Professor Gimme Walter
My associates and I approach ecological research as an interactive process between theory development and empirical investigation. We focus on the ecological requirements of individuals and species (autecology) as a basis for understanding the distribution and abundance of organisms, for interpreting local diversity (community structure) and for contributing to management strategies for pest species. The specific problems tackled include the extent and consequences of movement of organisms, clarification of the host relationships of phytophagous insects (including crop pests), the ecology of parasitoid wasps and insect pollination mechanisms in cycads. Overall, these efforts have led to the first formalisation of the structure of autecology, an approach that is particularly important in applied entomology.
Postdoctoral Research Fellows
Dr Michelle Rafter
The focus of my research is generalist horticultural insects that are pests of agriculture and stored products. Currently I am working collaboratively with Indian and Australian colleagues across several university and research institutes, to investigate the dispersal characteristics and fitness consequences of phosphine resistance of several key storage pests in the field. My most concerted research experience solved the conundrum of an invasive generalist pest that failed to attack its major horticultural host in Australia – why was this pest (the South African citrus thrips) not attacking its citrus host in Australia? This research incorporated several scientific disciplines including ecological host testing (Rafter et al. 2008, Rafter and Walter 2013a), behavioural assessments of mate recognition and reciprocal cross mating tests (Rafter and Walter 2013b), and population genetics (Rafter et al. 2013). The combined output from these assessments demonstrated conclusively that a cryptic species complex is present within S. aurantii, and that not all of them are host generalists, pests of horticulture or biosecurity risks. This finding has significant implications for current quarantine risk assessment in Australia (Rafter et al. 2013) as the horticultural pest that was thought to have invaded Australia in early 2000 in fact still remains offshore.
Dr Sharon van Brunschot
My research is focussed on investigating the intricate relationships between the insect pest Bemisia tabaci (whitefly), a group of damaging plant viruses they transmit (begomoviruses), and the microbial endosymbionts that are harboured by the insect host.
Whiteflies are a major global pest of many varied horticultural and agricultural crops. In Australia, they are a pest of cotton, causing feeding damage and contaminating lint with honeydew secretions. They are also vectors of the exotic plant-infecting virus complex that causes cotton leaf curl disease, a significant biosecurity threat to Australian cotton. Whiteflies, like many arthropods, harbour a diverse array of microbial endosymbionts. Recent research has demonstrated these maternally inherited bacteria can directly influence the biology, ecology and evolution of their arthropod hosts.
My current research aims to determine the influence of these endosymbionts on key processes such as host fitness, insecticide resistance, and plant virus transmission, to explore possibilities for manipulating these processes to control whitefly populations in the future.
Dr Graham McCulloch
My main area of research is the ecological and evolutionary genetics of insects. I have a particular interest in assessing how evolutionary traits, for example wing reduction and phosphine resistance, affect genetic structuring within and among populations.
My PhD research at the University of Otago focused on the evolutionary genetics of South Hemisphere stoneflies, specifically on how wingless stoneflies evolve, and how this wing loss shapes the biogeographic structuring of lineages. I am currently involved in the collaborative Australia-India Strategic Research Fund project focusing on two key pests of stored grain, Tribolium castaneum and Rhyzopertha dominica. My primary focus is determining the evolutionary origins and population structuring of these pests, as well as examining how phosphine resistance spreads through and among populations.
Dr James Hereward
I am currently working on the evolution of Glyphosate resistance in agricultural weeds, this work is funded by the Cotton Research and Development Corporation. I am using a number of NGS (Next Generation Sequencing) approaches to test whether genomic data can be used to find novel resistance mechanisms in barnyard grass and fleabane. My background is in population genetics and molecular ecology. In my previous research I have used molecular techniques to assess movement patterns, gene flow, host use (diet analysis), species status, and even fighting behaviour in a number of different insect species.
Dr Alicia Toon
My research is focused on biodiversity, biogeography and systematics of Australian plants, insects and birds. I use molecular tools to investigate how changes in our environment and interactions with other species shapes traits, distributions and diversity of species.
In the Walter lab, I am currently working on the population genetics of grain storage pests to infer the potential for the spread of phosphine resistance among Australian grain growing regions.
