bluuebunny/crossref_metadata_2025 huggingface dataset:
Short‐term fitness benefits of physiological integration in the clonal herb Hydrocotyle peduncularis
Authors: Peterson Andrew G. , Chesson Peter
Published: March 2003

Abstract  We test whether physiological integration enhances the short‐term fitness of the clonal herb Hydrocotyle peduncularis (Apiaceae, R. Brown ex A. Richards) subjected to spatial variation in water availability. Our measures of fitness and costs and benefits are based on the relative growth rate of fragmented genets. Physiological integration over a gradient in soil moisture resulted in a highly significant net benefit to genet growth of 0.015 g g−1 day−1. This net benefit represents a significant enhancement of the average fitness of fragmented genets spanning the moisture gradient relative to the average of those growing in homogeneous moist or dry conditions. Sections of genet fragments growing in dry conditions in spatially heterogeneous treatments had significantly higher growth than the sections they were connected to that were growing in moist conditions. Within fragments, older (parent) sections growing in moist conditions experienced significant costs from connection to younger (offspring) sections growing in dry conditions. In contrast, offspring sections with ample water did not experience any costs when connected to parent sections growing in dry conditions. However, the net benefit of physiological integration was similar for parent and offspring sections, suggesting that parent and offspring sections contributed equally to the net benefit of physiological integration to genet growth and short‐term fitness.
Experiments on tree and shrub establishment in temperate grassy woodlands: Seedling survival
Authors: Clarke Peter J.
Published: March 2003

Abstract  Experimental studies of the emergence of shrubs and trees in grassy woodlands on the New England Tablelands, New South Wales, Australia, showed that emergence of seedlings was determined by seed supply, seed predators and seed burial. The survival of these seedlings was then observed in an experiment to test the effects of previous land use, grazing by stock and grazing by other vertebrates. The fate of four eucalypts and six shrub species was followed over 5 years. Across all species more than 50% mortality occurred in the first 6 months prior to the imposition of grazing treatments. These deaths were attributed to the combined effects of insect defoliation, cold, and low soil moisture. Average mortality over all treatments showed two distinct trends: eucalypts and one unpalatable shrub (Leptospermum) had greater than 1% survival over 5 years, whereas Acacia, Cassinia, Indigophera, Lomatia and Xanthorrhoea either had very low or no survival after 5 years. The effect of livestock grazing on seedling numbers was rarely detected because of patchy emergence and mortality due to other causes. However, proportional hazard regression models showed that there was often an increased hazard associated with grazing or grazed landscapes. Overall, those species with high hazard coefficients associated with stock are rare in the landscape, whereas those with lesser risk are more common. Recruitment is likely to be an extremely rare event because the highest proportion of germinable seed sown that survived to a juvenile stage was 0.42% and the mean across all species was 0.12%. No natural recruitment of shrub species was observed over 5 years of observation, suggesting that recruitment is episodic and disturbance driven. Enhancing natural ‘regeneration’ of woody plants under these circumstances may be more challenging than simply fencing off remnants.
Thermal ecology and structural habitat use of two sympatric lizards (Carlia vivax and Lygisaurus foliorum) in subtropical Australia
Authors: Singh Sarinda , Smyth Anita K. , Blomberg Simon P.
Published: March 2003

Abstract  The thermal ecology and structural habitat use of two closely related sympatric lizards, Carlia vivax (de Vis) and Lygisaurus foliorum de Vis, were examined in an open sclerophyll forest in subtropical Australia. Comparable mean body temperatures (Tb) and habitat temperatures (Thab) at the point of capture were recorded for both species. However, sex‐related differences in the thermal variables for C. vivax, with females displaying higher temperatures than males, resulted in some significant differences in Tb and Thab between the species. Variation in Tb and Thab within and between species was unrelated to time of capture. The difference in Thab within C. vivax suggested that females were selecting warmer thermal environments than males. Both C. vivax and L. foliorum used most structural features of their habitat randomly as indicated by a similarity in canopy, shrub, ground, log and litter cover and litter depth between habitat surveys and random surveys. However, C. vivax displayed a preference for ground vegetation (height <1 m) and litter cover with significantly higher cover recorded where these lizards were captured compared with random surveys. There was no effect of sex on structural habitat used by either species. Thus, the warmer thermal environments selected by female C. vivax may differ from those selected by males in sun/shade patterns or additional habitat features not measured in the present study. Significant associations between specific habitat features and Tb matched broad habitat descriptions for C. vivax and L. foliorum. This suggests that thermal considerations have direct interactions with the structural habitat preferences of these species. The significant association between Tb and ground cover for C. vivax corresponded with the non‐random use of ground cover by this species, whereas L. foliorum utilized all structural features randomly, despite an association between Tb and litter cover. The relative abundance or scarcity of individual structural habitat features may influence whether an association between those features and Tb is reflected in non‐random patterns of habitat use.
Estimating bird species richness: How should repeat surveys be organized in time?
Authors: Field Scott A. , Tyre Andrew J. , Possingham Hugh P.
Published: March 2003

