The Pheromone Frontalin and its Dual Function in the Invasive Bark Beetle Dendroctonus valens

Abstract

The red turpentine beetle, Dendroctonus valens LeConte, is one of the most destructive invasive forest pests in China, having killed more than 6 million pines since its first outbreak in 1999. Little is known about D. valens pheromone biology and no aggregation pheromone has yet been identified. Analysis by gas chromatograph/mass spectrometer of volatiles collected from live beetles in China showed that female beetles produce frontalin and males do not. Olfactory assays in the laboratory showed that males were attracted to frontalin at a wide range of concentrations, whereas females were attracted to it at a narrow range of concentrations. In field trials, 3-carene, a monoterpene kairomone from a pine tree selected to host the beetles attracted both sexes, and when frontalin was added, the total number of beetles captured increased by almost 200%. However, increasing concentrations of frontalin significantly decreased the percentage of female beetles trapped. These results suggest a new role of frontalin as an aggregation pheromone in addition to a female-produced sex pheromone, which was previously shown in a North American population. The dual functions of the pheromone frontalin produced by D. valens females, as well as its ecological significance for overcoming host resistance, are discussed.

The pheromone verbenone and its function in Dendroctonus armandi (Coleoptera: Curculionidae: Scolytinae)

“…D. armandi females attack a tree and then use some kind of semiochemical to attract both males and females, which is similar to what is recorded for Dendroctonus valens (Liu et al, 2006;Pureswaran et al, 2008a). Semiochemical communication in bark beetles "enables host and mate location, aggregation and resource partitioning" (Borden et al, 1986;Liu et al, 2013), and aggregation pheromones ensure successful rate of 40 mL/min. The open end of the metal tube was positioned 1.2 cm away from the antenna.…”

Effectiveness of Odor-Baited Trap Trees for Plum Curculio (Coleoptera: Curculionidae) Monitoring in Commercial Apple Orchards in the Northeast

“…For example, more Dendroctonus valens LeConte females than males were attracted to 3-carene when this host volatile was evaluated alone. However, when the pheromone, frontalin, was added to 3-carene, a male-biased attraction was observed (Liu et al 2013). The sexually dimorphic responses of S. incurrens suggest that the pheromone may have a dual function, functioning as sex attractant and aggregation pheromone, but future studies will clarify the role of this compound in the chemical ecology of this weevil species.…”

“…However, in the case of S. incurrens, this pattern of response was inverted when the host volatiles were added to the pheromone; males responded to the concentration of 10 ng/µL, and females were attracted to the concentration of 100 ng/µL. A number of studies showed that host plants can influence the attraction of insects to their pheromones (Landolt & Phillips 1997;Reddy & Guerrero 2004;Dickens 2006;Liu et al 2013). For example, more Dendroctonus valens LeConte females than males were attracted to 3-carene when this host volatile was evaluated alone.…”

Mechanisms of action and co-optive evolution for hypervariable courtship pheromones in plethodontid salamanders.

“…Notably, the three PRF fractions (11)(12)(13) show molecular weights larger than the ~22 kDa predicted from DNA sequences. Mass spectral identification of P. cinereus pheromones All proteins in fractions 1 -5 and 6L were identified to be different isoforms of PMF (Table 13; herein referred to as PMF-1 through PMF-6 respectively).…”

“…In the 50+ years since the discovery of bombykol, thousands of different chemicals have been identified in insects to perform similar functions, including frontalin in the invasive bark beetle (Dendroctonus valens) [12], heptacosadiene in fruit flies (Drosophila melanogaster) [13], derivatized fatty acids in ermine moths (Yponomeuta spp.) [14], and tetradecenyl acetates in European corn borer (Ostrinia nubialis) [15].…”