12903 research outputs found
Sort by
Using pre-emergent herbicides for the control of Sicklepod (Senna obtusifolia) in the wet tropics
No full textSicklepod (Senna obtusifolia) is a significant weed of many parts of Queensland, from Mackay to Cape York. It can invade pastures, crops, road and power line corridors, clearings and creek banks. Previous research identified a suite of pre-emergent herbicides that when applied pre-wet season proved to be successful in controlling the seed/seedling bank during the short “Wet” season in the Dry Tropics. This study tests whether these herbicides will also prove effective in wetter tropical areas infested with sicklepod.
The herbicides are being tested in various landscapes of the Wet Tropics where sicklepod has become dominant such as riparian zones, steep hillsides, adjacent pasture and fallow agricultural areas.
Additional impediments to weed control in the wet tropics include a shorter window of opportunity for herbicide application and longer wet periods with higher rainfall totals. However, the higher productivity of arable and grazing land in the wet tropics environment makes herbicide application for weed control a viable option.
Using the same herbicides and rates as proven successful in the Dry Tropics, with the addition of Valor®, initial baseline data has been collected and treatments of both post and pre-emergent herbicides have been applied. Valor® was included as a post emergent treatment as it may be more suited to higher rainfall areas. The postemergent treatments were added to ensure the ground is clear of sicklepod prior to pre-emergent herbicide application.
Early results indicate a significant reduction in seedling emergence. Further preemergent treatments will need to be applied to exhaust the existing seed bank
Controlling five invasive woody weed species using the drill and fill stem injection method
No full textA series of field trials were conducted on five invasive woody weeds to determine the efficacy of applying small doses of liquid herbicide directly into the sapwood layer of target plant stems using the application method known as ‘drill and fill’. The five target weeds included four trees: leucaena (Leucaena leucocephala (Lam.) de Wit), pond apple (Annona glabra L.), neem (Azadirachta indica A. Jus,), and African tulip (Spathodea campanulata P.Beauv,), and the vine rubber vine (Cryptostegia grandiflora R. Br.). All five weeds can cause detrimental effects in native ecosystems and significant problems for land managers if unmanaged. Drill and fill is a portable, userfriendly application method that can be safely applied anytime of the year on target weeds growing within desirable vegetation and in environmentally sensitive areas. This paper highlights this technique as an effective management option using minimal volumes of herbicides to achieve high mortality rates
Getting ahead of the game: preparing for novel incursions
No full textThe invasion curve highlights the importance of prevention and quick eradication in preventing establishment of new populations. Surveillance programs aim to prevent new animal pests from arriving in Australia through early detection of stowaways and illegal imports. Detecting new animal pests in the wild following release or escape can be difficult as there is often little local knowledge of their behaviours. To be prepared for these events, toolkits are being developed, applying best practice management techniques refined on established vertebrate pests, to aid in quick detection and capture to prevent establishment following an incursion of these novel pests.
