Temporal variation in arthropod sampling effectiveness: The case for using the beat sheet method in cotton

Predatory insects and spiders are key elements of integrated pest management (IPM) programmes in agricultural crops such as cotton. Management decisions in IPM programmes should to be based on a reliable and efficient method for counting both predators and pests. Knowledge of the temporal constraints that influence sampling is required because arthropod abundance estimates are likely to vary over a growing season and within a day. Few studies have adequately quantified this effect using the beat sheet, a potentially important sampling method. We compared the commonly used methods of suction and visual sampling to the beat sheet, with reference to an absolute cage clamp method for determining the abundance of various arthropod taxa over 5 weeks. There were significantly more entomophagous arthropods recorded using the beat sheet and cage clamp methods than by using suction or visual sampling, and these differences were more pronounced as the plants grew. In a second trial, relative estimates of entomophagous and phytophagous arthropod abundance were made using beat sheet samples collected over a day. Beat sheet estimates of the abundance of only eight of the 43 taxa examined were found to vary significantly over a day. Beat sheet sampling is recommended in further studies of arthropod abundance in cotton, but researchers and pest management advisors should bear in mind the time of season and time of day effects.

Spatial and temporal variation and effects of changes in management in discard rates from the commercial reef line fishery of the Great Barrier Reef, Australia

Discarding in commercially exploited fisheries has received considerable attention in the last decade, though only more recently in Australia. The Reef Line fishery (RLF) of the Great Barrier Reef (GBR) in Australia is a large-scale multi-sector, multi-species, highly regulated hook and line fishery with the potential for high levels of discarding. We used a range of data sources to estimate discard rates and discard quantities for the two main target groups of the RLF, the coral trout, Plectropomus spp, and the red throat emperor, Lethrinus miniatus, and investigated possible effects on discarding of recent changes in management of the fishery. Fleet-wide estimates of total annual quantities discarded from 1989 to 2003 were 292-622 t and 33-95 t for coral trout and red throat emperor, respectively. Hypothetical scenarios of high-grading after the introduction of a total allowable commercial catch for coral trout resulted in increases in discard quantities up to 3895 t, while no high-grading still meant 421 t were discarded. Increasing the minimum size limit of red throat emperor from 35 to 38 cm also increased discards to an estimated 103 t. We provide spatially and temporally explicit estimates of discarding for the two most important species in the GBR RLF of Australia to demonstrate the importance of accounting for regional variation in quantification of discarding. Effects of management changes on discarding are also highlighted. This study provides a template for exploring discarding levels for other species in the RLF and elsewhere.

Spatial and temporal patterns of feral pig diggings in rainforests of north Queensland

Feral pigs (Sus scrofa) are believed to have a severe negative impact on the ecological values of tropical rainforests in north Queensland, Australia. Most perceptions of the environmental impacts of feral pigs focus on their disturbance of the soil or surface material (diggings). Spatial and temporal patterns of feral pig diggings were identified in this study: most diggings occurred in the early dry season and predominantly in moist soil (swamp and creek) microhabitats, with only minimal pig diggings found elsewhere through the general forest floor. The overall mean daily pig diggings were 0.09% of the rainforest floor. Most diggings occurred 3-4 months after the month of maximum rainfall. Most pig diggings were recorded in highland swamps, with over 80% of the swamp areas dug by pigs at some time during the 18-month study period. These results suggest that management of feral pig impacts should focus on protecting swamp and creek microhabitats in the rainforest, which are preferred by pigs for digging and which have a high environmental significance.

