An invasive human commensal and a native marsupial maintain tick populations at the urban fringe.

Ticks (Acari: Ixodidae) are major disease vectors globally making it increasingly important to understand how altered vertebrate communities in urban areas shape tick population dynamics. In urban landscapes of Australia, little is known about which native and introduced small mammals maintain tick populations preventing host-targeted tick management and leading to human-wildlife conflict. Here, we determined (1) larval, nymphal, and adult tick burdens on host species and potential drivers, (2) the number of ticks supported by the different host populations, and (3) the proportion of medically significant tick species feeding on the different host species in Northern Sydney. We counted 3551 ticks on 241 mammals at 15 sites and found that long-nosed bandicoots (Perameles nasuta) hosted more ticks of all life stages than other small mammals but introduced black rats (Rattus rattus) were more abundant at most sites (33%-100%) and therefore important in supporting larval and nymphal ticks in our study areas. Black rats and bandicoots hosted a greater proportion of medically significant tick species including Ixodes holocyclus than other hosts. Our results show that an introduced human commensal contributes to maintaining urban tick populations and suggests ticks could be managed by controlling rat populations on urban fringes.

Urban children's connections to nature and environmental behaviors differ with age and gender.

Global conservation is increasingly reliant on young people forming meaningful connections with urban nature. However, interactions with nearby nature do not inspire all children and adolescents living in cities to act pro-environmentally. Our survey of over 1,000 school students from Sydney, Australia, revealed that 28% of respondents maintained strong nature connections. Younger students (aged 8-11) were more strongly connected with nature than their older peers (aged 12-14), and environmental behaviors were negatively associated with increasing age. Differences between boys and girls were less consistent, resulting in part from differential functioning of questionnaire items. Regardless, girls were more willing than boys to volunteer for conservation. Our findings suggest that policies designed to strengthen urban children's nature connections will be most effective if they explicitly address the "adolescent dip" and other emerging demographic patterns, thereby ensuring all young people reap the health, wellbeing, and conservation benefits of connecting with nature.

A global horizon scan of the future impacts of robotics and autonomous systems on urban ecosystems.

Technology is transforming societies worldwide. A major innovation is the emergence of robotics and autonomous systems (RAS), which have the potential to revolutionize cities for both people and nature. Nonetheless, the opportunities and challenges associated with RAS for urban ecosystems have yet to be considered systematically. Here, we report the findings of an online horizon scan involving 170 expert participants from 35 countries. We conclude that RAS are likely to transform land use, transport systems and human-nature interactions. The prioritized opportunities were primarily centred on the deployment of RAS for the monitoring and management of biodiversity and ecosystems. Fewer challenges were prioritized. Those that were emphasized concerns surrounding waste from unrecovered RAS, and the quality and interpretation of RAS-collected data. Although the future impacts of RAS for urban ecosystems are difficult to predict, examining potentially important developments early is essential if we are to avoid detrimental consequences but fully realize the benefits.

Invasive rabbits host immature Ixodes ticks at the urban-forest interface.

Introduced wildlife may be important alternative hosts for generalist ticks that cause health issues for humans and companion animals in urban areas, but to date are rarely considered as part of the tick-host community compared to native wildlife. In Australia, European rabbits, Oryctolagus cuniculus, are a widespread and abundant invasive species common to a range of human-modified ecosystems. To understand the potential role of rabbits in the life cycle of Australian ticks, we investigated the seasonal abundance of all tick life stages (larva, nymph, and adult) on rabbits collected from pest control programs in two urban forest remnants in Sydney, Australia. We also recorded whether larvae, nymphs, and adults were attached to the head, body, or limbs of rabbits to reveal patterns of tick attachment. Of the 2426 Ixodes ticks collected from 42 rabbits, larvae were by far the most abundant life stage (2360), peaking in abundance in autumn, while small numbers of nymphs (62) and adults (4) were present in winter and summer respectively. Larvae were found all over the body, whereas adults and nymphs were predominantly attached to the head, suggesting that the mature life stages use the host landscape differently, or that adults or nymphs may be groomed off the body. The most abundant tick species, as determined by morphology and DNA sequencing, was Ixodes holocyclus, a generalist tick responsible for significant human and companion animal health concerns in Australia. Our findings highlight the importance of understanding the role of introduced wildlife in tick dynamics particularly in novel ecosystems where non-native hosts may be more abundant than native hosts.