My PhD focusses on how endemic and threatened invertebrates inhabiting outback springs respond to their restricted and fluctuating surroundings. I approach this question from both a theoretical and empirical angle. In collaboration with Lauren Kaye we are looking at how ecologists approach questions about where organisms are and why, and particularly how language use carries theoretical baggage into modern theory. I am then applying these lessons into documenting what the springs are like as a habitat, and how the diverse species of snails that have evolved in springs respond to their environment. Are all species found in all springs? Or in all areas of springs? And if not, why? What is the specific environmental response system of each species that maintains their patchy distribution? This work also lets me spend lots of time in western Queensland where I have worked previously in the Walter lab fostering outreach efforts with rural and Indigenous high school students aimed at raising aspirations to work in biological sciences and pursue tertiary education.
Tribolium castaneum, the rust-red flour beetle, is a globally important pest of stored grain products. Fumigation with phosphine is used to protect global food reserves from these insect pests. Chemically, phosphine is a strong reducing agent that can disrupt energy metabolism in aerobically respiring organisms, leading to a decrease in ATP synthesis. T. castaneum has evolved resistance to phosphine fumigation, mainly through genetic changes that affect basic metabolic pathways. Are other activities reliant on metabolic enzymes including movement also affected through genetic changes leading to phosphine resistance?
My PhD project investigates the dispersal behaviour of phosphine resistant populations of T. castaneum to find if phosphine resistance alleles have any pleiotropic effect. Since movement play an important role in evolution and spread of phosphine resistance into new area, this understanding will help for more effective resistance management strategies.
Insect pest infestations lead to significant food and economic loss. The primary means of dealing with insect infestation in food grains is phosphine fumigation. However, common grain pests like Rhyzopertha dominica (lesser grain borer) and Tribolium castaneum (red rust flour beetle) have developed resistance to phosphine. This challenges current grain pest management protocols. Hence, development of new control methods and application strategies that reduce the risk of resistance are essential.
My PhD project is focused on the use of external and internal markers for beetle pests of stored grain for mark and recapture studies and age determination. The other aspect of my PhD involves studying the flight behaviour of field Tribolium castaneum by laboratory simulations and relating this with different aspects like age, fecundity and polyandry. It is hoped that the markers and tests will assist in better understanding of phosphine resistance and its relation with the pests’ ecology and behaviour.
My research focuses on the host use of the green mirids (Hemiptera: Creontiades dilutus) in central and eastern Australia. These small bugs are extreme generalists that feed on over 100 species of plants from the deserts in the continental interior and from crops across Queensland and New South Wales. In agricultural regions they are the primary pest of cotton crops, despite observations that green mirid populations in cotton build up much slower relative some alternative crops.
In particular, I am investigating why mirids choose to feed on cotton (an apparent poor-quality host) when apparently better-quality host plants are available. My approach is to use a combination of field and molecular techniques to identify consistent foraging patterns in mirid food choices within natural and agricultural settings. Once consistent foraging behaviours are identified, then the environmental and physiological basis for host choice can be determined. My findings will be evaluated in the context of both quantitative autecology and traditional demographic ecology to explore how we as ecologists can interpret the concept of “host quality” in meaningful ways.
My awesome research focusses on Tribolium castaneum, the rust red flour beetle. These beetles are a major pest of bulk stored grain products across the globe and infest a variety of economically important grains including wheat, maize and sorghum. Bulk stored cotton seeds are also heavily infested with T. castaneum, but the insects do not consume the seeds. Instead, the beetles are attracted to the cotton seeds because of the fungal species that infest the lint on the seeds, though the identity of these species is not well known. This is significant because little is known about the ecology of T. castaneum outside of grain storage and its association with microorganisms. Furthermore, the volatiles produced by these attractive fungal species could be used to improve the chemical lures designed to monitor T. castaneum in the field. My thesis investigates the attraction of T. castaneum to specific fungal species, isolated from linted cotton seeds, and the chemical compounds that those species produce.
