Reinfestation of Eucalyptus marginata ground coppice by jarrah leafminer after scorch by autumn or spring fires

Population densities of jarrah leafminer Perthida glyphopa in adjoining areas of jarrah Eucalyptus marginata forest in southwest Western Australia were monitored before and after autumn and spring fires, then compared to examine the effect of fire season and intensity. Densities of leafminer were reduced in tree canopies and on ground coppice after autumn fire scorched the host canopies. Densities of larval mines on ground coppice increased by the second spring after an autumn fire. Numbers of mines on leaves returned to levels indistinguishable from pre-fire values by the second autumn after fire. Leafminer populations on ground coppice appeared unaffected by a spring fire. Mechanisms that may account for observed differences between the effects of spring and autumn fires are discussed. Managed fires are not considered a practical tool for control of leafminer populations.     

Ecology of the pest insect jarrah leaf miner (Lepidoptera) in relation to fire and timber harvesting in jarrah forest in Western Australia

During a period of 7 years we undertook 25 investigations of the ecology of jarrah leafminer Perthida glyphopa Common in relation to fire and logging of jarrah Eucalyptus marginata Donn ex Sm. forest. Prescribed low intensity fires in spring or timber harvesting did not consistently favour jarrah leafminer or disfavour parasitization of its mines. Moderate intensity fire in autumn reduced the density of jarrah leafminer for 18 months.

We integrate these findings with other relevant ecological and historical knowledge and theorize that scarcity of extensive scorching of codominant crowns in jarrah forest from the mid 1950s may have facilitated the spread of the outbreak. We recommend that more extensive autumn burning should be operationally introduced to both test the theory and subdue outbreaks of jarrah leafminer.     

The influence of the jarrah leafminer Perthida glyphopa Common (Lepidoptera: Incurvariidae) and prescribed burning on the girth increment of jarrah Eucalyptus marginata Donn ex Smith

Girth increment in jarrah trees, E. marginata, both resistant and susceptible to the jarrah leafminer, P. glyphopa, was measured at 3 sites between 1971 and 1986 and at another site between 1971 and 1981. Significant annual losses of girth increment were detected in the susceptible trees damaged by the leafminer before and during the time of observation. In trees observed through the development of heavy infestation, significant girth increment losses occurred some 5 years after the damage began. Over the period of observation the mean losses of girth increment in the susceptible trees ranged from 44 to 70%.

Rainfall in both current and preceding years had a significant effect on the girth increment in all trees, but varied between sites. At the drier sites both resistant and susceptible trees responded significantly only to the current year's rainfall, while those at the wetter sites were significantly influenced by rainfall of the previous year. In the susceptible trees this effect was overridden by the influence of damage by the leafminer. Girth increment in both resistant and susceptible trees increased for 1 year after 4 out of 5 ground fires in spring that occurred during the time of observation.     

A refined method for estimating capsule crops in individual jarrah (Eucalyptus marginata) crowns

An accurate measure of the number of capsules in the crowns of jarrah (Eucalyptus marginata) trees is needed to assess the potential for seedling regeneration prior to silvicultural treatment in jarrah forests. The current method of estimating capsule crops on jarrah trees uses stem diameter and estimates of capsule density in the crown, but has not been fully validated. In this study, we sought to develop an accurate and practical method of assessing capsule crops in the crowns of individual jarrah trees. We did this by measuring a number of tree characteristics prior to felling them. A total of 24 trees were selected, spanning a range of sizes and crown conditions, and the total number of capsules was counted for each tree. Multiple linear regression was used to model capsule number against various combinations of eight different tree/crown variables, with model fit compared using an adjusted coefficient of determination (adjR²). The final model recommended for field use included three easily measured variables (stem diameter, subjective assessment of capsule density, and subjective assessment of capsule clump distribution in the crown) and had a high degree of predictability (adjR² = 0.83), which was the same as that of the full model. This method substantially improved estimates of crown capsule numbers compared with the method currently used (adjR² increased from 0.29 to 0.83), which tended to underestimate canopy capsule numbers.     