Acute exposure to urban air pollution impairs olfactory learning and memory in honeybees.

While the ecological effects of pesticides have been well studied in honeybees, it is unclear to what extent other anthropogenic contaminants such as air pollution may also negatively affect bee cognition and behaviour. To answer this question, we assessed the impacts of acute exposure to four ecologically relevant concentrations of a common urban air pollutant-diesel generated air pollution on honeybee odour learning and memory using a conditioned proboscis extension response assay. The proportion of bees that successfully learnt odours following direct air pollution exposure was significantly lower in bees exposed to low, medium and high air pollutant concentrations, than in bees exposed to current ambient levels. Furthermore, short- and long-term odour memory was significantly impaired in bees exposed to low medium and high air pollutant concentrations than in bees exposed to current ambient levels. These results demonstrate a clear and direct cognitive cost of air pollution. Given learning and memory play significant roles in foraging, we suggest air pollution will have increasing negative impacts on the ecosystem services bees provide and may add to the current threats such as pesticides, mites and disease affecting colony fitness.

Counting Ticks (Acari: Ixodida) on Hosts Is Complex: A Review and Comparison of Methods.

Locating and counting parasites on a host is a fundamental aspect of ecological research and basic veterinary and clinical practice. Variability in the biology and behavior of both hosts and parasites creates many methodological, logistical, and ethical considerations that must be made to collect this deceptively simple measurement. We identified methods that are used to count ticks (Acari: Ixodida, Leach 1815) on hosts by reviewing the methods sections of relevant published studies. Unfortunately, there is no best method agreed upon by scientists to collect ticks from hosts. In general, we suggest that studies focusing purely on counting ticks on hosts should use more sensitive methods to determine patterns of tick distribution on the surfaces of unconscious or deceased hosts in order to provide host body regions to target in future studies to maximize tick detection ability and limit the costs of research for researchers and the host animals involved. As ticks are counted on hosts for many different reasons, researchers must be goal oriented and chose methods that are appropriate for addressing their specific aims.

Peri-urban black rats host a rich assembly of ticks and healthier rats have more ticks.

The black rat Rattus rattus has a distribution that includes much of Earth's terrestrial surface, and has adapted to exploit both habitats extensively modified by humans and rural habitats. Despite the fact that R. rattus are nearly ubiquitous, few studies have investigated urban or peri-urban R. rattus as potential hosts for ticks. In this study, we identified the species of ticks that parasitize R. rattus in a remnant bush area within Sydney, Australia. We then examined the relationship between ticks and R. rattus by testing several rat body characteristics as predictors of tick abundance. We show that larva and nymphs of five species of native Australian tick parasitize R. rattus in urban Australia. The most abundance species was Ixodes holocyclus, a tick of veterinary and human health concern. We found that ticks were more abundant on R. rattus in better condition, for larva and nymphs of I. holocyclus and I. tasmani. Rattus rattus supports a rich assembly of ticks in a remnant forest in urban Australia, and as the R. rattus in best condition have the most ticks, tick parasitism at the levels observed does not appear to negatively impact R. rattus. Our findings illustrate that R. rattus, and other human commensal species, may be important hosts for ticks in human modified environments.

Oviposition Behavior of Culex annulirostris (Diptera: Culicidae) Is Affected by the Recent Presence of Invasive Gambusia holbrooki (Cyprinodontiformes: Poeciliidae).

