Venom chemistry of ants in the genusMonomorium

Links between prey assemblages and poison frog toxins: A landscape ecology approach to assess how biotic interactions affect species phenotypes

Ecological studies of species pairs showed that biotic interactions promote phenotypic change and eco-evolutionary feedbacks. However, it is unclear how phenotypes respond to synergistic interactions with multiple taxa. We investigate whether interactions with multiple prey species explain spatially structured variation in the skin toxins of the neotropical poison frog Oophaga pumilio. Specifically, we assess how dissimilarity (i.e., beta diversity) of alkaloid-bearing arthropod prey assemblages (68 ant species) and evolutionary divergence between frog populations (from a neutral genetic marker) contribute to frog poison dissimilarity (toxin profiles composed of 230 different lipophilic alkaloids sampled from 934 frogs at 46 sites). We find that models that incorporate spatial turnover in the composition of ant assemblages explain part of the frog alkaloid variation, and we infer unique alkaloid combinations across the range of O. pumilio. Moreover, we find that alkaloid variation increases weakly with the evolutionary divergence between frog populations. Our results pose two hypotheses: First, the distribution of only a few prey species may explain most of the geographic variation in poison frog alkaloids; second, different codistributed prey species may be redundant alkaloid sources. The analytical framework proposed here can be extended to other multitrophic systems, coevolutionary mosaics, microbial assemblages, and ecosystem services.

Volatile Terpenes and Terpenoids from Workers and Queens of Monomorium chinense (Hymenoptera: Formicidae)

Twenty-one volatile terpenes and terpenoids were found in Monomoriumchinense Santschi (Hymenoptera: Formicidae), a native Chinese ant, by using headspace solid-phase microextraction (HS-SPME) coupled with gas-phase chromatography and mass spectrometry (GC-MS), which makes this ant one of the most prolific terpene producers in insect. A sesquiterpene with unknown structure (terpene 1) was the main terpene in workers and neocembrene in queens. Terpenes and terpenoids were detected in poison, Dufour’s and mandibular glands of both workers and queens. Worker ants raised on a terpene-free diet showed the same terpene profile as ants collected in the field, indicating that denovo terpene and terpenoid synthesis occurs in M. chinense.

Analysis of Cuticular Lipids of the Pharaoh Ant (Monomorium pharaonis) and Their Selective Adsorption on Insecticidal Zeolite Powders

The pharaoh ant is a notorious and hard to eradicate pest, which poses a threat in hospitals, spreading pathogens and contaminating sterile equipment. When applied on ants, zeolites adsorb part of their epicuticular wax layer. The ants are then vulnerable to desiccation, since this layer regulates water exchange. We analyzed the chemical composition of this wax layer using GC-MS (Gas Chromatography-Mass Spectrometry). A hexane wash of M. pharaonis foragers resulted in the identification of 53 components, four of which were not previously defined in Monomorium species. Selective adsorption of specific compounds on zeolites assisted in the identification of compounds which could not be separated on the GC column and allowed for the identification of three additional compounds. Zeolites show different affinities for the wax compounds depending on pore structure and chemical composition. Selective adsorption of alkanes on zeolites is also investigated in the fields of refinery processes and catalysis. Pore mouth and key lock adsorption mechanisms and selectivity according to molecular weight and branching, investigated in these fields, are also involved in adsorption processes of epicuticular waxes. The insecticidal activity of a zeolite is related to adsorption selectivity rather than capacity. One of the best adsorbing zeolites showed limited insecticidal activity and can be considered as a non-lethal alternative for epicuticular wax sampling.

Update on the defensive chemicals of the little black ant, Monomorium minimum (Hymenoptera: Formicidae)

Alkaloids, including 2,5-dialkylpyrrolidines and 2,5-dialkylpyrrolines, have been reported to be components in the venom of little black ants, Monomorium minimum (Buckley). Two fatty amines were recently reported as minor compounds. By analyzing the discharge collected from the stinger apparatus (milking), this study revealed the presence of an additional seven compounds in the defensive secretion of this ant species. Compounds identified were 9-decenyl-1-amine, N-methylenedecan-1-amine, N-methylenedodecan-1-amine, 2-(1-non-8-enyl)-5-(1-hex-5-enyl)-1-pyrroline, N-methyl-2-(hex-5-enyl)-5-nonanyl-1-pyrrolidine, β-springene ((E,E)-7,11,15-trimethyl-3-methylene-1,6,10,14-hexadecatetraene) and neocembrene ((E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene). β-springene and neocembrene were found only in the defensive secretion of queens. Analyses of the contents of isolated poison and Dufour's glands of the queen indicated that all amines and alkaloids were from the poison gland and that β-springene and neocembrene were from the Dufour's gland. This demonstrated that the defensive secretion in M. minimum queens consists of components from both glands. This is also the first report on the natural occurrence of 9-decenyl-1-amine, N-methylenedecan-1-amine, and N-methyllenedodecan-1-amine.