Abstract  Estimates of species richness for a given area require that repeat surveys be taken, so that the statistical robustness of the estimate can be assessed. But how should these repeat surveys be organized in time? Here we present a case study of Australian woodland birds, surveyed using the ‘active timed area search’ method, which has become the standard unit for the Australian Bird Atlas, a continental‐scale bird survey. To date, there has been no assessment of how estimates of species richness derived from this method are affected by the temporal organization of the repeat surveys. For instance, can conducting the repeat surveys in sequence on the same day effectively capture richness, or will additional species be obtained by repeating the surveys on different days within a season? If so, does the spacing of the repeat visits throughout the season have an effect? To answer these questions, we surveyed woodland birds in the Mount Lofty Ranges, South Australia, during late spring–summer 1999–2000, and compared the performance of two different temporal configurations of repeat visits to sites: (i) six repeat surveys performed on the same day; and (ii) three repeat surveys on different days. For both, we calculated the average number of species actually sighted and also estimated total species richness. The data supported our hypothesis that the same‐day surveys would yield fewer species and underestimate total species richness. The different‐day repeats captured significantly more species per unit of survey effort, and yielded a higher richness estimate. However, the timespan over which different‐day surveys were conducted within a season did not have a significant influence on species richness estimates, evincing a qualitative advantage to surveying on different days, regardless of the spacing of repeat visits. These results may be of assistance to conservation managers when planning cost‐efficient monitoring regimes.
Habitat selection of the long‐nosed bandicoot, Perameles nasuta (Mammalia, Peramelidae), in a patchy urban environment
Authors: Chambers Lisa K. , Dickman Chris R.
Published: March 2003

Habitat selection in an omnivorous marsupial, the long‐nosed bandicoot, Perameles nasuta Geoffroy, was investigated in an urban environment with both natural and highly modified habitats at North Head, New South Wales, Australia. Habitat use at both macro‐ and microhabitat scales was determined using live‐trapping, and P. nasuta was shown to be a habitat specialist at this site. At night, animals used open grass macrohabitats disproportionately more for foraging than other macrohabitats. Trap‐revealed macrohabitat use was supported by radiotracking three males. Lack of understorey and absence of leaf litter were the major microhabitat features affecting habitat choice, although soil type probably also had some effect. Open areas may provide a more abundant and/or accessible food supply for P. nasuta, although better manoeuvrability or increased visibility to detect predators may also be important. Diurnal nest sites, located using radiotracking, were primarily in dense scrub vegetation, often comprising introduced species of plants. The dependence of P. nasuta on: (i) dense undergrowth for diurnal nesting and temporary nocturnal sheltering; and (ii) open areas for foraging indicates the importance of conserving a mosaic of open and dense vegetation to ensure the continued persistence of this endangered population at North Head.
Gall‐forming insect species richness along a non‐scleromorphic vegetation rainfall gradient in South Africa: The importance of plant community composition
Authors: VELDTMAN R. , MCGEOCH M. A.
Published: March 2003

Abstract
Currently there is no single accepted hypothesis to explain gall‐forming insect species richness at a particular locality. Hygrothermal stress, soil nutrient availability, plant species richness, plant structural complexity, plant family or genus size, and host plant geographical range size have all been implicated in the determination of gall‐forming insect species richness. Previous studies of such richness at xeric sites have included predominantly scleromorphic vegetation, usually on nutrient‐poor soils. This study is the first to investigate gall‐forming insect species richness of xeric, non‐scleromorphic vegetation. Two habitat types were sampled at each of five localities across a rainfall gradient in the savanna biome of South Africa. The habitat types differed with respect to plant species composition and topography. Gall‐forming insect species richness did not increase with increasing hygrothermal stress or decreasing soil fertility. Rather, gall‐forming insect species richness was largely dependent on the presence of Terminalia sericea as well as other members of the Combretaceae and Mimosaceae. Plots where all these taxa were present had the highest gall‐forming insect species richness, up to 15 species, whereas plots with none of these taxa had a maximum of four galling‐insect species. Despite herb, shrub and tree strata not differing in gall‐forming insect species richness, insect galls were more common on woody than non‐woody plants. Also, stem galls were more frequent than apical or leaf galls. An alternative hypothesis to explain local gall‐forming insect species richness is suggested: galling insects may preferentially select those plant species with characteristics such as chemical toxicity, mechanical strength, degree of lignification or longevity that can be manipulated to benefit the galler. Thus plant community composition should be considered when attempting to explain gall‐forming insect species richness patterns.
Direct and indirect effects of exotic annual grasses on species composition of a South Australian grassland
Authors: LENZ TANJA I. , MOYLE‐CROFT JESSICA L. , FACELLI JOSE M.
Published: March 2003

