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opencc-zeroDec 2014View details →

Data from: Small beetle, large-scale drivers: how regional and landscape factors affect outbreaks of the European spruce bark beetle

Unprecedented bark beetle outbreaks have been observed for a variety of forest ecosystems recently, and damage is expected to further intensify as a consequence of climate change. In Central Europe, the response of ecosystem management to increasing infestation risk has hitherto focused largely on the stand level, while the contingency of outbreak dynamics on large-scale drivers remains poorly understood. To investigate how factors beyond the local scale contribute to the infestation risk from Ips typographus (Col., Scol.), we analysed drivers across seven orders of magnitude in scale (from 103 to 1010 m²) over a 23-year period, focusing on the Bavarian Forest National Park. Time-discrete hazard modelling was used to account for local factors and temporal dependencies. Subsequently, beta regression was applied to determine the influence of regional and landscape factors, the latter characterized by means of graph theory. We found that in addition to stand variables, large-scale drivers also strongly influenced bark beetle infestation risk. Outbreak waves were closely related to landscape-scale connectedness of both host and beetle populations as well as to regional bark beetle infestation levels. Furthermore, regional summer drought was identified as an important trigger for infestation pulses. Large-scale synchrony and connectivity are thus key drivers of the recently observed bark beetle outbreak in the area. Synthesis and applications. Our multiscale analysis provides evidence that the risk for biotic disturbances is highly dependent on drivers beyond the control of traditional stand-scale management. This finding highlights the importance of fostering the ability to cope with and recover from disturbance. It furthermore suggests that a stronger consideration of landscape and regional processes is needed to address changing disturbance regimes in ecosystem management.

opencc-zeroDec 2014View details →

Data from: Comparative multi-locus phylogeography of two Palaearctic spruce bark beetles: influence of contrasting ecological strategies on genetic variation

While phylogeographic patterns of organisms are often interpreted through past environmental disturbances, mediated by climate changes, and geographic barriers, they may also be strongly influenced by species-specific traits. To investigate the impact of such traits, we focused on two Eurasian spruce bark beetles that share a similar geographic distribution, but differ in their ecology and reproduction. Ips typographus is an aggressive tree-killing species characterized by strong dispersal, whereas Dendroctonus micans is a discrete inbreeding species (sib mating is the rule), parasite of living trees and a poor disperser. We compared genetic variation between the two species over both beetles' entire range in Eurasia with five independent gene fragments, to evaluate whether their intrinsic differences could have an influence over their phylogeographic patterns. We highlighted widely divergent patterns of genetic variation for the two species and argue that the difference is indeed largely compatible with their contrasting dispersal strategies and modes of reproduction. In addition, genetic structure in I. typographus divides European populations in a northern and a southern group, as was previously observed for its host plant, and suggests past allopatric divergence. A long divergence time was estimated between East Asian and other populations of both species, indicating their long-standing presence in Eurasia, prior to the last glacial maximum. Finally, the strong population structure observed in D. micans for the mitochondrial locus provides insights into the recent colonization history of this species, from its native European range to regions where it was recently introduced.

opencc-zeroMay 2019View details →

Data from: Ants, fire and bark traits affect how African savanna trees recover following damage

Bark damage resulting from elephant feeding is common in African savanna trees with subsequent interactions with fire, insects and other pathogens often resulting in tree mortality. Yet, surprisingly little is known about how savanna trees respond to bark damage. We addressed this by investigating how the inner bark of marula (Sclerocarya birrea), a widespread tree species favoured by elephants, recovers after bark damage. We used a long-term fire experiment in the Kruger National Park to measure bark recovery with and without fire. At 24 months post-damage, mean wound closure was 98, 92, and 72% respectively in annual and biennial burns and fire exclusion treatments. Fire exclusion resulted in higher rates of ant colonisation of bark wounds, and such ant colonisation resulted in significantly lower bark recovery. We also investigated how ten common savanna tree species respond to bark damage and tested for relationships between bark damage, bark recovery and bark traits while accounting for phylogeny. We found phylogenetic signal in bark dry matter content, bark N and bark P, but not in bark thickness. Bark recovery and damage was highest in species which had thick moist inner bark and low wood densities (Anacardiaceae), intermediate in species which had moderate inner bark thickness and wood densities (Fabaceae) and lowest in species which had thin inner bark and high wood densities (Combretaceae). Elephants prefer species with thick, moist inner bark, traits that also appear to result in faster recovery rates.

opencc-zeroDec 2014View details →

Data from: Prescribed fire does not promote outbreaks of a primary bark beetle at low-density populations