Temporal acuity in developmental dyslexia across the life span : Tactile, auditory, visual, and crossmodal estimations

Taustaa Kehityksellinen dysleksia (lukivaikeus) on erityinen lukemaan oppimisen vaikeus, johon liittyy usein myös vaikeuksia kirjoittamaan oppimisessa. Lukivaikeuden oletetaan useissa tapauksissa johtuvan vaikeudesta käsitellä kielen äännerakenteita (fonologinen prosessointi). Tämä poikkeavuus voi olla joko lukivaikeuden perimmäinen syy tai vaihtoehtoisesti ongelmat äänteiden käsittelyssä voivat heijastaa jotain vielä perustavamman tason vaikeutta. Eräs tällainen ehdotettu perustavan tasoin syy on poikkeavuus aistien toiminnoissa, erityisesti aistien aikatarkkuudessa. Aikatarkkuudella tarkoitetaan kykyä ja rajoja siinä, kuinka nopeasti esitettyä aistitiedon virtaa henkilö kykenee vastaanottamaan ja käsittelemään. Monet arjen toiminnot lukemisen rinnalla edellyttävät aistien erittäin tarkkaa ajallista erottelukykyä (esimerkiksi kuulo puheen ymmärtämisessä, tunto pintamateriaalin tunnistamisessa). Aikatarkkuusvaikeuksien esiintyvyyttä lukivaikeudessa on tutkittu aiemminkin, mutta yksimielisyyteen ei ole päästy siitä, onko kaikilla lukivaikeuksisilla näitä ongelmia tai mihin aisteihin vaikeudet mahdollisesti rajoittuvat. Myöskään ei tiedetä, havaitaanko aikatarkkuuden ongelmia kaiken ikäisillä lukivaikeuksisilla vai vaihteleeko mahdollinen ongelmien kuva iän mukana. Lisäksi on epäselvää, kuinka aikatarkkuuden ongelmat itseasiassa ovat yhteydessä kielen käsittelyn ja varsinaisen lukemisen vaikeuksiin. Tutkimussarjan aihe Tässä tutkimussarjassa aikatarkkuutta tutkittiin kolmessa yksittäisessä aistissa, joita olivat tunto, näkö ja kuulo, sekä kolmessa aistien välisessä yhdistelmässä, joita olivat audiotaktiilinen (kuulo-tunto), visuotaktiilinen (näkö-tunto) ja audiovisuaalinen (näkö-kuulo). Aikatarkkuutta arvioitiin kahdella eri menetelmällä, jotta saataisiin lisää tietoa siitä, missä tietyssä aikatarkkuuden osa-alueessa lukivaikeuksisilla mahdollisesti on vaikeuksia. Ensimmäisessä tehtävässä tutkittavan tuli arvioida, ovatko esitetyt ei-kielelliset ärsykkeet samanaikaisia vai eriaikaisia. Toisessa tehtävässä koehenkilön tuli arvioida esitettyjen ei-kielellisten ärsykkeiden esitysjärjestys. Molemmissa tehtävissä määriteltiin millisekuntitasolla (sekunnin tuhannesosa) se esitysnopeus, jolla koehenkilö kykeni arvioimaan ärsykkeiden ajalliset suhteet oikein. Englanninkielinen demonstraatio aikatarkkuustehtävistä löytyy internetistä (http://www.helsinki.fi/hum/ylpsy/neuropsy). Itse aikatarkkuustehtävien lisäksi tutkimussarjassa arvioitiin tutkimushenkilöiden päättelykykyä, kielellisiä toimintoja ja lukemista. Tutkimushenkilöt Tutkimuksiin osallistui 53 lukivaikeuksista ja 66 sujuvaa lukijaa, jotka oli jaettu kolmeen pääikäryhmään: lapset (8-12 vuotta), nuoret aikuiset (20-36 vuotta) ja ikääntyneemmät aikuiset (20-59 vuotta). Ikääntyneempien