Marie-Claire Cammaerts

3-ethyl-2,5-dimethylpyrazine, the trail pheromone from the venom gland of eight species of Myrmica ants

Abstract Trail-following behaviour is evoked by a single substance from the venom gland of the ant Myrmica rubra L. The compound has been identified as 3-ethyl-2,5-dimethylpyrazine by microchemical methods and by comparison with the synthetic compounds. Seven other Myrmica species, which follow trails made with each others venom glands and show no species selectivity, have all been shown to produce the same substance in similar quantities. Individual analyses on 10 samples of single venom glands by a solid sampling technique showed that M. rubra workers contain a mean of 5.8 ± 1.7 ng of the substance (± S.D.). The synthetic substance also evoked a strong trail-following response in workers at the same concentration, and statistical tests revealed no difference between synthetic pyrazine and venom gland contents.

Comparative study of the pheromones emitted by workers of the ants Myrmica rubra and Myrmica scabrinodis

Abstract The two species of Myrmica produce similar compounds in their mandibular glands, but in very different proportions. Though the secretion has similar ethological activity in both species, the activity is due to different compounds in each. There are no obvious differences in the volatile components of the poison secretion, and workers follow trails of their own or the other species equally well. The volatile components of the Dufour gland secretion are similar in both species and have the short-term effect of encouraging workers to forage. The less volatile part is quite different in the two species and workers recognize their own from the other species secretion when the volatile components have evaporated away. The less volatile part is used for territorial marking, and a territory marked with the pheromone of one species can be overmarked with the secretion of the second species.

Comparative study of the dufour gland secretions of workers of four species of Myrmica ants

The Dufour gland secretions of myrmica rubra, M. ruginodis, M. sabuleti and M. scabrinodis have been studied. The most volatile portions of the secretion of workers of all four species were found to be similar, containing C2C4 oxygenated compounds. The less volatile portion consists of a mixture of hydrocarbons. In M. ruginodis this is chiefly a mixture of linear saturated and mono-unsaturated hydrocarbons, similar in composition to that of M. rubra, while in M. sabuleti it consists of (Z,E)-α-farnesene and its homologues, homofarnesene, bishomofarnesene and trishomofarnesene, similar in composition to that of M. scabrinodis. Workers of each species studied were attracted to the Dufour gland volatiles of all four species, these substances chiefly causing an increase in running speed, with the workers not distinguishing between conspecific and allospecific secretions, though small quantitative differences could be demonstrated between the speed and orientation reaction of workers of each species. The less volatile fraction of the Dufour gland secretion is used for territorial marking by foraging workers. This marking is specific for each species except between M. rubra and M. ruginodis.

Behavioural activity of pure chiral 3‐octanol for the ants Myrmica scabrinodis Nyl. and Myrmica rubra L.

ABSTRACT. The mandibular glands of Myrmica ants contain, among other substances, 3‐octanol, a chiral substance, 90% of it being the R‐enantiomer in M. scabrinodis Nyl., ruhra L. and ruginodis Nyl. (Cammaerts et al., 1985). Pure R and S 3‐octanol has been prepared and tested on M. rubra and scabrinodis, workers. Both species react specifically only to the R enantiomer; in M. rubra this constituent arrests foragers briefly, and in M. scahrinodis it attracts them and incites them to walk more quickly. It is shown that, in M. scahrinodis, the naturally produced mixture of R and S 3‐octanol (proportions of 9:1, v/v) is more active than the pure R enantiomer or a mixture of R and S 3‐octanol (5:5 v/v).

The volatile components of the mandibular gland secretion of workers of the ants Myrmica lobicornis and Myrmica sulcinodis

Abstract The mandibular glands of workers of M. lobicornis produce a mixture of 3-alkanones and 3-alkanols in the C 6 –C 10 carbon chain length range, in addition to nanogram amounts of acetone, ethanal and 2-methylpropanal. Ethological studies have shown that the three major constituents, 3-octanol, 3-octanone and 3-decanol, are also the major pheromonally active components. When presented together they stimulate an alarm response in the workers similar to that induced by a workers crushed head. In M. sulcinodis the mandibular gland secretion is composed of a mixture of the same ketones and alcohols, but in different proportions.

