bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective predation on the broad‐toothed rat, Mastacomys fuscus (Rodentia: Muridae), by the introduced red fox, Vulpes vulpes (Carnivora: Canidae), in the Snowy Mountains, Australia
Authors: Green K.
Published: March 2003

Abstract  Since 1981 there has been debate over whether foxes (Vulpes vulpes Linnaeus) selectively prey on the broad‐toothed rat (Mastacomys fuscus Thomas) relative to the bush rat (Rattus fuscipes (Waterhouse)). In the present study, three areas of the argument are examined. (i) In a study of fox diet over 3 years at both alpine and subalpine altitudes, M. fuscus outnumbered R. fuscipes in faecal remains in all seasons, in all years, and at both altitudes. Overall, M. fuscus occurred in scats five times as frequently as did R. fuscipes in the alpine zone and twice as often in the subalpine zone. (ii) Data from population studies of M. fuscus and R. fuscipes showed no evidence that M. fuscus is trap shy; neither the pattern of captures of individuals caught once, twice and so on, nor the proportion of the estimated population of each species captured during trapping sessions was significantly different. (iii) The suitable habitat for M. fuscus within the potential home ranges of foxes contributing to the subalpine fox scat collection constituted approximately 50% of the total area. However, there was no significant difference between the numbers of fox trails encountered in habitat suitable or unsuitable for M. fuscus in 19 paired transects skied in winter, indicating no preferential foraging in either habitat. Selective feeding on M. fuscus was therefore established, but how that choice is exercised was not determined.
Patch dieback of Colophospermum mopane in a dysfunctional semi‐arid African savanna
Authors: Macgregor Shaun D. , O'Connor Timothy G.
Published: March 2003

Abstract  Patch dieback occurred in an almost monospecific Colophospermum mopane (Kirk ex Benth.) Kirk ex J. Léonard woodland in the Northern Province, South Africa, following severe droughts in 1988–1989 and 1991–1992. Discrete patches of dieback and adjacent paired areas of ‘healthy’ vegetation lost an average of 87 and 13% of basal area to mortality, respectively. Whole trees mostly died on ‘dead’ plots, while single‐stem mortality prevailed on ‘live’ plots. Tree mortality decreased with increasing stem number per tree. Patch dieback did not occur on sandy soils. On fine‐textured soils, variation in soil type, topography or slope did not affect dieback. Dieback was influenced by vegetation structure, soil surface condition and soil chemistry. Intense intertree competition, shown by self‐thinning occurring prior to dieback, was a precondition for dieback. Intertree competition had heightened during the 30 years prior to dieback because of an increase in woody cover. Dieback patches had changed from functioning as sinks of water and sediment to sources of these as a result of loss of perennial herbaceous cover, decreased water retention on bared surfaces, and accelerated erosion during 50 years of livestock ranching. Vegetation had thus become increasingly drought‐prone, exacerbated in places by soils with a high sodium concentration. Dieback had occurred because the water requirements of C. mopane could no longer be met during drought years on the dysfunctional patches.
Proportionate spatial sampling and equal‐time sampling of mobile animals: A dilemma for inferring areal dependence
Authors: Mac Nally Ralph , Horrocks Gregory
Published: March 2003

Abstract   Patch or island area is one of the most frequently used variables for inference in conservation biology and biogeography, and is often used in ecological applications. Given that all of these disciplines deal with large spatial scales, exhaustive censusing is not often possible, especially when there are large numbers of patches (e.g. for replication and control purposes). Therefore, data for patches or islands are usually collected by sampling. We argue that if area is to be used as an inferential factor, then the objects under study (i.e. the patches) must be characterized on an areal basis. This necessarily means that fixed‐area sampling is inadequate (e.g. a single standard quadrat or transect set within patches irrespective of the patch area) and that some form of area‐proportionate sampling is needed (e.g. a fixed areal proportion of each patch is surveyed by random allocation of standard quadrats across each patch). However, use of area‐proportionate sampling is not usually dissociated from the increased temporal intensity of sampling that arises from using this approach. The dilemma we see is deciding how much of the area‐specificity of variables such as species richness, rare‐species indices or probabilities of occurrence of individual species is related to the area‐proportionate survey protocol and how much is due to the temporal intensity of surveys. We undertook a study in which we balanced temporal and spatial effects by increasing the time spent surveying smaller patches of vegetation to account for the area‐ratio difference. The estimated species richness of birds of the box–ironbark system of central Victoria, Australia, was found to depend strongly upon area when area‐proportionate sampling alone was performed. When time‐balancing was imposed upon area‐proportionate sampling, the differences between smaller (10‐ha) and larger (40‐ha) areas were much reduced or effectively disappeared. We show that species found in the additional surveys used to conduct the time‐balancing were significantly less abundant than species recorded in area‐proportionate sampling. This effect is probably most severe for mobile animals, but may emerge in other forms of sampling.
Multiple effects of shrubs on annual plant communities in arid lands of South Australia
Authors: Facelli José M. , Temby Amanda M.
Published: March 2003

