Use of novel attraction compounds increases monitoring success of a rare beetle, Elater ferrugineus

Harvey DJ, Harvey H, Harvey RP, Kadej M, Hedenström E, Gange AC, et al. Use of novel attraction compounds increases monitoring success of a rare beetle, Elater ferrugineus. Insect Conservation and Diversity. 2017;10(2):161–70.

The use of pheromones to determine distributions of rare saproxylic insects is an increasingly popular technique. Pheromones may, however, also be used to elucidate the biology of these cryptic species, a vital requirement if they are to be accurately monitored and conserved. We used non-invasive aerial trapping to compare the effectiveness of chemicals produced by Elater ferrugineus L (Coleoptera: Elateridae), namely 7-methyloctyl (Z)-4-decenoate (the female-produced sex pheromone), and male compounds (geranyl and neryl acetone and 6-methyl-5-heptene-2-one). The male compounds were identified using headspace analysis by solid phase micro-extraction gas chromatography-mass spectrometry. We discovered that males only produce these two compounds after having been attracted to a female, and that this serves to attract further males to a female. Such compounds do not appear to attract females but for a species that has a short activity period and is non-feeding in the adult stage, may ensure breeding success when populations are low. By marking all beetles caught, we were able to demonstrate that recapture rate using this method is low (approximately 11% of total captures annually). Therefore, the method does not limit dispersal or breeding opportunities, making it a valuable tool for monitoring endangered saproxylic beetle species.