Growth and physiological response of six Australian rainforest tree species to a light gradient

An understanding of growth and photosynthetic potential of subtropical rainforest species to variations in light environment can be useful for determining the sequence of species introductions in rainforest restoration projects and mixed species plantations. We examined the growth and physiology of six Australian subtropical rainforest tree species in a greenhouse consisting of three artificial light environments (10%, 30%, and 60% full sunlight). Morphological responses followed the typical sun-shade dichotomy, with early and late secondary species (Elaeocarpus grandis, Flindersia brayleyana, Flindersia schottiana, and Gmelina leichhardtii) displaying higher relative growth rate (RGR) compared to mature stage species (Cryptocarya erythroxyion and Heritiera trifoliolatum). Growth and photosynthetic performance of most species reached a maximum in 30-60% full sunlight. Physiological responses provided limited evidence of a distinct dichotomy between early and late successional species. E. grandis and F brayleyana, provided a clear representation of early successional species, with marked increase in Am in high light and an ability to down regulate photosynthetic machinery in low light conditions. The remaining species (F. schottiana, G. leichhardtii, and H. trifoliolatum) were better represented as failing along a shade-tolerant continuum, with limited ability to adjust physiologically to an increase or decrease in light, maintaining similar A(max) across all light environments. Results show that most species belong to a shade-tolerant constituency, with an ability to grow and persist across a wide range of light environments. The species offer a wide range of potential planting scenarios and silvicultural options, with ample potential to achieve rapid canopy closure and rainforest restoration goals.

Modelling predicts positive and negative interactions between three Australian tropical tree species in monoculture and binary mixture

Computer modelling promises to be an important tool for analysing and predicting interactions between trees within mixed species forest plantations. This study explored the use of an individual-based mechanistic model as a predictive tool for designing mixed species plantations of Australian tropical trees. The `spatially explicit individually based-forest simulator' (SeXI-FS) modelling system was used to describe the spatial interaction of individual tree crowns within a binary mixed-species experiment. The three-dimensional model was developed and verified with field data from three forest tree species grown in tropical Australia. The model predicted the interactions within monocultures and binary mixtures of Flindersia brayleyana, Eucalyptus pellita and Elaeocarpus grandis, accounting for an average of 42% of the growth variation exhibited by species in different treatments. The model requires only structural dimensions and shade tolerance as species parameters. By modelling interactions in existing tree mixtures, the model predicted both increases and reductions in the growth of mixtures (up to +/-50% of stem volume at 7 years) compared to monocultures. This modelling approach may be useful for designing mixed tree plantations.

Resolving cryptic species complexes of major tephritid pests

An FAO/IAEA Co-ordinated Research Project (CRP) on “Resolution of Cryptic Species Complexes of Tephritid Pests to Overcome Constraints to SIT Application and International Trade” was conducted from 2010 to 2015. As captured in the CRP title, the objective was to undertake targeted research into the systematics and diagnostics of taxonomically challenging fruit fly groups of economic importance. The scientific output was the accurate alignment of biological species with taxonomic names; which led to the applied outcome of assisting FAO and IAEA Member States in overcoming technical constraints to the application of the Sterile Insect Technique (SIT) against pest fruit flies and the facilitation of international agricultural trade. Close to 50 researchers from over 20 countries participated in the CRP, using coordinated, multidisciplinary research to address, within an integrative taxonomic framework, cryptic species complexes of major tephritid pests. The following progress was made for the four complexes selected and studied: Anastrepha fraterculus complex – Eight morphotypes and their geographic and ecological distributions in Latin America were defined. The morphotypes can be considered as distinct biological species on the basis of differences in karyotype, sexual incompatibility, post-mating isolation, cuticular hydrocarbon, pheromone, and molecular analyses. Discriminative taxonomic tools using linear and geometric morphometrics of both adult and larval morphology were developed for this complex. Bactrocera dorsalis complex – Based on genetic, cytogenetic, pheromonal, morphometric, and behavioural data, which showed no or only minor variation between the Asian/African pest fruit flies Bactrocera dorsalis, B. papayae, B. philippinensis and B. invadens, the latter three species were synonymized with B. dorsalis. Of the five target pest taxa studied, only B. dorsalis and B. carambolae remain as scientifically valid names. Molecular and pheromone markers are now available to distinguish B. dorsalis from B. carambolae. Ceratitis FAR Complex (C. fasciventris, C. anonae, C. rosa) – Morphology, morphometry, genetic, genomic, pheromone, cuticular hydrocarbon, ecology, behaviour, and developmental physiology data provide evidence for the existence of five different entities within this fruit fly complex from the African region. These are currently recognised as Ceratitis anonae, C. fasciventris (F1 and F2), C. rosa and a new species related to C. rosa (R2). The biological limits within C. fasciventris (i.e. F1 and F2) are not fully resolved. Microsatellites markers and morphological identification tools for the adult males of the five different FAR entities were developed based on male leg structures. Zeugodacus cucurbitae (formerly Bactrocera (Zeugodacus) cucurbitae) – Genetic variability was studied among melon fly populations throughout its geographic range in Africa and the Asia/Pacific region and found to be limited. Cross-mating studies indicated no incompatibility or sexual isolation. Host preference and genetic studies showed no evidence for the existence of host races. It was concluded that the melon fly does not represent a cryptic species complex, neither with regard to geographic distribution nor to host range. Nevertheless, the higher taxonomic classification under which this species had been placed, by the time the CRP was started, was found to be paraphyletic; as a result the subgenus Zeugodacus was elevated to genus level.