Response of bird populations in jarrah and yarri forest in Western Australia following removal of half the canopy of the jarrah forest

Counts of birds present in jarrah (Eucalyptus marginata) forest on ridges and in yarri (E. patens) forest along streams were made during spring in three consecutive years, 1981–83. Thirty-eight species were recorded in set transects during the study. Six species were restricted to yarri, nine occurred only in jarrah, and eleven tended to be more abundant in yarri. The number of birds of all species was greater in the yarri forest.

Early in 1983, part of the jarrah forest was thinned, reducing canopy cover by about one-half, including removal of all Banksia grandis. The bird community showed few immediate changes. Two species were recorded as significantly more frequent after treatment and no species was recorded as significantly less frequent after treatment. The number of bird species present was similar in unlogged and logged jarrah forest. Two species became significantly more abundant in the yarri forest after the jarrah forest was logged. These findings suggest that most bird species in the jarrah forest may be adaptable to gross disturbance of the forest.     

Forestcheck: the response of vascular flora to silviculture in jarrah (Eucalyptus marginata) forest

Forest understorey vascular plants were monitored across a sequence of time since treatment to assess the effects of silviculture (timber harvesting and regeneration systems) in jarrah (Eucalyptus marginata) forest in south-west Western Australia. Species richness, abundance and structure were assessed at 48 sites in four jarrah forest ecosystems. Monitoring grids in reference forest, which was either uncut or had not been harvested for at least 40 y, were compared to grids in forest that had undergone shelterwood/selective cut and gap release silvicultural treatments. A total of 446 plant species was recorded of which 68, 22 and 35 species were recorded on only one grid within the reference, shelterwood/selective cut and gap release treatments respectively. Silvicultural treatments had no significant long-term effect on mean species richness and abundance of understorey plants, but had a distinct influence on plant community composition. Reference forest had more species of small and medium shrubs compared with silvicultural treatments. Xanthorrhoea preisii (a grass tree) was significantly less common in silvicultural treatments compared with reference forest and Allocasuarina fraseriana (a small to medium tree) and Kennedia coccinea (a vine) were more common on harvested grids. The mean number of plant species per grid was not significantly different between treatments or forest ecosystems. There was, however, strong regional variation in plant community composition, especially in the Jarrah Blackwood Plateau and Jarrah South forest ecosystems and which probably reflects the influence of climatic and edaphic factors on jarrah forest species composition. Dominance-diversity curves for each treatment showed that ranking of species with high abundance was similar in all treatments, but varied between treatments for species with very low abundances. There was no significant relationship between species richness and time since last fire because field assessments were carried out at least 3–13 y after disturbance, by which time species assemblages had stabilised.     

A note on the height variation of foliage clumping: comparison with remote sensing retrievals

Clumping index (CI), quantifying the level of foliage grouping within distinct canopy structures relative to a random distribution, is a key structural parameter of plant canopies and is very useful in ecological and meteorological models. In this letter, we report on validating the global foliage clumping map derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) data at 500 m resolution using new information about vertical profiles of foliage clumping in a wide range of forest type stands. We report that in moderate to dense forest stands with developed undergrowth layer, in situ measurements near the ground surface may considerably underestimate the overall canopy-level clumping effect. This is because the large gaps between tree crowns at upper levels of the canopy may not be all measured near the ground due to obscurity by lower vegetation of branches. This information about height variation of CI is shown to be important for correct estimating and validating the foliage clumping from airborne/satellite remote sensing.     

Crown Recovery of Eucalyptus dives Following Wildfire

The restoration of crowns of 5–7 m tall trees of E. dives of coppice origin was studied after a wildfire on October 1, 1971, near Captains Flat, N.S.W. Unburned plants were compared with those which had their crowns completely scorched but not burned and those which had their leaves completely burned off by crown fire. All trees survived. Approximately 50 per cent of the height of crown-burned trees was killed and 30 per cent in the case of crown-scorched trees. While these results were significantly different most measurements of crown recovery were similar for these two classes of fire-affected plants. Leaf weight was restored within 8 months of the fire. The clumped pattern of epicormic shoots emergent along surviving trunks soon after the fire was replaced by that of the normal branching pattern less than three years later.     

