The relationship between epicuticular long-chained hydrocarbons and surface area - volume ratios in insects (Diptera, Hymenoptera, Lepidoptera)

Abstract

Long-chain cuticular hydrocarbons (CHCs) are common components of the epicuticle of terrestrial arthropods. CHC serve as a protective barrier against environmental influences but also act as semiochemicals in animal communication. Regarding the latter aspect, species- or intra-functional group specific CHCs composition and variation are relatively well studied. However, comparative knowledge about the relationship of CHC quantity and their relation to surface area—volume ratios in the context of water loss and protection is fragmentary. Hence, we aim to study the taxon-specific relationship of the CHC amount and surface-area to volume ratio related to their functional role (e.g. in water loss). We focused on flower visiting insects and analyzed the CHC amounts of three insect orders (Hymenoptera, Lepidoptera and Diptera) using gas chromatography—mass spectrometry (GC-MS). We included 113 species from two grassland plots, quantified their CHCs, and measured their body mass and surface area. We found differences in the surface area, CHCs per body mass and the CHC density (= amount of CHCs per surface area) across the three insect taxa. Especially the Hymenoptera had a higher CHC density compared to Diptera and Lepidoptera. CHC density could be explained by surface area-volume ratios in Hymenoptera but not in Diptera and Lepidoptera. Unexpectedly, CHC density decreased with increasing surface area—volume ratios.

Chemical and behavioral integration of army ant-associated rove beetles – a comparison between specialists and generalists

“…In the present study, we used an animal’s dry weight as estimator for body size. The dry weight, and in particular the dry weight 2/3 , is generally a good predictor of an insect’s surface area [ 76 , 77 ]. Ideally, future studies will assess surface areas via 3-D scans directly to calculate CHC concentrations of ants and their mimics [ 76 , 77 ], but we suggest the dry weight as a reliable and feasibly measurable surrogate.…”

“…The dry weight, and in particular the dry weight 2/3 , is generally a good predictor of an insect’s surface area [ 76 , 77 ]. Ideally, future studies will assess surface areas via 3-D scans directly to calculate CHC concentrations of ants and their mimics [ 76 , 77 ], but we suggest the dry weight as a reliable and feasibly measurable surrogate. Using dry weight as surface area predictor might be useful in studying both, the role of CHC concentration in ant nestmate recognition (e.g., [ 108 ]) and in the recognition of chemical mimics (e.g., [ 41 ]).…”

“…The amounts of CHCs [in ng] were calculated based on the internal standard hexadecane as described in [ 76 ]. To consider differences in body size among specimens we either standardized using the body mass [in mg dry weight; see Additional file 3 : Figure S2 for all dry weight measurements] or the estimated surface area with the obtained dry weight data [in mg 2/3 ] (see [ 77 ]).…”

An automated device for the digitization and 3D modelling of insects, combining extended-depth-of-field and all-side multi-view imaging

“…Hence, many of these functional traits relate to 3D structures, but have been characterized only in 1D or 2D, largely constrained by the availability of methods. In particular, surfaces and volumes are important characteristics that are relevant in a functional eco-physiological context but can only be measured in 3D ( Brückner et al 2017 ; Kühsel et al 2017 ). Therefore, besides archiving and digitizing museum collections, trait-based research areas in functional ecology, eco-physiology, and evolutionary biology would greatly benefit from easily available 3D scanning techniques.…”

Cuticular Hydrocarbon Profile of Parasitic Beetles, Aethina tumida (Coleoptera: Nitidulidae)

“…In addition, there are differences in body shape between SHBs and honey bees, leading to differences in surface area to volume ratios. This can also influence the total amount of CHCs present [64] and might partially explain the observed differences. In any case, the low amount of CHCs taken together with the relative simplicity of the CHC profile before entering host colonies might represent an adaptation to at least partly evade the honey bees' nestmate recognition system [10].…”