Abstract  The presence of shrubs in arid lands creates spatial heterogeneity that affects the distribution and performance of annual plants; several possible mechanisms have been implicated. A preliminary survey in a chenopod shrubland in South Australia showed differences in the distribution of annual plants under canopies of Atriplex vesicaria and Maireana sedifolia (the two dominant shrub species) and open spaces. A series of experiments were conducted to test the potential contribution to these patterns of nutrient enrichment under shrubs, differential seed accumulation, stress reduction by the canopy, competition by shrub roots, and protection against grazing. The germinable soil seed‐bank under A. vesicaria and M. sedifolia was different from that in open spaces, but these differences can only explain a fraction of the differences observed in the growing annual plant community in different microsites. The soil under A. vesicaria had higher total nitrogen content than soil in open spaces, whereas soil under M. sedifolia had lower available phosphorus than open spaces. Although annual plant densities under A. vesicaria were higher than in open spaces, experimental removal of shrubs increased their density, suggesting that shrub canopies inhibit annual plants in this system. Surprisingly, trenching of open areas close to shrubs (severing lateral shrub roots) decreased annual plant density. We suggest that water moves laterally through shrub roots, in a process akin to a hydraulic lift, increasing water availability for the annual plants. Exclusion of vertebrate grazers had a stronger effect on annual plant biomass in open spaces than under M. sedifolia, suggesting that this shrub provides shelter against herbivory. Overall our results show that shrubs can have simultaneously facilitative and inhibitory effects on the annual plant community through different mechanisms, but more importantly that different shrub species have different effects. This is a potential mechanism allowing for species coexistence of annual plants.
Phenological patterns in monsoon rainforests in the Northern Territory, Australia
Authors: Bach Christine Susanne
Published: March 2003

Abstract  Monsoon rainforests occur as scattered patches within a landscape dominated by eucalypt savannas across the wet–dry tropics of northern Australia. This study formed part of a larger project that investigated the interactions between frugivores and monsoon rainforest patches in the Top End of the Northern Territory. Phenological patterns in a set of 12 wet monsoon forests (WMF) and four dry monsoon forests (DMF) were examined by monitoring individuals of more than 100 species over 30 months. Phenological patterns of both WMF and DMF were closely related to the strongly seasonal climate. Leaf flush occurred before the onset of the wet season in WMF, and coincided with the onset of the wet in DMF. Major flowering peaks coincided with leaf flush in both forest types. Fruiting was concentrated in the wet season in both forest types, but fruiting peaks of WMF and DMF were separated by 3–4 months. Variations in fruiting patterns among forest types, patches, seasons and groupings of plant species (based on life form and ecological positioning) provide a mosaic of food resources for frugivores. This has important implications for the conservation and maintenance of the frugivore–rainforest system in northern Australia.
Influence of woodland remnant edges on small skinks (Richmond, New South Wales)
Authors: Anderson Lyn , Burgin Shelley
Published: March 2003

Abstract  Habitat fragmentation due to clearing often results in an increase in edge areas compared with overall remnant size, but there are limited data on the influence of increased edge areas on generalist species. Therefore, the abundance of small (<55 mm) generalist scinid lizards in small woodland remnants of the Cumberland Plain (western Sydney, Australia) was compared. Using pitfall trapping and points of transect survey techniques, three species were encountered: Lampropholis guichenoti, Lampropholis delicata and Cryptoblepharus virgatus. The abundance and diversity of these skinks differed significantly between edge and core areas; fewer individuals were encountered on the edge of the remnants than in core sites. Cryptoblepharus virgatus was only observed in edge sites where L. guichenoti made up the greatest skink abundance. In contrast, L. delicata abundance was greatest at core sites. There was also a significant difference between the edge and core with respect to the size structure of the L. guichenoti population. Larger numbers of subadults were observed in the edge sites, whereas there were significantly fewer adults and juveniles in these areas. Habitat characteristics did not account for the skink distribution observed.
Response of the soil seed‐bank of Cumberland Plain Woodland to heating
Authors: HILL SARAH J. , FRENCH KRISTINE
Published: March 2003

Abstract
Soil was investigated in a Cumberland Plain Woodland community to determine the presence of a soil seed‐bank and whether species richness and abundance of plants germinating from it were affected by heating such as that experienced in a fire. Soil samples were taken from the Holsworthy Military Area, in the south‐eastern region of the Sydney Basin, New South Wales, Australia, and one of four treatments was applied; soil was heated to 80°C, 40°C, unheated or unheated with litter not removed. Sixty‐eight species, representing 26 families including 11 exotic and 57 native species germinated from the soil. Herbs and grasses dominated and were in similar proportions to those surveyed in the above‐ground vegetation, suggesting that the soil seed‐bank reflected the current structure of the vegetation, although species composition differed. Species responded differently to heating. The seeds of some species germinated when heated at a higher temperature (80°C), particularly those from the family Fabaceae, whereas other species were more common in unheated or lightly heated samples (40°C). This suggests that fire is likely to change the species composition of the above‐ground vegetation and indicates that management must ensure that species that do not germinate when heated are maintained, as well as those species that germinate following heating. A large proportion of soil seed‐bank species showed low germination rates in the trials, and 112 above‐ground species did not germinate in the soil samples. We do not understand whether species of these two sets do not produce a soil‐stored seed‐bank or whether the seed‐bank has been depleted by past practices at Holsworthy. Further research is needed.
Oviposition site selection by mosquitoes is affected by cues from conspecific larvae and anuran tadpoles
Authors: MOKANY A. , SHINE R.
Published: March 2003