Resolution of Cryptic Species Complexes of Tephritid Pests to Enhance SIT Application and Facilitate International Trade

Tephritid fruit flies (Diptera: Tephritidae) are considered by far the most important group of horticultural pests worldwide. Female fruit flies lay eggs directly into ripening fruit, where the maggots feed causing fruit loss. Each and every continent is plagued by a number of fruit fly pests, both indigenous as well as invasive ones, causing tremendous economic losses. In addition to the direct losses through damage, they can negatively impact commodity trade through restrictions to market access. The quarantine and regulatory controls put in place to manage them are expensive, while the on-farm control costs and loss of crop affect the general well-being of growers. These constraints can have huge implications on loss in revenues and limitations to developing fruit and vegetable-based agroindustries in developing, emergent and developed nations. Because fruit flies are a global problem, the study of their biology and management requires significant international attention to overcome the hurdles they pose. The Joint Food and Agriculture Organisation / International Atomic Energy Agency (FAO/IAEA) Programme on Nuclear Techniques in Food and Agriculture has been on the foreground in assisting Member States in developing and validating environment-friendly fruit fly suppression systems to support viable fresh fruit and vegetable production and export industries. Such international attention has resulted in the successful development and validation of a Sterile Insect Technique (SIT) package for the Mediterranean fruit fly. Although demands for R&D support with respect to Mediterranean fruit fly are diminishing due to successful integration of this package into sustainable control programmes against this pest in many countries, there were increasing demands from Member States in Africa, Asia and Latin America, to address other major fruit fly pests and a related, but sometimes neglected issue of tephritid species complexes of economic importance. Any research, whether it is basic or applied, requires a taxonomic framework that provides reliable and universally recognized entities and names. Among the currently recognized major fruit fly pests, there are groups of species whose morphology is very similar or identical, but biologically they are distinct species. As such, some insect populations that are grouped taxonomically within the same pest species, display different biological and genetic traits and show reproductive isolation which suggest that they are different species. On the other hand, different species may have been taxonomically described, but there may be doubt as to whether they actually represent distinct biological species or merely geographical variants of the same species. This uncertain taxonomic status has practical implications on the effective development and use of the SIT against such complexes, particularly at the time of determining which species to mass-rear, and significantly affects international movement of fruit and vegetables through the establishment of trade barriers to important agricultural commodities which are hosts to these pest tephritid species...

