The major component of the trail pheromone of the leaf-cutting ant,Atta sexdens rubropilosa forel

The major component of the trail pheromone of the South American leaf-cutting ant,Atta sexdens rubropilosa Forel, is 3-ethyl-2,5-dimethylpyrazine (II). Methyl and ethyl phenylacetate and methyl 4-methylpyrrole-2-carboxylate (I), which is the major component of the trail pheromone ofA. texana (Buckley) andA. cephalotes (L.), were also identified and may be minor components. The pheromone is stored in the poison gland.Atta sexdens sexdens (L.) also responds strongly to the pyrazine, which in large amounts evokes a weak response fromA. texana, A. cephalotes, andAcromyrmex octospinosus (Reich). Foraging workers ofAtta sexdens rubropilosa did not preferentially pick up baits impregnated with the pyrazine. The pyrazine was puffed into the nests ofA. cephalotes, and a particular response called milling was noted.     

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.     

Chemistry of metapleural gland secretions of three attine ants,Atta sexdens rubropilosa,Atta cephalotes,andAcromyrmex octospinosus (Hymenoptera: Formicidae)

The chemical composition of the secretions of the metapleural glands of workers and soldiers of twoAtta species,Atta sexdens rubropilosa andA. cephalotes, and workers ofAcromyrmex octospinosus, has been studied. As indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. Of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers ofA. s. rubropilosa andA. cephalotes. BothAtta species also contain 3-hydroxydecanoic acid and its homolog as minor components together with indoleacetic acid. While there are qualitative similarities in the acidic composition in the secretions ofA. s. rubropilosa andA. cephalotes, they differ quantitatively. The secretion ofAcromyrmex octospinosus contains 3-hydroxydecanoic and indoleacetic acids, but lacks phenylacetic acid. The bactericidal and fungicidal actions of the three major substances have been confirmed.     

Mandibular Gland Chemistry of Grass-cutting Ants: Species, Caste, and Colony Variation

The compositions of the alarm pheromones of two species of grass-cutting ant, Atta bisphaerica and A. capiguara, were examined, and caste and colony variations quantified. The pheromones of A. bisphaerica and A. capiguara were remarkably similar and were composed of a complex mixture of volatiles in which 4-methyl-3-heptanone and 2-heptanone were the most abundant compounds. Small but consistent intraspecific differences were found between the worker castes and between individual colonies. The results support the view that alarm pheromones are rarely species specific. The possible importance of intercolony variation is discussed.     

Mandibular gland allomones ofDasymutilla occidentalis and other mutillid wasps

The mandibular gland secretion of the mutillid wasp,Dasymutilla occidentalis, possesses three short-chained ketones-4-methyl-3-heptanone (4MH), 4,6-dimethyl-3-nonanone (4,6DMN), 4,6-dimethyl-3-octanone (4,6DMO)—and several unidentified compounds. This is the first report of 4,6DMN as a natural product and its synthesis is described. These ketones, which are either known to be ant alarm pheromones or are structurally very similar to ant alarm pheromones, appear to function as allomones against ants, major potential predators of mutillid wasps. The major secretory component, 4-methyl-3-heptanone, which was identified in females and/ or males of the species analyzed within the generaDasymutilla, Timulla, Traumatomutilla, andPappognatha, appears to constitute a chemical character of the defensive secretions of these genera.     

Behavioral Changes in Workers of the Leaf-Cutting Ant Atta sexdens rubropilosa Induced by Chemical Components of Eucalyptus maculata Leaves

The response of Atta sexdens rubropilosa Forel workers to essential oils, epicuticular wax and hexane, dichloromethane, ethyl acetate, and methanol extracts of Eucalyptus maculata was evaluated. Hexane extracts of E. maculata interfered with the recognition mechanism among workers. The main active compounds identified from this plant were the sesquiterpenes elemol and beta-eudesmol. These compounds may be responsible for the resistance of this species to ant attack.     

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.     

Absolute Configuration of 4-Methyl-3-Heptanone and 4-Methyl-3-Heptanol from Mandibular Glands of Virgin Males and Females ofAtta sexdens rubropilosa

(S)-;(+)-4-Methyl-3-heptanone is the principal component in the secretion from the mandibular glands of unmated and mated males and females ofAtta sexdens rubropilosa. In mated and unmated females, it is essentially the only component in the glandular secretion. In unmated males up to 50% of the secretion is a mixture of (3S, 4S)- and (3R, 4S)-4-methyl-3-heptanol. After mating, the amount of alcohol in the males decreases markedly.     