Abstract
The oviposition site that a female mosquito selects will influence the fitness of her larvae. We conducted a series of artificial pond experiments to compare the oviposition responses of two species of mosquitoes with the presence of tadpoles, conspecifics and chemical cues from these organisms. The two mosquito species differ markedly in larval ecology. The larvae of one species, Culex quinquefasciatus, co‐occur with numerous freshwater organisms, including tadpoles of Linmodynastes peronii (the striped marsh frog). Larvae of the other mosquito, Ochlerotatus australis, inhabit small brackish rock ponds where the main potential competitors are tadpoles of Crinia signifera (the common eastern froglet). In field trials, females of both mosquito species oviposited significantly more often in water that contained (or had previously contained) conspecific larvae. However, these superficially similar responses were mediated via different pathways: fungicide abolished the response by C. quinquefasciatus but not by O. australis. The two mosquito species also responded differently to cues associated with syntopic tadpoles. The presence of tadpoles did not influence oviposition by C. quinquefasciatus, but O. australis oviposited less often if tadpoles were present. These interspecific differences in oviposition behaviour may be adaptive to differences in larval ecology: competition with tadpoles is likely to be more significant for O. australis than for C. quinquefasciatus. Our findings thus support the hypothesis that mosquitoes oviposit selectively to avoid potential anuran larval competitors.
Seedling mortality and damage due to non‐trophic animal interactions in a northern New Zealand forest
Authors: GILLMAN L. N. , OGDEN J.
Published: March 2003

Abstract
The importance of non‐trophic animal damage (biting and uprooting without consumption) and mortality of canopy tree seedlings were investigated in a warm temperate forest, in northern New Zealand. Two hundred seedlings 10‐30 cm in height were monitored at 4‐6‐week intervals for 2 years. Non‐trophic animal damage accounted for more seedling mortality in the first year (37.5% of all mortalities) than any other cause. Of the seedlings damaged in non‐trophic animal interactions 73% were bitten off close to the ground and left uneaten and the remainder were uprooted. In the second year all non‐trophic animal damage and mortality ceased following the control of rabbits (Oryctolagus cuniculus), suggesting that rabbits were the major cause of this damage. Total annual mortality rates (6‐8%) were low. However, measured seedling growth rates indicated an average time for seedlings to grow from 10 to 30 cm of 37 years. Therefore, in the absence of rabbit control, mortality due to non‐trophic animal interactions (3% per year) can have an important cumulative effect. Non‐trophic animal damage found in the present study before rabbits were culled (5% per year) was similar to that reported for two tropical forests, but much less than that reported for some other tropical and temperate forests.
Foraging behaviour of bird pollinators on Embothrium coccineum (Proteaceae) trees in forest fragments and pastures in southern Chile
Authors: SMITH‐RAMIREZ CECILIA , ARMESTO JUAN J.
Published: March 2003

Abstract
We investigated the effects of forest patch size on the behaviour of birds feeding on the flower nectar of the proteaceous tree Embothrium coccineum J. R. et G. Forster, which is typically restricted to forest edges in agricultural landscapes in southern Chile. We quantified reproductive parameters of trees (no. inflorescences per branch, total and open flowers per inflorescence) in forest fragments varying from 1 ha (small), to 20 ha (medium) and to >150 ha (large), and in remnant trees in pastures. Visits to flowers by nectar‐feeding birds were recorded during 30‐min observation periods, spread throughout the day during two flowering seasons, November 1992 and 1993 (n = 242 periods overall). Aggressive encounters among flower visitors were recorded in 1992. We expected less visits to trees in pastures and small forest patches because abundances of Embothrium's main pollinators, the flycatcher Elaenia albiceps and the hummingbird Sephanoides sephaniodes, decreased in smaller patches. We found, however, that pollinator visiting rates were negatively correlated with forest patch area and were highest for pasture trees. This trend was largely due a decline in the number of visits by E. albiceps, the main flower visitor, in larger patches. Hummingbird visits did not change with forest patch size. Lower visitation rates to flowering trees in larger forest fragments seemed to be a consequence of territorial defence by E. albiceps and were unrelated to differences in floral display.
Are there commonalities among audit tools used to measure carotid endarterectomy outcomes in New South Wales?
Authors: Middleton Sandy , Ward Jeanette ,   on behalf of the New South Wales Carotid Endarterectomy Audit Project Working Group
Published: March 2003

Background: To prepare for a state‐wide audit of carotid endarterectomy (CEA), we sought to ascertain pre‐existing practices and identify common process and outcome measures among audits tools used by NSW vascular surgeons.

Method: Telephone survey comprising five questions about CEA audit practices.

