by Dr. Molly Darr | Jun 9, 2022 | 2011-2020 Publications
Abstract
Surface fuels were characterized in loblolly pine (Pinus taeda L.) plantations severely impacted by southern pine beetle (Dendroctonus frontalis Ehrh.) (SPB) outbreaks in the upper South Carolina Piedmont. Prescribed burning and mastication were then tested as fuel reduction treatments in these areas. Prescribed burning reduced fuelbed continuity by consuming litter (Oi layer), duff (Oe + Oa), and woody surface fuels (1-, 10-, and 100-h timelag size classes) immediately after the treatment. Total loading of 1- and 10-h fuels in burned stands (3.1 Mg ha-1) remained significantly lower than that in the control (no treatment) (5.6 Mg ha-1) in the 2nd year post-treatment. However, 100- and 1000-h fuels increased post-burn due to accelerated failure of remaining pine snags and totaled 14.5 Mg ha-1 in the 2nd year post-treatment which was not significantly different than the control (17.3 Mg ha-1). Mineral soil exposure averaged 73% of burned stands after consumption of the duff layer in many areas. Custom low, moderate, and high load fuel models were developed for SPB-killed stands and produced simulated fire behavior (flame length and rate of spread) similar to two standard slash-blowdown fuel models (SB2 and SB3) when input to the BehavePlus fire modeling system. Mastication resulted in a compacted (bulk density = 131.3 kg m-3) and continuous layer of woody debris that averaged 15.1 cm in depth. Equations were developed for estimating masticated debris load and utilize fuelbed depth as input. The masticated debris load averaged 192.4 Mg ha-1 in the 1st year post-treatment and was significantly higher than total fuel loading in burned (16.3 Mg ha-1) and control (24.3 Mg ha-1) stands. The treatments tested in this study provide different options for preparing
Keywords
Forest disturbance, Site preparation, Hazard reduction, Fire behavior, Masticated debris
To read the full article please visit the link below:
Stottlemyer, Aaron D., Thomas A. Waldrop, and G. Geoff Wang. 2015. “Prescribed Burning and Mastication Effects on Surface Fuels in Southern Pine Beetle-Killed Loblolly Pine Plantations.” Ecological Engineering 81 (August): 514–24. https://doi.org/10.1016/j.ecoleng.2015.04.076.
by Dr. Molly Darr | Jun 9, 2022 | 2011-2020 Publications
Abstract
Multi-trophic interactions between pine bark beetles, their host trees, and predators are mediated in part by volatile terpenes in host tree oleoresin that can influence aggregation and/or host finding by both prey and predator species. The southern pine beetle, Dendroctonus frontalis Zimmermann, mass-attacks pine trees in response to its aggregation pheromone combined with host resin odors including α-pinene. We investigated discrimination of α-pinene enantiomers in olfactory responses of D. frontalis, and in behavioral responses of D. frontalis and its major clerid predator, Thanasimus dubius (Fabricius). Trapping trials in the spring and fall assessed attraction of both species to the D. frontalis aggregation pheromone components, frontalin and endo-brevicomin, either alone or in combination with α-pinene lures of differing enantiomeric compositions. α-pinene lures enriched with the (+)-enantiomer (97.5 %) increased D. frontalis catches significantly more than (-)-enriched (93 %) lures, but did not differ from racemic lures. Sexes of D. frontalis did not differ from one another in their responses to the enantiomers, and there was no difference in lure discrimination by D. frontalis and T. dubius. Thanasimus dubius did not distinguish between different a-pinene enantiomers. Dose–response electroantennogram studies of D. frontalis indicated that their antennae had a slightly lower response threshold to (+) than (-)-α-pinene. Each enantiomer habituated the antennae more to itself than to its antipode, implying the existence of olfactory receptors with differing affinities for enantiomers. The preference of D. frontalis for (+)-α-pinene may affect its host selection behavior,
Keywords
α-Pinene, Dendroctonus frontalis, endo-Brevicomin, Enantiomer, Frontalin, Thanasimus dubius
To read the full article please visit the link below:
Staeben, Jenny C., Brian T. Sullivan, John T. Nowak, and Kamal J. K. Gandhi. 2015. “Enantiospecific Responses of Southern Pine Beetle (Dendroctonus Frontalis) and Its Clerid Predator, Thanasimus Dubius, to Alpha-Pinene.” Chemoecology 25 (2): 73–83. https://doi.org/10.1007/s00049-014-0175-0.
by Dr. Molly Darr | Jun 9, 2022 | 2021-Present Publications
Abstract
Native and nonnative insects and diseases can result in detrimental impacts to trees and forests, including the loss of economic resources and ecosystem services. Increases in globalization and changing human behaviors have created new anthropogenic pathways for long distance pest dispersal. In North America, literature suggests that once a forest or tree pest is established, the movement of firewood by the general public for recreational or home heating purposes is one of the primary pathways for its dispersal. Understanding human perceptions and behaviors is essential to inform the most effective strategies for modifying firewood and pest dispersal by humans. This scoping review seeks to assess trends and gaps in the existing literature, as well as patterns in behavior related to forest pest dispersal through firewood movement in North America. We identified 76 documents that addressed this topic to which we applied inclusion and exclusion criteria to select articles for further analysis. Twenty-five articles met the inclusion criteria and were categorized based on five identified themes: 1) insect incidence in firewood, 2) insect dispersal via firewood, 3) recreational firewood movement, 4) firewood treatments, and 5) behavior and rule compliance. The selected articles show trends that suggest that firewood movement presents a risk for forest insect dispersal, but that behavior can be modified, and compliance, monitoring, and treatments should be strengthened. This scoping review found limited research about western United States, Mexico, and Canada, various insect species and other organisms, regulation and management, awareness, and behavioral dimensions of firewood movement.