Abstract
Invasion by Mediterranean annual grasses, such as Avena L. spp. and Bronms L. spp, is one of the major threats to temperate perennial grassland. This study investigated the effects of annual grasses and their litter on the species composition of a grassland near Burra, South Australia. The placement of annual grass litter on soil samples in the glasshouse decreased the establishment or growth of several exotic annual dicots. In the field the addition of annual grass litter slightly decreased the frequency of Danthonia Lam. & DC. tussocks. Furthermore, litter strongly reduced the species richness from 13 species in plots with no litter to nine species in plots with the highest litter level, mainly by decreasing the frequency of common exotic dicots. Native dicot frequency similarly appeared to be decreased by litter addition. In addition to the negative effects of their litter, annual grasses also directly competed with perennial grasses. The magnitude of the competitive effect varied systematically along a slope, suggesting that other factors such as soil properties may control competitive inter actions. The biomass of annual grasses also tended to increase with the addition of their own litter. This combination of positive and negative feedback mechanisms suggests that brief periods favourable for annual grasses, either through management changes or environmental conditions, can lead to persistent changes in the species composition of the system.
Site‐to‐site variation in the demography of a fire‐affected perennial. Acacia suaveolens, at Ku‐ring‐gai Chase National Park, New South Wales, Australia
Authors: WARTON DAVID I. , WARDLE GLENDA M.
Published: March 2003

Abstract
Acacia suaveolens (Sm.) Willd is a perennial shrub that forms even‐aged stands, recruited from a soil seed‐bank following fire. It has previously been subject to demographic studies, which used a space‐for‐time substitution to investigate temporal patterns following fire. In the present study the potential for spatial variation across sites was investigated by sampling at several similarly aged populations in Ku‐ring‐gai Chase National Park, northern Sydney, Australia. Significant variation in mean size and fecundity of A. suaveolens individuals was observed among sites, over a 2‐4.6‐fold range in plant size, and a sevenfold range in mean fecundity. The observed variation at 3 years after fire encapsulated most of the variation previously observed among sites 0‐17 years since fire, emphasizing the importance of spatial variation in this species. For each site a two‐stage (seed, plant) matrix model was constructed, and projected from 3 to 25 years following fire. Population growth was measured as number of seeds per 3‐year‐old plant, and found to vary 1.4‐fold across models for different sites. This site‐to‐site variation, as well as that in size, fecundity and survival, was statistically significant. Variation in projected seeds per plant could mostly be attributed to differences in fecundity rather than plant survival. Sensitivity analyses emphasized the biological significance of the variation in fecundity. Whereas previous studies have focused on temporal variation, this work demonstrates the importance of extending our understanding of a species to include the spatial component of population dynamics.
Testing models of trophic dynamics: The problem of translating from model to nature
Authors: ENGLUND GORAN , MOEN JON
Published: March 2003

Abstract
Mathematical models of interacting populations have a prominent position in population and community ecology, but are often criticized for not being testable. The authors reviewed tests of a particular model, the exploitation ecosystem hypothesis as it was formulated in Oksanen et al. (1981), in order to study problems that may be encountered when testing models. A general problem is how to determine if an experimental system should be regarded as within the model's theoretical domain or not. The theoretical domain defines the type of system the model is meant to apply to. It is noted that both liberal and strict domain definitions can be problematic. Most important is that a too liberal domain definition can result in false understanding (i.e. that it is falsely concluded that the processes included in the model are controlling the study system). Other problems encountered were more system‐specific. Equilibrium predictions were tested in experiments that were too short to reach steady state and in several studies ambiguous definitions and measurements of model variables were found such as productivity, biomass and the number trophic levels. It is concluded that a major obstacle when performing tests is the conceptual and methodological problems encountered when translating model abstractions into an empirical reality.
Eucalypt hybrid susceptibility to Gonipterus scutellatus (Coleoptera: Curculionidae)
Authors: DUNGEY H. S. , POTTS B. M.
Published: March 2003

Abstract
Damage caused by the eucalypt snout weevil Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) (=G.gibberus Boisduval) was found on a greater proportion of F1Eucalyptus amygdalina Labill. X E. risdonii J. D. Hook, hybrid trees than either of the pure species, in a replicated field trial in south‐east Tasmania. A greater proportion of E. risdonii trees was also damaged than E. amygdalina trees. A study of the pattern of oviposition within the trial revealed no difference in oviposition by G. scutellatus between E. risdonii and E. amygdalina. Oviposition by G. scutellatus was significantly higher on the F1 and F2interspecific hybrids between these two eucalypt species compared with pure species crosses. There were no apparent differences in damage or oviposition levels between the F1 hybrids and the single large F2 progeny included in the trial. This finding provides little evidence that hybrid susceptibility is due to hybrid breakdown after the first generation. Rather, the evidence is consistent with the hypothesis that there may be different mechanisms of host defence operating in each species that are somehow diluted below a threshold level in the hybrids.
Increased death of new leaves of coastal banksia (Banksia integrifolia L.f) around ocean sewage outfall sites
Authors: MORRIS E. CHARLES
Published: March 2003