The Grey Falcon Falco hypoleucos is Australia’s rarest bird of prey and one of the rarest falcons in the world; its estimated total population size is less than 1000 individuals. Its habitat is the arid and semi-arid interior of the continent, an environment characterized by an extreme and unpredictable climate. The species’ breeding distribution appears to be confined to areas of the highest temperature zones, and I am interested in how the species manages to persist at low density in its habitat, which is characterised by periods of boom and bust. Of key concern is the way in which the species-specific interactions with the environment actually affect the spatio-temporal dynamics of the individuals. To establish how the birds use the environment over time, selected individuals are tracked short- and long-term, and possibly across landscapes, by using satellite telemetry. Further of interest is the prolonged juvenile dependence period, which is unusual among falcons and other raptors of similar size. The question how individuals recruit mates, given the extremely low density of the species over an expansive distribution area, is a further topic I am interested in. Understanding the mechanisms behind the Grey Falcon’s survival strategy will both provide insights into the functioning of arid ecosystems and benefit the management of these systems.
The large cabbage moth (Crocidolomia pavonana) is a widespread pest of Brassica crops in many parts of world. A biological control program is desired for the control of C. pavonana, but until recently no effective natural enemies were known. A population of a minute parasitoid wasp (Trichogramma chilonis) in Samoa appears to be a good candidate for development as a biological control agent for the pest. However, unusual patterns of host use in Samoa as well as historical taxonomic confusion in the group warrants investigation into the species status of the wasp. My research uses molecular techniques to address questions surrounding the identity and origin of the Trichogramma population in Samoa, and to assess if there is gene flow between wasps utilising different host eggs in the agricultural landscape.
My research focuses on flower thrips Frankliniella schultzei, a pest on cotton and found in a range of garden plants in the Brisbane region. I am testing in the field, through flower sampling and sticky trapping, how thrips respond to weather variables including rainfall, air pressure, temperature, humidity and wind, and if sensitivity to changing weather helps them avoid exposure to rainy weather. I am also investigating the cues used by these insects to find and choose between two major flower hosts, Hibiscus rosasinensis and Malvaviscus arboreus. This second aim involves field choice tests to determine relative colonisation rates between the two flowers, and testing the role of flower scent in the thrips’ flower choice in the laboratory.
I am using differential gene expression analysis to examine some of the interesting patterns of host-plant use by the green mirid, Creontiades dilutus. The majority of herbivorous insects like the green mirid have very specific relationships with one or only a small number of host-plant species. The green mirid, however, has been identified at different developmental life stages on more than 100 plant species. These host-plants have been described as being either good or poor hosts depending on the relative abundance of green mirids found on each species. I am studying the differential genetic response of green mirids when they are associated with a number of host-plants of different quality. I am including Australian native endemic host-plants and agricultural crop species in my study as the green mirid is endemic to the arid regions of central Australia and has emerged as a pest of economically important crops such as cotton with changing insect pest management regimes in the last decade.
Michelle Gleeson – BugsEd
Michelle is an entomologist and director of Bugs Ed., an insect education business based in Brisbane which delivers interactive insect workshops to around 10,000 children across Queensland each year. As an adjunct industry fellow with UQ, Michelle uses her passion for teaching to consult and coordinate various outreach and educational programs within the School of Biological Sciences. Michelle also collaborates on field research projects within the Walter Lab.
Dr Andrew Ridley – Queensland Department of Agriculture and Fisheries
Andrew is an Entomologist in the Postharvest Grain Protection Unit of the Queensland Department of Agriculture and Fisheries. He works on a variety of research projects involving grain storage ranging from the development of a device to allow farmers to test the performance of their aeration systems, to investigating the sublethal effects of phosphine on stored product pests and the spread of phosphine resistance genes in the field by active dispersal of beetles.
Dr Greg Daglish – Queensland Department of Agriculture and Fisheries
Greg works for the Queensland Department of Agriculture and Fisheries, and conducts research on the ecology and management of insects that attack grain after harvest. Greg’s aim is to provide the grain industry and their advisers with recommendations based on sound science. In recent years, DAF-UQ collaborative efforts have major insights into the field ecology of major pests, and these have implications for pest and resistance management.
Dr Raghu Sathyamurthy
Raghu works with CSIRO. His interests are in understanding ecological and evolutionary aspects of plant-herbivore interactions, with a view to assisting weed/pest management.
Header pictures by Renee Rossini and Rehan Silva. Used with permission.