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Biology, host specificity and varietal preference of the lantana gall fly: lessons learnt in time
No full textLantana camara L. (Verbenaceae) is a Weed of National Significance in Australia. This aggressive perennial woody shrub invades national parks, forestry, grazing lands, and riparian areas, displacing native species and reducing productivity. Effective control using mechanical or chemical means is both difficult and costly. Lantana was one of the first weeds to be targeted for classical biological control. Thirty agents were deliberately introduced to Australia, of which twenty agents, including a mite and a fungal pathogen, have become established and contribute to seasonal damage of the weed. Despite this, control of the lantana is still not adequate.
The lantana gall fly, Eutreta xanthochaeta Aldrich (Tephritidae), which aids control in Hawai’i, was field released in Australia in 1914, and again in 1971. This fly forms monothalamous galls on young shoots of lantana, significantly reducing the production of inflorescences on galled branches. Historically, difficulties mass rearing this agent resulted in only a very limited number of flies ever being released, and at only two locations in Queensland. Ultimately the agent failed to establish, and it was deemed a low priority to pursue further, as other potential agents were investigated. In 2022, E. xanthochaeta was re-imported into quarantine at the Ecosciences Precinct in Brisbane. A colony was successfully established from one female fly and five male flies, the only survivors from imported galls from Hawaii. This paper reports on the optimisation of rearing methods, biology of the lantana gall fly, and preliminary results of supplementary host specificity testing being undertaken
Refinement of splatter gun technology for control of bellyache bush (Jatropha gossypiifolia)
No full textBellyache bush (Jatropha gossypiifolia L.) is an erect perennial shrub that is toxic to livestock and capable of forming dense infestations in riparian and rangeland areas. It is widespread throughout northern Australia and, as such, has been classified as a Weed of National Significance. Previous work has shown that splatter gun application (i.e. low-volume high concentration) of metsulfuron-methyl can achieve 100% mortality of bellyache bush plants when each plant is treated individually. The focus of this study was to determine whether similar results could be obtained with this technology to control medium to high density infestations using a broadcast approach (i.e. applying a certain amount of herbicide mixture on a surface area basis). The efficacy of metsulfuronmethyl was compared to that of triclopyr/picloram/aminopyralid and aminopyralid/metsulfuron-methyl. Two rates of each herbicide were applied to plots of c.a. 5 m x 5 m size, in which efficacy associated with distance from the spray operator (i.e. spray front) was also assessed by sub-dividing the plots into 1 m strips. Eleven months after treatment (MAT), average plant mortality for metsulfuron-methyl was 93 and 99% for the low and high application rates, respectively. Furthermore, efficacy declined only slightly with increasing distance from the spray operator, with >90% mortality recorded at a distance of 4-5 m. Inclusion of aminopyralid did not enhance the efficacy of metsulfuron-methyl, whilst triclopyr/picloram/aminopyralid was relatively ineffective, achieving no more than 55% mortality at the highest application rate. Metsulfuron-methyl appears to be the best herbicide for treating isolated to dense infestations of bellyache bush using low-volume high concentration applications but follow up control will be needed to treat surviving plants and to control subsequent seedling growth
Tomato spotted wilt virus resistance breaking strains in Australia
No full textResistance to tomato spotted wilt virus (TSWV) in commercial tomatoes and capsicums are controlled by two single dominant genes, Sw5b and Tsw. The Sw5b was identified in Solanum peruvianum and has been introgressed into tomato lines for high level resistance against TSWV and other tospoviruses. TSWV resistant capsicum lines have the Tsw gene originally from Capsicum chinense ‘PI’ accessions. Resistance is displayed as a hypersensitive response, which prevents systemic spread of the virus. There has been the emergence of resistance-breaking strains of TSWV, both worldwide and occasionally in Australia. The Sw5b resistance-breaking strains exhibiting a conserved mutation in the NsM gene, the viral movement protein. Resistance-breaking of the Tsw gene has been identified as changes in the NsS gene (silencing suppressor), but no consensus has been reached on what changes contribute to the phenotype. We have sequenced TSWV isolates from across Australia from a variety of crops and alternative hosts, collected over the last 40 years with a number of these isolates wellcharacterised for Tsw resistance-breaking. We will present the current situation of resistance-breaking isolates in Australia
Investigating resistance breakdown and alternative management strategies for tomato yellow leaf curl virus