Keywords
Coleoptera, firewood movement, human behavior, invasive species, regulations
To read the full article please visit the link below:
Solano, Angelica, Shari L. Rodriguez, Leigh Greenwood, Kevin J. Dodds, and David R. Coyle. 2021. “Firewood Transport as a Vector of Forest Pest Dispersal in North America: A Scoping Review.” Journal of Economic Entomology 114 (1): 14–23. https://doi.org/10.1093/jee/toaa278.
by Dr. Molly Darr | Jun 9, 2022 | 2011-2020 Publications
Abstract
A field study was conducted to evaluate the response of Dendroctonus frontalis and Dendroctonus mexicanus to two commercially available semiochemical lures (1) frontalin + α-pinene, (2) frontalin + blend of α-pinene and β-pinene + endobrevicomin, and to know the relative abundance of both species in an altitudinal gradient. The study was carried out on pine-oak forests within the Sierra Gorda Biosphere Reserve, in the state of Queretaro, Mexico. Study sites were on an altitude gradient of 1,672 to 2,530 m asl. Semiochemicals were attached to 12-unit Lindgren funnel traps hung from non-host trees, and bark beetles were collected biweekly during 1 year. The identification of the species was based on external characters as well as on the form of genitalia. The response to the treatments was determined through an analysis of variance at a 0.05 level of significance, followed by a Tukey- Kramer mean comparison test. The abundance of D. frontalis and D. mexicanus was different in response to the two semiochemical lures. Frontalin + blend of α-pinene and β-pineno + endo-brevicomin attracted 30 times more bark beetles than frontalin + α-pinene. On the other hand, both species were found coexisting at all five elevation points; however, D. frontalis was more abundant from 1,672 to 2,040 m asl, while D. mexicanus was more abundant from 2,291 to 2,530 m asl. These results have implications for monitoring and mass trapping these two pine bark beetle species since for each 100 specimens captured in traps baited with frontalin + α- pinene, 3,000 would be captured if frontalin + blend of α-pinene and β-pineno + endobrevicomin is used. That means 30 times more time and effort for insect identification and counting. Therefore, if the objective of a trapping system is to detect the presence of D. frontalis and D. mexicanus, or to determine the flight periodicity of these species in an area of interest, it is sufficient to use frontalin + α-pinene. On the other hand, if we aim to complement sanitation cutting to help control small infestations, or to avoid bark beetle dispersion from infested logs in log collection centers, it is more appropriate to use frontalin + endo-brevicomin + blend of monoterpenes, with the necessary measures to avoid spill over the attacks.
To read the full article please visit the link below:
Sánchez-Martínez, Guillermo, and José Francisco Reséndiz-Martínez. “Respuesta de Dendroctonus frontalis Zimmerman y Dendroctonus mexicanus Hopkins1 a Dos Atrayentes Semioquímicos en la Sierra Gorda de Querétaro, México.” Southwestern Entomologist 45.2 (2020): 511-520. https://bioone.org/journals/southwestern-entomologist/volume-45/issue-2/059.045.0219/Respuesta-de-Dendroctonus-frontalis-Zimmerman-y-Dendroctonus-mexicanus-Hopkins1-a/10.3958/059.045.0219.short
by Dr. Molly Darr | Jun 9, 2022 | 2011-2020 Publications
Abstract
All higher organisms are involved in symbioses with microbes. The importance of these partnerships has led to the concept of the holobiont, defined as the animal or plant with all its associated microbes. Indeed, the interactions between insects and symbionts form much of the basis for the success and diversity of this group of arthropods. Insects rely on microbes to perform basic life functions and to exploit resources and habitats. By “partnering” with microbes, insects access new genomic variation instantaneously allowing the exploitation of new adaptive zones, influencing not only outcomes in ecological time, but the degree of innovation and change that occurs over evolutionary time. In this review, I present a brief overview of the importance of insect-microbe holobionts to illustrate how critical an understanding of the holobiont is to understanding the insect host and it interactions with its environment. I then review what is known about the most influential insect holobionts in many forest ecosystems—bark beetles and their microbes—and how new approaches and technologies are allowing us to illuminate how these symbioses function. Finally, I discuss why it will be critical to study bark beetles as a holobiont to understand the ramifications and extent of anthropogenic change in forest ecosystems.
Keywords
Symbiosis, Mutualism, Endosymbiont, Ectosymbiont, Fungi, Yeast, Bacteria, Dendroctonus, Ips, Ophiostoma, Grosmannia, Ogataea, Rhanella
To read the full article please visit the link below:
Six, Diana L. 2013. “The Bark Beetle Holobiont: Why Microbes Matter.” Journal of Chemical Ecology 39 (7): 989–1002. https://doi.org/10.1007/s10886-013-0318-8.