Paropsine beetles (Coleoptera: Chrysomelidae) in south-eastern Queensland hardwood plantations: identifying potential pest species

Paropsine chrysomelid beetles are significant defoliators of Australian eucalypts. In Queensland, the relatively recent expansion of hardwood plantations has resulted in the emergence of new pest species. Here I identify paropsine beetles collected from Eucalyptus cloeziana Muell. and E. dunnii Maiden, two of the major Eucalyptus species grown in plantations in south-eastern Queensland, and estimate the relative abundance of each paropsine species. Although I was unable to identify all taxa to species level, at least 17 paropsine species were collected, about one-third of which have not been previously associated with hardwood plantations. Paropsis atomaria Olivier and P. charybdis Stål were the most abundant species collected in E. cloeziana plantations, while Chrysophtharta cloelia (Stål) and P. atomaria were most commonly collected from E. dunnii. Occasional collections from Corymbia citriodora (Hook.) Hill and Johns, ssp. variegata revealed an additional four species implicated in plantation damage. Abundance and voltinism varied between species and sites. I predict which paropsine species are likely to threaten plantation productivity.

Potential of imidacloprid to control four species of psocids (Psocoptera: Liposcelididae) infesting stored grain

The effectiveness of the neonicotinoid insecticide imidacloprid was evaluated against four psocid pests of stored grain. This research was undertaken because of the growing importance of psocids in stored grain and the need to identify methods for their control. The mortality and reproduction of adults of Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman in wheat treated with imidacloprid were determined. There were five application rates (0.5, 1, 2, 5 and 10 mg AI kg -1 grain) and an untreated control. There were significant effects of application rate on both adult mortality and reproduction for all four species, but the effect of imidacloprid was sometimes more pronounced on reproduction. Imidacloprid was most effective against L. bostrychophila, with 100% adult mortality after 7 d at 5 mg AI kg-1, 14 d at 2 mg AI kg-1 and 28 d at 0.5 and 1 mg AI kg-1. No live progeny were produced at 2 mg AI kg-1. For L. decolor, there was 100% adult mortality after 28 d at 10 mg AI kg-1 and no live progeny were produced at 2 mg AI kg-1. For L. entomophila, there was 100% adult mortality after 14 d at 10 mg AI kg-1 and 28 d at 2 and 5 mg AI kg-1. No live progeny were produced at 10 mg AI kg-1. At 10 mg AI kg-1 there was 100% mortality of L. paeta adults after 28 d exposure and no live progeny developed. Because reproduction at some application rates occurred only in the first 14 d of exposure, it is concluded that the application rate leading to population extinction was 1 mg AI kg-1 for L. bostrychophila, 2 mg AI kg-1 for L. decolor and L. entomophila and 5 mg AI kg -1 for L. paeta. This study shows that imidacloprid has potential as a grain protectant to control all four Liposcelis species in stored grain.

Achievements in forest tree genetic improvement in Australia and New Zealand 2: Development of Corymbia species and hybrids for plantations in eastern Australia

This paper describes the establishment of provenance seedling seed orchards of three spotted gums and cadaga (all species of Corymbia ex Eucalyptus). It also discusses the limitations of growing the spotted gums as pure species including: lack of mass flowering, susceptibility to a fungal shoot blight and low amenability to vegetative propagation. These limitations, together with observation of putative natural hybrids of the spotted gums with cadaga, and the early promise of manipulated hybrids, led to an intensive breeding and testing program. Many hybrid families have significant advantages in growth and tolerance to disease, insects and frost, and can be vegetatively propagated. They also exhibit broad environmental plasticity, allowing the best varieties to be planted across a wider range of sites than the spotted gums, resulting in more land being suitable for plantation development.