No full textTomato yellow leaf curl virus (TYLCV), a single-stranded DNA virus in the Begomovirus genus, is transmitted by whitefly Bemisia tabaci in a persistent, circulative manner. This virus poses a significant threat to global tomato production. In Australia, TYLCV-Israel (TYLCV-IL) was first detected in 2006 in southeast Queensland and later spread to northern Queensland, causing substantial economic impact. Introducing TYLCV-resistant tomato hybrids containing the Ty-1 resistance gene has effectively managed the virus in Queensland for several years. However, recently, resistance breakdown has been observed in Bundaberg. To investigate the factors contributing to this and explore alternative management strategies, PCR was conducted on samples collected from symptomatic plants of the TYLCV-resistant variety SV0215TH collected in Bundaberg in 2023. In addition, Sanger sequencing was conducted to obtain the genome sequence of the TYLCV 2023 isolate (AU23) for phylogenetic and severity prediction analysis using the machine learning software IML-TYLCVs. The results showed no detectable mixed infection of tomato leaf curl virus (ToLCV), tomato chlorosis virus, or ToLCV betasatellite. Although AU23 was predicted to be a mild isolate based on amino acid sequence, the phylogenetic analysis revealed that the pairwise distance of the nucleotide sequence of AU23 is far from that of the other Australian isolates retrieved from the NCBI virus database. Subsequently, spray-induced RNA interference (RNAi) was evaluated to protect tomato plants from AU23. Plants treated with dsRNA targeting the viral transcripts V1 and C3, combined with an 41 additive, showed reduced symptom expression and virus titre. Further research is needed to identify the major factors affecting the resistance breakdown, providing insights into developing new protection strategies for reemerging viruses
Acaciothrips ebneri, a new biological control agent for the invasive prickly acacia (Vachellia nilotica subsp. indica) in Australia
No full textPrickly acacia (Vachellia nilotica subsp. indica) was introduced into Australia in the 1890s as a drought resistant species for shade, fodder and ornamental purposes. It has since become invasive, being widespread throughout grazing areas in northern, central, and western Queensland and coastal, semi-arid and arid areas elsewhere in northern Australia. It has been designated as a Weed of National Significance. The plant exhibits a number of negative impacts on local ecosystems and agricultural production. Biological control is the most economically viable management option for prickly acacia in Australia. Six agents have been released for prickly acacia with only two agents, a seed-feeding beetle (Bruchidius sahlbergi) and a leaf-feeding moth (Chiasmia assimilis), have established, and with limited impacts. Native range surveys were directed to Ethiopia and Senegal based on genetic and climatic matching. A gall-inducing thrips (Acaciothrips ebneri) was prioritised from Ethiopia for host specificity testing in Brisbane, Australia where host specificity testing was completed for 59 test plant species. The gall thrips is host specific and has been approved for release by Australian Government. It is the first gall insect released for prickly acacia in Australia. Field releases commenced in January 2023 and are continuing, across sites along inland and coastal areas in Queensland. There are early signs of field establishment, host damage, and dispersal of the gall thrips. Future research will focus on monitoring its establishment, dispersal, and impact on prickly acacia
Minor use permits for chemical control of environmental weeds in Queensland
No full textInvasive weeds can cause significant, negative economic, social and environmental impacts. They can displace native flora and fauna, fuel intense bushfires, and disrupt primary production, water resources and tourism. Effective weed management is essential for minimising these impacts and relies on a combination of appropriate land management, and mechanical and chemical control methods. Many emerging and declared weed species in Queensland have limited herbicide options registered for their control. In some cases, there may be registered products available, but the approved application method is unsuitable for the situation. The chemical registration process is costly, so addition of minor environmental weeds on product labels is often not economical for chemical manufacturers. Minor use permits from the Australian Pesticides and Veterinary Medicines Authority (APVMA) can be sought to allow off-label use of chemicals for controlling environmental weeds. Biosecurity Queensland collaborates with Landcare groups, academic researchers, local council and state government to gather efficacy and off-target damage data to support applications for minor use permits. There are 50 permits currently issued to Biosecurity Queensland that allow control of a range of weed species with various chemicals and methods of application. This poster outlines the permit application process and highlights some permits that have been recently acquired or are in the planning phase
Pigeonpea weed management – testing herbicide crop safety and agronomic approaches to maximise crop competition
No full textFor pigeonpea, weeds are a major constraint, worsened by the poor early competitiveness of the crop. To establish pigeonpea as a viable grain crop in Queensland, effective crop safe, pre- and postemergence herbicides will be critical. In addition, maximising the competitiveness of pigeonpea crops could help reduce crop losses and minimise the impact of weeds.
