Ipsenol and ipsdienol attract Monochamus titillator (Coleoptera: Cerambycidae) and associated large pine woodborers in southeastern United States

Smoke, pheromone and kairomone olfactory receptor neurons in males and females of the pine sawyer Monochamus galloprovincialis (Olivier) (Coleoptera: Cerambycidae)

The response of antennal olfactory receptor neurons (ORNs) of Monochamus galloprovincialis to several odourants was tested using single sensillum electrophysiology. Behaviourally active pheromone, and kairomone (host and sympatric bark beetle pheromone) odours were tested alongside smoke compounds released by burnt wood that are potentially attractive to the insect. The antennae bore several types of sensilla. Two plate areas in the proximal and distal ends of each antennal segment were covered with basiconic sensilla that responded to the odour stimuli. Sensilla basiconica contained one or two cells of different spike amplitude. The 32 male and 38 female ORNs tested responded with excitations or inhibitions to the different plant odours. In general the response of male and female receptors was very similar so they were pooled to perform a cluster analysis on ORN responses. Six ORNs were clearly specialised for pheromone reception. Responses to kairomone and smoke odours were less specific than those of pheromone, but a group of 9 cells was clearly excited by smoke compounds (mainly eugenol and 4-methyl 2-methoxyphenol), a group of 8 cells was very responsive to α-pinene, β-pinene and cis-verbenol, and a group of 14 cells responded to a wider range of compounds. The rest of the cells (47%) were either non-responsive or slightly inhibited by smoke compounds. Dose-response curves were obtained for several compounds. Different compounds induced significantly different latencies and these appeared to be unrelated to their boiling point.

Molecular evidence of facultative intraguild predation by Monochamus titillator larvae (Coleoptera: Cerambycidae) on members of the southern pine beetle guild

The southern pine bark beetle guild (SPBG) is arguably the most destructive group of forest insects in the southeastern USA. This guild contains five species of bark beetles (Coleoptera: Curculionidae: Scolytinae): Dendroctonus frontalis, Dendroctonus terebrans, Ips avulsus, Ips calligraphus, and Ips grandicollis. A diverse community of illicit receivers is attracted to pheromones emitted by the SPBG, including the woodborers Monochamus carolinensis and Monochamus titillator (Coleoptera: Cerambycidae). These woodborers have been traditionally classified as resource competitors; however, laboratory assays suggest that larval M. carolinensis may be facultative intraguild predators of SPBG larvae. This study used polymerase chain reaction (PCR)-based molecular gut content analyses to characterize subcortical interactions between M. titillator and members of the SPBG. The half-lives of SPBG DNA were estimated in the laboratory prior to examining these interactions in the field. A total of 271 field-collected M. titillator larvae were analyzed and 26 (9.6 %) tested positive for DNA of members of the SPBG. Of these larvae, 25 (96.2 %) tested positive for I. grandicollis and one (3.8 %) for I. calligraphus. Failure to detect D. terebrans and D. frontalis was likely due to their absence in the field. I. avulsus was present, but primers developed using adult tissues failed to amplify larval tissue. Results from this study support the hypothesis that larval Monochamus spp. are facultative intraguild predators of bark beetle larvae. Additionally, this study demonstrates the capabilities of PCR in elucidating the interactions of cryptic forest insects and provides a tool to better understand mechanisms driving southern pine beetle guild population fluctuations.

A male-produced aggregation pheromone of Monochamus alternatus (Coleoptera: Cerambycidae), a major vector of pine wood nematode

The beetle Monochamus alternatus Hope (Coleoptera: Cerambycidae) is an efficient vector of pine wood nematode, the causal pathogen of pine wilt disease, that has resulted in devastating losses of pines in much of Asia. We assessed the response of adult M. alternatus to 2-(undecyloxy)-ethanol, the male-produced pheromone of the congeneric M. galloprovincialis Dejean, in field experiments in Fujian Province, People's Republic of China. Both sexes of M. alternatus were attracted to lures consisting of 2-(undecyloxy)-ethanol combined with the host plant volatiles alpha-pinene and ethanol. A follow-up experiment showed that 2-(undecyloxy)-ethanol was synergized by both ethanol and alpha-pinene. Coupled gas-chromatography mass-spectrometry analyses of volatiles sampled from field-collected beetles of both sexes revealed that 2-(undecyloxy)-ethanol was a sex-specific pheromone component produced only by males. The combination of 2- (undecyloxy) -ethanol with ethanol and/or alpha-pinene will provide a valuable and badly needed tool for quarantine detection, monitoring, and management of M. alternatus.