Results: Of 37 known vascular surgeons in NSW, all performed CEA and agreed to participate in our telephone survey (response rate 100%). All but one reported collecting CEA data (97%). Two thirds of these collected data prospectively. From those 19 surgeons (51%) who stated that they used standard tools for audit, we received five CEA‐specific tools. Process measures common to all five were: side of CEA, date of operation, sex, past history of hypertension, history of diabetes, use of shunt, use of patch. There were only three outcome measures common to all five CEA‐specific tools: postoperative transient ischaemic attack (TIA), postoperative stroke, and postoperative death. Data about outcomes beyond discharge were inconsistently collected.

Conclusions: While most vascular surgeons in NSW report collecting information about CEA outcomes, not all do so prospectively. Only three outcomes (postoperative TIA, postoperative stroke and death) were common to all tools, inviting the development and use of a comprehensive and standard tool.
Walnut development affects chemical composition and codling moth performance
Authors: Bezemer T. Martijn , Mills Nick J.
Published: March 2003

1 We investigated for early and late blooming walnut cultivars in California whether variation in nut phenology resulted in differences in nutritional quality and whether this, in turn, affected the performance of the codling moth, Cydia pomonella (L.), and the extent of nut damage.

2 Mid‐season, during the period of nut growth, nuts from the early cultivars were larger than those from the late cultivars and had higher nitrogen content in both husk and kernel tissue, while kernel phenolic content was significantly lower. No major differences were observed later in the season after nuts from all cultivars had reached their final size.

3 Throughout the season establishment of neonate larvae was highest on nuts from the early cultivars but this was only significantly so at the beginning of the third codling moth generation. During the second codling moth generation (mid season) relative growth rates of third‐instar larvae were significantly higher on early than on late cultivars. Nut damage in the field was also significantly greater on early than on late cultivars during generation 2, while no significant differences were observed during generation 3.

4 The data suggest that the variation in codling moth damage among walnut cultivars is related to bloom phenology due to the influence of nut phenology on larval performance.
Spiders (Araneae) associated with downed woody material in a deciduous forest in central Alberta, Canada
Authors: Buddle Christopher M.
Published: March 2003

1 Spiders (Araneae) were collected on and near downed woody material (DWM) in aPopulus‐dominated forest to determine if spiders utilize wood surfaces, and to ascertain the importance of DWM habitat and wood elevation for spider assemblages.

2 Over 10 000 spiders representing 100 species were collected. Although more spiders were collected on the forest floor, spider diversity was higher in traps located on wood surfaces than on the forest floor, and 11 species were collected more frequently on wood surfaces.

3 Spiders utilized DWM at different stages in their development. FemalePardosa mackenziana(Keyserling) (Lycosidae) carrying egg sacs were caught most often on the surface of DWM, possibly to sun their egg sacs. Additionally, the proportion of immature spiders was higher on the wood surface than on the forest floor.

4 Spiders collected on logs with and without bark were compared to assemblages collected on telephone poles to assess what features of DWM habitat may be important. Web‐building species were seldom collected on telephone poles, suggesting that they depend on the greater habitat complexity provided by DWM. In contrast, hunting spiders did not distinguish between telephone poles and logs.

5 Fewer spiders and a less diverse fauna utilized elevated compared to ground‐level wood. Additionally, Detrended Correspondence Analysis revealed that the spider community from elevated wood was distinguishable from the spider community from ground‐level wood, and from the forest floor spider community.
The history and control of the pine beauty moth, Panolis flammea (D. & S.) (Lepidoptera: Noctuidae), in Scotland from 1976 to 2000
Authors: Hicks B. J. , Barbour D. A. , Evans H. F. , Heritage S. , Leather S. R. , Milne R. , Watt A. D.
Published: March 2003

1 The pine beauty moth, Panolis flammea, has been a serious pest of lodgepole pine plantations in Scotland since 1976. It historically feeds on native Scots pine throughout Europe but population levels of P. flammea on this host have never been high enough to cause tree mortality in the U.K.

2 This paper reviews recent advances in the biology of the pest and documents control programmes from 1976 to 1999.

3 There has been practically uninterrupted population monitoring of P. flammea from 1977 to the present day in Scottish lodgepole pine plantations. Intervention with chemical spraying has often been necessary.

4 The population data suggest that populations of P. flammea may have had a cyclic pattern over the monitoring period, with outbreaks occurring at regular intervals of between 6 and 7 years.

5 The amplitude of population cycles was large during the 1970s and 1980s, but has dampened in recent years. Natural enemies are believed to contribute to this trend. Fungal disease, specifically, appears to have had a greater effect on pest populations in recent years than in the past and is suggested to have contributed significantly to the population dynamics observed since 1990.
Interaction between relative humidity and resistance to Dasineura tetensi in blackcurrant
Authors: Hellqvist Sven
Published: March 2003

1 Infestation by the blackcurrant leaf midge Dasineura tetensi and galling incidence on a susceptible (cv. ‘Öjebyn’) and a moderately resistant (cv. ‘Storklas’) blackcurrant genotype was studied in the field for two midge generations in the same growing season. On the resistant genotype gall initiation is delayed.