A soil heating index for interpreting ecological impacts of jarrah forest fires

Soil heating during forest fires gives rise to numerous ecological responses, many of which are poorly understood. To interpret, predict and manage these responses, such as fire-induced legume regeneration, it is necessary to identify the key fire, fuel and soil factors that affect heat transfer to the soil, and to determine functional relationships incorporating these factors. Heat transfer to the soil was investigated in the laboratory using jarrah forest litter as the heat source to develop a soil heating index for jarrah forest fires. Maximum soil temperature and heat load (the area beneath the temperature history trace) depended on the quantity of surface litter fuel consumed and soil and fuel moisture content, but was independent of fire rate of spread. A linear relationship incorporating these factors was developed to predict the maximum soil temperature at a depth of 10 mm, thus deriving the soil heating index. This relationship, together with knowledge of the temperatures necessary to achieve optimum germination of soil stored seed, can be used to interpret regeneration responses and to prescribe fires to optimise the regeneration of desired species.     

Characteristics of rifampin-resistant variants obtained from clinical isolates of Staphylococcus aureus.

Twenty clinical isolates of Staphylococcus aureus were examined to determine the frequency of rifampin-resistant variants. All isolates were highly susceptible to rifampin, with mean minimum inhibitory concentrations of 0.11 +/- 0.1 microgram/ml and mean minimum bactericidal concentrations of 0.22 +/- 0.2 microgram/ml. The frequency of isolation of resistant variants was similar to all rifampin concentrations tested. Rifampin-resistant variants maintained their resistance upon daily subculture in rifampin-free broth. Rifampin-susceptible S. aureus exhibited a growth and survival advantage over the rifampin-resistant mutants both in pure cultures and in mixtures with rifampin-resistant antecedents. A comparison of the virulence for mice of five susceptible isolates and their 100 microgram/ml-rifampin-resistant variants showed that two of the resistant variants were less virulent than the susceptible strains via intraperitoneal challenge, whereas three of the resistant variants were less virulent by intravenous challenge (P less than 0.05).     

Forestcheck: the response of birds to silviculture in jarrah (Eucalyptus marginata) forest

In the five-year period from 2001 to 2006, 48 monitoring grids comprising the FORESTCHECK initiative were established in open eucalypt (jarrah, Eucalyptus marginata) forest in south-west Western Australia. Since 1985, revised silvicultural objectives have necessitated detailed monitoring of responses by bird species and assemblages to silvicultural treatments (timber harvesting and associated burning). Few marked changes in the avifauna were detected. Species accumulated (in terms of numbers of grids) at similar rates in gap release, shelterwood/selective cut, and reference (either never harvested or harvested more than 40 years previously) forests. In terms of individuals, species accumulated faster in the gap release forests. The number of species represented as singletons was greatest on the never harvested (8), coupe buffer (7) and gap release (6) grids. Dominance-diversity curves also showed only minor differences between silvicultural treatments. Neither nMDS nor CAP ordinations showed any clear separation between the treatments. There was little evidence of any substantial effect of silvicultural treatments on avian community structure or on individual bird species. Community structure was, however, significantly associated with forest ecosystem/year of sampling. The basal area of live trees was not correlated with bird species richness or abundance on each grid. These results are consistent with previous studies, which indicate that most bird species in jarrah forest have a high threshold level of tolerance to disturbance. It is likely that the rapid regeneration of dominant tree species after harvesting and associated fire, the patchiness of treatments at the landscape scale, the high degree of connectivity of harvested and burnt forests with forests not recently harvested or burnt, and the retention of habitat trees in the most heavily—harvested (gap release) forests all conduce to dampen local-scale impacts and conserve the avifauna in relation to the home range and normal movements of its constituent bird species.     