Behavioural information of how species use their micro-environment, shelter preferences, diet and feeding can help to identify techniques to enhance their subsequent detection and capture. While some techniques may be applicable for multiple species there may be key differences which influence how they are applied. Detailed review and examination of behaviours and detection programs in the native range of these species can also highlight critical knowledge gaps. It is important to identify and explore these gaps both prior (to improve the probability of detection and capture) or post incursion (to assess impacts on ecosystems and how the species use the Australian landscapes). Here, I will use several exotic species as examples to describe the approaches undertaken to identify behavioural attributes that can be exploited to enhance detection and capture of likely, high-risk species to Queensland to ‘get ahead of the curve’
A seasonal aggregation of juvenile scalloped hammerheads Sphyrna lewini along beaches of the Gold Coast, Australia
No full textWe document a recurring seasonal aggregation of juvenile scalloped hammerhead sharks Sphyrna lewini along the beaches of the Gold Coast, Australia, with notable occurrences at Burleigh Heads and Kirra Reef. The aggregation consists of individuals of varying sizes, which likely suggests the presence of different cohorts, though it remains uncertain whether this area meets the criteria for a nursery habitat. Given the global population declines of S. lewini, its classification as Critically Endangered by the IUCN and its Conservation Dependent status under Australian legislation, we recommend standardised surveys and tracking studies to assess habitat use, seasonality and the potential role of Gold Coast waters as a critical habitat for juvenile S. lewini
Geographic Distribution of Phosphine Resistance and Frequency of Resistance Genes in Two Species of Grain Beetles, Tribolium castaneum and Rhyzopertha dominica, in North America
No full textResistance to the fumigant phosphine (PH3) was studied for 28 populations of Rhyzopertha dominica from eight states of the USA and four provinces of Canada, as well as for 34 populations of Tribolium castaneum from twelve states of the USA and four provinces of Canada, using both a discriminating dose bioassay and molecular marker analysis. We used a molecular marker analysis for a point mutation in the gene that encodes dihydrolipoamide dehydrogenase and facilitates the “strong resistance” phenotype in both species. Our results showed that PH3 resistance was correlated with higher frequencies of the strong resistance R allele in both species (R2 = 0.59 in R. dominica and R2 = 0.79 in T. castaneum). We also found that recessive R allele frequency did not correlate well with the geographic distribution of the resistant populations of these two species (R2 = 0.21 in R. dominica and R2 = 0.15 in T. castaneum). Therefore, populations of both species with higher R allele frequencies had higher resistance levels to PH3. Our results showed that the geographic distribution of PH3 resistance in both species varied and was not related geographically, but this supports the idea that the adaptive evolution of PH3 resistance in these species is caused by selection pressure for their resistance genes
Narrow, Open Canopy Architecture Enables More Effective Management of Mango Scale, Aulacaspis tubercularis Newstead in Mango Orchards
No full textPest management in horticultural crops must become more efficient, capitalising on non‐chemical means of pest reduction. In mango ( Mangifera Indica ), the development of highly productive orchard and canopy management systems offers a potential means to reduce pressure and damage from economically important pests such as mango scale ( Aulacaspis tubercularis Newstead), but these effects have not previously been examined. High‐density narrow hedge and espalier canopy management systems were compared with Australian industry standard low‐density wide open‐vase canopies. Initially, female scale populations on infested foliage were assessed in three commercial mango varieties for the three canopy systems over three years. Scale fruit damage in the three canopy systems was then assessed in Calypso variety for two following harvests. Narrow canopy management systems had significantly fewer female scale present on foliage, and significantly less fruit damage from scale (64%–84% reduction), resulting in fewer fruit downgrades (58%–89% reduction). This effect may result from changes in the canopy microclimate, with a potential contribution from greater spray penetration in narrow canopies. We suggest that the adoption of highly productive mango canopy designs will provide additional benefit to farmers and consumers by improving pest control and potentially reducing pesticide use
Tangled evolutionary history: genetically divergent taxa and hybrids characterise lantana invasions in Australia
No full textAim:
To investigate population genomics and phylogeography in invasive lantana, including its taxonomy, spatial distribution, and patterns of morphological and genetic variation across the Australian continent.
Location:
The main area invaded by lantana on the Australian continent, i.e., coastal and subcoastal eastern Australia from northern Queensland to southern New South Wales up to approximately 100 km inland, across 22 degrees latitude. The native range of lantana in the Americas was also represented.
Methods:
We used DArTseq to generate genome-wide single nucleotide polymorphism (SNP) data for >600 individuals representing the native and Australian invaded ranges of lantana. We analysed data from >20,000 SNPs to identify distinct genetic clusters, and test the extent to which they corresponded with taxonomic descriptions and morphotype concepts used in lantana biological control. Genome sizes were estimated for a small representative subset of individuals using flow cytometry. We used MaxEnt to estimate habitat suitability for different lantana genetic clusters, and compared these predictions with observed patterns in biological control agent host-specificity.
Results:
Invasive lantana in Australia consisted of several divergent genetic clusters of most likely tetraploid individuals. Gene flow between genetic clusters was limited, consistent with the notion that multiple species introductions and/or hybridisation events were part of the invasion history. Two widespread, homogeneous genetic clusters were found to be dominant in Australia; two other genetic clusters with more limited distributions were identified with potential for future spread. Biological control agent host preferences were consistent with identified genetic clusters.