2 The relation between infestation and galling incidence showed considerable variation between the two generations. Galling symptoms produced by the second midge generation were weak on the resistant as compared with the susceptible blackcurrant.

3 Because larval development of that generation coincided with a period of dry and warm weather, it is possible that larvae on the resistant genotype suffered desiccation to a greater extent than larvae on the susceptible genotype where gall development was stronger.

4 The possible interaction of relative humidity and expression of resistance was investigated in controlled environment experiments. The resistant ‘Storklas’ and a susceptible (‘7801–31’) currant genotype were studied at two constant relative humidities, 30 and 70%.

5 Larvae of D. tetensi suffered from higher mortality and reduced growth rate on both genotypes in the low humidity environment.

6 There was also a significant plant genotype by humidity interaction on larval performance; no galls were produced and no larvae completed development on the resistant currant at low humidity.

7 There was a trend for a positive correlation between larval length and larval density on a plant at low humidity but not at high humidity.
Interactions between green spruce aphid (Elatobium abietinum (Walker)) and Norway and Sitka spruce under high and low nutrient conditions
Authors: Straw N. A. , Green G.
Published: March 2003

1 Green spruce aphid (Elatobium abietinum) is a serious pest of spruce (Picea spp.) in north‐west Europe, causing defoliation of one‐year‐old and older needles.

2 Relationships between population development of E. abietinum, needle loss and tree growth were compared for five pure genotypes of Sitka spruce and mixed‐genotype material of Sitka and Norway spruce, grown under high and low nutrient conditions.

3 Despite wide differences in flushing date between spruce genotypes, E. abietinum populations peaked on the same date on each genotype and on the mixed‐genotype material, irrespective of nutrient supply.

4 Larger aphid populations developed on trees grown under high nutrient conditions than under low nutrients. However, more needles were lost per aphid in the low nutrient treatment and overall defoliation rates in the two nutrient treatments were similar.

5 Total aphid numbers differed significantly between Sitka spruce genotypes within nutrient treatments, but not in relation to bud‐burst or needle terpene content. Reductions in height growth caused by infestation were greater (15–44%), and related to mean aphid densities and defoliation, in the low nutrient treatment, but were smaller (11–27%) and not related to aphid density and defoliation in the high nutrient treatment.

6 Development of E. abietinum populations was similar on Norway and Sitka spruce, but Norway spruce lost fewer needles. However, the effects of infestation on tree growth were more closely related to aphid density and were similar for Norway and Sitka spruce.

7 Infestation caused a decrease in total root dry weight of Norway and Sitka spruce in proportion to the reductions observed in above‐ground growth.
Diet‐dependent fecundity of the spidersAtypena formosanaandPardosa pseudoannulata, predators in irrigated rice
Authors: Sigsgaard Lene , Toft Søren , Villareal Sylvia
Published: March 2003

1 The fecundity of the spidersAtypena formosanaandPardosa pseudoannulatawas assessed on diets of brown planthopperNilaparvata lugens(BPH), green leafhopperNephotettix virescens(GLH), Collembola (Entomobryidae),Droso phila melanogasterand three prey mixtures; BPH–GLH, BPH–GLH–Collembola and a full mixed diet of BPH–GLH–Collembola–D. melanogaster.

2 Egg production and hatching success was high inA. formosanaexcept on the BPH, the GLH and the BPH–GLH diets. InP. pseudoannulataegg production and hatching success was lowest on diets of GLH and BPH–GLH, whereas this spider used BPH better.

3 Differences between offspring sizes were small.

4 Survival ofA. formosanafemales was lowest on the GLH and BPH–GLH diets. InP. pseudoannulatasurvival did not differ significantly.

5 Food conversion efficiency was highest on the Collembola and theD. melanogasterdiets for both spiders.

6 Overall, diets of Collembola andD. melanogasterhad the highest quality for both spiders, the BPH–GLH–Collembola and the full mixed diets were intermediate in quality, the quality of the BPH diet was intermediate to low and quality of the GLH and BPH–GLH diets was low.

7 There need not be a contradiction between low dietary value of hoppers and successful natural biological control provided that the nutritional needs of the spiders are met by sufficient alternative prey.

8 The hopper‐spider relationship is comparable to that of aphids and spiders in temperate cereals, suggesting that low dietary quality of Homopterans to spiders may be widespread.
Interactions between the willow beetle Phratora vulgatissima and different genotypes of Salix viminalis
Authors: Peacock L. , Herrick S. , Harris J.
Published: March 2003

Abstract 1 Planting of species mixtures is a strategy for the non‐chemical management of willow beetles in short‐rotation coppice willows. However, the relatively susceptible Salix viminalis genotypes and their hybrids dominate current high‐yielding willows. Interactions between Phratora vulgatissima and different genotypes of S. viminalis were examined under laboratory conditions to determine if these genotypes exhibit genetic differences in susceptibility to willow beetle damage.

2 Seven S. viminalis genotypes and four hybrids were tested for the feeding preference of adult P. vulgatissima, larval performance and within‐season plant response to manual defoliation (50% and 75%).

