Cuticular hydrocarbon profiles as a taxonomic tool: advantages, limitations and technical aspects

Abstract

Abstract. Cuticular hydrocarbons (CHCs) are expressed on an insect's cuticle and are one of the major factors allowing insects to identify members of their own species, colony and gender. As a result of their species-specificity, CHCs are increasingly used to delimit species in addition to more conventional methods, such as morphology or genetic markers, and so play an important role in chemotaxonomy. Species vary in the type of CHCs that they produce, as well as in the relative quantities of shared compounds. This review summarizes not only how taxonomists may differentiate between species based on CHC profiles, but also the incentive for using CHC composition as taxonomic tool. Benefits regarding the identification of cryptic species and early signs of reproductive isolation are then discussed, giving examples from studies of taxonomy, behaviour and biosynthesis. For taxonomic characters to reliably indicate species boundaries, their limitations need to be known. Potential problems caused by environmental effects, intra-species variation in profiles and other technical issues are highlighted, and suggestions are made regarding their avoidance. It remains a challenge to determine the variation beyond which two species can be called independent; a problem shared by most methods of delimitation. Recently, there has been a shift towards using a combination of different taxonomic tools, both molecular and non-molecular, to test observed species differences.

How do cuticular hydrocarbons evolve? Physiological constraints and climatic and biotic selection pressures act on a complex functional trait

“…Usually, samples of the same species possessed similar quantitative and identical qualitative composition of CHC profiles [45]. In these cases, we considered one sample per species.…”

“…Blaimer, T. Schmit 2013, unpublished data). For these six species, the presence of strongly different profiles suggests the existence of cryptic species [45], which is why we retained both chemotypes per species in the dataset.…”

A coat of many scents: Cuticular hydrocarbons in multitrophic interactions of fig wasps with ants

“…For each CHC extract, we immersed 100 freshly freeze-killed females of each species in 5 ml of pentane for 10 min ( Van der Meer et al, 1989;Kather and Martin, 2012); freshly eclosed wasps were collected from D-phase figs in the laboratory. These numbers of wasps were required for each sample since the wasps are very small (0.22e0.35 mg per wasp; data from Ghara and Borges, 2010).…”

The Long and the Short of Mate Attraction in a Psylloid: do Semiochemicals Mediate Mating in Aacanthocnema dobsoni Froggatt?

“…For these reasons, cuticular hydrocarbons (CHCs) and substrate-borne vibrations (SBVs) have been used in systematic studies of a range of taxa (Bagnères and Wicker Thomas 2010; Kather and Martin 2012; Percy et al 2006. Cuticular hydrocarbons can provide evolutionary insight into taxa because they are species specific, with some compounds conserved among related taxa (Kather and Martin 2012; Martin et al 2008a, b ; Martin and Drijfhout 2009 ). Insect CHCs typically comprise a complex mixture of long chain aliphatic and methyl branched alkanes and alkenes (Howard and Blomquist 2005 ).…”