2018 Completion Abstracts
Talk Title: Learning, Memory and Cue Choice in Navigating Ants
Abstract: A critical reoccurring challenge facing mobile animals is the need to reliably find goal locations (e.g. food or the nest). To solve this problem, animal navigators acquire and use multiple cue sets within their environment, which designate direction and distance estimates of these locations. Navigational cues can conflict, which adds a further challenge, requiring the navigator to integrate these cues before moving. Foraging ants are expert visual navigators known to use both learned panorama cues and path integration to navigate. Here we examine the navigational memory, learning and cue choice in the Australian desert ant species, Melophorus bagoti. M. bagoti is a solitary foraging desert ant endemic to Central Australia. In Experiment 1, we show that foragers retain robust memories of both the nest skyline and multiple non-nest site skylines. Forager orientation performance shows evidence of retroactive interference after changes are made to the skyline at the same site. In Experiment 2, when M. bagoti foragers are presented with cue conflicts between the terrestrial and celestial cue sets, foragers appear to choose dynamically based on experience and cue reliability in accordance with the Temporal Weighting Rule. In Experiment 3 we tested foragers with directional conflicts in their inbound and outbound routes. Foragers repeatedly presented this conflict show evidence of rapid vector calibration to the inbound route. This calibration appears to have a directional limit of around 45˚. Finally, in Experiment 4 we tested foragers ability to learn panorama cues away from the nest. When foragers are restricted to the nest site, they appear unable to extrapolate panorama cues from the nest to local sites. Yet, these foragers only require one experience of the homeward route to learn the correct nest direction. Furthermore, exposure to the outbound foraging path appears critical for efficient homeward route formation in this species.
Talk Title: Causes and consequences of individual forager variability in social bees
Abstract: In social bees, it is assumed that behavioural variability among foragers contributes to an optimisation of colony performance. The causes and consequence of such inter-individual variability are not well understood. Using an automatic tracking system, I showed that honey bees and bumblebees foragers exhibit high inter-individual variability within their colonies. Then, using manipulative experiments, I found that bees exhibit consistent different behaviours in a spatial learning task and that pesticides impair visual learning. These results highlight the fact that behavioural diversity can be an adaptation for social insects, as well as a potential dimension of colony-level vulnerability to environmental stressors.
Talk Title: The neural mechanisms of honey bee (Apis mellifera) social cohesion
Abstract: The development and neurobiology of sociability and subsequent affiliations between group members have been extensively studied in mammals, particularly monogamous prairie voles and their lifelong partnerships. Eusocial insects depend upon group members being highly sociable for their individual and group survival, yet their sociability has not been examined. Furthermore, honey bees (Apis mellifera) are a model organism of insect neurobiology, providing an excellent opportunity to explore the neural mechanisms of insect sociability and social affiliations. I will talk you through my rationale for comparing vertebrate and eusocial insect group cohesion and present the behavioural assay I developed to directly compare findings in bees and vertebrates. I will then present the results of neuropharmacological manipulations paired with the assay, and tie it together with an insect-inclusive theory of how sociality may possibly have come about. To wrap up In collaboration with the Evolutionary Genetics Department at Heinrich Heine University, Germany, I also developed a contemporary neuroimaging tool for the bee that offers the possibility to visualise whole-brain circuit activation in freely moving animals, ideal for studying the neurobiology of social behaviours. I will briefly explain the development of this with you.
Talk Title: Effect of short-term cool storage to assist mass rearing of two dipterans: Exorista larvarum (L.) and Bactrocera tryoni (Froggatt)
Abstract: Cool storage is a valuable technology for prolonging the developmental time of insects and thus increasing the efficiency of insect rearing. Rearing techniques providing high-quality insects are essential for pest control strategies entailing mass rearing and release in the field, such as augmentative biological control and Sterile Insect Technique (SIT). The advantages that this technology offers include a more flexible rearing schedule, the possibility to overcome periods of low production and the synchronisation of field releases during pest outbreaks. Cool storage of two model fly species, Exorista larvarum (L.) (Diptera: Tachinidae) and Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), was studied in my thesis by investigating the best conditions for an efficient storage and the consequences for fly quality. Native to the Palearctic region, E. larvarum is a parasitoid introduced in the USA as a biological control agent of Lymantria dispar (L.). The possibility to store the tachinid eggs at suboptimal temperatures once placed on artificial medium was evaluated. Results showed that cool storage of this tachinid fly is possible to create a useful reserve of immature, but the quality of the resulting females can be compromised. Bactrocera tryoni (Queensland fruit fly, Q-fly) is an endemic phytophagous species that represents a serious challenge for Australian growers, attacking many commercial fruit and vegetable crops. At present, a SIT program is in place for controlling this pest. Part of my thesis investigated the effects of cool storage on 1-day old Q-fly pupae for use in rearing programs. Survival and quality of the resulting adults were assessed and negative effects, of various intensity, were shown on standard and non-standard quality control parameters.
Md. Mohasinul Hasque
Talk Title: Knowns and Unknowns: An Assessment of Knowledge Shortfalls in the Digitised Collection of Australia’s Flora
Abstract: Massive digitisation of natural history collections (NHC), the predominant source of primary biodiversity data (i.e. species occurrence information), has provided myriad opportunities for studying on biological diversity across space and time. Despite recent efforts to collate centuries of biodiversity inventories into comprehensive databases, these collections suffer inherent limitations in their spatial, temporal and taxonomic dimensions. Identifying these limitations is a priority to ensure that multiple targets specified by the Convention on Biological Diversity are met. In this thesis, which consists of four data chapters, I assess spatial, temporal and taxonomic patterns in the digitisation of data held within the Australasian Virtual Herbarium (AVH) – the largest electronic source of plant occurrence records in the country. In Chapter 2, I document spatial biases in the number of occurrence records from across Australia, with the Human Influence Index being a strong predictor of this bias. In Chapter 3, I demonstrate temporal biases, with 80% of records collected from 1970-1999. Further, only 18% of the continent is represented by a relatively complete inventory consistently sampled over the last 200 years. I also found that around 25% of digitised specimens are missing key attribute information (i.e. collection date, taxonomic identification or geographic coordinates). An assessment of taxonomic bias in Chapter 4 indicates that, for one-third of Australia’s plant families, the number of preserved specimens per family is not proportional to the family’s known species richness. There is also a strong positive correlation between the number of collectors sampling a family and the taxonomic bias of that family. Finally, in Chapter 5, I demonstrate that digitisation effort over the last three decades varies significantly among Australia’s herbaria: a time lag in digitisation means that only 28% of specimens are digitised within a year of collection. As the uses of primary biodiversity data continue to expand, my findings can direct future strategic sampling and digitisation efforts to increase our knowledge of Australia’s flora.