Fatty Amines from Little Black Ants, Monomorium minimum, and Their Biological Activities Against Red Imported Fire Ants, Solenopsis invicta

Red imported fire ants, Solenopsis invicta, are significant invasive pests. Certain native ant species can compete with S. invicta, such as the little black ant, Monomorium minimum. Defensive secretions may contribute to the competition capacity of native ants. The chemistry of ant defensive secretions in the genus Monomorium has been subjected to extensive research. The insecticidal alkaloids, 2,5-dialkyl-pyrrolidines and 2,5-dialkyl-pyrrolines have been reported to dominate the venom of M. minimum. In this study, analysis of defensive secretions of workers and queens of M. minimum revealed two primary amines, decylamine and dodecylamine. Neither amine has been reported previously from natural sources. Toxicity and digging suppression by these two amines against S. invicta were examined. Decylamine had higher toxicity to S. invicta workers than dodecylamine, a quicker knockdown effect, and suppressed the digging behavior of S. invicta workers at lower concentration. However, the amount of fatty amines in an individual ant was not enough to knockdown a fire ant or suppress its digging behavior. These amines most likely work in concert with other components in the chemical defense of M. minimum.

Diversity of peptide toxins from stinging ant venoms

Ants (Hymenoptera: Formicidae) represent a taxonomically diverse group of arthropods comprising nearly 13,000 extant species. Sixteen ant subfamilies have individuals that possess a stinger and use their venom for purposes such as a defence against predators, competitors and microbial pathogens, for predation, as well as for social communication. They exhibit a range of activities including antimicrobial, haemolytic, cytolytic, paralytic, insecticidal and pain-producing pharmacologies. While ant venoms are known to be rich in alkaloids and hydrocarbons, ant venoms rich in peptides are becoming more common, yet remain understudied. Recent advances in mass spectrometry techniques have begun to reveal the true complexity of ant venom peptide composition. In the few venoms explored thus far, most peptide toxins appear to occur as small polycationic linear toxins, with antibacterial properties and insecticidal activity. Unlike other venomous animals, a number of ant venoms also contain a range of homodimeric and heterodimeric peptides with one or two interchain disulfide bonds possessing pore-forming, allergenic and paralytic actions. However, ant venoms seem to have only a small number of monomeric disulfide-linked peptides. The present review details the structure and pharmacology of known ant venom peptide toxins and their potential as a source of novel bioinsecticides and therapeutic agents.

Chemistry of male mandibular gland secretions ofPhilanthus basilaris cresson andPhilanthus bicinctus (Mickel) (Hymenoptera: Sphecidae)

Detailed chemical characterizations are provided for the species-specific mixtures of marking pheromones utilized by the male beewolvesPhilanthus basilaris andP. bicinctus. Successful analysis of these complex mixtures of 2-ketones, fatty acids, ethyl esters, and aldehydes was facilitated by the treatment of the crude extracts with 1,1-dimethylhydrazine and direct analysis of the resulting hydrazones, methyl esters, and starting ethyl esters by GC-MS.

Novel 2-ethyl-5-alkylpyrrolidines in the venom of an australian ant of the genusMonomorium

Novel 2-ethyl-5-alkylpyrrolidines and their corresponding 1-pyrrolines have been identified as poison gland products from an unidentified Australian species ofMonomorium. The major alkaloids present in the venom of this ant aretrans-2-ethyl-5-undecylpyrrolidine andtrans-2-ethyl-5-(12-tridecen-1-yl)pyrrolidine. The position of the double bond in the latter was established from its dimethyl-disulfide adduct after the amine function had been protected, and the stereochemistry of the alkyl groups was determined by direct comparison with synthetic compounds. The corresponding 1-pyrrolines were also detected in varying amounts in this venom. The pyrrolidines and 1-pyrrolines possess considerable insecticidal activity when evaluated against termite workers. The alkaloidal venoms ofMonomorium appear to be an important factor contributing to the success of these small ants both as competitors and as predators.