Constructed wetlands are popular tools for managing threatened flora and fauna in urban settings, but there are concerns that these habitats may increase mosquito populations and mosquito-related public health risks. Understanding the interactions occurring between mosquitoes of public health concern and co-occurring organisms is critical to informing management of these habitats to mitigate potential health risks and balance the multiple values of urban wetlands. This study examined how oviposition behavior of Culex annulirostris Skuse, the most important pest mosquito species associated with freshwater wetland habitats in Australia, is influenced by the presence of Gambusia holbrooki Girard, a widespread invasive fish. Water was collected from urban wetlands that are intensively managed to reduce G. holbrooki populations to assist conservation of locally threatened frogs, and adjacent unmanaged wetlands where G. holbrooki was abundant. Laboratory experiments were conducted to examine the oviposition response by Cx. annulirostris to water samples from these two habitats. Experiments were conducted on two occasions, once in February following draining and refilling of the urban wetlands, and repeated following a substantial rainfall event in March. The results clearly demonstrate that ovipositing mosquitoes were able to detect and avoid water derived from habitats containing fish, even in the absence of the fish themselves. Understanding how invasive species affect the behavior and spatial distribution of pest species such as Cx. annulirostris will enable future wetland design and management to maximize benefits of urban wetlands and minimize potential public health risks.

Landscapes within landscapes: A parasite utilizes different ecological niches on the host landscapes of two host species.

Parasites are distributed across populations of hosts, but also across microhabitats on or inside hosts: together the host population distribution and "host landscape" distribution comprise a part of the ecological niche of a parasite. In this paper we examine how a generalist parasite, the tick Ixodes holocyclus, is distributed at both the host population and host landscape scales in two species of host (Perameles nasuta and Rattus rattus) that co-occur. We anaesthetized wildlife to locate ticks from five generalized host body regions; we then analysed the distribution of ticks among the populations of hosts (aggregation) and the distribution of ticks among the available host body regions as niches. Ixodes holocyclus is more aggregated in the R. rattus population. At the host landscape scale, I. holocyclus's utilized niche includes the entire surface of P. nasuta equally, while the niche on R. rattus is focused on the head. Differences in tick aggregation between host species may reflect tick habitat suitability at the host landscape scale, as well as differences in ecological and evolutionary histories. By exploring the distribution of parasites at multiple scales, including host landscapes, we can better understand the complex ecology of parasites.

Urbanisation and wing asymmetry in the western honey bee (Apis mellifera, Linnaeus 1758) at multiple scales.

Changes in the mean and variance of phenotypic traits like wing and head morphology are frequently used as indicators of environmental stress experienced during development and may serve as a convenient index of urbanization exposure. To test this claim, we collected adult western honey bee (Apis mellifera Linnaeus 1758, Hymenoptera, Apidae) workers from colonies located across an urbanization gradient, and quantified associations between the symmetries of both wing size and wing shape, and several landscape traits associated with urbanization. Landscape traits were assessed at two spatial scales (three km and 500 m) and included vegetation and anthropogenic land cover, total road length, road proximity and, population and dwelling density. We then used geometric morphometric techniques to determine two wing asymmetry scores-centroid size, a measure of wing size asymmetry and Procrustes distance, a measure of wing shape asymmetry. We found colony dependent differences in both wing size and shape asymmetry. Additionally, we found a negative association between wing shape asymmetry and road proximity at the three km buffer, and associations between wing shape asymmetry and road proximity, anthropogenic land cover and vegetation cover at the 500 m buffer. Whilst we were unable to account for additional variables that may influence asymmetry including temperature, pesticide presence, and parasitism our results demonstrate the potential usefulness of wing shape asymmetry for assessing the impact of certain landscape traits associated with urbanization. Furthermore, they highlight important spatial scale considerations that warrant investigation in future phenotypic studies assessing urbanization impact.

Effect of copper on multiple successional stages of a marine fouling assemblage.

Copper based paints are used to prevent fouling on the hulls of ships. The widely documented effect of copper on hull assemblages may be primarily due to direct effects on the invertebrates themselves or indirect effects from copper absorbed into the microbial biofilm before settlement has commenced. Artificial units of habitat were exposed to varied regimes of copper to examine (1) the photosynthetic efficiency and pigments of early-colonising biofilms, and (2) subsequent macroinvertebrate assemblage change in response to the different regimes of copper. Macroinvertebrate assemblages were found to be less sensitive to the direct effects of copper than indirect effects as delivered through biofilms that have been historically exposed to copper, with some species more tolerant than others. This raises further concern for the efficacy of copper as a universal antifoulant on the hulls of ships, which may continue to assist the invasion of copper-tolerant invertebrate species.