There are currently limited registered herbicides for pigeonpea grain crops. Previous seedling pot screening identified several promising herbicides which are now being tested in field trials. Trials were conducted at the Department of Agriculture and Fisheries (DAF) Wellcamp research farm comparing the crop safety of post-emergent (2023 and 2024) and pre-emergent (2024) herbicides with untreated controls. Several tested herbicides showed good crop safety, with minimal visual symptoms of crop damage, reduced growth, or yield. More trial work is required to confirm the crop safety of these encouraging herbicides, and to allow registration for use in pigeonpea grain crops.
With limited options for in-crop weed control and increasing concerns about herbicide resistance, agronomic practices with the potential to supress weed growth and seed production have potential to complement herbicide use. This study tested the effect of pigeonpea row spacing and plant density on “mimic” weed growth and seed production. The highest pigeonpea yields were achieved with the high population and narrow rows (45 plants/m² and 250 mm). The mimic weeds (Rhodes grass and millet) significantly reduced the yields of pigeonpea. Importantly, the pigeonpea crop also significantly reduced yield and dry weight of mimic weeds. The effect of narrow row spacing was larger than the effect of increasing crop density. Light interception of pigeonpea was significantly higher with narrow row spacing, suggesting narrow rows may be useful for increasing crop competition and weed control
Projections of future bioclimatic indicators using bias-corrected CMIP6 models: a case study in a tropical monsoon region
No full textThis study evaluates the potential impacts of climate change on Bangladesh by analyzing 19 bioclimatic indicators based on temperature and precipitation. Data from 18 bias-corrected CMIP6 global climate models (GCMs) were used, covering four Shared Socioeconomic Pathways (SSPs)—SSP126, SSP245, SSP370, and SSP585—across three future timeframes: near-term (2015–2044), mid-term (2045–2074), and long-term (2075–2100). Under the high-emission SSP585 scenario, average temperatures are projected to rise by up to 3.76 °C, and annual precipitation could increase by 52.6%, reaching up to 3446.38 mm by the end of the century. The maximum temperature (Bio5) could reach 32.91 °C, while the minimum temperature (Bio6) might rise by 4.43 °C, particularly during winter. Precipitation seasonality (Bio15) is projected to increase by as much as 7.9% in the northwest, indicating heightened variability between wet and dry seasons. The diurnal temperature range (Bio2) is expected to decrease by up to − 1.3 °C, signifying reduced nighttime cooling, which could exacerbate heat stress. Significant reductions in temperature seasonality (Bio4) are forecast for the northeast, with notable declines in isothermality (Bio3) under SSP585, pointing to increased climatic extremes. These climatic shifts pose severe risks to agricultural productivity, water resource availability, and biodiversity, particularly in flood-prone regions. The findings highlight the need for urgent adaptation measures, including improved flood management systems, efficient water resource use, and climate-resilient agricultural practices. By providing robust region-specific projections, this study offers critical insights for policymakers and stakeholders to mitigate the adverse effects of climate change and safeguard environmental and economic sustainability in Bangladesh
Design characteristics of integrated surveillance of antimicrobial resistance at the human, animal, and environment interfaces
