Seasonality influences the abundance and activity of forest insects. Harvesting during periods of reduced activity could minimise colonisation risk on logs and reduce the need for phytosanitary ...treatments. We describe the winter colonisation dynamics of
Pinus radiata
logs in operational harvest sites in New Zealand and assess the probability of log colonisation as a function of captures in flight interception traps. After 15 days, 3% and 1% of logs were colonised by
Hylastes ater
and
Hylurgus ligniperda
(Coleoptera: Scolytinae), respectively, and 1% by
Xenocnema spinipes
(Coleoptera: Curculionidae). The same three species were captured in traps. Our observations showed that logs exposed for ≥ 2 weeks are predicted to have a more than 1% probability of bark beetle colonisation, whereas logs removed from forests within 24 or 48 h had predicted colonisation rates of 0.13% and 0.26%, respectively. A positive relationship between trap capture and log colonisation was also observed. Average catches of < 1 bark beetle per trap, three bark beetles per trap or ten bark beetles per trap equated to estimated log colonisation rates of < 10%, 14–98% or > 98% log colonisation. A positive relationship was also shown between log colonisation rates and temperature. A 12.3 °C temperature threshold predicted colonisation rates of 5, 50 and 95% with thermal sums of 10, 20 and 30 degree-hours, respectively. Models based on exposure time, trap catches, or environmental factors can estimate seasonal probability of insect colonisation, which aids identification of periods of low pest pressure when treatments could be avoided or reduced.
Reports the results of polymerase chain reaction procedures (UP-PCR) on extracted DNA of of Armillaria novae-zelandiae and Armillaria limonea wood decay fungi, the species identities of which had ...been determined earlier by incompatibility reactions between paired cultures, in order to verify whether or not their vegetative compatibility groups (VCG) represent distinct individual genets. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Early detection of bark- and wood-boring beetles is critical to support the eradication of recently established populations in novel regions. Flight intercept traps baited with semiochemical lures ...are essential for surveillance and population monitoring of introduced insects. We present laboratory and field data to test potential improvements in trap sensitivity to detect Hylastes ater (Paykull), Hylurgus ligniperda (Fabricius) (Coleoptera:Scolytinae), and Arhopalus ferus (Mulsant) (Coleoptera:Cerambycidae). We evaluated the effects of type and permeability of plastic material on release rates of host-plant volatiles and the addition of the pheromone racemic E-fuscumol on beetle species catch within an exotic Pinus radiata (D. Don) plantation forest. We trapped 228,278 H. ligniperda, 91 H. ater, and 2,504 A. ferus over two experiments. Our results show strong attraction of H. ligniperda to host-plant volatiles with a positive relationship between increased release rates and trap catch. H. ater follows this trend, with attraction to ethanol and (–)-β-pinene. H. ligniperda was more strongly attracted to host volatiles than H. ater, the average ratio between baited and unbaited traps being 51.25:1 and 3.75:1, respectively for each species. There was no effect of host-plant volatiles or release rate on A. ferus catch, but a weak attraction by A. ferus to racemic E-fuscumol. Overall, we demonstrate species-specific differences in Coleoptera attraction to host-plant volatile release rates and semiochemical blends. Results demonstrate mechanisms to improve trap catch of H. ligniperda and H. ater. Racemic E-fuscumol shows some promise for A. ferus, but further investigation is required to determine whether chirality affects attraction.
