Towards an Understanding of Molecule Capture by the Antennae of Male Beetles Belonging to the Genus Rhipicera (Coleoptera, Rhipiceridae)

Abstract

Working on the hypothesis that an important function of the lamellate antennae of adult male beetles belonging to the genus Rhipicera is to detect scent associated with female conspecifics, and using field observations, anatomical models derived from X-ray microcomputed tomography, and scanning electron microscopy, we have investigated the behavioral, morphological, and morphometric factors that may influence molecule capture by these antennae. We found that male beetles fly upwind in a zigzag manner, or face upwind when perching, behavior consistent with an animal that is tracking scent. Furthermore, the ultrastructure of the male and female antennae, like their gross morphology, is sexually dimorphic, with male antennae possessing many more of a particular type of receptor-the sensillum placodeum-than their female counterparts (approximately 30,000 vs. 100 per antenna, respectively). Based on this disparity, we assume that the sensilla placodea on the male antennae are responsible for detecting scent associated with female Rhipicera beetles. Molecule capture by male antennae in their alert, fanned states is likely to be favoured by: (a) male beetles adopting prominent, upright positions on high points when searching for scent; (b) the partitioning of antennae into many small segments; (c) antennal morphometry (height, width, outline area, total surface area, leakiness, and narrow channels); (d) the location of the sensilla placodea where they are most likely to encounter odorant molecules; and (e) well dispersed sensilla placodea. The molecule-capturing ability of male Rhipicera antennae may be similar to that of the pectinate antennae of certain male moths. Anat Rec, 298:1519Rec, 298: -1534Rec, 298: , 2015. V C 2015 Wiley Periodicals, Inc.

Olfactory flow in the sturgeon is externally driven

“…Much of the methodology has been described before (Cox, 2008;Abel et al, 2010;Holmes et al, 2011;Rygg et al, 2013;Howard et al, 2013;Ramsey et al, 2015;Agbesi et al, 2016aAgbesi et al, , 2016b. Therefore, only essential details are given below.…”

“…The TIFF images were then transformed into a mask of the head (Fig. 2C, Ma) using methodology described previously (Abel et al, 2010;Holmes et al, 2011;Howard et al, 2013;Ramsey et al, 2015;Agbesi et al, 2016aAgbesi et al, , 2016b. During this process, we removed a barbel that would have obstructed flow into one of the model's nasal chambers (Fig.…”

“…3C, Op and Tr) were created according to our previous methodology (e.g. Ramsey et al, 2015). The three surface models were then each exported in binary format as stereolithography (STL) files ([dataset] Haysom et al, 2019).…”

“…Morphometric measurements were made using ParaView, Rhinoceros (Version 4.0, Robert McNeel & Associates), and ScanIP, usually according to previous methodology (Cox, 2008;Abel et al, 2010;Holmes et al, 2011;Cox, 2013;Howard et al, 2013;Ramsey et al, 2015).…”

A Cretaceous bug with exaggerated antennae might be a double-edged sword in evolution

“…The presence of nymph suggests that if we find an adult in the future, the antennae may be larger and expansion of the third and fourth segments of the antennae may be more remarkable. The similar large, exquisite lamellate antennae and pectinate antennae significantly increase the surface area of the antennae and enhance the interaction between odors and receptors ( Ramsey et al., 2015 ). When the recognition of certain odors becomes an important factor in reproductive fitness, the evolution of olfactory receptors tends to maximize the surface area of antennae ( Mankin and Mayer, 1984 ).…”