Serial analysis of gene expression in the southern cattle tick following acaricide treatment of larvae from organophosphate resistant and susceptible strains

Organophosphate resistant and susceptible tick larvae from laboratory strains of the southern cattle tick, Rhipicephalus (Boophilus) microplus were exposed to low doses of the organophosphate (OP) acaricide, coumaphos. Serial analysis of gene expression (SAGE) was used to analyse differential gene expression in response to OP treatment and to compare the responses of OP-treated and -untreated resistant and susceptible tick larvae. An R. microplus Gene Index was used as an EST database to identify genes which corresponded to SAGE tags whose abundance changed in response to acaricide exposure. Relative quantitative RT-PCR was used to confirm the differential expression results from the SAGE experiments. Of particular interest is a SAGE tag which corresponds to a cytochrome P450-like EST in the Gene Index which was more abundant in untreated OP resistant larvae compared to untreated OP susceptible larvae. This SAGE tag was also more abundant in OP resistant larvae treated with OP compared to OP susceptible larvae treated with OP.     

Streptococcus pneumoniae in the USA: in vitro susceptibility and pharmacodynamic analysis

Ninety-two laboratories in the USA submitted isolates of Streptococcus pneumoniae to a single laboratory for susceptibility testing. Overall, 64% of 4489 isolates were susceptible to penicillin, 24% were intermediate and 13% were resistant to penicillin, although susceptibilities varied depending on geographical region. Macrolide/azalide resistance varied from 4 to 30%, with some regions having macrolide/azalide resistance higher than penicillin resistance. Children 12 years of age were significantly more likely to be infected with a penicillin-resistant pneumococcus than were adolescents or adults. Isolates from the respiratory tract were more likely to be penicillin resistant and >50% of pneumococci from the ear were resistant to penicillin. Almost 25% of penicillin-susceptible isolates had cefaclor MICs 2.0 mg/L and 15% of penicillin-susceptible isolates had loracarbef MICs 2.0 mg/L. These isolates would be erroneously reported as susceptible using NCCLS guidelines, and this finding may explain the lack of clinical response in patients treated with these antibiotics. The predicted plasma concentrations of all cephalosporins tested exceeded the geometric mean MIC for at least 40% of the dosing interval for penicillin-susceptible S. pneumoniae; for penicillin-intermediate S. pneumoniae, only cefprozil (56%), cefuroxime (64%) and cefpodoxime (63%) reached >40% of time above the geometric mean MIC in the dosing interval. None of the cephalosporins evaluated achieved a substantial time above the geometric mean MIC during its dosing interval for fully penicillin-resistant S. pneumoniae.     

JARRAH STEM DISTRIBUTIONS

Laboratory bioassays were conducted on the susceptibility of air-dried sapwood specimens, from trees of both regrowth and mature karri (Eucalyptus diversicolor) and jarrah (Eucalyptus marginata), to attack by the powder post borer (Lyctus brunneus). The susceptibility of regrowth karri was determined using material collected from 10 trees (five trees x two areas) each at three positions (the butt, midway along the bole and the crown). Material from the butts of 64 mature trees, representing three different areas in the south west of Western Australia, was similarly assessed. Both regrowth and mature karri specimens were collected from trees within the main karri estate. The susceptibility of both regrowth and mature jarrah was compared concurrently in a bioassay which evaluated butt specimens of approximately 20 trees from each of three different areas in the jarrah forest. Prior to the bioassays, all specimens were assessed for starch concentration in the sapwood.

Some sapwood specimens of both regrowth and mature karri were susceptible to attack by L. brunneus. Specimens cut from the butt position of regrowth karri trees contained the highest concentration of starch and were more heavily attacked by L. brunneus. Similarly, some regrowth and mature jarrah specimens from some areas were susceptible to attack.