Uromycladium acaciae has damaged plantations of Acacia mearnsii in southern Africa since 2013. Uredinia of a species of Uromycladium have been known on A. mearnsii in South Africa since the 1980s. ...However, the recent damage is associated with telia and spermogonia. Uredinia and telia were previously treated as conspecific with a phylogenetic species concept. However, uredinia did not form after previous artificial inoculation experiments with teliospores. Controlled studies identified the optimum conditions for basidiospore infection, but the optimum conditions for sporulation and dispersal have not been identified. To investigate the life cycle and field epidemiology of Uromycladium on A. mearnsii, spores were trapped weekly and development of disease symptoms and plant phenology were monitored monthly at three plantations. Telia and spermogonia developed independently from uredinia, and nucleotide polymorphisms between rDNA of uredinia and telia were fixed based on high throughput sequencing and PCRs. All three weather variables measured had a significant effect on teliospore abundance at two of the three sites. Teliospore abundance was greatest during trapping periods when mean relative humidity was high, mean rainfall was 4–5 mm day−1 and mean temperature was 15–16°C. Teliospore counts peaked at the end of summer, potentially the result of epidemic build‐up. Results support the hypothesis that despite sharing a most recent common ancestor, uredinia on A. mearnsii in southern Africa are independent to the life cycle of the telial rust, which likely constitutes a new introduction. Furthermore, teliospores of U. acaciae disperse under wet conditions, and the wet season between October and March is the optimal period for wattle rust development.
Field observations combined with rDNA data suggest two lineages of Uromycladium (Pucciniales) infect Acacia mearnsii in South Africa: a highly damaging one that produces spermogonia and telia on immature host tissues and a less damaging one that produces uredinia mostly on mature tissues. Teliospore counts of the telial lineage peaked towards the end of the wet summer season, likely the result of epidemic build‐up. Spore trapping indicated that water was important for dispersal of teliospores: abundance was greatest during periods when mean relative humidity was high, mean rainfall was 4–5 mm day−1 and mean temperature was 15–16°C.
Paralytic shellfish poisoning is a worldwide problem induced by shellfish contaminated with paralytic shellfish toxins. To protect human health, a regulatory limit for these toxins in shellfish flesh ...has been adopted by many countries. In a recent study, mice were dosed with saxitoxin and tetrodotoxin mixtures daily for 28 days showing toxicity at low concentrations, which appeared to be at odds with other work. To further investigate this reported toxicity, we dosed groups of mice with saxitoxin and tetrodotoxin mixtures daily for 21 days. In contrast to the previous study, no effects on mouse bodyweight, food consumption, heart rate, blood pressure, grip strength, blood chemistry or hematology were observed. Furthermore, no histological findings were associated with dosing in this trial. The dose rates in this study were 2.6, 3.8 and 4.9 times greater, respectively, than the highest dose of the previous study. As rapid mortality in three out of five mice was observed in the previous study, the deaths are likely to be due to the methodology used rather than the shellfish toxins. To convert animal data to that used in a human risk assessment, a 100-fold safety factor is required. After applying this safety factor, the dose rates used in the current study were 3.5, 5.0 and 6.5 times greater, respectively, than the acute reference dose for each toxin type set by the European Union. Furthermore, it has previously been proposed that tetrodotoxin be included in the paralytic shellfish poisoning suite of toxins. If this were done, the highest dose rate used in this study would be 13 times the acute reference dose. This study suggests that the previous 28-day trial was flawed and that the current paralytic shellfish toxin regulatory limit is fit for purpose. An additional study, feeding mice a diet laced with the test compounds at higher concentrations than those of the current experiment, would be required to comment on whether the current paralytic shellfish toxin regulatory limit should be modified.
Austropuccinia psidii, cause of myrtle rust, has spread globally where Myrtaceae occur. Multiple strains of A. psidii have been identified, including a unique strain found only in South Africa. The ...South African strain is a biosecurity concern for species of Myrtaceae worldwide. This is because preliminary testing of South African Myrtaceae suggests it could have a wide host range, and thus has the potential to be invasive. In this study, we assessed the ability of the South African strain to infect other species of Myrtaceae by testing the susceptibility of New Zealand provenance Myrtaceae. Seedlings of four native New Zealand Myrtaceae species (Metrosideros excelsa, Leptospermum scoparium, Kunzea robusta, and Kunzea linearis) were artificially inoculated in South Africa with a single‐uredinium isolate of the South African strain. Fourteen days after inoculation, uredinia, and in many cases telia, had developed on the young leaves and stems of all four host species, which led to shoot tip dieback in the more severe cases. When comparisons were made between the species, K. robusta was the least susceptible to the South African strain of A. psidii, while L. scoparium and M. excelsa were the most susceptible. While only a limited number of seed families were tested, only a small proportion of the seedlings showed resistance to infection by the South African strain. This preliminary testing highlights the potential invasive risk the South African strain poses to global Myrtaceae communities, including New Zealand Myrtaceae.
