Parasitoids of the uniquely social colletid bee Amphylaeus morosus (Hymenoptera: Colletidae) in Victoria

Understanding how nest parasites contribute to brood mortality rates in host species is an important step towards uncovering the potential implications for host behaviour. This can be especially important for understanding the evolution of social living, where defence against parasites is often posited as a major benefit of cooperative nesting. Only two parasitoid species have previously been reported for the only known social colletid bee, Amphylaeus morosus: the gasteruptiid wasp, Gasteruption primotarsale, and the mutillid, Ephutomorpha tyla. Here we report six additional parasitoid species of A. morosus: the gasteruptiid wasps G. atrinerve, G. globiceps, G. melanopoda and G. cinerescens; the bombyliid fly Anthrax maculatus; and the mutillid wasp Ephutomorpha aff. varipes. The mechanisms of parasitism for these eight parasitoid species are described in combination with how they operate throughout the host brood rearing period and whether benefits of social nesting vary across the season.

Novel System to Monitor In Vivo Neural Graft Activity After Spinal Cord Injury

Expectations for neural stem/progenitor cell (NS/PC) transplantation as a treatment for spinal cord injury (SCI) are increasing. However, whether and how grafted cells are incorporated into the host neural circuit and contribute to motor function recovery remain unknown. The aim of this project was to establish a novel non-invasive in vivo imaging system to visualize the activity of neural grafts by which we can simultaneously demonstrate the circuit-level integration between the graft and host, and the contribution of graft neuronal activity to host behaviour. We introduced Akaluc, a newly engineered luciferase, under control of a potent neuronal activity-dependent synthetic promoter, E-SARE, into NS/PCs and engrafted the cells into SCI model mice. Through the use of this system, we reveal that the activity of grafted cells was integrated with host behaviour and driven by host neural circuit inputs. This non-invasive system is expected to help elucidate the therapeutic mechanism of cell transplantation treatment for SCI and determine better therapy techniques that maximize the function of cells in the host circuit.

Neofunctionalization of an ancient domain allows parasites to avoid intraspecific competition by manipulating host behaviour

Intraspecific competition is a major force in mediating population dynamics, fuelling adaptation, and potentially leading to evolutionary diversification. Among the evolutionary arms races between parasites, one of the most fundamental and intriguing behavioural adaptations and counter-adaptations are superparasitism and superparasitism avoidance. However, the underlying mechanisms and ecological contexts of these phenomena remain underexplored. Here, we apply the Drosophila parasite Leptopilina boulardi as a study system and find that this solitary endoparasitic wasp provokes a host escape response for superparasitism avoidance. We combine multi-omics and in vivo functional studies to characterize a small set of RhoGAP domain-containing genes that mediate the parasite’s manipulation of host escape behaviour by inducing reactive oxygen species in the host central nervous system. We further uncover an evolutionary scenario in which neofunctionalization and specialization gave rise to the novel role of RhoGAP domain in avoiding superparasitism, with an ancestral origin prior to the divergence between Leptopilina specialist and generalist species. Our study suggests that superparasitism avoidance is adaptive for a parasite and adds to our understanding of how the molecular manipulation of host behaviour has evolved in this system.

Novel System to Monitor In Vivo Neural Graft Activity After Spinal Cord Injury

Expectations for neural stem/progenitor cell (NS/PC) transplantation as a treatment for spinal cord injury (SCI) are increasing. However, whether and how grafted cells are incorporated into the host neural circuit and contribute to motor function recovery remain unknown. The aim of this project was to establish a novel non-invasive in vivo imaging system to visualize the activity of neural grafts by which we can simultaneously demonstrate the circuit-level integration between the graft and host, and the contribution of graft neuronal activity to host behaviour. We introduced Akaluc, a newly engineered luciferase, under control of a potent neuronal activity-dependent synthetic promoter, E-SARE, into NS/PCs and engrafted the cells into SCI model mice. Through the use of this system, we reveal that the activity of grafted cells was integrated with host behaviour and driven by host neural circuit inputs. This non-invasive system is expected to help elucidate the therapeutic mechanism of cell transplantation treatment for SCI and determine better therapy techniques that maximize the function of cells in the host circuit.

Parasite immune evasion and manipulation of host phenotype

All parasites manipulate their hosts by interference with immune defences and host behaviour. Passive evasion, for example, is by molecular mimicry or by changing surfaces. Active interference involves production of molecules that block or modify host immune defence regulation or affect metabolism and neuronal systems. All steps of the immune defence cascades are attacked by parasites, including the microbiota. Manipulation can increase the duration of infection or transmission success. The latter is particularly prominent in intermediate hosts that need to be consumed by a final host. Host fecundity reduction and gigantism provide extra resources for the parasite. Theory can predict what manipulation should be best; conflicts arise among co-infecting parasites.

The call of the wild: using non-model systems to investigate microbiome–behaviour relationships

ABSTRACT On and within most sites across an animal's body live complex communities of microorganisms. These microorganisms perform a variety of important functions for their hosts, including communicating with the brain, immune system and endocrine axes to mediate physiological processes and affect individual behaviour. Microbiome research has primarily focused on the functions of the microbiome within the gastrointestinal tract (gut microbiome) using biomedically relevant laboratory species (i.e. model organisms). These studies have identified important connections between the gut microbiome and host immune, neuroendocrine and nervous systems, as well as how these connections, in turn, influence host behaviour and health. Recently, the field has expanded beyond traditional model systems as it has become apparent that the microbiome can drive differences in behaviour and diet, play a fundamental role in host fitness and influence community-scale dynamics in wild populations. In this Review, we highlight the value of conducting hypothesis-driven research in non-model organisms and the benefits of a comparative approach that assesses patterns across different species or taxa. Using social behaviour as an intellectual framework, we review the bidirectional relationship between the gut microbiome and host behaviour, and identify understudied mechanisms by which these effects may be mediated.

Comparing the host behaviour of roof-shaped compounds trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid and its dimethyl ester in the presence of mixtures of xylene and ethylbenzene guests

Here we compare the host behaviour of two roof-shaped compounds, trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid H1 and its dimethyl ester, trans-dimethyl 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylate H4, when presented with mixed xylene (o-Xy, m-Xy and p-Xy) and...

Infectious disease and sickness behaviour: tumour progression affects interaction patterns and social network structure in wild Tasmanian devils

Infectious diseases, including transmissible cancers, can have a broad range of impacts on host behaviour, particularly in the latter stages of disease progression. However, the difficulty of early diagnoses makes the study of behavioural influences of disease in wild animals a challenging task. Tasmanian devils ( Sarcophilus harrisii ) are affected by a transmissible cancer, devil facial tumour disease (DFTD), in which tumours are externally visible as they progress. Using telemetry and mark–recapture datasets, we quantify the impacts of cancer progression on the behaviour of wild devils by assessing how interaction patterns within the social network of a population change with increasing tumour load. The progression of DFTD negatively influences devils' likelihood of interaction within their network. Infected devils were more active within their network late in the mating season, a pattern with repercussions for DFTD transmission. Our study provides a rare opportunity to quantify and understand the behavioural feedbacks of disease in wildlife and how they may affect transmission and population dynamics in general.