Demonstration of sex pheromones in the predaceous diving beetle Rhantus suturalis (MacLeay 1825) (Dytiscidae)

Abstract

Sex pheromones are used by a wide variety of species in terrestrial ecosystems. Much less is known about these pheromones in aquatic systems e.g., for diving beetles. To test the use of pheromones and visual signals for mate finding by the diving beetle Rhantus suturalis (MacLeay 1825), behavioral experiments were performed using three different types of vessels containing conspecific. In experiments with non-permeable glass flasks, which did not allow the diffusion of chemical substances, males and females did not stimulate any reaction by conspecific of either sex. In experiments with opaque but water permeable vessels, and in experiments with vessels made of finely woven steel, which allowed the perception of chemical as well as optical cues, male diving beetles were significantly attracted to females. Females were attracted to other females only in the last experiment, when simultaneously perceiving chemical and optical cues. These results indicate that R. suturalis females release sex pheromones to attract mating partners, which is the first experimental demonstration of pheromones in the Dytiscidae.

Interspecific competition amongst three species of large-bodied diving beetles: is the species with expanded distribution an active swimmer and a better forager?

“…Our experiments suggest that six beetles in an aquarium of the size we used may provide an appropriate density for aggregation. Beetles in such aggregations may emit certain sex pheromones (Herbst et al, 2011;Dettner, 2014), especially in the case of C. brevis. In contrast, the PC1 scores did not change in C. chinensis, even when the beetle density was increased (Figs.…”

The Chemosensory Transcriptome of a Diving Beetle

“…In the absence of biological replicates, we could not carry out a differential expression analysis able to capture subtle differences of expression between samples, notably between males and females. Anyway, no R. suturalis chemosensory gene showed any hint of sex-biased expression, a quite puzzling result in light of the recent experimental demonstration that in this species, males are attracted underwater by a sex pheromone (of unknown composition) emitted by females (Herbst et al, 2011). With the exception of D. melanogaster, all pheromone receptors identified so far in insects belong to the OR family (see Fleischer and Krieger, 2021 for a comprehensive review).…”

“…Species of the genus Rhantus are prominent predators of mosquito larvae (Culler et al, 2014). Furthermore, it was recently demonstrated that R. suturalis males are attracted underwater by a sex pheromone of unknown composition emitted by females (Herbst et al, 2011). The R. suturalis transcriptome was used to annotate genes belonging to major families of soluble proteins and transmembrane receptors responsible for semiochemical detection in insects, and to estimate their expression levels in antennae and palps.…”

Male tarsi specific odorant-binding proteins in the diving beetle Cybister japonicus sharp

“…The high expression of OBPs in the specialized front tarsi of males may suggest significant roles interfering with sex communication. Because during the underwater courtship the female C. japonicus could release sex pheromones used by males for partner localization that was observed in the diving beetle Rhantus suturalis 59 . Therefore it is reasonable to hypothesize that these OBPs specific expressed in male foreleg tarsi C. japonicus may be involved in the sex pheromone reception.…”