No full textEfforts have been made to strengthen national and global antimicrobial resistance (AMR) surveillance programs by integrating data collection across the human, animal, and environmental sectors. We searched the literature to review published studies reporting the implementation of integrated AMR surveillance approaches, and we identified a total of 96 articles from 36 countries published from 2000 to 2022, which met our inclusion criteria. Standard review protocols were applied in our study. Out of 96 studies, 47 (49%) articles integrated AMR analysis from human and animal (HA) populations, 24 (25%) considered human, animal, and environmental (HAE) samples together, 11 (12%) studies included animal and environment (AE) samples, and 12 (13%) integrated human and environmental (HE) surveillance. Human isolate-based and animal isolate-based surveillance were the most common study designs (38, 52.8%), with the remainder applying human case-based and isolate-based for animal populations (32, 44.4%). Finally, our results demonstrate that AMR studies on E. coli revealed a lower correlation between human and animal AMR prevalence compared to Salmonella spp. and Campylobacter spp. studies. Different aspects of surveillance design were associated with the level of correlation of AMR prevalence between sectors. Our study found that while global efforts for integrated AMR surveillance have increased in the past 10 years, significant variation exists between studies with regard to the epidemiological and laboratory aspects of their surveillance designs. Our findings indicate that to enable the generation of comparable epidemiological data across countries and sectors, there is a need for the development of a global protocol to support the design of surveillance programs that aim to conduct integrated surveillance of AMR
Detection and Characterisation of Colistin-Resistant Escherichia coli in Broiler Meats
No full textThe irrational use of antimicrobials has led to the emergence of resistance, impacting not only pathogenic bacteria but also commensal bacteria. Resistance against colistin, a last-resort antibiotic, mediated by globally disseminated plasmid-borne mobile colistin resistance (mcr) genes, has raised significant global concerns. This cross-sectional study aimed to investigate the antimicrobial resistance patterns of colistin-resistant Escherichia coli (E. coli) and mobilised colistin resistance (mcr 1–5) genes from broiler meat. A total of 570 broiler samples (285 liver and 285 muscle) were collected from 7 supermarkets and 11 live bird markets (LBMs) in Chattogram metropolitan areas of Bangladesh. The isolation and identification of E. coli were carried out using standard bacteriological and molecular techniques. Antimicrobial susceptibility testing (AST) was performed using the Kirby–Bauer disc diffusion method, and colistin’s minimum inhibitory concentration (MIC) was determined by the broth microdilution (BMD) method. Colistin-resistant isolates were further tested for the presence of mcr (1–5) genes using polymerase chain reaction (PCR). Out of the 570 samples, 311 (54.56%; 95% confidence interval: 50.46–58.60) were positive for E. coli. AST results showed the highest resistance to sulphamethoxazole–trimethoprim (89.39%), while the highest susceptibility was observed for cefalexin (62.70%). A total of 296 isolates (95.18%) were found to be multidrug-resistant (MDR), with the multiple antibiotic resistance (MAR) index ranging from 0.38 to 1. Additionally, 41 isolates (13.18%) exhibited resistance to five antimicrobial classes, with resistance patterns of CIP + SXT + AMP + DO + TE + CT. A total of 233 isolates (74.92%) were resistant to colistin (MIC > 2 mg/L). A strong correlation between colistin resistance and the presence of the mcr-1 gene was observed (r = 1). All phenotypic colistin-resistant E. coli isolates carried the mcr-1 gene, while no isolates were positive for mcr (2–5). The detection of mcr genes in E. coli strains from poultry sources poses a significant risk, as these resistance genes can be transferred to humans through the food chain. The prevalence of multidrug-resistant Escherichia coli and the mcr-1 gene in poultry products in Bangladesh presents a significant public health and food safety concern