Main conclusions:
Treating invasive lantana as a single taxon may be counterproductive for effective management. Comprehensive taxonomic revision is needed to enable more precise identification of invasive taxa. Improved identification will support improved management, particularly if using biological control
Sterol-modified plants reduce aphid performance by limiting sterol availability
No full textSterols are essential for eukaryotic cell structure and metabolism, yet insects cannot synthesize them de novo and must acquire them through their diet. For insect herbivores, plant-derived sterols are typically converted into cholesterol to support development and reproduction. We previously engineered Arabidopsis thaliana lines with silenced HYD1, resulting in altered sterol composition. In this study, we evaluated the performance of the phloem-feeding aphid Myzus persicae on these sterol-modified plants. Aphids reared on the modified lines (HYD1RNAi10, 12, 25) exhibited significantly reduced growth, reproduction, and survival compared to those on wild-type Col-0. However, choice assays and electropenetrography (EPG) revealed no differences in host preference or probing and feeding behaviors. Unlike the chewing insect Plutella xylostella, M. persica did not accumulate atypical sterols but instead showed a significant reduction of total sterol content. Phloem-sap analysis mirrored aphid sterol profiles, lacking the atypical sterols found in leaf tissue of the modified lines. RNA-seq of HYD1RNAi lines revealed no induction of known plant defense pathways; instead, genes involved in translation and nitrate metabolism were upregulated. These findings show that HYD1 silencing reduces host suitability for aphids by limiting sterol availability for insect development and reproduction. Our results highlight the potential of sterol-modified plants as a promising strategy for managing phloem sap-feeding insect pests
First molecular phylogeny of mycoparasitic species of Sphaerellopsis isolated from rust fungi in Australia
No full textThree species, Sphaerellopsis filum , S. macroconidialis , and S. paraphysata , from Queensland and Victoria, Australia, were identified and characterised by multilocus sequence analyses. This study clarifies earlier reports of Sphaerellopsis in Australia and provides the first report of S. filum in Australia. We also confirm the presence of S. macroconidialis and S. paraphysata in Australia. A single-locus phylogeny based on the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) provided sufficient resolution for species-level identification and yielded a topology consistent with that of the combined dataset of ITS, large subunit of the rDNA, and the RNA polymerase II second largest subunit. The high intron variability in the translation elongation factor 1-α region among Sphaerellopsis spp. made it unsuitable for phylogenetic analysis. The specimens and data generated here lay the groundwork for future studies into the evolution and molecular basis of mycoparasitism in Sphaerellopsis
Identification and epidemiological analysis of a putative novel hantavirus in Australian flying foxes
Full text linkIn July 2017, an investigation into the cause of neurological signs in a black flying fox (Pteropus alecto, family Pteropodidae) identified a putative novel hantavirus (Robina virus, ROBV, order Bunyavirales, family Hantaviridae, genus Mobatvirus) in its brain. Analysis of the evolutionary relationship between other hantaviruses using maximum-likelihood, a systematic Bayesian clustering approach, and a minimum spanning tree, all suggest that ROBV is most closely related to another Mobatvirus, Quezon virus, previously identified in the lung of a Philippine frugivorous bat (Rousettus amplexicaudatus, also family Pteropodidae). Subsequently, between March 2018 and October 2023, a total of 495 bats were opportunistically screened for ROBV with an experimental qRT-PCR. The total prevalence of ROBV RNA detected in Pteropus spp. was 4.2% (95% CI 2.8–6.4%). Binomial modelling identified that there was substantial evidence supporting an increase (P = 0.033) in the detection of ROBV RNA in bats in 2019 and 2020 suggesting of a possible transient epidemic. There was also moderate evidence to support the effect of season (P = 0.064), with peak detection in the cooler seasons, autumn, and winter, possibly driven by physiological and ecological factors similar to those already identified for other bat-borne viruses. This is Australia’s first reported putative hantavirus and its identification could expand the southern known range of hantaviruses in Australasia