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

Abstract

The aim of the research reported here was to determine whether 3-ethyl-4-methylpentanol, a minor but crucial component of the sex pheromone of the North American slave-making ant species Polyergus breviceps, was also a component of the sex pheromone of the European congener Polyergus rufescens. Thus, the contents of mandibular glands of P. rufescens virgin queen were extracted and analysed. The main component of the extracts was methyl 6-methylsalicylate and 3-ethyl-4-methylpentanol was identified as one of several minor components. Further analyses showed that the insects produce mainly the (R)-enantiomer of the alcohol. Males responses to various blends of methyl 6-methylsalicylate with the racemate or the pure enantiomers of 3-ethyl-4-methylpentanol were tested in field behavioural bioassays. The data showed that blends of methyl 6-methylsalicylate and 3-ethyl-4-methylpentanol were strongly synergistic, with the most active ratios being biased toward the first component. The addition of other minor components to the binary blend neither increased nor decreased responses by males. Only the (R)-enantiomer of the alcohol was biologically active; its antipode did not inhibit attraction. The results are discussed in terms of the evolution of signals, and are compared with the results previously obtained for the allopatric species Polyergus breviceps.

Coffee Berry Borer Joins Bark Beetles in Coffee Klatch

“…Also identified were methyl 3-ethyl-4-methylpentanoate, previously identified from Formica ants [40], and trace amounts of its reduction product, the corresponding alcohol, 3-ethyl-4-methylpentanol. This alcohol is part of the sex attractant queen pheromone of ants of the genus Polyergus [41], [42] and a component of an attractive blend of VOCs previously identified for the coffee berry borer [27]. In coupled GC/EAD analysis of VOCs obtained by head space collection of coffee berries conophthorin and its unsubstituted derivative elicited strong EAG responses in antennae of H. hampei.…”

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

“…It acts as a sex pheromone in Polyergus breviceps and P. rufescens (Greenberg et al, 2004;Castracani et al, 2005); a trail pheromone in Tetramorium impurum and Mayriella overbecki (Morgan and Ollett, 1987;Kohl et al, 2000); and as an alarm pheromone in Gnamptogenys pleurodon (Duffield and Blum, 1975). Sometimes methyl 6-methylsalicylate is mixed with other compounds to elicit a response, such as in P. breviceps and P. rufescens (Greenberg et al, 2004;Castracani et al, 2008); or it is the only compound needed to elicit a sexual response, such as in P. rufescens (Castracani et al, 2005). In Camponotus spp., Bothroponera soror, P. breviceps, P. rufescens, and G. pleurodon, methyl 6-methysalicylate comes from the mandibles (Brand et al, 1973;Longhurst et al, 1980;Blum et al, 1987;Greenberg et al, 2004;Castracani et al, 2005).…”

Bacteria may contribute to distant species recognition in ant–aphid mutualistic relationships

“…Although qualitative VOCs profiles detected are very close, even nearly identical for the 2 tested bacterial cultures, ants still shown a preference for Aphis fabae-related samples, suggesting recognition based on ratios between compounds instead of the attractiveness of a single molecule or group of molecules. The impact of compounds ratios on insects' communication is a well-known phenomenon which has already been highlighted for numerous insect species, including ant and aphid species (Castracani et al, 2008;Cardé & Millar, 2009;Byers et al, 2013;Han et al, 2014).…”