3 The feeding preference of adult beetles, the growth rate of larvae, and the weight at 33 days of larvae and pupae differed significantly between genotypes. Genotypes also differed significantly in their height and weight responses to mechanical defoliation. Two genotypes were taller, with longer internodes, after defoliation than were undamaged plants. Two hybrids and their S. viminalis parent showed no significant reduction in final dry weight between 0% and 50% defoliation treatments.

4 Susceptibility of genotypes to adult feeding was not correlated with their tolerance to defoliation in terms of weight or height responses; however, larval growth rate on genotypes was negatively correlated both with final height and number of leaves after 75% defoliation and with the susceptibility of genotype to adult feeding.

5 Salix viminalis showed genetic differences for all parameters tested. This suggests that the planting of a mixture of these genotypes would contain genetic differences with respect to host susceptibility to P. vulgatissima. Some parameters showed similarities between a hybrid and its parent, whereas others showed differences between siblings. This offers potential for effective breeding of desirable traits.
The impact of spruce aphids on nutrient flows in the canopy of Norway spruce
Authors: Stadler Bernhard , Michalzik Beate
Published: March 2003

1 This study investigated the effects of honeydew from aphids in the canopy of Norway spruce (Picea abies (L.) Karst.) on the nitrogen chemistry of throughfall using a rainfall simulation experiment. Throughfall collected beneath infested trees was compared with that from beneath uninfested trees, while standardizing the quality and quantity of the precipitation and plant age.

2 Honeydew excreted by Cinara pilicornis (Hartig) and C. costata (Zett.) significantly increased the concentrations of dissolved organic carbon (DOC) and hexose‐C in throughfall. The average concentrations of nitrogenous compounds (NH4‐N, NO3‐N) in throughfall collected beneath infested trees were significantly lower than beneath uninfested trees.

3 Multiple regression analysis indicated that the amount of rain and NH4‐N concentrations were the best predictors of the concentrations of dissolved organic nitrogen (DON) in throughfall. Parameters that were closely associated with the level of infestation (DOC, hexose‐C concentrations) did not have a direct relationship with DON. About 40% of the reduction in the concentration of DON in the throughfall was attributed to aphid–micro‐organism interactions.

4 Particle amino nitrogen (PAN)‐concentrations were highest under infested trees in July after aphid numbers had declined, indicating a concomitant decline in microbial biomass after honeydew becomes a limiting resource.

5 The comparison of the concentrations of different nitrogen compounds in throughfall of infested and uninfested trees indicated that aphids affect the carbon and nitrogen cycles in the phyllosphere by providing energy that fuels the metabolism of the micro‐organisms. These processes seem to occur very rapidly.

6 We discuss the significance of the results and the prospects of linking the ecology of micro‐organisms and herbivores with flows of nutrients through the canopy of trees.
The effect of simulated ‘wash off’ from spot‐sprays containing either Malathion or Phloxine B on ground‐dwelling arthropods in an orchard.
Authors: Thomas B. J. , Meats A.
Published: March 2003

1 Leaf‐litter samples were taken from treated patches of ground in an orchard 7 days after the application of a diluted spot‐spray mixture (simulating washed off residue). The mixture contained either 1% Phloxine B or one of two concentrations (1% or 0.1%) of Malathion; the control treatment was water.

2 Half of the replicates of each treatment were left open to immigration and emigration of the leaf litter animals in the assemblage for a week before sampling, the other half were not.

3 Malathion at either concentration altered the assemblage in the treated patches by significantly decreasing abundance and species richness. However, the latter was less affected in treatments open to invasion. Phloxine B had no detectable effect.

4 When patches of leaf litter were completely cleared and replaced with sterilized peat moss (simulating complete insecticide kill without residual effect), the peat moss was rapidly colonized by microarthropods.

Keywords Arthropods, diversity, Malathion, Phloxine B, spot sprays.
Oviposition and development of the immature stages of Tomicus minor (Coleoptera, Scolytidae)
Authors: Fernández M. M. Fernández , Alonso J. A. Pajares , Costas J. M. Salgado
Published: March 2003

1 This paper describes the construction process of the brood gallery of Tomicus minor and its total length as well as the length of each arm, the fertile part where the female lays her eggs and also, the infertile part.

>2 The presence of the parents during the process and their position in the brood gallery (arms or mating chamber) is studied and how it influences the number of eggs laid. Both the first brood galleries and those burrowed by the repenetrating females were observed.

3 The development and duration of the immature stages of the insect in the 3‐year study period, from laying to the emergence of the young beetles from the F1 generation, were also studied.
Factors affecting the relative abundance of two coexisting aphid species on sugar beet
Authors: Williams I. S. , Van Der Werf W. , Dewar A. M. , Dixon A. F. G.
Published: March 2003

1 The two most common species of aphid colonizing sugar beet Beta vulgaris L. are Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Aphis fabae Scopoli (Hemiptera: Aphididae).

2 M. persicae colonizes sugar beet earlier than A. fabae but the population of the former also declines earlier. Despite similar numbers of each species migrating at the time of colonization, M. persicae is usually less abundant on the crop than A. fabae, suggesting differences between the species in their selection of, and performance on, sugar beet.

