Determination of the mandibular gland secretion of Polyergus rufescens queens by solid‐phase microextraction and gas chromatography/mass spectrometry

Abstract

Determination of the mandibular gland secretion of Polyergus rufescens queens by solid-phase microextraction and gas chromatography/mass spectrometry The mating pattern of the European amazon ant Polyergus rufescens is mainly characterized by the presence of isolated virgin queens that call for males through chemical signals. 1 This strategy can be classified as an example of 'female-calling syndrome' and is typical of phylogenetically primitive species or socially parasitic ants. 2 The sources of ant sex pheromones released by calling females are various: the poison gland in several myrmicine species such as the Canadian slave-maker Harpagoxenus canadensis, Dufour's gland in the myrmicine Monomorium pharaonis and the pygidial gland in the ponerine Rhytidoponera metallica. 3,4 Attempts to investigate the contents of these glands have been very limited: in Rhytidoponera metallica, the female pygidial gland includes isogeraniol and mhydroxybenzaldehyde; in four leptothorancine ants, the contents of the female poison gland have a predominance of 3-methyl-1-(3-methylbutyl)pyrrolidine.Usually, the mandibular gland is the source of sex pheromones in several ant species, whose mating pattern is defined as 'maleaggregation syndrome.' This reproductive strategy is characterized by the presence of species-specific mating sites for the gathering of both sexes. 2 In some genera such as Pogonomyrmex, the mandibular sex pheromones are attractants for females whereas in Camponotus herculeanus and in some species of the genera Atta and Acromyrmex, they are 'synchronizing' sex pheromones that induce the female nuptial flights. 3,4 Structural determination of pheromones is of great importance and nowadays it is conveniently performed by means of coupled gas chromatographic/mass spectrometric (GC/MS) techniques. 5 Conventionally, pheromones are sampled by solvent extraction of the whole insect or of the producer glands, or by trapping the volatile pheromones by an absorbent matrix and then eluting the absorbed molecules with a solvent. 6 Recently, the newly developed solidphase microextraction (SPME) technique has been also successfully exploited for pheromone analysis. 5,7 Following this strategy, we have just published a report on the Dufour's gland content of workers of two ant species of the genus Messor, analyzed by SPME/GC/MS directly on the intact insect gland. 8 In a previous study, 1 we demonstrated the implication of mandibular glands of P. rufescens virgin queens in the attraction of males for mating. A similar result was reached in the American species P. breviceps. 9 In this letter, we present the chemical analysis by SPME/GC/MS of the mandibular gland content of virgin queens of the European slave-making ant Polyergus rufescens.Virgin queens of P. rufescens were collected at the entrance of four different nests in the field area of the University Campus in Parma (Italy) during summer 2002. Mandibular glands were dissected from ants and individually placed at the bottom of a 5 cm thin-walled glass capillary of 1.28 mm ...

Chemical communication in mating behaviour of the slave-making ant Polyergus rufescens (Hymenoptera, Formicidae): 3-ethyl-4-methylpentanol as a critical component of the queen sex pheromone

“…In contrast, 3-ethyl-4-methylpentanol has been reported from only a few ant species (Francke et al, 1985;do Nascimento et al, 1993;Greenberg et al, 2004Greenberg et al, , 2007. However, because of the small quantities in which it is present and its high volatility, this chemical was more difficult to find in extracts than methyl 6-methylsalicylate (e.g., Castracani et al, 2003;Greenberg et al, 2004). Thus, more careful analyses may reveal that it is also relatively common in other ant species.…”

Methyl 6-Methylsalicylate: A Female-Produced Pheromone Component of the Parasitoid Wasp Spalangia endius

“…Methyl 3-and methyl 5-methylsalicylate were purchased from Aldrich (St. Louis, MO, USA). Methyl 6-methylsalicylate was synthesized from ethyl 6-methylsalicylate (APIN, Abingdon, Oxon) according to Castracani et al (2003), except that the reaction ran for 5 hr. Reaction completion was checked by GC-MS.…”