Bark beetle pheromones and pine volatiles: attractant kairomone lure blend for longhorn beetles (Cerambycidae) in pine stands of the southeastern United States

In 2006, we examined the flight responses of 43 species of longhorn beetles (Coleoptera: Cerambycidae) to multiple-funnel traps baited with binary lure blends of (1) ipsenol + ipsdienol, (2) ethanol + alpha-pinene, and a quaternary lure blend of (3) ipsenol + ipsdienol + ethanol + alpha-pinene in the southeastern United States. In addition, we monitored responses of Buprestidae, Elateridae, and Curculionidae commonly associated with pine longhorn beetles. Field trials were conducted in mature pine (Pinus pp.) stands in Florida, Georgia, Louisiana, and Virginia. The following species preferred traps baited with the quaternary blend over those baited with ethanol + alpha-pinene: Acanthocinus nodosus (F.), Acanthocinus obsoletus (Olivier), Astylopsis arcuata (LeConte), Astylopsis sexguttata (Say), Monochamus scutellatus (Say), Monochamus titillator (F.) complex, Rhagium inquisitor (L.) (Cerambycidae), Buprestis consularis Gory, Buprestis lineata F. (Buprestidae), Ips avulsus (Eichhoff), Ips calligraphus (Germar), Ips grandicollis (Eichhoff), Orthotomicus caelatus (Eichhoff), and Gnathotrichus materiarus (Fitch) (Curculionidae). The addition ofipsenol and ipsdienol had no effect on catches of 17 other species of bark and wood boring beetles in traps baited with ethanol and a-pinene. Ethanol + alpha-pinene interrupted the attraction of Ips avulsus, I. grandicollis, and Pityophthorus Eichhoff spp. (but not I. calligraphus) (Curculionidae) to traps baited with ipsenol + ipsdienol. Our results support the use of traps baited with a quaternary blend of ipsenol + ipsdienol + ethanol + alpha-pinene for common saproxylic beetles in pine forests of the southeastern United States.

Ethanol and (-)-alpha-pinene: attractant kairomones for some large wood-boring beetles in southeastern USA

Ethanol and alpha-pinene were tested as attractants for large wood-boring pine beetles in Alabama, Florida, Georgia, North Carolina, and South Carolina in 2002-2004. Multiple-funnel traps baited with (-)-alpha-pinene (released at about 2 g/d at 25-28 degrees C) were attractive to the following Cerambycidae: Acanthocinus nodosus, A. obsoletus, Arhopalus rusticus nubilus, Asemum striatum, Monochamus titillator, Prionus pocularis, Xylotrechus integer, and X. sagittatus sagittatus. Buprestis lineata (Buprestidae), Alaus myops (Elateridae), and Hylobius pales and Pachylobius picivorus (Curculionidae) were also attracted to traps baited with (-)-alpha-pinene. In many locations, ethanol synergized attraction of the cerambycids Acanthocinus nodosus, A. obsoletus, Arhopalus r. nubilus, Monochamus titillator, and Xylotrechus s. sagittatus (but not Asemum striatum, Prionus pocularis, or Xylotrechus integer) to traps baited with (-)-alpha-pinene. Similarly, attraction of Alaus myops, Hylobius pales, and Pachylobius picivorus (but not Buprestis lineata) to traps baited with (-)-alpha-pinene was synergized by ethanol. These results provide support for the use of traps baited with ethanol and (-)-alpha-pinene to detect and monitor common large wood-boring beetles from the southeastern region of the USA at ports-of-entry in other countries, as well as forested areas in the USA.