Identification of the components of Dufour gland secretion of the ant Myrmica rubra and responses to them

Abstract The Dufour gland secretion consists of a solution of volatile oxygenated compounds in a mixture of higher hydrocarbons and sesquiterpenoid alkenes. Methanol, butenone, 2-methylpropanal, and 1-butanol have now been identified as the remaining major volatile components. These substances have no strong behavioural effect upon ants, nor do they induce trail following behaviour. The principal activity of the Dufour gland can be traced to the three more abundant volatile components, ethanal, acetone, and butanone, together with the minor component ethanol.

Dufour gland secretions of workers of the ants Myrmica sulcinodis and Myrmica lobicornis, and comparison with six other species of Myrmica

Abstract The investigation of the chemical composition of the secretions of the Dufour glands of Myrmica sulcinodis and M. lobicornis , as a part of an extended study on Myrmica ants, has shown that the Dufour gland of M. sulcinodis is filled with a mixture of hydrocarbons consisting of straight chain alkanes and alkenes with 15–19 carbon atoms as found in M. rubra , and a mixture of terpenoid hydrocarbons, namely (Z,E)-α-farnesene, homofarnesene, and bishomofarnesene as found in M. scabrinodis . In M. lobicornis , only (Z,E)-α-farnesene and its homologues, homofarnesene and bishomofarnesene are present. The complete absence of linear hydrocarbons in the latter species makes it similar to M. scabrinodis . In both species the very volatile portion of the Dufour gland secretion is composed of ethanal, propanone and methylpropanal as found in the other species of Myrmica , studied earlier.

Chemical and ethological studies of the trail pheromone of the ant Manica rubida (Hymenoptera: Formicidae)

ABSTRACT. The poison gland of Manica rubida contains nanogram quantities of four alkylpyrazines, methylpyrazine, 2,5‐dimethylpyrazine, trimethylpyrazine and 3‐ethyl‐2,5‐dimethylpyrazine, of which only the last induces pronounced trail‐following behaviour. Myrmica rubra and M. rubida workers follow each others trails equally well when allowance is made for the much greater size of M. rubida workers. The cross activity in trail‐following between M. rubida, M. rubra and Tetramorium caespitum is understandable in terms of the amounts and proportions of the different pyrazines present in their glands and their responses to the synthetic substances and appropriate mixtures of them.

The pheromonal activity of chiral 3‐octanol for Myrmica ants

ABSTRACT. The (R)‐(‐)‐3‐octanol from the mandibular glands of Myrmica ants is the only enantiomer active as an attractant pheromone for M.scabrinodis Nyl. The S enantiomer is inactive and its presence decreases slightly the response of M.scabrinodis to the R enantiomer. (R) and (S)‐2‐octanol are inactive.

The mandibular gland secretion of the ant, Myrmica scabrinodis

ABSTRACT. The volatile secretion of the mandibular gland of the common elbowed red ant, Myrmica scabrinodis Nyl., is shown to consist of ethanal, ethanol, acetone, 3‐hexanone, 3‐hexanol, 3‐heptanone, 3‐heptanol, 3‐octanone, 3‐octanol, 6‐methyl‐3‐octanone, 6‐methyl‐3‐octanol, 3‐nonanone, 3‐nonanol, 3‐decanone and 3‐undecanone. The electroantennographic response to the major components was recorded and compared with some related compounds. Behavioural tests were carried out on the major constituents, showing that 3‐octanol is an attractant for workers, that 3‐octanone increases the effect of 3‐octanol, and 3‐nonanone augments the linear speed of the ants.