I have completed two of the three proposed experiments for my honours project so far. I have completed the secondary seed dispersal experiment, looking at how tunneller dung beetle species, Onthophagous binodis, and dweller dung beetle species, Aphodius fimetarius, contribute to the ecosystem service of secondary seed dispersal in Australia by using beads as surrogates for seeds, and observing and recording if they take the bead seed mimics underground when creating brood balls, or if they move the beads around in general through their manipulation of the cattle dung, and the depths at which they take these broods. I have counted all the beads in the brood balls and am currently putting the data together in spreadsheets for analysis. I have also completed the roller experiments proposed using the arena. I used species Sisyphus spinipes and Sisyphus rubrus for these experiments and conducted a number of pilot studies looking at how far roller species take their brood balls, if they have preferential burial sites, and if they would take seeds within the dung (bead mimics) in their broods. The data from this experiment is ready for further analysis. At present and I am conducting the third proposed experiment for my honours project, which involves looking at the difference in gas emissions in frozen cattle dung vs. unfrozen cattle dung. For this experiment I am using the Gasmet machine in the zoology glasshouse for a period of time yet to be fully determined. Furthermore, I am in the process of organising the data collected from my experiments so I can analysis it statistically and make a series of graphs, and am also in the process of reading papers and writing my thesis.
I am now seven months into my MSc., investigating beetle diversity on Acacia host-plants along an environmental gradient. Since the last issue of Myrmecia I have been busy in the lab sorting through the Coleoptera specimens, which were collected over six seasons. Coleoptera from seasons 1-3 will be sorted into morphospecies by the end of October. Voucher specimens are being identified to family level, photographed and databased using Biota (biodiversity database manager). Photographs are being catalogued separately using Adobe Lightroom (see Figure 2). Preliminary results for the first two seasons (spring & summer) are showing that temperate sites host the highest beetle diversity, while the chrysomelids (leaf beetles) are currently the most diverse beetle taxa across the gradient.
I started my PhD investigating the interactions between two parasitoid wasps (Encarsia formosa and Eretmocerus warrae) and a predatory Hemiptera (Nesidiocoris tenuis) as natural enemies of greenhouse whitefly (Trialeurodes vaporariorum). Greenhouse grown tomatoes are an important industry in the New England area. The use of biological control can minimise or eliminate the need for chemical control of these pests. I will commence confirmation of identification of the parasitoid and whitefly species in the greenhouse and then undertake laboratory experiments to examine the feeding and oviposition preferences, the extent of multiparasitism, the level of competition and the outcome of interactions between these natural enemies. Greenhouse tests will then be conducted to determine the most effective combination for control of T. vaporariorum.
My temperature controlled chambers have been completed and are ready for the effects of temperature on dung beetle experiment. They work very well and I have high hopes for them. Currently I’m just waiting for beetle season to commence before beginning the experiment. In meantime I have been sorting through samples from my altitudinal gradient survey. As expected there are few beetles active in the winter months but there have been one or two surprise finds. It’s almost time to do another run to collect samples from my wonderful volunteers and drop off some more supplies. The endnote dung beetle library has been updated again and now has close to 1900 papers.
Acacia falcata plants exude a sugary substance from the leaf-like phyllodes that attracts various insects, particularly ants. Two ant species, an Iridomyrmex sp. and a Polyrhachis sp. both commonly harvest this sugary secretion from A. falcata. To locate this resource, ant’s antennal sensilla come in contact with volatiles that come off the secretion when it is exposed to air. The specific structures responsible for the detection of these volatiles are porous sensilla trichoidea/chaetica which appears on both Iridomyrmex sp. and Polyrhachis s.p antennae (see Figures). These structures can be found on all sides of each antennal flagellomere and increase in shape and number closer to the end of the antenna. By using Scanning and Transmission electron microscopy (SEM and TEM), I am able to determine the function of several antennal sensilla found on the Iridomyrmex sp. and Polyrhachis sp.
