by Dr. Molly Darr | Jun 7, 2022 | 2011-2020 Publications
Abstract
The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) utilizes a multi-component aggregation pheromone to mediate mass-attacks and thereby colonize otherwise unsusceptible trees. Females produce the attractant frontalin and a synergist, trans-verbenol. We investigated trans-verbenol to determine whether enantiomeric composition, airborne concentration, and possibly other factors might affect its biological activity. Newly-emerged females from Mississippi populations produced 54–87% of the (−)-enantiomer; females initiating galleries in logs produced lower amounts and a wider range of enantiomeric ratios [12–92% (−)]. Coupled gas chromatography-electroantennographic detection (GC-EAD) studies did not suggest large differences in the concentration threshold of olfaction for the two enantiomers. We examined the effect of adding trans-verbenol to traps located outside infested areas and baited with components of the aggregation attractant. Male attraction was similarly increased by lures with 3, 81, or 98% of the (−)-enantiomer of trans-verbenol, whereas females preferred 81 over 3%. When release rate of 81% (−)-trans-verbenol in traps was varied across three orders of magnitude (0.3, 3, and 30 mg/d), the data suggested a positive dose–response trend. A high release (i.e., 2–5 g/d) device of host odor alpha-pinene had a much stronger enhancing effect on trap catches than a trans-verbenol device (~30 mg/d), and trans-verbenol did not further enhance attraction when alpha-pinene was present. Our results suggest that the weak attraction-enhancing activity of trans-verbenol reported previously cannot be improved by adjusting the enantiomeric composition or release rate of lures, and furthermore there are no anticipated benefits of adding trans-verbenol to the D. frontalis monitoring lure.
Keywords
Dendroctonus frontalis, lure, bark beetle, enantiomer, dose–response
To read the full article please visit the link below:
Shepherd, William P., and Brian T. Sullivan. 2019. “Southern Pine Beetle (Coleoptera: Curculionidae: Scolytinae) Pheromone Component Trans-Verbenol: Enantiomeric Specificity and Potential as a Lure Adjuvant.” Environmental Entomology 48 (1): 193–201. https://doi.org/10.1093/ee/nvy169.
by Dr. Molly Darr | Jun 7, 2022 | 2011-2020 Publications
Abstract
Local outbreak risk for the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae), is forecast with a trapping survey conducted every spring throughout the southeastern United States. Traps baited with pine odors and components of the D. frontalis aggregation pheromone are used to obtain abundance estimates of both this species and its clerid predator Thanasimus dubius (F.) (Coleoptera: Cleridae); these data are entered into a predictive model that estimates outbreak risk. An attractant synergist for D. frontalis, endo-brevicomin, has recently been included in the survey lure, but it can have the unintended effect of attracting nontarget species Hylesinus pruinosus Eichhoff (Coleoptera: Curculionidae: Scolytinae) and Enoclerus nigripes (Say) (Coleoptera: Cleridae) which, due to their sometimes large numbers and general similarity in appearance to the target species, could complicate sorting and counting of trap catches. Analysis of bycatch data from a previously-published, 31-mo trapping study in Mississippi indicated that displacement of the endo-brevicomin releaser 6 m from the trap largely eliminated catches of the nontarget species H. pruinosus and E. nigripes while not reducing catches of the target species D. frontalis and T. dubius. Our analysis demonstrates that interspecific differences in spatial responses to attractive semiochemicals can be used to improve insect trap selectivity. Both nontarget beetle species were captured in highest numbers during late winter/early spring, coinciding with the D. frontalis survey.
Keywords
Hylesinus pruinosus, Enoclerus nigripes, Dendroctonus frontalis, Thanasimus dubius, bycatch
To read the full article please visit the link below:
Shepherd, William P., and Brian T. Sullivan. 2018. “Spatial Displacement of a Lure Component Can Reduce Catches of Two Nontarget Species During Spring Monitoring of Southern Pine Beetle.” Journal of Insect Science (Online) 18 (1). https://doi.org/10.1093/jisesa/iex106.