Volatile secretions of old world army antAenictus rotundatus and chemotaxonomic implications of army ant dufour gland chemistry

The Dufour glands ofAenictus rotundatus contain a complex mixture of terpenoids with geranylgeraniol comprising over 50% of the secretion. Some novel compounds have been tentatively identified as higher homologs of 1,3,3-trimethyl-2,7-dioxabicyclo[2,2,1]heptane based on GC-MS data. The Dufour gland secretion ofA. rotundatus is more similar in composition to the secretions of members of the subfamily Ecitoninae than to its closer relatives from the tribe Dorylini, a result that further complicates studies on the phylogeny of army ants. The mandibular glands ofA. rotundatus contain a mixture of 4-methyl-3-heptanone and limonene in trace amounts, and the well-developed postpygidial glands contain methyl anthranilate only.     

Virgin Queen Mandibular Gland Signals of Apis mellifera capensis Change with Age and Affect Honeybee Worker Responses

The mandibular gland secretions of Apis mellifera capensis virgin queens were analyzed by gas chromatography–mass spectroscopy. Changes in the patterns of the mandibular gland volatiles of A. m. capensis virgin queens were followed from emergence until 14-d old. Ontogenetic changes in the mandibular gland secretions were largely quantitative in nature, delineating the age categories (global R = 0.612, P = 0.001), except for 7- and 14-d-old queens, which cannot be separated on their mandibular gland profiles (P = 0.2). (E)-9-Oxodec-2-enoic acid (9ODA) contributes most and most consistently to the dissimilarity between groups as well as the similarity within groups. Worker reactions to introduced virgin queens of various ages were recorded. Workers showed a significant increase in hostile reactions as queens aged (r = 0.615, N = 20, P < 0.05). Consequently, worker reactions and relative 9ODA production exhibit a positive queen age-dependent response.     

Mandibular Gland Secretion of <Emphasis Type="Italic">Melipona beecheii</Emphasis>: Chemistry and Behavior

The mandibular gland secretion of Melipona beecheii contains a rich mixture of terpenoid and oxygenated compounds and unsaturated and saturated hydrocarbons. However, it differs markedly from the 11 other Brazilian species examined in previous studies, both by the absence of 2-heptanol and the presence of rose oxides. The most abundant compound was geranyl hexanoate, whereas the most volatile compounds were cis- and trans-rose oxide and geraniol. The complete blend and five individual components found in the gland secretion were tested by electroantennography (EAG) and behavioral assays. The complete mandibular gland extract and geraniol elicited the strongest EAG responses, whereas these and farnesyl acetate induced the strongest attack response from workers. The role of the rose oxides remains to be elucidated, as they do not appear to play a major role as an alarm pheromone of this species.     

Toxicity of lignans to symbiotic fungus of leaf-cutting ants

Lignans fromVirola sebifera Aubl.,Virola sp., andOtoba parvifolia (Mkfg.) A. Gentry (Myristicaceae) inhibited the in vitro growth of the fungus cultivated by leaf-cutting ants of the speciesAtta sexdens rubropilosa Forel (Hymenoptera: Formicidae). A comparison of activity among the lignans was obtained.     

Bioassay of compounds derived from the honeybee sting

Nine compounds identified from honeybee,Apis mettifera L., sting extracts and one compound identified from the honeybee mandibular gland were evaluated in a standardized laboratory test for their effectiveness in eliciting an alarm response from caged honeybees. Two,n-decyl acetate and benzyl alcohol, were judged ineffective as alarm pheromones. The remaining eight—2-nonanol, isopentyl acetate,n-butyl acetate,n-hexyl acetate, benzyl acetate, isopentyl alcohol, andn-octyl acetate from the sting and 2-heptanone from the mandibular gland-produced responses of similar frequency and strength.in cooperation with Louisiana Agricultural Experiment Station. Mention of a proprietory product does not constitute an endorsement by the USDA.     

Foreign-language Skills in Rove-Beetles? Evidence for Chemical Mimicry of Ant Alarm Pheromones in Myrmecophilous <Emphasis Type="Italic">Pella</Emphasis> Beetles (Coleoptera: Staphylinidae)

By using chemical analyses, as well as laboratory and field behavioral tests, we tested the hypothesis that rove beetles of the myrmecophilous genus Pella use alarm pheromone compounds to avert attacks by their host ant Lasius fuliginosus. The secretions of Pella funestus and P. humeralis contain quinones and different aliphatic compounds, mainly undecane and 6-methyl-5-hepten-2-one (sulcatone). The latter two chemicals are also found in L. fuliginosus pheromone glands. Behavioral tests confirmed that undecane serves as an “aggressive alarm”-inducing pheromone in L. fuliginosus, whereas sulcatone most likely is a “panic-alarm”-inducing pheromone. The main tergal-secretion compounds, various quinones and undecane, individually and in mixtures induced aggression in L. fuliginosus workers. When sulcatone was added to these compounds, the space around the odor source was avoided and a reduced number of aggressive acts observed, suggesting that sulcatone blocks the aggression-inducing effect of undecane and the quinones. These results support the hypothesis that Pella beetles mimic alarm pheromones of their hosts. This is a rare example of chemical mimicry in myrmecophilous insects in which chemicals other than cuticular hydrocarbons are used.     