I have just finished the final experiments of my PhD project assessing the thermal tolerances of aphids (Myzus persicae). I have investigated the effect of repeated high temperature on many physiological characters such as thermal tolerance, respiration, and osmolytes such as polyols and sugars. Also, with using chemically defined diets, I have been revealing the central role of sucrose concentration, amino acid concentration and composition, and sucrose: amino acid ratio in shaping aphid performance, and examining the effect of these vital compounds on physiological character at high temperature. Finally I have been investigating the costs and benefits of different time of recovery between high temperature conditions by measurement important compounds and their thermal tolerance. I had presentation for some findings of my PhD at the sixth International Symposium on the Environmental Physiology of Ectotherms and Plants (ISEPEP6) in Aarhus, Denmark, 3-7 August 2015.
I am about to submit my thesis assessing the response of grassland Thysanoptera to climate. Thysanoptera were collected from Themeda triandra grasslands across a climatic gradient in NSW and Victoria, Australia across four seasons. The R package mvabund was used to determine how different species are associated with different environmental variables, and how environmental variables and morphological traits interact to determine abundance. It was found that mostly microclimate data obtained at tussock level was best at explaining the variation of thysanoptera abundances. Microclimate data at certain periods, such as during thysanoptera growth periods and near sampling, was important to consider in addition to annual means. I also simulated a warmer, drier climate by performing a transplant experiment across three different sites using both diploid and tetraploid Themeda triandra plants. I found that two species of thrips preferentially colonised foreign Themeda triandra when transplanted in the field. The indication that plants of foreign genotype could be particularly attractive to generalist herbivores may imply an increase in herbivory pressure on the plants when insect shift their range to accommodate changing climatic conditions.
School of Ants – Kirsti Abbott and Sarah Hill
Throughout the year, School of Ants has been engaging with citizens scientists across Australian to conduct a year long ecological project collecting data on the diet of dominant ground foraging ants in backyards, school grounds and adjacent bushland plots. As discussed in a previous lab update (July 2015) this synchronous collection has also coincided with full day educational visits each month in participating schools by Kirsti as part of the School of Ants on Tour program. Kirsti has visited schools in Lockhart, Brewarrina, Gympie, Longreach, Cairns, Alice Springs and Kununurra. To date we have identified over 1400 individuals which include 28 different species from over 25 locations around Australia. We have identified three invasive ant species: Trichomyrmex destructor at Longreach, Paratrechina longicornis in Cairns and Pheidole megacephala from numerous sites – Cairns, Bucasia, Longreach and Brewarrina.
But like all good things, we are coming to the end of our tour around the country. Two more collections, and schools left to visit until the data is in and more than 600 citizens around Australia will have engaged directly with collections, education days or ant festivals. We have 50 registered participants in this year’s attempt at collecting data synchronously each month, and excited to look at the patterns in the number and types of dominant ground foraging ants coming to food baits in high use school and backyards. Lots of great research projects will come out of this year, so if you’re interested in being part of the School of Ants team, keep your eyes on our website or sign up for emails. As part of our vision to see citizen science part of every day schooling around the country, we are developing a toolkit for teachers to start using in their classrooms in 2016. We are holding a teacher workshop at the University of Melbourne 5th December that will highlight for participants the strong links between science communication, research and education and give them resources to help embed citizen science into classrooms, whether formal or not. School of Ants’ new webpage is also due to be up and running in December. We’d love you to do a collection; help us uncover the diversity, distribution and diet of ants in your backyard.
I am currently preparing to start a large series of experiments that will investigate the effect of climate change on the dung burial ability of dung beetles. In these experiments, custom built climate controlled chambers will be used to expose dung beetles to the temperature regimes that are expected under climate change. The project is unique in that it will expose beetles to temperature regimes that fluctuate with the day-night cycle, rather than a simple fixed temperature. The amount of dung that is buried by different beetle species will be measured to test if climate change will hinder or enhance the crucial ecosystem services that dung beetles provide. I will also test if increasing species diversity enhances or inhibits ecosystem functioning (as measured by dung burial) under climate change. This project is funded by Dairy Australia.