aikuisten ryhmä oli edelleen jaettu ikävuosikymmenluokkiin, mikä mahdollisti sen tutkimisen, vaikuttaako lisääntyvä aikuisikä lukivaikeuksisten aikatarkkuuteen (20-29, 30-39, 40-49 ja 50-59 -vuotiaat). Tutkimussarjan tulokset Aikatarkkuuden ongelmat lukivaikeuksisilla olivat yleistyneitä yli iän, aistien ja tehtävien Lukivaikeuksiset kaikissa pääikäryhmissä (lapset, nuoret aikuiset, ikääntyneemmän aikuiset) tarvitsivat samanikäisiä sujuvia lukijoita hitaamman esitystahdin, jotta he kykenivät arvioimaan ei-kielellisten ärsykkeiden ajallisen esitystavan oikein. Tämä aikatarkkuuden ongelma havaittiin lukivaikeuksisilla kaikissa aisteissa (tunto, kuulo, näkö) ja niiden yhdistelmissä (audiotaktiilinen, visuotaktiilinen, audiovisuaalinen). Lukivaikeuksisten aikatarkkuusongelmat ilmenivät edelleen molemmissa tehtävätyypeissä (samanaikaisuuden ja järjestyksen arvioinnissa). Aikatarkkuus ja sen ongelmat olivat yhteydessä äänteiden käsittelyyn Aikatarkkuus oli yhteydessä äänteiden käsittelykykyyn (fonologiseen prosessointiin), niin lapsilla kuin aikuisillakin, kaikissa aisteissa, niiden yhdistelmissä ja tehtävätyypeissä. Yhteys ei-kielellisen aikatarkkuuden ja kielellisten toimintojen välillä oli kuitenkin selkeämpi lukivaikeuksisilla kuin sujuvilla lukijoilla. Tämä tarkoittaa, että etenkin lukivaikeuksisilla ryhmätason huono aikatarkkuus oli yhteydessä huonoon äänteiden käsittelyyn (fonologiseen prosessointiin) ja päinvastoin. Suoraa yhteyttä lukemisen ja aikatarkkuuden välillä ei kuitenkaan havaittu. Lisääntyvä aikuisikä heikensi lukivaikeuksisten aikatarkkuutta suhteettoman paljon Tiedonkäsittelyn nopeuden on toistuvasti osoitettu hidastuvan normaalissa ikääntymisessä. Lisääntyvä aikuisikä (20-59 -vuotiailla) heikensikin sekä sujuvien että lukivaikeuksisten aikatarkkuutta. Toisin sanoen, mitä iäkkäämmästä aikuisesta oli kysymys, sitä hitaammin hänelle tuli esittää ärsykkeet, jotta hän kykeni arvioimaan niiden ajalliset suhteet oikein. Tämä ikään liittyvä tavanomainen hidastuminen oli kuitenkin yllättäen suhteettoman nopeaa lukivaikeuksisilla. Toisin sanoen, jo nuorilla lukivaikeuksisilla havaittu aikatarkkuuden vaikeus (ryhmäero verrattuna sujuviin lukijoihin) ei pysynyt saman suuruisena, vaan ryhmien ero kasvoi aikuisiän lisääntyessä. Tulosten merkitys Lukivaikeuden osoitettiin tässä tutkimussarjassa olevan yhteydessä yleistyneeseen vaikeuteen käsitellä ajassa nopeasti muuttuvaa ei-kielellistä aistitietoa (yli aistien ja niiden yhdistelmien, tehtävätyyppien, tutkittavien iän). Tämä osoittaa, että lukivaikeus ei ole ongelma, joka rajoittuu vain kielellisen materiaalin käsittelyn vaikeuksiin (äänteiden käsittely, lukeminen, kirjoittaminen). Nyt havaitut vaikeudet eivät myöskään rajoittuneet vain niihin aisteihin, jotka selkeimmin liittyvät lukemiseen (näkö) ja puhuttuun kieleen (kuulo); Ongelmia esiintyi myös muissa aisteissa (tunto). Lukivaikeuksisten lukijoiden ryhmätasolla havaittu aikatarkkuuden ongelma ei kuitenkaan heijastunut yksilötasolle; Jokainen lukivaikeuksinen ei ollut huono aikatarkkuustehtävissä. Näin ollen ei siis voida väittää, että kaikkien lukivaikeuksisten äänteiden käsittelyn tai lukemaan oppimisen vaikeudet voisivat selittyä aistien toimintojen poikkeavuudella. Aikatarkkuuden ongelmat eivät olleet yhteydessä varsinaiseen lukemiseen. Sekä lukivaikeuksisilla lapsilla että aikuisilla todettiin kuitenkin selkeä yhteys aikatarkkuuden ongelmien ja lukemaan oppimisen keskeisen ennakkoehdon, fonologisen prosessoinnin, välillä. Saattaa siis olla, että synnynnäinen aistien toimintojen poikkeavuus vaikuttaa yksilön suoriutumiseen jo ennen varsinaista lukemaan oppimista, kun ne taidot kehittyvät (fonologinen prosessointi), joille myöhempi lukemaan oppiminen perustuu. Ikäännyttäessä havaittu lukivaikeuksisten suhteettoman nopea aikatarkkuuden heikkeneminen osoittaa, että lukivaikeus ei voi olla ongelma, joka koskee vain lapsuusikää, tai vaikeus, joka johtuu vain kehityksen viivästymästä joka kurottaisiin iän myötä umpeen. Tulosten ymmärtämiseksi onkin muistettava kaksi seikkaa. Lukivaikeus on ensinnäkin yhdistetty synnynnäisiin, pieniin, poikkeavuuksiin aivojen rakenteissa ja toiminnoissa. Toisaalta tavanomaiseen ikääntymiseen liittyy se, että aivot kykenevät yhä huonommin korjaamaan ja kiertämään (kompensoimaan) pieniä vaurioita. Tämän perusteella tutkimussarjan tuloksista voidaan päätellä, että lukivaikeuksisten jo synnynnäisesti heikentyneet aivojen kompensointimahdollisuudet eivät ole yhtä tehokkaita puskuroimaan ikääntymisen tavanomaisia vaikutuksia kuin sujuvilla lukijoilla. Yllättävää kuitenkin on, että tämä korostunut heikkeneminen havaittiin jo suhteellisen nuorilla, työikäisillä, lukivaikeuksisilla, ennen 60 ikävuotta. Samanlaista ikäännyttäessä korostuvaa vaikeutta ei lukivaikeuksilla kuitenkaan havaittu päättelyssä, kielellisissä toiminnoissa tai itse lukemisessa. Vaikuttaakin siis siltä, että ne toiminnot, joita on harjaannutettu aktiivisesti, eivät heikkene kasvavan aikuisiän myötä yhtä suhteettomasti. Alkuperäiset artikkelit Laasonen M, Tomma-Halme J, Lahti-Nuuttila P, Service E, and Virsu V (2000) Rate of information segregation in developmentally dyslexic children, Brain and Language, 75(1), 66-81. Laasonen M, Service E, and Virsu V (2001) Temporal order and processing acuity of visual, auditory, and tactile perception in developmentally dyslexic young adults, Cognitive, Affective, and Behavioral Neuroscience, 1(4), 394-410. Laasonen M, Service E, and Virsu V (2002) Crossmodal temporal order and processing acuity in developmentally dyslexic young adults, Brain and Language, 80(3), 340-354. Laasonen M, Lahti-Nuuttila P, and Virsu V (2002) Developmentally impaired processing speed decreases more than normally with age, NeuroReport, 13(9), 1111-1113.

