Southern pine beetle (Dendroctonus frontalis Zimmermann)
Staeben, Jenny Cheryl
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The economically damaging southern pine beetle (Dendroctonus frontalis Zimmermann) is one of the most destructive insect pests in southeastern United States. SPB populations are monitored using a racemic kairomone, α-pinene, and pheromone, frontalin to capture SPB and predator, Thanasimus dubius (Fabricius). I assessed whether SPB and T. dubius differentiate between enantiomers of α-pinene. Results indicated the response of female and male SPB to α-pinene enantiomers did not significantly differ, although males were somewhat more responsive to (+)-α-pinene. Captures of T. dubius increased with volumes of α-pinene, and T. dubius did not differentiate between enantiomers. Typically SPB infest pines other southern pine bark beetle guild (SPBBG) members (which include Dendroctonus terebrans (Olivier) and Ips beetle species). Colonizing Ips species release either ipsdienol and/or ipsenol. I assessed the inter- and intraspecies attraction among SPBBG and their predators. Results indicate SPB and T. dubius are not attracted to Ips attractants and vice versa. BTB and Ips calligraphus (Germar) were attracted to Ips attractants. SPBBG predators (other than Pycnomerus sulcicollis LeConte) did not differentiate between SPB and Ips attractants. Using linear regression, I assessed the relationship between lightning strike and SPB infestations. Results indicated a relationship between SPB infestations developing within 100-250 m of a negatively-charged lightning strike with a magnitude of > 150 kilo amps. There was no relationship between the basal area pine stands and the likelihood of lightning strike. There was no relationship between the distance of a strike and the number of trees infested with SPB. The ecological impacts of forest management techniques used to control SPB populations in loblolly pine (Pinus taeda L.) stands were also assessed. Ground-foraging ant assemblages were used to indicate the ecological impacts of loblolly stands that were unmanaged, thinned, prescribed burned, or clear-cut and replanted with longleaf pine. Ant species diversity was highest in unmanaged stands. Species assemblages were more similar in prescribed burned or thinned stands and differed greatly between unmanaged stands and clear-cut, replanted stands. However, species assemblages and richness did not differ among stands overall.