Abstract
Salt‐spray damage to coastal vegetation is a worldwide phenomenon. Worsening of such damage by surfactants present in sewage disposed of at sea has been observed in Europe and on trees planted around metropolitan beaches in Australia. Whether adverse impacts of sewage occur on the more widespread native vegetation around non‐metropolitan outfalls in Australia is unknown. The present study investigated the survivorship of existing leaves, and of new shoots and leaves, on Banksia integrifolia around three outfall and three non‐outfall sites in spring/summer of 1997‐1998. Survivorship of existing leaves was almost identical at outfall and non‐outfall sites. When plants initiated new shoots over the spring/summer, plants at outfall sites initiated more than plants at non‐outfall sites; but the proportion of these new shoots lost subsequently differed little between outfall and non‐outfall sites. Survivorship of newly initiated leaves on the new shoots differed between outfall and non‐outfall sites, with 65% of the new leaves on average being lost at outfall sites, and 47% being lost at non‐outfall sites by the end of summer. The probability of observing a difference of this magnitude ranged between P= 0.057 and 0.11 (February‐April 1998). This is the first report of a possible adverse impact on an Australian native plant from sewage discharged to the ocean.
Mechanisms controlling establishment of the non‐bradysporous Banksia integrifolia (Coast Banksia) in an unburnt coastal woodland
Authors: PRICE J. N. , MORGAN J. W.
Published: March 2003

Abstract
Remnant stands of the non‐bradysporous Banksia integrifolia on the Mornington Peninsula, Victoria appear to be in decline due to old age and other unknown factors. Many stands have been unburnt for >55‐100 years and there is little evidence of successful regeneration by seed. The cause(s) for this lack of recruitment are unclear. In the present study we quantified (i) seed production and germinability in four remnant forests in the region; (ii) the microsite conditions necessary for seedling emergence; and (iii) the effect of herbivore browsing on early seedling survival in order to understand this apparent recruitment failure. Despite large intra‐annual variation, no evidence was found that old forest trees do not produce viable seed. Emergence and survival of seedlings were not inhibited by the presence of groundlayer vegetation. Rather, vegetation facilitated early seedling survival by providing protection from browsing. Seedling transplants exhibited extremely high mortality (≥75%) due to browsing and summer soil desiccation and these factors appear to be major contributors to the lack of recruitment at the study site. Stand‐replacing recruitment is therefore considered to remain unlikely under the present conditions. Developing fire and/or grazing management regimes will be necessary to conserve the structural integrity of these coastal ecosystems.
Anatomical dissection: Why are we cutting it out? Dissection in undergraduate teaching
Authors: Parker Lisa M.
Published: March 2003

Anatomy teaching and, more specifically, the use of dissection in undergraduate anatomy teaching is undergoing a sea change in Australian medical schools. Until as recently as the 1970s, all medical students in Australia underwent an extensive course in dissection, taking up as much as 700 hours of curriculum time. Today, dissection is compulsory in only a minority of anatomy departments. There has been much discussion about the use of dissection in anatomy teaching, and both sides of the argument have considerable merit. Less widely discussed have been the other benefits of anatomical dissection, such as the development of surgical skills, an appreciation of whole‐body pathology, and the teaching of ethical and moral issues that are central to the development of the professional doctor. Dissection still has an important role to play in undergraduate medical education.
Host selection and performance of the giant willow aphid, Tuberolachnus salignus Gmelin – implications for pest management
Authors: Collins C. Matilda , Fellowes Mark D. E. , Sage Rufus B. , Leather Simon R.
Published: March 2003

1 The recent increase in planting of selected willow clones as energy crops for biomass production has resulted in a need to understand the relationship between commonly grown, clonally propagated genotypes and their pests.

2 For the first time, we present a study of the interactions of six willow clones and a previously unconsidered pest, the giant willow aphid Tuberolachnus salignus.

3 Tuberolachnus salignus alatae displayed no preference between the clones, but there was genetic variation in resistance between the clones; Q83 was the most resistant and led to the lowest reproductive performance in the aphid

4 Maternal effects buffered changes in aphid performance. On four tested willow clones fecundity of first generation aphids on the new host clone was intermediate to that of the second generation and that of the clone used to maintain the aphids in culture.

5 In the field, patterns of aphid infestation were highly variable between years, with the duration of attack being up to four times longer in 1999. In both years there was a significant effect of willow clone on the intensity of infestation. However, whereas Orm had the lowest intensity of infestation in the first year, Dasyclados supported a lower population level than other monitored clones in the second year.
Host resistance in defoliated pine: effects of single and mass inoculations using bark beetle‐associated blue‐stain fungi
Authors: Långström Bo , Solheim Halvor , Hellqvist Claes , Krokene Paal
Published: March 2003

1 In 1996, 7000 ha of pine forests were defoliated by the pine looper Bupalus piniaria in south‐western Sweden.

2 The susceptibility of trees of different defoliation classes (0, 30, 60, 90 and 100% defoliation) to beetle‐vectored blue‐stain fungi was tested in inoculation experiments. Forty and 120‐year‐old Scots pine trees were inoculated with ‘single’, i.e. a few inoculations of Leptographium wingfieldii and Ophiostoma minus, two blue‐stain fungi associated with the pine shoot beetle Tomicus piniperda. The young trees were also ‘mass’ inoculated with L. wingfieldii at a density of 400 inoculation points per m2 over a 60 cm stem belt.

3 Host tree symptoms indicated that only trees with 90–100% defoliation were susceptible to the mass inoculation.

4 Single inoculations did not result in any consistent differences in fungal performance between trees of different defoliation classes, regardless of inoculated species or tree age class.