The causes of bark beetle outbreaks – particularly the role of disturbances – are poorly understood. Stand-scale disturbances, like fires, can suddenly improve local host susceptibility and may attract beetles; however, whether such increases can lead to outbreaks in post-disturbance stands is unclear. Using low-density Dendroctonus ponderosae mountain pine beetle populations in Pinus contorta lodgepole pine forests in western Canada, we investigated whether prescribed fires promote outbreaks or provide only short-term resources. Proportionally more burned than non-burned trees were attacked. At one site, beetle attacks increased in response to a resource pulse, but the proportions of attacked trees and numbers of attacks per tree declined over four years after fire. Elsewhere, beetle attacks remained very low. As the resource (phloem) quality of burned trees remained high three years after fire, we propose that post-fire mortality, resulting in fewer available host trees, can at least partially explain why D. ponderosae did not build up populations in burned stands. Synthesis and applications. Our study emphasizes the importance of examining long-term trends in fire–bark beetle interactions, and of understanding low-density beetle populations. Because fire does not seem to promote mountain pine beetle outbreaks, we recommend the continued use of prescribed fire for the general management of P. contorta forests with low-density beetle populations.

opencc-zeroDec 2012View details →

Data from: Ecological co-associations influence species' responses to past climatic change: an example from a Sonoran Desert bark beetle

Ecologically interacting species may have phylogeographic histories that are shaped both by features of their abiotic landscape, and by biotic constraints imposed by their co-association. The Baja California peninsula provides an excellent opportunity to examine the influence of abiotic vs. biotic factors on patterns of diversity in plant-insect species. This is because past climatic and geological changes impacted the genetic structure of plants quite differently to that of co-distributed free-living animals (e.g., herpetofauna and small mammals). Thus, 'plant-like' patterns should be discernible in host-specific insect herbivores. Here we investigate the population history of a monophagous bark beetle, Araptus attenuatus, and consider drivers of phylogeographic patterns in light of previous work on its host plant, Euphorbia lomelii. Based on mitochondrial and nuclear markers, we found that the evolutionary history of A. attenuatus exhibits similarities to host plant that are attributable to both biotic and abiotic processes. Southward range expansion and recent colonization of continental Sonora peninsula appear to be unique to this taxon pair, and likely reflect influences of the host plant. On the other hand, abiotic factors with landscape-level influences on suites of co-distributed taxa, such as Plio- and Pleistocene-aged marine incursions in the region, also left genetic signatures in beetle populations. Superimposed on these similarities, bark beetle-specific patterns and processes were also evident. Taken together, this work illustrates that the evolutionary history of species-specific insect herbivores may represent a mosaic of influences, including—but not limited to—those imposed by the host plant.

opencc-zeroDec 2015View details →

Data from: Spatial variability in tree regeneration after wildfire delays and dampens future bark beetle outbreaks

Climate change is altering the frequency and severity of forest disturbances such as wildfires and bark beetle outbreaks, thereby increasing the potential for sequential disturbances to interact. Interactions can amplify or dampen disturbances, yet the direction and magnitude of future disturbance interactions are difficult to anticipate because underlying mechanisms remain poorly understood. We tested how variability in postfire forest development affects future susceptibility to bark beetle outbreaks, focusing on mountain pine beetle (Dendroctonus ponderosae) and Douglas-fir beetle (Dendroctonus pseudotsugae) in forests regenerating from the large high-severity fires that affected Yellowstone National Park in Wyoming in 1988. We combined extensive field data on postfire tree regeneration with a well-tested simulation model to assess susceptibility to bark beetle outbreaks over 130 y of stand development. Despite originating from the same fire event, among-stand variation in forest structure was very high and remained considerable for over a century. Thus, simulated emergence of stands susceptible to bark beetles was not temporally synchronized but was protracted by several decades, compared with stand development from spatially homogeneous regeneration. Furthermore, because of fire-mediated variability in forest structure, the habitat connectivity required to support broad-scale outbreaks and amplifying cross-scale feedbacks did not develop until well into the second century after the initial burn. We conclude that variability in tree regeneration after disturbance can dampen and delay future disturbance by breaking spatiotemporal synchrony on the landscape. This highlights the importance of fostering landscape variability in the context of ecosystem management given changing disturbance regimes.

FIGURES 35–37. Tarsonemus bistridentati, larva paratype. 35 in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 35–37. Tarsonemus bistridentati, larva paratype. 35, idiosoma; 36, gnathosoma dorsum; 37, gnathosoma venter.

FIGURES 31–34. Tarsonemus bistridentati, male paratype. 31,leg I in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 31–34. Tarsonemus bistridentati, male paratype. 31,leg I; 32, leg II; 33, leg III; 34, leg IV.

FIGURES 1–3. Tarsonemus fraxini, female holotype. 1 in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 1–3. Tarsonemus fraxini, female holotype. 1, idiosoma; 2, gnathosoma dorsum, 3, gnathosoma venter.

FIGURES 24–27. Tarsonemus bistridentati, female holotype. 24,leg I in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 24–27. Tarsonemus bistridentati, female holotype. 24,leg I; 25, leg II; 26, leg III; 27, leg IV.