Temporal patterns in incidence and abundance of Aconophora compressa (Hemiptera: Membracidae), a biological control agent for Lantana camara, on target and nontarget plants

The membracid Aconophora compressa Walker, a biological control agent released in 1995 to control Lantana camara (Verbenaceae) in Australia, has since been collected on several nontarget plant species. Our survey suggests that sustained populations of A. compressa are found only on the introduced nontarget ornamental Citharexylum spinosum (Verbenaceae) and the target weed L. camara. It is found on other nontarget plant species only when populations on C. spinosum and L. camara are high, suggesting that the presence of populations on nontarget species may be a spill-over effect. Some of the incidence and abundance on nontarget plants could have been anticipated from host specificity studies done on this agent before release, whereas others could not. This raises important issues about predicting risks posed by weed biological control agents and the need for long-term postintroduction monitoring on nontarget species.

Using harvest statistics to monitor temporal variation in kangaroo density and harvest rate

Management of the commercial harvest of kangaroos relies on quotas set annually as a proportion of regular estimates of population size. Surveys to generate these estimates are expensive and, in the larger states, logistically difficult; a cheaper alternative is desirable. Rainfall is a disappointingly poor predictor of kangaroo rate of increase in many areas, but harvest statistics (sex ratio, carcass weight, skin size and animals shot per unit time) potentially offer cost-effective indirect monitoring of population abundance (and therefore trend) and status (i.e. under-or overharvest). Furthermore, because harvest data are collected continuously and throughout the harvested areas, they offer the promise of more intensive and more representative coverage of harvest areas than aerial surveys do. To be useful, harvest statistics would need to have a close and known relationship with either population size or harvest rate. We assessed this using longterm (11-22 years) data for three kangaroo species (Macropus rufus, M. giganteus and M. fuliginosus) and common wallaroos (M. robustus) across South Australia, New South Wales and Queensland. Regional variation in kangaroo body size, population composition, shooter efficiency and selectivity required separate analyses in different regions. Two approaches were taken. First, monthly harvest statistics were modelled as a function of a number of explanatory variables, including kangaroo density, harvest rate and rainfall. Second, density and harvest rate were modelled as a function of harvest statistics. Both approaches incorporated a correlated error structure. Many but not all regions had relationships with sufficient precision to be useful for indirect monitoring. However, there was no single relationship that could be applied across an entire state or across species. Combined with rainfall-driven population models and applied at a regional level, these relationships could be used to reduce the frequency of aerial surveys without compromising decisions about harvest management.

Reassessing spatial and temporal dynamics of kangaroo populations

Long-running datasets from aerial surveys of kangaroos (Macropus giganteus, Macropus [uliginosus, Macropus robustus and Macropus rufus) across Queensland, New South Wales and South Australia have been analysed, seeking better predictors of rates of increase which would allow aerial surveys to be undertaken less frequently than annually. Early models of changes in kangaroo numbers in response to rainfall had shown great promise, but much variability. We used normalised difference vegetation index (NDVI) instead, reasoning that changes in pasture condition would provide a better predictor than rainfall. However, except at a fine scale, NDVI proved no better; although two linked periods of rainfall proved useful predictors of rates of increase, this was only in some areas for some species. The good correlations reported in earlier studies were a consequence of data dominated by large droughtinduced adult mortality, whereas over a longer time frame and where changes between years are less dramatic, juvenile survival has the strongest influence on dynamics. Further, harvesting, density dependence and competition with domestic stock are additional and important influences and it is now clear that kangaroo movement has a greater influence on population dynamics than had been assumed. Accordingly, previous conclusions about kangaroo populations as simple systems driven by rainfall need to be reassessed. Examination of this large dataset has permitted descriptions of shifts in distribution of three species across eastern Australia, changes in dispersion in response to rainfall, and an evaluation of using harvest statistics as an index of density and harvest rate. These results have been combined into a risk assessment and decision theory framework to identify optimal monitoring strategies.

Temporal genetic structure patterns in tropical maize populations under reciprocal recurrent selection.

In order to investigate the effect of long term recurrent selection on the pattern of gene diversity, thirty randomly-selected individuals from the progenitors (p) and four selection cycles (C0, C3, C6 and C11) were sampled for DNA analysis from the tropical maize (Zea mays L.) breeding populations, Atherton 1 (AT1) and Atherton 2 (AT2). Fifteen polymorphic Simple Sequence Repeat markers amplified a total of 284 and 257 alleles in AT1 and AT2 populations, respectively. Reductions in the number of alleles were observed at advanced selection cycles. About 11 and 12% of the alleles in AT1 and AT2 populations respectively, were near to fixation. However, a higher number of alleles (37% in AT1 and 33% in AT2) were close to extinction. Fisher's exact test and analysis of molecular variance (AMOVA) showed significant population differentiations. Gene diversity estimates and AMOVA revealed increased genetic differentiations at the expense of loss of heterozygosity. Population differentiations were mainly due to fixation of complementary alleles at a locus in the two breeding populations. The estimates of effective population at an advanced selection cycle were close to the population size predicted by the breeding method.