Differences in starch concentration and susceptibility between areas from which each timber species was harvested were revealed. Positive correlations, between starch concentration and susceptibility of mature karri and regrowth and mature jarrah, were obtained. A revision of previously published ratings for both karri and jarrah is recommended. We further recommend that a re-assessment of the susceptibility to L. brunneus of all commercially available hardwood timber species be undertaken, particularly if a regrowth resource of those species is being utilised or likely to be utilised in the near future.     

Virus-induced diabetes mellitus. VI. Genetically determined host differences in the replicating of encephalomyocarditis virus in pancreatic beta cells

Beta cells were isolated from strains of mice that were susceptible and resistant to encephalomyocarditis (EMC) viral-induced diabetes mellitus. Beta cells from susceptible mice that were infected in vivo with EMC virus showed higher viral titers, more severe degranulation, and lower concentrations of immunoreactive insulin than beta cells from resistant mice. Immunofluorescence and infectious center assays revealed that pancreas from susceptible mice contained at least 10 times more infected cells than pancreas from resistant mice. Beta cell cultures prepared from susceptible mice and infected in vitro also showed higher viral titers and more severe cytopathologic changes than beta cell cultures from resistant mice. In contrast to beta cell cultures, virus replicated equally well in primary embryo and kidney cell cultures from susceptible and resistant strains of mice. It is concluded that the development of EMC virus-induced diabetes is related to genetically determined host differences in the capacity of the virus to infect beta cells.     

PRODUCER GAS IN WESTERN AUSTRALIA

A survey was undertaken lo assess 5 to 10-year-old rehabilitated bauxite minesite vegetation as suitable habitat for birds while breeding during spring in the jarrah (Eucalyptus marginata) and marri (E. calophylla) forest at Jarrahdale. Western Australia. The minesites had been rehabilitated and revegetated with local shrub species and a mix of local and eastern eucalypts resistant to the root rot fungus Phytophthora cinnamomi.

Twenty-one species of birds used the former minesites for foraging or hunting while breeding; twelve of these were found nesting or rearing fledglings in the revegetation. Among the breeders were four understorey dwelling species which were otherwise uncommon in surrounding upland forest or (in two cases) confined in stream zone undergrowth. Total densities of all pairs or groups breeding in minesites were similar to those in nearby forest. Breeding territories often spanned areas of both minesite and forest around the edge of pits.

Eleven other species were found breeding only in the adjacent forest and all were nesting in sites as yet unavailable within minesites, such as tree hollows, fissures, bark crevices and crown foliage. The possible use of nest-boxes to aid in the early provision of sites for hollow-nesting species is being investigated.     

In vitro activity of RU29246. The metabolite of a new HR916 cephalosporin ester.

Compound RU29246 (RU) is the active metabolite of an orally absorpted cephalosporin ester HR916. The RU spectrum of activity includes the majority of Enterobacteriaceae species, Haemophilus influenzae, pathogenic Neisseria spp., Moraxella catarrhalis, Acinetobacter antiratus, staphylococci, and Streptococcus spp. Pseudomonas species and enterococci were routinely resistant to RU. The RU spectrum was most similar to cefixime against the Gram-negative bacilli and to cefuroxime against the Gram-positive organisms. RU was bactericidal and its mean inhibitory concentrations (MICs) were not greatly increased by high inoculum concentrations. Many strains producing various beta-lactamases generally remained susceptible to RU by MIC tests. However, isolates with extended broad spectrum beta-lactamases capable of hydrolyzing cefotaxime and ceftazidime were also resistant to RU. Broth and agar RU MICs were comparable. Its activity was increased against enterococci in the presence of blood products.     

Activities of oral and parenteral agents against penicillin-susceptible and -resistant pneumococci.