Evaluating temperate species for the subtropics. 1. Annual ryegrasses

In the subtropics of Australia, irrigated temperate species are the key to reliable cool season feed on dairy farms. Persistence of perennial species is a major limitation to achieving reliable production from irrigated areas and yearly sowings of annual ryegrasses have replaced them as the most productive cool season forage production system in the subtropics. This series of experiments evaluated the yield, and resistance to rust damage, of commercially available cultivars and breeders' lines of annually sown ryegrasses (Lolium multiflorum, L. rigidum, L. x boucheanum and L perenne) in pure, nitrogen-fertilised swards under irrigation in the subtropics over a 22-year period. Barberia and Aristocrat 2 were the most adapted cultivars for subtropical conditions, producing high yields (119 and 114% of mean yield, respectively) and demonstrating the least rust damage. Newer selections from New Zealand, South African, United States of America and European breeding programs are performing better under subtropical conditions than older cultivars, particularly if a component of the selection process has been conducted in that environment. Cultivars such as Passerei Plus, Crusader, Hulk, Status and Warrior are examples of this process, producing between 105 and 115% of mean yield. Yields of annual ryegrass cultivars, which have been available or still are available for sale in Australia, ranged from 14-30 t/ha DM, depending on cultivar, site and seasonal conditions. Yields were lower at the site, which had inferior soil structure and drainage. Up to 50% of yield was produced in the 3 winter months. There was a trend towards improved yields and better tolerance of crown rust from experimental lines in the subtropics, as breeders strive for wider adaptation. Around 70% of the variation in total yield of annual ryegrass and 50 and 60% of the variation in winter and spring yield, respectively, were significantly explained by cultivar, site and climatic variables in autumn, winter and spring. While level of rust damage had no effect on total or seasonal yields, it affected the amount of green leaf available in spring. Under subtropical conditions, winter, spring and overall (autumn to mid-summer) temperatures influenced the- development of rust, which along with cultivar, accounted for 46% of the variation in rust damage. Cultivars showed a range of adaptation, with some performing well only under adverse conditions, some being well adapted to all conditions and some which performed well only under favoured conditions. Cultivars with high winter yields were most suited to subtropical conditions and included Aristocrat 2 (now released as CM 108), Barberia, Warrior, Crusader, Status, Passerei Plus and Hulk. Short growing season types such as Winter Star and T Rex performed well in winter but achieved lower total production, and long season cultivars such as Flanker rarely achieved their potential because of unfavourable conditions in late summer.

Two new species and a new Australian record of Bactrocera Macquart (Diptera : Tephritidae : Dacinae) from Northern Queensland, Torres Strait and Papua New Guinea

Bactrocera (Bactrocera) speewahensis Fay & Hancock sp. n. is described from northern Queensland and B. (B.) torresiae Huxham & Hancock sp. n. is described from Boigu, Saibai and Dauan islands in Torres Strait and southern Papua New Guinea. Bactrocera (B.) nigrovittata Drew is newly recorded from Australia. All records are of male flies responding to chemical lures.

Ruminal protein degradability of a range of tropical pastures

The rumen degradability parameters of the diet selected by two to four oesophageal-fistulated Brahman steers grazing a range of tropical pastures were determined by incubation of extrusa in nylon bags suspended in the rumen of rumen-fistulated (RF) Brahman steers. The effective protein degradability (Edg) was determined by measuring the rate of disappearance of neutral detergent insoluble nitrogen (NDIN) less acid detergent insoluble nitrogen (ADIN) in the incubated extrusa. Six to eight RF steers also grazed each of the pastures along with the oesophageal-fistulated steers, to allow determination of key rumen parameters and rumen particulate matter fractional outflow rates (FOR). The seven pastures studied included: native tropical grass (C4) pasture (major species Heteropogon contortus and Bothriochloa bladhii), studied in the early wet (NPEW), the wet/dry transition (NPT) and the dry (NPD) seasons; introduced tropical grass (C4) pasture (Bothriochloa insculpta), studied in the mid wet season (BB); the introduced tropical legumes (C3), Lablab purpureus (LL) and Clitoria ternatea (BP); and the temperate grass (C3) pasture, ryegrass (Lolium multiflorum, RG). Using the measured particle FOR values in calculations, the Edg estimates were very high for both C4 and C3 species: 0.82–0.91 and 0.95–0.98 g/g crude protein (CP), respectively. Substitution of an assumed FOR (kp = 0.02/h) for the measured values for each pasture type did not markedly affect estimates of Edg. However, C4 tropical grasses had much lower effective rumen degradable protein (ERDP) fractions (23–66 g/kg DM) than the C3 pasture species RG and LL (356 and 243 g/kg DM, respectively). This was associated with a lower potential degradability and degradation rate of organic matter (OM) in sacco, lower in vitro organic matter digestibility (IVOMD) and CP concentrations in the extrusa, and lower ammonia-N and branched-chain fatty acid concentrations in rumen fluid for the tropical grasses. As tropical grass pastures senesced, there was a decline in Edg, the ERDP and rumen undegradable protein (UDP) fractions, the potential degradability and degradation rate of OM and the IVOMD. These results provide useful data for estimating protein supply to cattle grazing tropical pastures.