Unpacking the perceived opportunity to misbehave: The influence of spatio-temporal and social dimensions on consumer misbehavior

Purpose This study aims to use opportunity as a theoretical lens to investigate how the spatio-temporal and social dimensions of the consumption environment create perceived opportunities for consumers to misbehave. Design/methodology/approach Drawing on routine activity theory and social impact theory, the authors use two experiments to demonstrate that spatio-temporal and social dimensions can explain consumer theft in retail settings. Findings Study 1 reveals mixed empirical support for the basic dimensions of routine activity theory, which posits that the opportunity to thieve is optimised when a motivated offender, suitable target and the absence of a capable formal guardian transpire in time and space. Extending the notion of guardianship, Study 2 tests social impact theory and shows that informal guardianship impacts the likelihood of theft under optimal routine activity conditions. Originality/value The study findings highlight important implications for academicians and retail managers: rather than focusing on the uncontrollable characteristics of thieving offenders, more controllable spatio-temporal and social factors of the retail environment can be actively monitored and manipulated to reduce perceived opportunities for consumer misbehaviour.

Spatial and temporal foraging patterns of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), for protein and implications for management

Fruit flies require protein for reproductive development and actively feed upon protein sources in the field. Liquid protein baits mixed with insecticide are used routinely to manage pest fruit flies, such as Bactrocera tryoni (Froggatt). However, there are still some gaps in the underpinning science required to improve the efficacy of bait spray technology. The spatial and temporal foraging behaviour of B. tryoni in response to protein was investigated in the field. A series of linked trials using either wild flies in the open field or laboratory-reared flies in field cages and a netted orchard were undertaken using nectarines and guavas. Key questions investigated were the fly's response to protein relative to: height of protein within the canopy, fruiting status of the tree, time of day, season and size of the experimental arena. Canopy height had a significant response on B. tryoni foraging, with more flies foraging on protein in the mid to upper canopy. Fruiting status also had a significant effect on foraging, with most flies responding to protein when applied to fruiting hosts. B. tryoni demonstrated a repeatable diurnal response pattern to protein, with the peak response being between 12:0016:00 h. Season showed significant but unpredictable effects on fruit fly response to protein in the subtropical environment where the work was undertaken. Relative humidity, but not temperature or rainfall, was positively correlated with protein response. The number of B. tryoni responding to protein decreased dramatically as the spatial scale increased from field cage through to the open field. Based on these results, it is recommend that, to be most effective, protein bait sprays should be applied to the mid to upper canopies of fruiting hosts. Overall, the results show that the protein used, an industry standard, has very low attractancy to B. tryoni and that further work is urgently needed to develop more volatile protein baits.

Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

Grazing by domestic livestock is one of the most widespread uses of the rangelands of Australia. There is limited information on the effects of grazing by domestic livestock on the vertebrate fauna of Australia and the establishment of a long-term grazing experiment in north-eastern Queensland at Wambiana provided an opportunity to attempt an examination of the changes in vertebrate fauna as a consequence of the manipulation of stocking rates. The aim was to identify what the relative effects of vegetation type, stocking rate and other landscape-scale environmental factors were on the patterns recorded. Sixteen 1-ha sites were established within three replicated treatments (moderate, heavy and variable stocking rates). The sites were sampled in the wet and dry seasons in 1999-2000 (T-0) and again in 2003-04 (T-1). All paddocks of the treatments were burnt in 1999. Average annual rainfall declined markedly between the two sampling periods, which made interpretation of the data difficult. A total of 127 species of vertebrate fauna comprising five amphibian, 83 bird, 27 reptile and 12 mammal species were recorded. There was strong separation in faunal composition from T-0 to T-1 although changes in mean compositional dissimilarity between the grazing stocking rate treatments were less well defined. There was a relative change in abundance of 24 bird, four mammal and five reptile species from T-0 to T-1. The generalised linear modelling identified that, in the T-1 data, there was significant variation in the abundance of 16 species explained by the grazing and vegetation factors. This study demonstrated that vertebrate fauna assemblage did change and that these changes were attributable to the interplay between the stocking rates, the vegetation types on the sites surveyed, the burning of the experimental paddocks and the decrease in rainfall over the course of the two surveys. It is recommended that the experiment is sampled again but that the focus should be on a rapid survey of abundant taxa (i.e. birds and reptiles) to allow an increase in the frequency of sampling and replication of the data. This would help to articulate more clearly the trajectory of vertebrate change due to the relative effects of stocking rates compared with wider landscape environmental changes. Given the increasing focus on pastoral development in northern Australia, any opportunity to incorporate the collection of data on biodiversity into grazing manipulation experiments should be taken for the assessment of the effects of land management on faunal species.