3 The intrinsic rate of increase of both species declines as sugar beet matures, however, at any given plant age the intrinsic rate of increase of A. fabae is one and a half times greater than that of M. persicae. This results in more rapid population growth and a later decline of the population.

4 Intraspecific competition appears to result in M. persicae becoming very restless, but there is no evidence for interspecific competition between the two species on this host.

5 A population growth model which takes account of the decline in host quality of sugar beet shows that the M. persicae population peaks 30 days before that of A. fabae, and, excluding differences in emigration rate, the maximum A. fabae population is 14 times greater than the maximum M. persicae population. These results are compared to field data.
Prolonged development time of the bark beetle predator Thanasimus formicarius (Col.: Cleridae) in relation to its prey species Tomicus piniperda (L.) and Ips typographus (L.) (Col.: Scolytidae)
Authors: Schroeder L. M.
Published: March 2003

1 The generation time of the bark beetle predator Thanasimus formicarius (L.) (Col.: Cleridae) was found to be predominantly two years both in the field and in rearing experiments conducted with two of its main prey species, the pine shoot beetle Tomicus piniperda (L.) and the spruce bark beetle Ips typographus (L.) (Col.: Scolytidae).

2 Emergence of T. formicarius adults in the first summer was only observed in one of the two rearing experiments, and these individuals represented only 6% of that generation.

3 All individuals not emerging as adults in the first summer remained as larvae in their pupal chambers until the second summer. Pupae were found starting around mid‐June, and adults (in pupal chambers) were found from late July through to the end of August.

4 Newly emerged adults had to feed in order to survive hibernation.

5 The existence of T. formicarius races, specialized on certain bark beetle species and with phenologies matching their hosts, could not be demonstrated. After hibernation there was no difference in feeding activity, timing of egg‐laying or proportion of egg‐laying females between the T. formicarius adults reared as larvae on T. piniperda (flight period in April) and those reared as larvae on I. typographus (main flight period generally starting in late May or early June) when exposed to a temperature and day‐length typical of the early spring conditions prevailing during the flight period of T. piniperda.

6 T. formicarius was parasitized by Enclisis vindex (Tschek) (Hym.: Ichneumonidae) in the pupal chamber.

7 The importance of these findings for the population dynamics of bark beetles is discussed.
Modelling herbivore movement and colonization: pest management potential of intercropping and trap cropping
Authors: Banks John E. , Ekbom Barbara
Published: March 2003

1 Using a stochastic simulation model, we explored the effects of agroecosystem diversity on herbivore densities.

2 Using parameters that included reproduction, colonization, and local movement rates, we simulated an insect herbivore population colonizing rows of plants in an agricultural setting.

3 Plant rows were comprised of either principal crop, intercrop, or trap crop. Herbivore parameters varied for different plant types.

4 Percent crop cover and movement rates were varied, and ensuing herbivore densities on crop rows were recorded.

5 In trap cropping schemes, both percent crop cover and movement rates were critical in determining herbivore densities. Intercropping schemes were governed primarily by colonization rates.

6 These results suggest that trap cropping schemes merit more attention than intercropping systems in the design and analysis of mixed cropping systems.
Influence of insecticide, wax and biofungicide treatments, applied to Pinus sylvestris and Picea abies, on the olfactory orientation of the large pine weevil, Hylobius abietis L. (Coleoptera: Curculionidae)
Authors: Watson Paul G.
Published: March 2003

1 A four‐arm olfactometer was used to test the effect of permethrin ‘Gori 920®’ and the wax treatment ‘CereNat® E30’ on the response of mature adult Hylobius abietis to olfactory stimuli from seedlings of Pinus sylvestris and Picea abies.

2 Also investigated in the olfactometer was the effect of Rotstop®, a biofungicide for the control of Fomes root and butt rot, Heterobasidion annosum, on the responses of mature adult female H. abietis to stump material of both P. sylvestris and P. abies.

3 Hylobius abietis was significantly more attracted to untreated P. sylvestris seedlings compared to those treated with CereNat® E30 or permethrin Gori 920®. No differences in response to P. abies seedlings were found.

4 With Rotstop®, no changes in the attractiveness of P. sylvestris stump material were found, but that of P. abies was significantly increased compared to untreated material.
Behavioural switch of female Mediterranean fruit fly, Ceratitis capitata: mating and oviposition activity in outdoor field cages in Hawaii
Authors: Jang Eric B. , McInnis Donald O. , Kurashima Rick , Carvalho Lori A.
Published: March 2003

1 Laboratory‐reared normal, and wild female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were assayed in outdoor field cages to assess the impact of a mating‐induced behavioural switch on mating and subsequent oviposition activity.

2 Virgin females preferred interactions with males leading to mating over attraction to, and oviposition in, artificial yellow spheres containing guava odour or green apples hung in a guava tree. Laboratory‐reared females previously mated with either laboratory‐reared normal males or laboratory‐reared irradiated (sterile) males showed little interest in remating with males and instead, were much more likely to be found arrested on artificial and real fruit and ovipositing. Oviposition on artificial fruit was five times greater by females that had mated with either normal or irradiated males than by virgin females. Wild females showed similar qualitative changes in the mating‐induced behavioural switch; however, oviposition activity was significantly less than for laboratory‐reared females.

