Doctor of Philosophy (PhD)



Document Type



The most common predaceous Histeridae (Coleoptera) found associated with Ips engraver beetles (Coleoptera: Scolytidae) in Louisiana were Platysoma attenuata LeConte, Pla. cylindrica (Paykull), Pla. parallelum (Say), and Plegaderus transversus (Say). Seasonal abundance of histerids in flight traps coincided with Ips spp. activity in the area. Histerid adults arrived at loblolly pine (Pinus taeda L.) logs one wk after Ips attacks had begun. As a group, histerids exhibited a bimodal emergence pattern with the first peak occurring during Ips emergence and a second four wks later, indicating that they fed on bark beetles and associated organisms arriving later in the colonization sequence. Visual orientation appeared to affect host tree location by histerids and may facilitate niche partitioning among species. Platysoma parallelum was attracted to horizontally positioned logs, representing trees more likely to be infested by Ips spp., while Pla. attenuata preferred vertical logs, representing standing pines, which tend to be colonized by the southern pine beetle, Dendroctonus frontalis Zimmermann. Histerid predators also utilized bark beetle pheromones as kairomonal odor cues to locate their prey. Histerid species had differential electrophysiological (antennal) and behavioral responses to three prey aggregation pheromones: ipsenol (produced by Ips grandicollis (Eichhoff)), ipsdienol (Ips avulsus (Eichhoff) and Ips calligraphus (Germar)), and frontalin (D. frontalis). Histerids may use various strategies of long-range host habitat finding and short-range host finding, which could reduce interspecific competition. Measurement of antennal threshold responses indicated that Pla. parallelum could perceive frontalin at lower quantities than Ple. transversus and, thus, may have the ability to locate D. frontalis attacks earlier. In a controlled study, Pla. parallelum was found to have a greater impact on I. grandicollis mortality than Ple. transversus when only one histerid and one prey species were present. More I. grandicollis brood was killed per introduced Pla. parallelum adult likely as a result of Pla. parallelum’s larger size and biomass requirements. In a separate experiment, Pla. parallelum adults consumed I. calligraphus larvae until satiation (up to four per day). Collectively, these experiments provide evidence that augmentative releases of histerids have potential use for biological control of bark beetles.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Richard A. Goyer



Included in

Entomology Commons