Canadian Forest Service Publications
Molecular evidence of facultative intraguild predation by Monochamus titillator larvae (Coleoptera: Cerambycidae) on members of the southern pine beetle guild. 2012. Schoeller, E. N.; Husseneder, C.; Allison, J. D. Naturwissenschaften 99: 913-924.
Issued by: Great Lakes Forestry Centre
Catalog ID: 34158
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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): Dendrocto nus frontalis, Dendroctonus terebrans, Ips avulsus, Ips calligraphus, and Ips grandicolUs. 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 re source competitors; however, laboratory assays suggest that larval M. carolinensis may be facultative intraguild preda tors 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 /. grandicolUs and one (3.8 %) for /. calligraphus. Failure to detect D. terebrans and D. frontalis was likely due to their absence in the field. /. 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. Addi tionally, 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.
Plain Language Summary
The southern pine bark beetle guild (SPBG) is the most destructive group of forest insects in the southeastern US. Other insects are attracted to pheromones emitted by the SPBG, including woodborers in the genus Monochamus. These woodborers have been traditionally classified as resource competitors; however, laboratory tests suggest that larvae may also be predators of SPBG larvae. We used molecular gut content analyses to show that larval Monochamus spp. are predators of bark beetle larvae. The lab technique used provides a tool to better understand the mechanisms driving bark beetle population fluctuations.