FIGURES 8–10. Tarsonemus fraxini, male paratype. 8 in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 8–10. Tarsonemus fraxini, male paratype. 8, idiosoma; 9, gnathosoma dorsum; 10, gnathosoma venter.

FIGURES 21–23. Tarsonemus bistridentati, female holotype. 21 in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 21–23. Tarsonemus bistridentati, female holotype. 21, idiosoma; 22, gnathosoma dorsum; 23, gnathosoma venter.

FIGURES 15–17. Tarsonemus fraxini, larva paratype. 15 in Two new species of Tars on em u s (Acari: Tarsonemidae) associated with bark beetles (Coleoptera: Scolytidae) from Crimea, Ukraine

FIGURES 15–17. Tarsonemus fraxini, larva paratype. 15, idiosoma; 16, gnathosoma dorsum; 17, gnathosoma venter.

opennotspecifiedDec 2013View details →

FIGURE 5 in Description of Phloeosinus laricionis sp. n. (Coleoptera: Curculionidae, Scolytinae), a new bark beetle species from southern Europe

FIGURE 5. Antennal club. The sutures of the club are straight on the first segment, slightly arcuate on the second, and strongly arcuate on the third.

opennotspecifiedDec 2013View details →

FIGURE 2 in The sexuales of giant black bark aphid, Pterochloroides persicae (Hemiptera, Aphidoidea: Lachninae)

FIGURE 2. Pterochloroides persicae—male: (a) general feature, (b) antenna, (c) mesosternal processes, (d) apical segment of rostrum, (e) hind tarsus, (f) siphunculus, (g) genitalia.

opennotspecifiedDec 2013View details →

FIGURE 1 in The sexuales of giant black bark aphid, Pterochloroides persicae (Hemiptera, Aphidoidea: Lachninae)

FIGURE 1. Pterochloroides persicae—oviparous female: (a) general feature, (b) antenna, (c) apical segment of rostrum, (d) hind tarsus, (e) sculpture of abdominal sclerite V, (f) spinal tubercle, (g) siphunculus, (h) cauda.

FIGURE 4 in Description of Cryptaphelenchus iranicus n. sp. (Nematoda: Ektaphelenchinae) recovered from bark samples of Pinus nigra from Iran

FIGURE 4. Phylogenetic relationships of Cryptaphelenchus iranicus n. sp and aphelenchid nematodes based on 28S rDNA sequences. The 10001st Bayesian tree inferred under the GTR+I+G model (ln L = -24880.1105; freqA = 0.1808; freqC = 0.1650; freqG = 0.3292; freqT = 0.3250; R(a) = 1.0714; R(b) = 4.9532; R(c) = 2.2091; R(d) = 0.7280; R(e) = 5.6708; R(f) = 1.0000; Pinvar = 0.1970; Shape = 0.7650). Aphelenchus avenae served as the outgroup species. Posterior probability and bootstrap values are given on appropriate clades.

FIGURE 3 in Description of Cryptaphelenchus iranicus n. sp. (Nematoda: Ektaphelenchinae) recovered from bark samples of Pinus nigra from Iran

FIGURE 3. Light micrographs of Cryptaphelenchus iranicus n. sp. A: Male entire body; B: Female entire body; C-F: Male posterior body with cloacal region (cl), spicules (sp) and papillae (P) arrangement indicated by arrows. (A & B = 40 µm, C = 20 µm, D, E & F = 15 µm).

FIGURE 1 in Description of Cryptaphelenchus iranicus n. sp. (Nematoda: Ektaphelenchinae) recovered from bark samples of Pinus nigra from Iran

FIGURE 1. Line drawing of Cryptaphelenchus iranicus n. sp. Female entire body; B: Male entire body; C: Female anterior end; D: Metacorpus region; E: Female pharynx region; F: Male posterior body and showing caudal papillae in lateral view (arrowhead); G: Male posterior body and showing caudal papillae in ventral view (arrowhead); H: Cross section of female showing lateral field; I: Spicule in detail; J: Vulva region showing post-uterin sac (PUS); K, L: Female posterior body end. (A, B, E, J, K & L = 20 µm, C, D, F, G & H= 10 µm, I = 5 µm).

FIGURE 2 in Description of Cryptaphelenchus iranicus n. sp. (Nematoda: Ektaphelenchinae) recovered from bark samples of Pinus nigra from Iran

FIGURE 2. Light micrographs of Cryptaphelenchus iranicus n. sp. female. A: Anterior body; B: Head region; C: Cross section of female showing lateral field; D: Posterior region of pharynx showing excretory pore and hemizonid by arrow; E: Anterior genital tract; F: Genital tract with spermatheca and PUS indicated by arrow; G: Spermatheca; H: Vulval region showing PUS by arrow; I & J: Posterior body. (A, D & E 15 = µm, B, F - J= 10 µm, C = 5 µm).