5 Leptographium wingfieldii produced larger reaction zones than O. minus, and both species produced larger lesions in old than in young trees.

6 As beetle‐induced tree mortality in the study area occurred only in totally defoliated stands, mass inoculations seem to mimic beetle‐attacks fairly well, and thus seem to be a useful tool for assessing host resistance.

7 As even severely defoliated pine trees were quite resistant, host defence reactions in Scots pine seem to be less dependent on carbon allocation than predicted by carbon‐based defence hypotheses.
Potential risk of accidental introduction of Asian gypsy moth (Lymantria dispar) to Australasia: effects of climatic conditions and suitability of native plants
Authors: Matsuki M. , Kay M. , Serin J. , Floyd R. , Scott John K.
Published: March 2003

1 The potential risk of the establishment of the Asian strain of the gypsy moth (AGM) (Lymantria dispar) in New Zealand and Australia (Australasia) was assessed from a study of the insect's host range and potential distribution. In New Zealand, viable eggs of AGM have been continuously intercepted on cargo from Asia, and therefore there is a high probability of accidental introductions of AGM to Australasia.

2 We predicted potential distribution ranges of AGM based on climatic conditions. Asian gypsy moth is predicted to be able to persist in N and SE New Zealand and SE and SW Australia.

3 Using three populations of AGM and 59 species (seven families) of plant (55 from Australasia and four from elsewhere), we also conducted laboratory trials to examine the ability of AGM larvae to complete development on native plants from Australasia. Asian gypsy moth was able to complete development on 26 out of the 55 native species tested. Furthermore, larval performance on at least five species of Australian native plant was as good as on AGM's preferred host species (Quercus pubescens and Q. robur).

4 Larval performance of AGM was poor on all but one species of New Zealand native tree species (Nothofagus solandri), and therefore the risk of establishment in the indigenous forests of New Zealand is considered to be low.

5 Given the suitability of some Australian plants and the climatic suitability for the establishment of AGM, this insect should be treated as a serious quarantine threat and managed accordingly, particularly in Australia.
Natural biological control of the pine processionary moth Thaumetopoea pityocampa (Den. & Schiff.) by the Argentine ant Linepithema humile (Mayr) in Portugal
Authors: Way M. J. , Paiva M. R. , Cammell M. E.
Published: March 2003

1 Defoliation by larvae of the pine processionary moth, Thaumetopoea pityocampa, is negligible in stands of Pinus pinaster colonized by the Argentine ant Linepithema humile which preys fiercely on the young moth larvae. In contrast, such damage is widespread where pine plantations are colonized by native ants, predominantly Tapinoma nigerrimum and Lasius niger, which seemingly disregard the larvae.

2 Where L. humile‐ and native ant‐occupied sectors adjoin, there is a 20–50 m overlap in the transition area between L. humile‐ and native ant‐occupied pines. This was most evident in a > 500 ha plantation where there was severe or very severe T. pityocampa attack in native ant sectors contrasting with none in adjoining L. humile sectors.

3 Predation by L. humile is no doubt enhanced by its existence as super‐colonies over very large areas, by its foraging activity and recruitment on trees throughout the time when T. pityocampa and other prey are present, and by honeydew‐ producing Homoptera which help retain foraging L. humile workers in pine tree crowns.

4 The role of L. humile could be enhanced by cultivations that disturb the soil and restrain ground vegetation.
Cost‐effectiveness analysis of options within an Integrated Crop Management regime against great spruce bark beetle, Dendroctonus micans, Kug. (Coleoptera: Scolytidae)
Authors: O’neill M. , Evans H. F.
Published: March 2003

1 Great spruce bark beetle Dendroctonus micans (Kug.) (Coleoptera: Scolytidae) has been subject to an Integrated Crop Management (ICM) regime in Great Britain since its first discovery in 1982. The elements of the ICM approach are sanitation felling of the initial infestations, restriction on movement of potentially infested conifers to prevent spread to uninfested parts of the country and biological control through rearing and release of the specific predatory beetle Rhizophagus grandis Gyll. (Coleoptera: Rhizophagidae). Such a programme carries costs that have to be evaluated against the benefits to the ICM strategy.

2 This paper presents a cost‐effectiveness analysis of three options – (i) continue with the current policy of restriction on movement of infested timber and use of the imported predator R. grandis, (ii) do nothing (i.e. drop all attempts to reduce the spread of D. micans), or, (iii) introduce a new east–west Dendroctonus Micans Control Area (DMCA) to define the management area. Assumptions on rates of mortality and natural spread were based on research into D. micans in Britain’s spruce forests.

3 Appraisal indicated that the current policy was the most cost‐effective, even when subject to sensitivity analysis to test the limits of the assumptions included in the models. It is concluded that the current policy should remain in force.
Can Norway spruce trees be ‘vaccinated’ against attack by Ips typographus?
Authors: Christiansen Erik , Krokene Paal
Published: March 2003

1 A field experiment was carried out to test the hypothesis that treatment of Norway spruce trees with the Ips typographus‐transmitted blue‐stain fungus Ceratocystis polonica enhances tree resistance to later mass attack by this bark beetle.