This study provides new insights into the host range of the South African strain of Austropuccinia psidii, suggesting this pathogen represents a threat for New Zealand native Myrtaceae and for other Myrtaceae species worldwide.
Exotic conifers are rapidly spreading in many regions of New Zealand, as well as in many other countries, with detrimental impacts on both natural ecosystems and some productive sector environments. ...Herbicides, in particular the active ingredient triclopyr, are an important tool to manage invasive conifers, yet there is a paucity of information that quantifies the amount of herbicide required to kill trees of different sizes when applied as a basal bark treatment. Two sequential experiments were conducted to define the amount of triclopyr required to kill individual invasive lodgepole pine (Pinus contorta Douglas ex Loudon), trees of different sizes when applied in a methylated seed oil to bark (either the whole stem or base of the tree) and to determine which tree size variates (height, diameter at breast height DBH, crown diameter CD) or derived attributes (crown area, crown volume index) best characterized this dose–response relationship. The outcomes of the dose–response research were compared with field operations where triclopyr was applied to the bark of trees from an aerial platform. Applying the herbicide to the whole stem, as opposed to the base of the tree only, significantly increased treatment efficacy. The tree size variates DBH, CD, crown area, and crown volume index all provided good fits to the tree mortality data, with >91% prediction accuracy. Of these variates, CD provided the most practical measure of tree size for ease of in-field calculation of dose by an operator. Herbicide rates used in field operations were seven to eight times higher than lethal doses calculated from experimental data. Our results highlight the potential for substantial reductions in herbicide rates for exotic conifer control, especially if dose–response data are combined with remotely sensed quantitative measurements of canopy area or volume using new precision technologies such as unmanned aerial vehicles.
Reports the results from three years of continuous trapping to assess the flight activity of seven bark- or wood-boring species (Arhopalus ferus(Mulsant), Hylastes ater (Paykull), Hylurgus ligniperda ...F., Mitrastethus baridioides Redtenbacher, Pachycotes peregrinus (Chapuis),Prionoplus reticularis White, and Sirex noctilio (F.)) at the five major log- and timber-exporting ports in New Zealand. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
To extend present knowledge of communities of wood decay fungi in native forests, basidiomycetes and ascomycetes were isolated from within 15 fallen stems in beech (Nothofagus, Nothofagaceae) forests ...in the South Island of New Zealand. Fungal species were identified as precisely as possible using traditional culturing and molecular approaches. The internal distribution of species within stems was determined. Common fungi that occupied significant portions of stems were Ganoderma applanatum sensu Wakefield, Australoporus tasmanicus, Inonotus nothofagi, Pleurotus purpureo-olivaceus, and an unidentified hymenochaetaceous species. Richness and diversity of basidiomycete species were greater in stems of red beech (Nothofagus fusca (Hook. f.) Oerst.) and silver beech (Nothofagus menziesii (Hook. f.) Oerst.) than in those of matai (Prumnopitys taxifolia (Banks & Sol. ex D. Don) de Laub.; Podocarpaceae) and tawa (Beilschmiedia tawa (A. Cunn.) Kirk; Lauraceae), as determined from earlier studies in podocarp hardwood and beech indigenous forests. There was greater similarity in the species composition of basidiomycete fungi colonising the three beech species compared with those colonising rimu (Dacrydium cupressinum Sol. ex Lamb.; Podocarpaceae), tawa, and matai. Based on observations in this study and on international research on the effects of selective logging on basidiomycete biodiversity, the decision to restrict to 50% the extraction of wood following storm damage in beech forests on the West Coast of the South Island appears to have been appropriate.
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