by Dr. Molly Darr | Jun 7, 2022 | 2011-2020 Publications
Abstract
A growing body of evidence suggests that bark beetles detect and avoid release points of volatile compounds associated with nonhost species, and thus such nonhost volatiles may have potential utility in the management of bark beetles. We used a coupled gas chromatograph-electroantennographic detector (GC-EAD) to assay the olfactory sensitivity of the southern pine beetle, Dendroctonus frontalis Zimmermann, to volatiles from leaves and bark of eight species of nonhost angiosperm trees that are common in the range of D. frontalis. Tree species sampled were red maple (Acer rubrum L.), mockernut hickory [Carya alba (L.) Nutt. ex Ell.], sweetgum (Liquidambar styraciflua L.), black tupelo (Nyssa sylvatica Marsh.), black cherry (Prunus serotina Ehrh.), southern red oak (Quercus falcata Michx.), blackjack oak [Quercus marilandica (L.) Muenchh.], and water oak (Quercus nigra L.). Beetle antennae responded to a total of 28 identifiable compounds in these samples. The relative olfactory responsiveness to 14 of these, as well as to nonanoic acid and four additional volatiles reported to be associated with nonhost angiosperms, was assessed in GC-EAD analyses of synthetic dilutions spanning six orders of magnitude. The largest response voltage amplitudes were obtained with trans-conophthorin, nonanoic acid, terpinen-4-ol, phenylethyl alcohol, and eucalyptol, whereas the lowest response thresholds were to nonanoic acid, nonanal, linalool, (E)-2-hexen-1-ol, and phenylethyl alcohol. Funnel traps baited with various combinations of eleven antennally-active angiosperm volatiles along with a standard attractant captured significantly fewer male and female D. frontalis than traps baited with the standard attractant alone. Our data suggest that a diversity of semiochemicals may be involved in host species discrimination by D. frontalis, and several may have utility in their management.
Keywords
Inhibitor, Bark beetle, GC-EAD, Scolytinae, Nonhost
To read the full article please visit the link below:
Shepherd, William P., and Brian T. Sullivan. 2013. “Southern Pine Beetle, Dendroctonus Frontalis, Antennal and Behavioral Responses to Nonhost Leaf and Bark Volatiles.” Journal of Chemical Ecology 39 (4): 481–93. https://doi.org/10.1007/s10886-013-0265-4.
by Dr. Molly Darr | Jun 7, 2022 | 2011-2020 Publications
Abstract
The southern pine beetle, Dendroctonus frontalis Zimmerman (Coleoptera: Curculionidae) is an economically important pest species throughout the southeastern United States, Arizona, Mexico, and Central America. Previous research identified population structure among widely distant locations, yet failed to detect population structure among national forests in the state of Mississippi. This study uses microsatellite variation throughout the southeastern United States to compare the southern pine beetle’s pattern of population structure to phylogeographic patterns in the region, and to provide information about dispersal. Bayesian clustering identified east and west genetic groups spanning multiple states. The east group had lower heterozygosity, possibly indicating greater habitat fragmentation or a more recent colonization. Significant genetic differentiation (θST = 0.01, p < 0.0001) followed an isolation-by-distance pattern (r = 0.39, p < 0.001) among samples, and a hierarchical AMOVA indicated slightly more differentiation occurred between multi-state groups. The observed population structure matches a previously identified phylogeographic pattern, division of groups along the Appalachian Mountain/Apalachicola River axis. Our results indicate that the species likely occurs as a large, stable metapopulation with considerable gene flow among subpopulations. Also, the relatively low magnitude of genetic differentiation among samples suggests that southern pine beetles may respond similarly to management across their range..
Keywords
Dendroctonus, microsatellites, phylogeographic concordance, southern pine beetle
To read the full article please visit the link below:
Schrey, Natalie M., Aaron W. Schrey, Edward J. Heist, and John D. Reeve. 2011. “Genetic Heterogeneity in a Cyclical Forest Pest, the Southern Pine Beetle, Dendroctonus Frontalis, Is Differentiated into East and West Groups in the Southeastern United States.” Journal of Insect Science (Tucson) 11 (August): 1–10.
by Dr. Molly Darr | Jun 7, 2022 | 2011-2020 Publications
Abstract
Bark beetles (Coleoptera: Curculionidae: Scolytinae) have been an important historic and current factor affecting pine forest production in the southern United States. Although tree mortality to bark beetles often detracts from forest management goals, the natural role of bark beetles is canopy opening, thinning, and diversification of stand structure and composition, effects that contribute to some ecosystem services in forests managed for multiple uses. Strategies to prevent bark beetle outbreaks exploit their sensitivity to host tree spacing and reliance on pheromones to attract sufficient numbers to overwhelm tree defenses. Tree species selection at planting or through selective thinning can favor pine species that are more tolerant of site conditions and resistant to bark beetles. Precommercial or commercial thinning improves tree condition and creates barriers to beetle population growth and spread. Remedial options include salvage harvest, pheromones for trap-out or disruption of host location, and white paint to disrupt the dark silhouette of the tree bole. Given the labor costs and trade-offs among tactics and the marginal profitability of fiber and timber production, harvest in advance of, or salvage harvest after, bark beetle attack often is the favored management strategy. However, this strategy is not as appropriate in public forests managed for values provided by older, more vulnerable trees. High-value sites for cultural or endangered species protection may require use of more expensive management options..
Keywords
Dendroctonus frontalis, Ips, thinning, pheromones, sanitation harvest
To read the full article please visit the link below:
Schowalter, T. D. 2012. “Ecology and Management of Bark Beetles (Coleoptera: Curculionidae: Scolytinae) in Southern Pine Forests.” Journal of Integrated Pest Management 3 (2). https://doi.org/10.1603/IPM11025.