2 Twenty‐five mature trees were pretreated by inoculating a non‐lethal dose of the fungus into the bark, while 18 trees served as untreated controls. Three and a half weeks after treatment a bark beetle attack was initiated by attaching dispensers with I. typographus pheromone to the tree trunks.

3 A significantly larger proportion (67%) of the control trees than of the pretreated trees (36%) were killed by the beetle attack. The result is discussed in relation to recent results regarding defence mechanisms in Norway spruce trees.
Suppression of Colorado potato beetle infestation by pheromone‐mediated augmentation of the predatory spined soldier bug, Podisus maculiventris (Say) (Heteroptera: Pentatomidae)
Authors: Aldrich J. R. , Cantelo W. W.
Published: March 2003

1 Hardware and protocols were tested to enable individual growers and insectary operators to mass‐produce predatory spined soldier bugs (SSBs), Podisus maculiventris (Say) (Heteroptera: Pentatomidae: Asopinae), for augmentative biological control. Using pheromone‐based technology, an average of 1775 female SSBs (potentially as many as 1.6 million offspring) were captured each year during 2–3 weeks in early spring.

2 Data for the first 2 years of a 3‐year project to use SSB for biological suppression of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), verified earlier research showing that augmentation of SSB (∼5 nymphs/plant) can significantly suppress CPB infestations. In the third year, wild SSBs were transferred directly from pheromone traps to mid‐plot nursery cages having a mesh size chosen to retain the adult predators but allow their offspring to escape. Pheromone dispensers were placed peripherally to promote dispersal of young predators and immigration of new wild spined soldier bug adults. Pheromone‐mediated augmentation using porous nursery cages and pheromone dispensers was less labour‐intensive than earlier methods, and resulted in significantly improved potato yield.

3 Trapping SSB adults early in the spring protects them from parasitization by tachinid flies and scelionid wasps that use the pheromone to facilitate host‐finding. The compatibility of pheromone‐mediated predator augmentation/conservation with implementation of transgenic plants, imidacloprid insecticide, and other biocontrol methods is discussed.
Host thermal biology: the key to understanding host–pathogen interactions and microbial pest control?
Authors: Blanford Simon , Thomas Matthew B.
Published: March 2003

1 The role of pathogens in insect population dynamics remains poorly understood and their performance in biological control is erratic. Here we identify that temperature and host thermal behaviour, both the active interaction with environmental temperature and solar radiation via thermoregulation and the passive interception of these factors by thermal generalists, are central to understanding host–pathogen interactions.

2 We demonstrate that pathogenicity, the latent period of infection and host recovery rate can all vary dramatically across and between seasons due to thermal biology of the host and changes in environmental temperature.

3 Such effects have not been thoroughly explored in any previous investigations but may have major implications for disease dynamics in insects and possibly in ectotherms in general, and for development of effective biopesticides.
Pathogenicity to western larch (Larix occidentalis) of two fungi, Ophiostoma pseudotsugae and Leptographium abietinum, associated with the Douglas fir beetle (Coleoptera: Scolytidae)
Authors: Neal Tiffany A. , Ross Darrell W.
Published: March 2003

1 Pole‐sized, live western larch Larix occidentalis Nutt. were mass‐inoculated with Ophiostoma pseudotsugae (Romb.) von Arx or Leptographium abietinum (Peck) Wingf., two blue‐stain fungi associated with the Douglas fir beetle Dendroctonus pseudotsugae Hopkins, to assess their pathogenicity.

2 Inoculation with O. pseudotsugae resulted in significantly greater percentages of necrotic phloem compared with L. abietinum inoculations.

3 The percentage of occluded sapwood was significantly greater after L. abietinum inoculations compared with O. pseudotsugae inoculations.

4 Within the inoculation band, all trees had more than 60% functional sapwood 4 months after treatment.

5 The results suggest that western larch can successfully limit colonization by O. pseudotsugae and L. abietinum.

6 The inability of the fungi to thrive in live western larch may be a factor in the consistent failure of Douglas fir beetle broods in this host tree species.
Differences between attractive diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), sex pheromone lures are not determinable through analysis of emissions
Authors: Mayer M. S. , Mitchell E. R.
Published: March 2003

1 Conjoint comparisons were made between trap captures of male diamondback moths, Plutella xylostella (L.), and gas chromatographic measures of sex pheromone emissions from grey and red rubber septa. The objective was to correlate trap captures with emissions.

2 Irrespective of their composition, all mixtures that were released from grey septa effected the capture of more males than the same mixtures released from red septa. There was no difference between captures by any of the mixtures when emitted from grey septa. However, when emitted from red septa, a nominal 50 : 50 ratio of (Z)‐11‐hexadecenal (Z11–16:Al) and (Z)‐11‐hexadecenyl acetate (Z11–16:Ac) effected the capture of more males than either nominal 70 : 30 or 67 : 23 ratios. Generally, the emitted ratios of Z11–16:Al and Z11–16:Ac from both types of septa were variable, ranging between 6 : 10 to about 40 : 10.