3 These results confirm that mating has a profound effect on the behaviour of female Mediterranean fruit flies and that irradiated males are functionally equal with normal males (lab‐reared or wild) in their ability to alter female behaviour. These results are discussed in the context of the sterile insect technique for control of Mediterranean fruit flies in the field.
Dynamics of the predatory arthropod community in Spanish olive groves
Authors: Morris T. I. , Campos M. , Kidd N. A. C. , Jervis M. A. , Symondson W. O. C.
Published: March 2003

1 A survey of the predatory fauna of olive pests, particularly the olive moth, Prays oleae, was undertaken in Granada, Spain, from May to September 1994–95.

2 At both experimental sites similar patterns of emergence were observed for all predatory species with peaks occurring in June, both in 1994 and 1995. More individuals and species were captured in the morning than in the evening.

3 A weak inverse relationship existed between the mean monthly temperatures and the total number of predators caught.

4 The number of predatory species and of individuals caught at both sites was, respectively, two and three times larger in 1994 than in 1995; This difference is assumed to have been due to the accumulated affect of 6 years of drought.

5 Synchrony between P. oleae and predator phenology was suggested by the coincidental timing of peak predator numbers with the oviposition and subsequent emergence of the most vulnerable stage of the olive moth’s lifecycle, i.e. the flower generation.

6 There were more individuals of ants caught, whilst more spider species were captured than all other groups; predatory Coleoptera and Heteroptera were poorly represented.

7 Ants appeared to have a detrimental affect on the number of all other predators.
Parasitoid assemblages of soybean defoliator Lepidoptera in north‐western Buenos Aires province, Argentina
Authors: Luna María G. , Sánchez Norma E.
Published: March 2003

1 The objective of this study was to examine the structure of parasitoid assemblages attacking soybean defoliator Lepidoptera in north‐western Buenos Aires province, Argentina.

2 Through larvae sampling from 1992 to 1996, and laboratory data plus the known biology of the species recorded during the study, parasitoid species composition, richness, number of guilds per host species, and levels of parasitism, were determined.

3 Total species richness was 23, all species were primary endoparasitoids, and categorized askoinobionts. They belonged to Hymenoptera (11 species) and Diptera (12 species).Rachiplusia nu(Noctuidae) hosted the highest number of parasitoid species.

4 Four parasitoid guilds were recorded forR. nu(egg–prepupal endoparasitoid, early larval endoparasitoid, late larval endoparasitoid, and larval–pupal endoparasitoid); two forSpilosoma virginica(Arctiidae) (late larval endoparasitoid and larval–pupal endoparasitoid) andColias lesbia(Pieridae) (early larval endoparasitoid and larval–pupal endoparasitoid); and one forAnticarsia gemmatalis(Noctuidae) andLoxostege biffidalis(Pyralidae) (early larval endoparasitoid).

5 Only four out of seven potential parasitoid guilds defined for Lepidoptera were recorded in a soybean agroecosystem located in north‐western Buenos Aires province, suggesting that potential host niches were not totally utilized.

6 Soybean lepidopteran defoliators supported a mean species richness of 4.8 parasitoids, a result that is similar to that reported for exophytic hosts in the Neotropics.

7 Parasitoid assemblages from each host differed in species composition, richness, number of guilds, and levels of parasitism.
Comparison of pome fruit orchard inhabiting spider assemblages at different geographical scales
Authors: Bogya S. , Markó V. , Szinetár CS.
Published: March 2003

1 The composition of pome fruit orchard inhabiting spider assemblages was investigated at different geographical scales (Holarctic, European, inter‐ and intraregional levels within Hungary) using previous faunistic studies and data collected in Hungary between 1995 and 1997. Samples in Hungary were taken from the canopy and herb layer of apple and pear orchards in five markedly different fruit‐growing regions by beating and sweep‐netting methods.

2 The composition of canopy spider assemblages of apple orchards was analysed for the Holartic region and found to be determined by latitude at family level, and by the main zoogoegraphical regions at genus level. At the European scale, both the genus and species composition changed along a north–south gradient.

3 A comparison among apple and pear orchards located in different regions in Hungary, showed that both foliage‐ and grass‐dwelling spider assemblages varied considerably in species composition and dominance order.

4 Within the same region, both the foliage‐ and grass‐dwelling spider assemblages showed moderate differences in apple and pear orchards submitted to different treatments. Although the assemblages of spiders inhabiting the canopy and the herbaceous layer can be unambiguously distinguished, some overlap still occurs.

5 We conclude that the composition of spider assemblages is basically determined by geographical location. Although both pesticide treatments and available prey densities can influence the population of spiders, such factors are of moderate importance when compared with the effect of regionality, even when considered at smaller scale. However, most members of the family Theridiidae and the large orb‐weavers (Araneidae) decreased considerably in treated plots. Scale‐specific differences are thus relevant in determining the composition of prey–predator systems in orchards, and should be taken into account when designing integrated pest management (IPM) programs for apple and pear orchards.