Effectiveness of vegetation-based biodiversity offset metrics as surrogates for ants.

Biodiversity offset schemes are globally popular policy tools for balancing the competing demands of conservation and development. Trading currencies for losses and gains in biodiversity value at development and credit sites are usually based on several vegetation attributes combined to yield a simple score (multimetric), but the score is rarely validated prior to implementation. Inaccurate biodiversity trading currencies are likely to accelerate global biodiversity loss through unrepresentative trades of losses and gains. We tested a model vegetation multimetric (i.e., vegetation structural and compositional attributes) typical of offset trading currencies to determine whether it represented measurable components of compositional and functional biodiversity. Study sites were located in remnant patches of a critically endangered ecological community in western Sydney, Australia, an area representative of global conflicts between conservation and expanding urban development. We sampled ant fauna composition with pitfall traps and enumerated removal by ants of native plant seeds from artificial seed containers (seed depots). Ants are an excellent model taxon because they are strongly associated with habitat complexity, respond rapidly to environmental change, and are functionally important at many trophic levels. The vegetation multimetric did not predict differences in ant community composition or seed removal, despite underlying assumptions that biodiversity trading currencies used in offset schemes represent all components of a site's biodiversity value. This suggests that vegetation multimetrics are inadequate surrogates for total biodiversity value. These findings highlight the urgent need to refine existing offsetting multimetrics to ensure they meet underlying assumptions of surrogacy. Despite the best intentions, offset schemes will never achieve their goal of no net loss of biodiversity values if trades are based on metrics unrepresentative of total biodiversity.

A multistressor, multitrait approach to assessing the effects of wind and dust on Eucalyptus tereticornis.

PREMISE OF THE STUDY: Plants are routinely subjected to multiple environmental stressors, and the ability to respond to these stressors determines species survival and ecological breadth. Despite stressors such as wind and dust significantly influencing plant development, morphology, and chemistry, the combined influence of these factors is yet to be investigated. METHODS: We used a manipulative glasshouse approach to compare the morphological, physiological, and biomechanical responses of Eucalyptus tereticornis to the independent and combined effects of wind and dust. KEY RESULTS: Wind decreased both E. tereticornis height and stem flexural stiffness. Additionally, wind had no effect on leaf physiology, nor did dust have any significant effect on any of the traits measured. CONCLUSIONS: Our results suggest that wind and dust in combination may have an additive effect on several plant traits and provide new insight into the effects and importance of studying wind, dust, and different stress combinations.

A limited legacy effect of copper in marine biofilms.

The effects of confounding by temporal factors remains understudied in pollution ecology. For example, there is little understanding of how disturbance history affects the development of assemblages. To begin addressing this gap in knowledge, marine biofilms were subjected to temporally-variable regimes of copper exposure and depuration. It was expected that the physical and biological structure of the biofilms would vary in response to copper regime. Biofilms were examined by inductively coupled plasma optical emission spectrometry, chlorophyll-a fluorescence and field spectrometry and it was found that (1) concentrations of copper were higher in those biofilms exposed to copper, (2) concentrations of copper remain high in biofilms after the source of copper is removed, and (3) exposure to and depuration from copper might have comparable effects on the photosynthetic microbial assemblages in biofilms. The persistence of copper in biofilms after depuration reinforces the need for consideration of temporal factors in ecology.

Head capsule stacking by caterpillars: morphology complements behaviour to provide a novel defence.