3 No statistical correlation was found between the emissions and trap captures by any single component, group or ratio of components. These results suggest that the environment substantially affects the emission of sex pheromone components from rubber septa. As a result, the demonstration of geographical biotypes of diamondback moths and other insects may be difficult.
The effects of drought upon epigeal Collembola from arable soils
Authors: Alvarez T. , Frampton G. K. , Goulson D.
Published: March 2003

1 Springtails (Hexapoda, Collembola) are usually associated with moist microhabitats. However, some species show adaptations to ecosystems subjected to periodic desiccation. This study examined the effects of short‐term drought conditions upon epigeal Collembola collected from arable fields.

2 An emergence trap was used in the laboratory to investigate collembolan activity, particularly the emergence of newly hatched juveniles from soils subjected to a simulated drought and to varied levels of simulated rainfall.

3 Addition of water to soils subjected to a 4‐month simulated drought resulted in synchronized emergence of juveniles ofSminthurinus elegans,Sminthurus viridisandBourletiella hortensis. As anhydrobiotic nymphs were not found in the soil, these juveniles are likely to have recently hatched from eggs in the soil.

4 The same species were shown to emerge when desiccated soil samples were treated with simulated heavy rainfall. No emergence occurred in soils which received no water, whilst only a few juveniles were present under a regime of the lowest monthly rainfall recorded for the area in the spring.

5 This study provides the first evidence that in northern European arable systems some epigeal Collembola can survive considerable periods of drought as eggs, emergence of which is triggered by rainfall. These findings have implications for the effects of predicted climatic changes upon collembolan populations, the recovery of collembolan communities following pesticide applications in agroecosystems, and also provide a plausible mechanism for dispersal of Collembola as wind‐blown eggs.
Attack density and breeding success of bark beetles (Coleoptera, Scolytidae) at different distances from forest‐clearcut edge
Authors: Peltonen Mikko , Heliövaara Kari
Published: March 2003

1 Attack density and breeding success of bark beetles (Coleoptera: Scolytidae) and the abundance of their predators were studied at forest‐clearcut edges in southern Finland on Norway spruce, Picea abies, bolts placed at different distances from a forest‐clearcut edge.

2 Attack densities of two species, Hylurgops palliatus and H. glabratus, increased markedly towards the forest interior. The breeding success of H. palliatus was increased with increasing distance from the stand edge. None of the recorded 10 bark beetle species was distinctly abundant near the edge, but Pityogenes chalcographus appeared to prefer this zone.

3 There were no significant differences in numbers of bark beetle predators between the forest interior and the edge. Forest‐clearcut edge had a significant effect on the desiccation of sample bolts.

4 Thus, forest edge is likely to affect the colonization behaviour and breeding success of bark beetles via host material properties.
Variability of Lycopersicon hirsutum f. typicum and possible compounds involved in its resistance to Tuta absoluta
Authors: Ecole C. C. , Picanço M. , Jham G. N. , Guedes R. N. C.
Published: March 2003

1 The resistance of Lycopersicon hirsutum f. typicum and L. esculentum to the leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was investigated in two experiments. The first experiment assessed the resistance of L. hirsutum f. typicum (accession LA 1777) to T. absoluta, the second assessed the variability of the resistance among plants of this accession.

2 It was found that L. hirsutum f. typicum was resistant to the leafminer, which showed longer larval phase, higher larval mortality, smaller numbers of large mines and greater numbers of small mines/leaf than on L. esculentum. Seven plants of the accession LA 1777 showed lower number of small mines/leaf, but their results of larval mortality and length of larval and pupal phase were similar. Twenty‐two peaks were observed in total ion chromatograms of L. hirsutum f. typicum hexane extracts of leaves subjected to a gas chromatographic‐mass spectrometric analysis (CG‐MS). However, the matches obtained between the peak spectra and the MS database were too low to justify even preliminary identification of the compounds.
Multiple host use by the egg parasitoid Trissolcus basalis (Wollaston) in a soybean agricultural system: biological control and environmental implications
Authors: Loch A. D. , Walter G. H.
Published: March 2003

1 Species of bugs (Hemiptera: Pentatomidae and other families) that are parasitized by the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) in the soybean agricultural system on the Darling Downs in south‐eastern Queensland, Australia, are reported. The degree to which eggs of each bug species are used by T. basalis is quantified, which allows assessment of the role of these alternative host species in the biological control of the green vegetable bug Nezara viridula (L.).

2 Egg masses of nine species of pentatomid bugs and one unidentified bug species were collected. Parasitism rates of egg masses of all species averaged 50–70% but were significantly lower for the more important pest species, including the green vegetable bug, than for some of the agriculturally less important species.

3 Trissolcus basalis emerged from nearly all species collected and was the major parasitoid to emerge from most species. A number of native species were parasitized heavily by T. basalis and parasitism of such species may enhance biological control of the green vegetable bug, but may also pose environmental concerns. Parasitism of predatory bugs by T. basalis may have a negative impact on the biological control of other pests, especially lepidopterous pests.