Chemistry of venom alkaloids in someSolenopsis (Diplorhoptrum) species from Puerto Rico

A number of 15-carbon alkaloids have been identified in venom extracts of four Puerto Rican species of ants in the genusSolenopsis (Diplorhoptrum). Workers of a species from El Verde produced thecis andtrans isomers of 2-methyl-6-nonylpiperidine with the latter isomer predominating. The same compounds were identified in queens of a species from Río Grande, but in this species no alkaloids were detected in worker extracts. Workers of aDiplorhoptrum species collected on Mona Island produced primarily atrans-2-methyl-6-(Z-4-nonenyl)piperidine,3, with smaller amounts of thecis isomer, whereas the major compound found in the queens of the same species on Mona Island was (5Z,9Z)-3-hexyl-5-methylindolizidine, identical with the alkaloid produced by queens of a species collected on Cabo Rojo. Surprisingly, workers of the Cabo Rojo species produced (5Z,9Z)- and (5E,9E)-3-butyl-5-propylindolizidine (4 and5, respectively) reported earlier as the 223AB indolizidines from skins of dendrobatid frogs. The possible significance of the qualitative and quantitative differences in the venom alkaloids synthesized by queens and workers is discussed as is the possibility that ants containing such alkaloids may serve as a dietary source for the skin alkaloids used by certain frogs in chemical defense.

Structure of alkaloid 275A, a novel 1-azabicyclo[5.3.0]decane from a dendrobatid frog, Dendrobates lehmanni: synthesis of the tetrahydrodiastereomers

The principal alkaloid 275A in skins of the Colombian poison frog Dendrobates lehmanni has been identified as the pyrrolo[1,2-a]azepane (1), the first occurrence in nature of this "izidine" system. Tetrahydro-1 proved identical to one of the four synthetic diastereomers, 2a--2d, thereby establishing that 1 has the 5Z,10E relative stereochemistry. Alkaloid 1 is often accompanied by other congeners, in particular a 5Z,10Z diastereomer 15, a dihydro analogue 16, and a ketone 17. Such izidines in frogs may arise from dietary ants, as do other classes of izidines.

Primary tetradecenyl amines from the ant Monomorium floricola

In contrast to other ants in the genus Monomorium that produce cyclic amines, extracts of Monomorium floricola contain (Z)-7-tetradecenylamine (1) and (Z)-9-tetradecenylamine (2). The structures of these compounds were established from their spectral data and by comparison with synthetic 2.

A new configuration for voltage clamp of axons used to demonstrate nerve conduction blockade by a 2,5-disubstituted pyrrolidine

An original voltage-clamp technique on axons from crayfish Procambarus clarkii is described in this paper. Its advantages are: a fast dissection leading to the availability of several fibers of different diameters (10-500 microns) that may contain different ion channels; and use of a double-electrode voltage clamp on a chosen fiber with good clamping characteristics (short time clamp and good space clamp, small leak conductance). Because of the absence of exogenous lipidic phase in the superfusion chamber, this technique appears particularly suited to studying how liposoluble neurotoxins affect nerve conduction. This method has been successfully applied to test the effect of a synthetic derivative (2-(1non-8enyl)-5(1non-8enyl)pyrrolidine (Pyr 9)) of ant venom alkaloids from Monomorium species on nerve conduction. We present here evidence of a strong blocking effect on inward current involved in spike conduction. The resting potential of the treated axons did not change and it appears that only the inward current was affected.

Venom alkaloids in Monomorium "rothsteini" Forel repel other ants: is this the secret to success by Monomorium in Australian ant communities?

Species of the cosmopolitan ant genus Monomorium are small, slow-moving and non-aggressive ants that are extremely successful members of diverse Australian ant communities. Unlike other abundant taxa, they have no obvious specializations enabling them to co-exist with the highly aggressive species of Iridomyrmex that dominate these communities. Here we report results which suggest that Monomorium species owe their success to the topical application of venom alkaloids which repel other ants. The venom alkaloids (trans-2-ethyl-5-undecylpyrrolidine and trans-2-ethyl-5-tridecylpyrrolidine) of Monomorium "rothsteini" were identified and synthesized, and the repellency to other ants of the synthetic alkaloids were tested using bioassays involving the attraction to honey baits of three native species of Iridomyrmex, three tropical "tramp" species, and M. "rothsteini" itself. Repellency to all other ant species was total or nearly so, but only partial to M. "rothsteini". Defensive alkaloids produced from a variety of glands are found in other ant genera, and may be a potent yet poorly appreciated force in interference competition between ant species and thereby the structure of ant communities.

The biochemical composition of venom from the pavement ant (Tetramorium caespitum L.)

The venom of the pavement ant, Tetramorium caespitum, is used for prey capture, defense and social communication. The venom is predominantly proteinaceous in nature and contains various free amino acids, predominantly aspartic and glutamic acid, as well as histamine. The activities of the enzymes phospholipase and hyaluronidase, which are believed to be present in all hymenopteran venoms could not be detected. The composition of Tetramorium caespitum venom is compared with other myrmicine venoms.