Weed species richness, density and relative abundance on farms in the subtropical grain region of Australia

Weed management is one of the most important economic and agronomic issues facing farmers in Australia's grain regions. Weed species occurrence and abundance was monitored between 1997 and 2000 on 46 paddocks (sites) across 18 commercial farms located in the Northern Grain Region. The sites generally fell within 4 disjunct regions, from south to north: Liverpool Plains, Moree, Goondiwindi and Kingaroy. While high species richness was found (139 species or species groups), only 8 species occurred in all 4 regions and many (56 species) only occurred at 1 site or region. No species were observed at every site but 7 species (Sonchus spp., Avena spp., Conyza spp., Echinochloa spp., Convolvulus erubescens, Phalaris spp. and Lactuca serriola) were recorded on more than 70% of sites. The average number of species observed within crops after treatment and before harvest was less than 13. Species richness tended to be higher in winter pulse crops, cotton and in fallows, but overall was similar at the different sampling seasons (summer v. winter). Separate species assemblages associated with the Goondiwindi and Kingaroy regions were identified by correspondence analysis but these appeared to form no logical functional group. The species richness and density was generally low, demonstrating that farmers are managing weed populations effectively in both summer and winter cropping phases. Despite the apparent adoption of conservation tillage, an increase in opportunity cropping and the diversity of crops grown (13) there was no obvious effect of management practices on weed species richness or relative abundance. Avena spp. and Sonchus spp. were 2 of the most dominant weeds, particularly in central and southern latitudes of the region; Amaranthus spp. and Raphanus raphanistrum were the most abundant species in the northern part of the region. The ubiquity of these and other species shows that continued vigilance is required to suppress weeds as a management issue.

Identification of quantitative trait loci for resistance to two species of root-lesion nematode (Pratylenchus thornei and P. neglectus) in wheat

Pratylenchus thornei and P. neglectus are two species of root-lesion nematode that cause substantial yield losses in wheat. No commercially available wheat variety has resistance to both species. A doubled-haploid population developed from a cross between the synthetic hexaploid wheat line CPI133872 and the bread wheat Janz was used to locate and tag quantitative trait loci (QTLs) associated with resistance to both P. thornei and P. neglectus. Wheat plants were inoculated with both species of nematode in independent replicated glasshouse trials repeated over 2 years. Known locations of wheat microsatellite markers were used to construct a framework map. After an initial single-marker analysis to detect marker-trait linkages, chromosome regions associated with putative QTLs were targetted with microsatellite markers to increase map density in the chromosome regions of interest. In total, 148 wheat microsatellite markers and 21 amplified fragment length polymorphism markers were mapped. The codominant microsatellite marker Xbarc183 on the distal end of chromosome 6DS was allelic for resistance to both P. thornei and P. neglectus. The QTL were designated QRlnt.lrc-6D.1 and QRlnn.lrc-6D.1, for the 2 traits, respectively. The allele inherited from CPI133872 explained 22.0-24.2% of the phenotypic variation for P. thornei resistance, and the allele inherited from Janz accounted for 11.3-14.0% of the phenotypic variation for P. neglectus resistance. Composite interval mapping identified markers that flank a second major QTL on chromosome 6DL (QRlnt.lrc-6D.2) that explained 8.3-13.4% of the phenotypic variation for P. thornei resistance. An additional major QTL associated with P. neglectus resistance was detected on chromosome 4DS (QRlnn.lrc-4D.1) and explained a further 10.3-15.4% of the phenotypic variation. The identification and tagging of nematode resistance genes with molecular markers will allow appropriate allele combinations to be selected, which will aid the successful breeding of wheat with dual nematode resistance.