Herbivores employ a variety of chemical, behavioural and morphological defences to reduce mortality from natural enemies. In some caterpillars the head capsules of successive instars are retained and stacked on top of each other and it has been suggested that this could serve as a defence against natural enemies. We tested this hypothesis by comparing the survival of groups of the gumleaf skeletoniser Uraba lugens Walker caterpillars, allocated to one of three treatments: "-HC," where stacked head capsules were removed from all individuals, "+HC," where the caterpillars retained their stacked head capsules, and "mixed," where only half of the caterpillars in a group had their stacked head capsules removed. We found no difference in predation rate between the three treatments, but within the mixed treatment, caterpillars with head capsules were more than twice as likely to survive. During predator choice trials, conducted to observe how head capsule stacking acts as a defence, the predatory pentatomid bug attacked the -HC caterpillar in four out of six trials. The two attacks on +HC caterpillars took over 10 times longer because the bug would poke its rostrum through the head capsule stack, while the caterpillar used its head capsule stack to deflect the bug's rostrum. Our results support the hypothesis that the retention of moulted head capsules by U. lugens provides some protection against their natural enemies and suggest that this is because stacked head capsules can function as a false target for natural enemies as well as a weapon to fend off attackers. This represents the first demonstration of a defensive function.

Urbanisation at multiple scales is associated with larger size and higher fecundity of an orb-weaving spider.

Urbanisation modifies landscapes at multiple scales, impacting the local climate and changing the extent and quality of natural habitats. These habitat modifications significantly alter species distributions and can result in increased abundance of select species which are able to exploit novel ecosystems. We examined the effect of urbanisation at local and landscape scales on the body size, lipid reserves and ovary weight of Nephila plumipes, an orb weaving spider commonly found in both urban and natural landscapes. Habitat variables at landscape, local and microhabitat scales were integrated to create a series of indexes that quantified the degree of urbanisation at each site. Spider size was negatively associated with vegetation cover at a landscape scale, and positively associated with hard surfaces and anthropogenic disturbance on a local and microhabitat scale. Ovary weight increased in higher socioeconomic areas and was positively associated with hard surfaces and leaf litter at a local scale. The larger size and increased reproductive capacity of N.plumipes in urban areas show that some species benefit from the habitat changes associated with urbanisation. Our results also highlight the importance of incorporating environmental variables from multiple scales when quantifying species responses to landscape modification.

Macrofaunal responses to edges are independent of habitat-heterogeneity in experimental landscapes.

Despite edges being common features of many natural habitats, there is little general understanding of the ways assemblages respond to them. Every edge between two contrasting habitats has characteristics governed by the composition of adjoining habitats and/or by the nature of any transitions between them. To develop better explanatory theory, we examined the extent to which edges act independently of the composition of the surrounding landscape and to which transitions between different types of habitats affect assemblages. Using experimental landscapes, we measured the responses of assemblages of marine molluscs colonising different experimental landscapes constructed with different compositions (i.e. different types of habitats within the landscape) and different types of transitions between habitats (i.e. sharp vs gradual). Edge effects (i.e. proximity to the edge of the landscape) were independent of the internal composition of experimental landscape; fewer species were found near the edges of landscapes. These reductions may be explained by differences in differential larval settlement between edges and interiors of experimental landscapes. We also found that the sharpness of transitions influenced the magnitude of interactions in the different types of habitats in experimental landscapes, most probably due to the increased number of species in areas of transition between two habitats. Our experiments allowed the effects of composition and transitions between habitats to be disentangled from those of proximity to edges of landscapes. Understanding and making predictions about the responses by species to edges depends on understanding not only the nature of transitions across boundaries, but also the landscape in which the edges are embedded.

Traumatic insemination in the plant bug genus Coridromius Signoret (Heteroptera: Miridae).

In traumatic insemination, males pierce females with hypodermic genitalia and ejaculate into the body cavity rather than into the genital tract. This has resulted in the evolution of female counter-adaptations in the form of paragenitalia to reduce the direct physical costs of mating. While rare in the animal kingdom, traumatic insemination is oddly prevalent in the true bug infraorder Cimicomorpha (Heteroptera), where it occurs in six families and is thought to have arisen twice. Here, we report the discovery of traumatic insemination and elaborate paragenital development in the plant bug genus Coridromius (Miridae), representing a third, independent emergence of traumatic insemination in this infraorder.