The non-pathogenic Australian rabbit calicivirus RCV-A1 provides temporal and partial cross protection to lethal Rabbit Haemorrhagic Disease Virus infection which is not dependent on antibody titres

The endemic non-pathogenic Australian rabbit calicivirus RCV-A1 is known to provide some cross protection to lethal infection with the closely related Rabbit Haemorrhagic Disease Virus (RHDV). Despite its obvious negative impacts on viral biocontrol of introduced European rabbits in Australia, little is known about the extent and mechanisms of this cross protection. In this study 46 rabbits from a colony naturally infected with RCV-A1 were exposed to RHDV. Survival rates and survival times did not correlate with titres of serum antibodies specific to RCV-A1 or cross reacting to RHDV, but were instead influenced by the time between infection with the two viruses, demonstrating for the first time that the cross protection to lethal RHDV infection is transient. These findings are an important step towards a better understanding of the complex interactions of co-occurring pathogenic and non-pathogenic lagoviruses.

Temporal and spatial patterns of soil water extraction and drought resistance among genotypes of a perennial C-4 grass

The objective of this study was to investigate patterns of soil water extraction and drought resistance among genotypes of bermudagrass (Cynodon spp.) a perennial C-4 grass. Four wild Australian ecotypes (1-1, 25a1, 40-1, and 81-1) and four cultivars (CT2, Grand Prix, Legend, and Wintergreen) were examined in field experiments with rainfall excluded to monitor soil water extraction at 30-190 cm depths. In the study we defined drought resistance as the ability to maintain green canopy cover under drought. The most drought resistant genotypes (40-1 and 25a1) maintained more green cover (55-85% vs 5-10%) during water deficit and extracted more soil water (120-160 mm vs 77-107 mm) than drought sensitive genotypes, especially at depths from 50 to 110 cm, though all genotypes extracted water to 190 cm. The maintenance of green cover and higher soil water extraction were associated with higher stomatal conductance, photosynthetic rate and relative water content. For all genotypes, the pattern of water use as a percentage of total water use was similar across depth and time We propose the observed genetic variation was related to different root characteristics (root length density, hydraulic conductivity, root activity) although shoot sensitivity to drying soil cannot be ruled out.

Sustainable grazing management for temporal and spatial variability in north Australian rangelands – a synthesis of the latest evidence and recommendations

Rainfall variability is a major challenge to sustainable grazing management in northern Australia, with management often complicated further by large, spatially-heterogeneous paddocks. This paper presents the latest grazing research and associated bio-economic modelling from northern Australia and assesses the extent to which current recommendations to manage for these issues are supported. Overall, stocking around the safe long-term carrying capacity will maintain land condition and maximise long-term profitability. However, stocking rates should be varied in a risk-averse manner as pasture availability varies between years. Periodic wet-season spelling is also essential to maintain pasture condition and allow recovery of overgrazed areas. Uneven grazing distributions can be partially managed through fencing, providing additional water-points and in some cases patch-burning, although the economics of infrastructure development are extremely context-dependent. Overall, complex multi-paddock grazing systems do not appear justified in northern Australia. Provided the key management principles outlined above are applied in an active, adaptive manner, acceptable economic and environmental outcomes will be achieved irrespective of the grazing system applied.