This study examined bacteriostatic and bactericidal activities of oral and parenteral antibiotics for penicillin-susceptible and intermediately and fully penicillin-resistant pneumococci. beta-Lactamase inhibitors did not affect beta-lactam results. The activities of ampicillin, amoxicillin +/- clavulanate, WY-49605, cefuroxime, cefpodoxime, cefdinir, cefixime, and cefaclor against two penicillin-susceptible, two intermediately penicillin-resistant, and two fully penicillin-resistant pneumococcal strains were tested. For all three groups, bacteriostatic values of amoxicillin and WY-49605 were lower than were those of other beta-lactams tested. Of the cephalosporins, cefdinir, cefuroxime, and cefpodoxime yielded the lowest bacteriostatic values. All beta-lactams were bactericidal (reduced original counts by > or = 3 log10 CFU/ml) at 1 dilution above bacteriostatic values, except for cefpodoxime (bactericidal at 2 dilutions above bacteriostatic values for one susceptible strain and one intermediately resistant strain), cefuroxime (bactericidal at 2 dilutions above bacteriostatic values for one intermediately resistant strain), and ampicillin (bactericidal at 2 dilutions above bacteriostatic values for one intermediately resistant strain). The activities of piperacillin, piperacillin-tazobactam, ticarcillin, ticarcillin-clavulanate, ampicillin, ampicillin-sulbactam, ceftriaxone, ceftazidime, and ciprofloxacin against four penicillin-susceptible, two intermediately penicillin-resistant, and four fully penicillin-resistant pneumococcal strains were evaluated. Bacteriostatic values of piperacillin, ampicillin, and ceftriaxone for all groups were lower than were those of ticarcillin and ceftazidime. Bacteriostatic values of ciprofloxacin were unaffected by penicillin susceptibility. All beta-lactams were bactericidal at 1 dilution above the bacteriostatic value, except for piperacillin (bactericidal at 2 dilutions above the bacteriostatic value for one intermediately resistant strain), ticarcillin (bactericidal at 2 dilutions above the bacteriostatic value for one susceptible strain and one resistant strain), ampicillin (bactericidal at 2 dilutions above the bacteriostatic value for two resistant strains), ceftriaxone (bactericidal at 2 dilutions above the bacteriostatic value for one resistant strain), and ceftazidime (bactericidal at 2 dilutions above the bacteriostatic value for one susceptible strain).     

The effect of pharmacokinetics on the bactericidal activity of ciprofloxacin and sparfloxacin against Streptococcus pneumoniae and the emergence of resistance.

The pharmacokinetics of ciprofloxacin and sparfloxacin were simulated in vitro and the effects of pharmacodynamic parameters on bactericidal activity and the emergence of quinolone resistance were examined for Streptococcus pneumoniae. Simulated serum concentrations of ciprofloxacin 500 mg bd were more rapidly bactericidal than sparfloxacin 200 mg bd, despite lower values for the key pharmacodynamic parameters (AUC/MIC and C(max)/MIC). This was possibly related to the slower oral absorption of sparfloxacin, which delayed achievement of the MIC compared with ciprofloxacin. In addition, sparfloxacin was shown to have similar bactericidal activity to ciprofloxacin when tested at the same concentrations, despite its four-fold better potency in MIC terms. The emergence of resistance following exposure to ciprofloxacin appeared to be dependent on the C(max)/MIC ratio and the AUC above the MIC, but not the AUC/MIC ratio. Resistance (at least four-fold increase in MIC) developed when the C(max)/MIC ratio was less than four or the AUC above the MIC was less than 10, and the resulting cultures regrew fully. In contrast, pneumococci with a two- to four-fold increase in sparfloxacin MIC were selected in the presence of serum concentrations of sparfloxacin despite a C(max)/MIC ratio higher than 12, but these isolates remained clinically susceptible by breakpoint MIC and their growth was inhibited by repeated dosage of sparfloxacin. Nevertheless, the selection of pneumococci with reduced susceptibility, and the possibility of further mutation to highly resistant strains supports the use of quinolones that rapidly eradicate pneumococci at conventional doses and achieve concentrations, in both serum and tissues, which exceed at least 4 x MIC.