid present, suggesting that either 1,2- or 1,3-diolein may be the attractant. Structure-activity correlations for lipid standards demonstrated a clear preference for the diglyceride 1,2-diolein. The data also suggest that ricinoleic acid is not the lipid eliciting the ant response toViola odorata, as had been previously suggested.     

Identification and source of a queen-specific chemical in the pharaoh's ant,Monomorium pharaonis (L.)

Fertile queens of the antMonomorium pharaonis produce a chemical substance which is not present in worker ants or in young, alate (virgin) queens. The material has been identified as (E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene (neocembrene). This chemical is produced in the Dufour's gland of fertile queens and may serve as a queen-recognition pheromone.