Screening selected myrtaceous tree species for production of essential oils in northern Queensland

Trials to identify alternative cropping options to Melaleuca alternifolia for northern Queensland essential oil growers were established at Dimbulah and Innot Hot Springs in 2001. Seed sources of Asteromyrtus symphyocarpa (1,8-cineole form), Eucalyptus staigeriana (citral), Melaleuca cajuputi subsp. cajuputi (trans-nerolidol), M. ericifolia (d-linalool), M. quinquenervia (trans-nerolidol and viridiflorol forms) and M. viridiflora (methyl cinnamate) with potential to produce commercial foliar oils were evaluated. Information was gathered on their adaptability, growth and oil yields over 49 months and 52 months (two harvests) from planting at Dimbulah and Innot Hot Springs, respectively. Of the species and chemotypes evaluated, M. quinquenervia showed potential for commercial production of trans-nerolidol, a compound used in perfumery. It had a very high survival rate (96%) and yields could be expected to improve dramatically from the average 100 kg/ha per harvest achieved in these trials with further research into selection of seed source, control of insect damage and breeding for genetic improvement. M. cajuputi subsp. cajuputi gave a similar performance to M. quinquenervia. The rarity of the trans-nerolidol form of this species and remoteness of its natural occurrence are impediments to further planting and research. E. staigeriana, with second harvest yields of ~600 kg/ha, performed exceptionally well on both sites but potential for development is limited by the ready availability of competitively priced E. staigeriana oil produced in South America. Survival of M. ericifolia ranged from 62% to 82% at 32 months (second harvest) at Innot Hot Springs and was deemed a failure at Dimbulah with poor growth and low survival, raising a major question about the suitability of this species for cultivation in the seasonally dry tropics. Planting of this species on a wider scale in northern Queensland cannot be recommended until more is known about factors affecting its survival. A. symphyocarpa and M. viridiflora were too slow-growing to warrant further consideration as potential oil-producing species at this time.

Recovery of the red-finned blue-eye: An endangered fish from springs of the Great Artesian Basin

The red-finned blue-eye (Scaturiginichthys vermeilipinnis) is endemic to a single complex of springs emanating from the Great Artesian Basin, Australia. The species has been recorded as naturally occurring in eight separate very shallow (generally <20 mm) springs, with a combined wetland area of ~0.3 ha. Since its discovery in 1990, five red-finned blue-eye (RFBE) populations have been lost and subsequent colonisation has occurred in two spring wetlands. Current population size is estimated at <3000 individuals. Artesian bores have reduced aquifer pressure, standing water levels and spring-flows in the district. There is evidence of spatial separation within the spring pools where RFBE and the introduced fish gambusia (Gambusia holbrooki) co-occur, although both species are forced together when seasonal extremes affect spring size and water temperature. Gambusia was present in four of the five springs where RFBE populations have been lost. Four out of the five remaining subpopulations of RFBE are Gambusia free. Circumstantial evidence suggests that gambusia is a major threat to red-finned blue-eyes. The impact of Gambusia is probably exacerbated by domestic stock (cattle and sheep), feral goats and pigs that utilise the springs and can negatively affect water quality and flow patterns. Three attempts to translocate RFBE to apparently suitable springs elsewhere within the complex have failed. Opportunities to mitigate threats are discussed, along with directions for future research to improve management of this extremely threatened fish and habitat.

Phototropic growth in a reef flat acroporid branching coral species

Many terrestrial plants form complex morphological structures and will alter these growth patterns in response to light direction. Similarly reef building corals have high morphological variation across coral families, with many species also displaying phenotypic plasticity across environmental gradients. In particular, the colony geometry in branching corals is altered by the frequency, location and direction of branch initiation and growth. This study demonstrates that for the branching species Acropora pulchra, light plays a key role in axial polyp differentiation and therefore axial corallite development - the basis for new branch formation. A. pulchra branches exhibited a directional growth response, with axial corallites only developing when light was available, and towards the incident light. Field experimentation revealed that there was a light intensity threshold of 45 mu mol m(-2) s(-1), below which axial corallites would not develop and this response was blue light (408-508 nm) dependent. There was a twofold increase in axial corallite growth above this light intensity threshold and a fourfold increase in axial corallite growth under the blue light treatment. These features of coral branch growth are highly reminiscent of the initiation of phototropic branch growth in terrestrial plants, which is directed by the blue light component of sunlight.