Identification of new components from anal glands ofTapinoma simrothi pheonicium

In addition to 2-methyl-4-heptanone, 6-methyl-5-hepten-2-one, and iridodials, the anal gland exudate of the dolichoderine ant,Tapinoma simrothi, contains 4-heptanone and 4-hydroxy-4-methyl-2-pentanone. The secretion functions as an alarm pheromone.     

Significance of the pyrrolic nitrogen atom in receptor recognition ofAtta texana (Buckley) (Hymenoptera:Formicidae) trail pheromone and parapheromones

Calculations of the charge of the pyrrolic nitrogen atom in the trail pheromone ofAtta texana, methyl 4-methylpyrrole-2-carboxylate, as well as 17 analogs, showed that the most active compounds all had the same charge of –0.51 electrons on the nitrogen atom. It is suggested that the close value for this charge may be important in recognition by the receptor.This work was supported in part by the University of Iowa Computer Center.     

Beyond 9-ODA: SEX Pheromone Communication in the European Honey Bee Apis mellifera L.

The major component of the mandibular gland secretion of queen honeybees (Apis mellifera L.), 9-ODA ((2E)-9-oxodecenoic acid), has been known for more than 40 yr to function as a long-range sex pheromone, attracting drones at congregation areas and drone flyways. Tests of other mandibular gland components failed to demonstrate attraction. It remained unclear whether these components served any function in mating behavior. We performed dual-choice experiments, using a rotating drone carousel, to test the attractiveness of 9-ODA compared to mixtures of 9-ODA with three other most abundant components in virgin queen mandibular gland secretions: (2E)-9-hydroxydecenoic acid (9-HDA), (2E)-10-hydroxydecenoic acid (10-HDA), and p-hydroxybenzoate (HOB). We found no differences in the number of drones attracted to 9-ODA or the respective mixtures over a distance. However, adding 9-HDA and 10-HDA, or 9-HDA, 10-HDA, and HOB to 9-ODA increased the number of drones making contact with the baited dummy. On the basis of these results, we suggest that at least 9-HDA and 10-HDA are additional components of the sex pheromone blend of A. mellifera.     

(<Emphasis Type="Italic">E,E</Emphasis>)-α-Farnesene,an Alarm Pheromone of the Termite <Emphasis Type="Italic">Prorhinotermes canalifrons</Emphasis>

The behavioral and electroantennographic responses of Prorhinotermes canalifrons to its soldier frontal gland secretion, and two separated major components of the secretion, (E)-1-nitropentadec-1-ene and (E,E)-α-farnesene, were studied in laboratory experiments. Behavioral experiments showed that both the frontal gland secretion and (E,E)-α-farnesene triggered alarm reactions in P. canalifrons, whereas (E)-1-nitropentadec-1-ene did not affect the behavior of termite groups. The alarm reactions were characterized by rapid walking of activated termites and efforts to alert and activate other members of the group. Behavioral responses to alarm pheromone differed between homogeneous and mixed groups, suggesting complex interactions. Antennae of both soldiers and pseudergates were sensitive to the frontal gland secretion and to (E,E)-α-farnesene, but soldiers showed stronger responses. The dose responses to (E,E)-α-farnesene were identical for both soldiers and pseudergates, suggesting that both castes use similar receptors to perceive (E,E)-α-farnesene. Our data confirm (E,E)-α-farnesene as an alarm pheromone of P. canalifrons.     

Leaf-cutting antAtta laevigata (Formicidae: Attini) marks its territory with colony-specific dufour gland secretion

The workers of the leaf-cutting antAtta laevigata were found to mark a territory around their nest and along trunk trails. Elsewhere, we reported that the territorial mark had orientation and agonistic functions. The presence of this mark induced an alarm behavior in intruder workers and stimulated the residents' aggressiveness. Of the parts of the body tested, only the extracts from gaster or Dufour gland were able to induce the same agonistic behavior. The compoundsn-heptadecane, (Z)-9-nonadecene, 8,11-nonadecadiene, and (Z)-9-tricosene, secreted by Dufour gland were identified on foraging trails in the field as components of the territorial odor.