First Evidence of a Volatile Sex Pheromone in Lady Beetles

Abstract

To date, volatile sex pheromones have not been identified in the Coccinellidae family; yet, various studies have suggested that such semiochemicals exist. Here, we collected volatile chemicals released by virgin females of the multicolored Asian lady beetle, Harmonia axyridis (Pallas), which were either allowed or not allowed to feed on aphids. Virgin females in the presence of aphids, exhibited “calling behavior”, which is commonly associated with the emission of a sex pheromone in several Coleoptera species. These calling females were found to release a blend of volatile compounds that is involved in the remote attraction (i.e., from a distance) of males. Gas Chromatography-Mass Spectrometry (GC-MS) analyses revealed that (–)-β-caryophyllene was the major constituent of the volatile blend (ranging from 80 to 86%), with four other chemical components also being present; β-elemene, methyl-eugenol, α-humulene, and α-bulnesene. In a second set of experiments, the emission of the five constituents identified from the blend was quantified daily over a 9-day period after exposure to aphids. We found that the quantity of all five chemicals significantly increased across the experimental period. Finally, we evaluated the activity of a synthetic blend of these chemicals by performing bioassays which demonstrated the same attractive effect in males only. The results confirm that female H. axyridis produce a volatile sex pheromone. These findings have potential in the development of more specific and efficient biological pest-control management methods aimed at manipulating the behavior of this invasive lady beetle.

Behavioral and Immunological Features Promoting the Invasive Performance of the Harlequin Ladybird Harmonia axyridis

“…Like other ladybeetle species, freshly emerged H. axyridis adults pass through a pre-mating period during which their gonads mature (Obata and Hidaka, 1987). Several behavioral observations suggest that males are attracted over a distance (e.g., Schaller and Nentwig, 2000;Omkar and Pervez, 2005), and H. axyridis is the only ladybird species in which a female volatile sex pheromone has been identified (Fassotte et al, 2014). In the presence of prey, virgin H. axyridis females display a typical calling behavior: they raise their elytra and squeeze their abdomen.…”

Comparison of the Sex Pheromone Composition of Harmonia axyridis Originating from Native and Invaded Areas

“…Several hundred Harmonia axyridis were captured at different locations in Tai’an (Shandong, China) and in Brookings (South Dakota, USA) and were transferred to the laboratory (Belgium) as adults and kept under the same rearing conditions as described by Fassotte et al (2014) [15]. To induce oviposition, pea aphids ( Acyrthosiphon pisum ) were introduced in the rearing boxes.…”

“…There is evidence that mate recognition in H. axyridis relies on a sex pheromone released by females to attract males before mating [15]. The pheromone blend is composed of one major (β-caryophyllene) and four minor chemical constituents (β-elemene, methyl-eugenol, α-humulene, α-bulnesene).…”

Identification of walnut husk (Juglans regia L.) volatiles and the behavioural response of the invasive Walnut Husk Fly, Rhagoletis completa Cresson

“…In both cases, the oven temperature program started at 40°C, was held for 2 min, and was increased at 4°C min −1 to 95°C, and then increased at 6°C min −1 to 155°C, and was finally increased at 25°C min −1 to 280°C, before being held at this temperature for 5 min. The mass spectra were recorded in the electron impact mode at 70 eV (source at 200°C, transfer line at 250°C, scanned mass range: 39 to 300 m / z ), and was adapted from the method used for sesquiterpenes analysis by Fassotte et al . The detected peaks were identified based on the GC retention index, with their mass spectra being compared to those of a spectral library (Wiley 275), and was confirmed by injecting commercial standards of high purity (>98%) (Sigma Aldrich, Bornem, Belgium) when available.…”