4 Although the impact of T. basalis on native and predatory host species was not directly quantified, these host species remain abundant and therefore do not appear to be affected adversely by such high rates of parasitism.
Spatio‐temporal dynamics of willow beetle (Phratora vulgatissima) in short‐rotation coppice willows grown as monocultures or a genetically diverse mixture
Authors: Peacock L. , Herrick S. , Brain P.
Published: March 2003

1 Phratora vulgatissima (Chrysomelidae) is the major pest of short‐rotation coppice willows in the U.K., capable of causing severe defoliation in monoculture plantations. As this beetle shows feeding preferences between willow clones, knowledge of the spatio‐temporal dynamics of P. vulgatissima is needed in order to assess the effects of mixed clonal plantings on the management of this pest.

2 Distribution patterns of adult P. vulgatissima were monitored over a season at a spatial scale of every tree or every other tree in single clone plantings (monocultures) of three willow clones and in a regular row mixture of these clones.

3 Distribution indices (deviation from Complete Spatial Randomness) demonstrated that P. vulgatissima adults were spatially aggregated on favourable clones in the monocultures and the mixture. The degree of aggregation (measured by the k‐parameter of the negative binomial) differed between willow clones. Beetles were highly aggregated at the start of the season, but less so later.

4 Dispersal studies of P. vulgatissima adults over time showed a pattern of beetle infestation along rows of the preferred clones in a regularly structured mixture. In the monocultures, movement was less directional.

5 Plantation design offers some potential for more effective non‐chemical pest management for P. vulgatissima. Monitoring of the pest must take account of our findings that adults occur in mobile aggregations.
Thermal ecology of Zonocerus variegatus and its effects on biocontrol using pathogens
Authors: Blanford Simon , Thomas Matthew B. , Langewald Jürgen
Published: March 2003

1 Thermal behaviour of the variegated grasshopper, Zonocerus variegatus, was investigated in the humid tropical zone of southern Benin, west Africa, in the dry seasons of 1996 and 1998. In 1998, investigations included studies of a population of grasshoppers sprayed with an oil‐based formulation of the entomopathogenic fungus Metarhizium anisopliae var acridum.

2 Body temperature measurements and observations of thermal behaviour both in the field and on thermal gradients in the laboratory, suggest that Z. variegatus was not an active behavioural thermoregulator. Although it did show shade‐seeking behaviour at high temperatures, no overt behavioural postures or microhabitat selection associated with heat gain and elevation of body temperatures was observed. Moreover, no alterations to thermal behaviour were found in response to infection by Metarhizium.

3 Body temperatures exhibited by Z. variegatus in the field will lengthen disease incubation of M. anisopliae var acridum compared with laboratory maintained, constant temperature conditions and may have a significant impact on pathogens with a lower thermal tolerance.

4 Habitat structure appeared to be an important factor determining the extent of body temperature elevation. The effect of habitat differences on infection and growth of M. anisopliae var acridum and other entomopathogenic fungi is discussed.
Horizontal transmission of Beauveria bassiana (Bals.) Vuill
Authors: Long David W. , Groden Eleanor , Drummond Francis A.
Published: March 2003

1 Factors influencing horizontal transmission of the entomopathogen Beauveria bassiana in the Colorado potato beetle (CPB) were examined through a series of laboratory studies.

2 Cadaver density, cadaver life stage, ambient temperature and conidial density were the factors manipulated.

3 Mortality and sporulation of burrowing CPB prepupae both increased significantly with increased sporulating second‐instar cadaver density on the soil surface.

4 Mortality rates were significantly higher when prepupae were released into laboratory arenas containing third‐instar cadavers compared to second‐instar cadavers.

5 Mortality and sporulation decreased significantly as temperature increased from 15 °C to 30 °C, however, no temperature‐dependent behavioural response by prepupae could be identified as a potential cause.

6 An 86.1% decrease in conidial density per cadaver had no significant effect on mortality or sporulation of prepupae, indicating that this level of environmental degradation of cadavers may not significantly reduce the probability of horizontal transmission.
Elevated CO2 affects the interactions between aphid pests and host plant flowering
Authors: Awmack Caroline S. , Harrington Richard
Published: March 2003

1 Broad beans (Vicia faba L.) were grown at either ambient (350 μL/L) or elevated (700 μL/L) CO2. Elevated CO2 increased shoot weight by 14% and root weight by 24% compared to ambient, but did not affect flowering.

2 A single pea aphid (Acyrthosiphon pisum (Harris)) and its progeny decreased shoot and root weights by 20 and 24%, respectively, at ambient CO2 after 20 days, but did not affect flower number. At elevated CO2A. pisum decreased shoot and root weights by 27 and 34% and flower number decreased by 73%.

3 A single glasshouse and potato aphid (Aulacorthum solani (Kaltenbach)) and its progeny had no effect on the growth of bean plants after 20 days at ambient CO2. At elevated CO2, A. solani decreased shoot and root weights by 20 and 18%, and flower number by 60%.

4 The large reduction in flowering caused by aphids at elevated CO2 suggests a change in resource allocation within the plants to compensate for aphid infestation.

5 Aphid density was unaffected by elevated CO2, although there were significant effects of CO2 on the resulting population structure of both A. pisum and A solani. We suggest that at elevated CO2, aphids appear not to achieve their maximum reproductive potential and their populations are limited by the lower carrying capacity of their host plants.