Cuticular Hydrocarbons Provide Reliable Cues of Fertility in the Ant Gnamptogenys striatula

Abstract

In ca. 150 species of queenless ants, a specialized queen caste is rare or absent, and mated workers take over the role of the queen in some or all of the colonies. Previously, it has been shown that reproduction in queenless ants is regulated by a combination of dominance behavior and chemical fertility signaling. It is unknown, however, whether chemical signals alone can sufficiently regulate reproduction. To investigate this possibility, we studied reproductive regulation in the facultatively queenless ant Gnamptogenys striatula, a species where dominance behavior is rare or absent. Active egg layers and infertile workers showed qualitative and quantitative differences in their cuticular hydrocarbon profile. Five long-chain methyl alkanes, 3,13-and 3,15-dimethyl pentriacontane, 3,13-and 3,15-dimethyl heptentriacontane, and 3,11,15-trimethyl heptentriacontane occurred only on the cuticles of virgin and mated egg layers. Pronounced quantitative differences were found in a further 27 alkenes; alkanes; and mono-, di-, and trimethyl alkanes. Workers that had recently stopped laying eggs had profiles similar to infertile workers, and mating status did not affect this chemical pattern. We conclude that the cuticular hydrocarbon profiles of G. striatula workers provide reliable information about their current fertility. In the interest of colony productivity, this allows reproduction to be regulated without the use of aggression.

Intraspecific Variation of the Composition of Linear Alkanes in Social Wasp Mischocyttarus consimilis

“…Therefore, the cuticular linear alkanes are important compounds used for the identification of individuals (Singer et al, 1998), which can vary according to their tasks in the colony (Leal, 2005). However, despite our results show that linear alkanes too may signal the different caste and sex, Lommelen et al (2006) reports that branched alkanes appear to be more involved in signaling during interspecific interactions, as this class has a high complexity molecular, showing a high potential to encode information (LeConte & Hefetz, 2008;Blomquist & Bagnères, 2010), and linear alkanes would be more involved in building a barrier to prevent water loss (Armold & Regnier, 1975).…”

Divergence in Cuticular Chemical Signatures between Isolated Populations of an Intraspecific Social Parasite

“…Both branched and long-chained hydrocarbons may also act as fertility cues in social insects. For example, there is a shift to long-chained and branched cuticular hydrocarbons as females become fertile in the drywood termite Cryptotermes secundus (Weil et al, 2009) and in the ant Gnamptogenys striatula (Lommelen et al, 2006). A shift toward long-chained hydrocarbons also occurs in females of the ponerine ants Pachycondyla inversa (Heinze et al, 2002) and Harpegnathos saltator (Liebig et al, 2000) and it is positively associated with fertility.…”

Disentangling the effect of insemination and ovary development on the cuticular hydrocarbon profile in the bumblebee Bombus terrestris (Hymenoptera: Apidae)

“…They lack physical castes and sterile workers are able to mate, lay eggs, and become sterile again. Findings in these studies suggest that the hydrocarbon profile is affected by ovarian activity but not by mating status, as workers that have recently stopped laying eggs have the same hydrocarbon profile as non-egg-laying workers and the chemical profile of gamergates and unmated workers with active ovaries is essentially the same (Lommelen et al 2006). However, we still lack studies in other eusocial insects with physical castes like in bumblebees.…”

“…To be able to discriminate between the effects of insemination and ovary development, a model species needs to provide similar individuals in an inseminated and a noninseminated condition which can have fully developed or undeveloped ovaries. So far, only some primitively eusocial polygynous queenless ant species from the subfamily Ponerinae have allowed for such investigations (e.g., Lommelen et al 2006;Cuvillier-Hot et al 2002;Liebig et al 2000). They lack physical castes and sterile workers are able to mate, lay eggs, and become sterile again.…”