Title page for ETD etd-06302011-143941

Type of Document Master's Thesis
Author Schoeller, Erich N.
Author's Email Address eschoeller@agcenter.lsu.edu
URN etd-06302011-143941
Title Characterization of the Subcortical Interactions Between Larvae of the Southern Pine Sawyer Monochamus titillator (F.) and the Larvae of the Southern Pine Beetle Guild Using Molecular Gut Analyses
Degree Master of Science (M.S.)
Department Entomology
Advisory Committee
Advisor Name Title
Allison, Jeremy D. Committee Chair
Johnson, Seth J. Committee Member
Husseneder, Claudia Committee Member
  • Facultative Predation
  • Louisiana
  • D. frontalis
  • M. titillator
  • Molecular Gut Analysis
  • Cerambycidae
Date of Defense 2011-06-27
Availability unrestricted
The southern pine beetle guild (Coleoptera: Curculionidae: Scolytinae) is arguably the

most destructive group of forest pests in the Southeastern United States. Laboratory assays suggest that larvae of wood borer associates from the genus Monochamus (Coleoptera: Cerambycidae) may be facultative intraguild predators of southern pine beetle guild. In this study the dynamics of the subcortical interactions between M. titillator (F.) and members of the southern pine beetle guild were examined using PCR-based molecular gut content analyses. Species-specific PCR primer sets were developed to work under multiplex PCR conditions to detect DNA of members of southern pine beetle guild in the gut contents of M. titillator larvae. The molecular half-life of the bark beetle Ips grandicollis (Eichhoff) was calculated as 6.89 hours post-consumption in the gut contents of M. titillator larvae under laboratory conditions. Comparison of the proportion of M. titillator larvae testing positive for each bark beetle species at 6.9 hours post-consumption showed that the proportion fed Dendroctonus terebrans (Olivier) differed significantly. A field study was performed to determine the detection frequencies of southern pine beetle guild DNA in the gut contents of M. titillator larvae under semi-natural conditions. A total of 271 M. titillator larvae were collected from experimental boles in the field. Twenty-six (9.6%) of the field-collected M.

titillator larvae tested positive for DNA of members of the southern pine beetle guild. Of

these larvae, 25 (96.2%), 1 (3.8%), 0 (0%), and 0 (0%) tested positive for I. grandicollis,

I. calligraphus (Germar), D. terebrans, and D. frontalis (Zimmerman) DNA respectively.

The species compositions of the southern pine beetle guild within the gut contents of the field-caught M. titillator larvae reflected those within the host, suggesting random predation. Results from this study support the hypothesis that Monochamus species may be facultative intraguild predators of bark beetle larvae in the field. Additionally, this study demonstrates the capabilities of PCR in elucidating the predator-prey interactions of cryptic forest insects and provides a powerful tool to better understand mechanisms driving southern pine beetle guild population fluctuations.

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