Ambient air temperature does not predict body size of foragers in bumble bees (Bombus impatiens)

Bumble bees are important pollinators of crops and other plants. However, many aspects of their basic biology remain relatively unexplored. For example, one important and unusual natural history feature in bumble bees is the massive size variation seen between workers of the same nest. This size polymorphism may be an adaptation for division of labor, colony economics, or be nonadaptive. It was also suggested that perhaps this variation allows for niche specialization in workers foraging at different temperatures: larger bees might be better suited to forage at cooler temperatures and smaller bees might be better suited to forage at warmer temperatures. This we tested here using a large, enclosed growth chamber, where we were able to regulate the ambient temperature.We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder. Instead, bees of all sizes successfully flew and foraged between 16C and 36C. Thus, large bees foraged even at very hot temperatures, which we thought might cause overheating. Size variation therefore could not be explained in terms of niche specialization for foragers at different temperature

An Herbivore’s Thermal Tolerance is Higher Than That of the Ant Defenders in a Desert Protection Mutualism

In North American deserts, many species of cactus attract ants to their extrafloral nectaries; the ants actively defend the food source, and hence the plant, against herbivores. In thermally extreme environments, however, networks of positive and negative interactions like these are likely to be sensitive to the thermal limitations of each of the interacting species. We compared the thermal tolerance of a common phytophagous cactus bug, Narnia pallidicornis (Hemiptera: Coreidae), to that of the ants that defend the cactus Ferocactus wislizeni in the Sonoran Desert, USA. We used flow-through respirometry to experimentally determine the thermal limit of the herbivore and compared this to the thermal limits of the ant defenders, determined previously. In the field, we recorded herbivore frequency (proportion of plants with N. pallidicornis) and abundance (the number of N. pallidicornis per plant) in relation to ambient temperature, ant species presence and identity, and fruit production. We show that N. pallidicornis has a higher thermal tolerance than the four most common ant mutualists, and in the laboratory can survive very high temperatures, up to 43°C. Herbivore frequency and abundance in the field were not related to the daily high temperatures observed. Plants that were not defended by ants were occupied by more N. pallidicornis, although they showed no reduction in fruit set. Therefore, herbivory is likely to continue on fishhook barrel cacti even at high temperatures, especially those temperatures beyond the thermal tolerance of the ant defenders. The consequences of increased herbivory, however, remain unclear. Mutualisms are essential for ecosystem functioning; it is important to understand the thermal sensitivity of these interactions, especially in light of expected increases in global temperature regimes

Thermal Ecology of Mutualism: The Consequences of Temperature for Ant-Plant Interactions

Mutualism is an often-complex positive interaction between species, each of which responds independently to varying biotic and abiotic conditions. Temperature is an important factor that can affect species both directly (e.g., physiologically) and indirectly (e.g., via its effects on interactions with consumers, competitors, and mutualists). Although much research has investigated the consequences of temperature for individual organisms, the effects of temperature on the formation, dissolution, and success of species interactions remain minimally understood. The unique ways in which species respond to temperature likely play a role in structuring communities. Environmental heterogeneity, including the thermal environment, can promote coexistence when species exploit resources in different ways, such as by occupying different thermal niches. This dissertation examines the consequences of temperature for participants in an ant-plant protection mutualism, and investigates how the thermal ecology of individual species affects the interaction. Many mutualisms involve multiple species, or interacting guilds. In these mutualisms, species interact with partner species that vary in multiple characteristics. Mutualists are quite sensitive to both partner quantity and partner quality (e.g., their effectiveness at performing a beneficial task). Mutualisms between ants and plants are common across a variety of habitats worldwide, which differ in thermal range, fluctuation, and seasonality. In light of ants’ well-studied and predictable responses to temperature, ant-plant interaction networks provide excellent systems for studying the thermal ecology of mutualisms. In ant-plant protection mutualisms, each of the participants (ants, plants, and enemies) likely differs in its response to temperature. In addition to the direct effects of temperature on ant species, temperature may affect the magnitude of mutualistic interactions among species by affecting the quantity and quality of the reward offered to partners, and the activity of the partners themselves and the plant’s enemies (i.e., herbivores). If herbivores are more thermally tolerant than the mutualistic ant defenders, the consequences for plants may well be severe; however, if herbivores are less thermally tolerant than are the ants, the effects of rising temperatures might be mitigated: although less-effective ants might be more frequent in a warmer world, herbivores would be less abundant there. This dissertation describes the thermal ecology of the participants in a mutualism between the cactus Ferocactus wislizeni and four of its common ant defenders (Forelius pruinosus, Crematogaster opuntiae, Solenopsis aurea, and Solenopsis xyloni) in the extreme environment of the Sonoran Desert, USA. The ants are attracted to extrafloral nectar produced by the plant, and in exchange protect the plants from herbivores, including a common phytophagous cactus bug, Narnia pallidicornis (Hemiptera: Coreidae). Specifically, it investigates how thermal ecology of the individual species affects the interactions among those species. Also, it considers the impact of a tradeoff between behavioral dominance and thermal tolerance among ants

Co-creating safe spaces: Study protocol for translational research on innovative alternatives to the emergency department for people experiencing emotional distress and/ or suicidal crisis

Introduction Safe spaces are an alternative to emergency departments, which are often unable to provide optimum care for people experiencing emotional distress and/or suicidal crisis. At present, there are several different safe space models being trialled in Australia. However, research examining the effectiveness of safe space models, especially in community settings, is rare. In this paper, we present a protocol for a study in which we will investigate the implementation, effectiveness, and sustainability of safe space models as genuine alternatives for people who might usually present to the emergency department or choose not to access help due to past negative experiences. Material and methods We will use a mixed methods, co-designed study design, conducted according to the principles of community-based participatory research to obtain deep insights into the benefits of different safe space models, potential challenges, and facilitators of effective practice. We developed the study plan and evaluation framework using the RE-AIM framework, and this will be used to assess key outcomes related to reach, effectiveness, adoption, implementation, and maintenance. Data collection will comprise quantitative measures on access, use, satisfaction, (cost) effectiveness, distress, and suicidal ideation; and qualitative assessments of service implementation, experience, feasibility, acceptability, community awareness, and the fidelity of the models to service co-design. Data will be collected and analysed concurrently throughout the trial period of the initiatives. Discussion This study will enable an extensive investigation of safe spaces that will inform local delivery and provide a broader understanding of the key features of safe spaces as acceptable and effective alternatives to hospital-based care for people experiencing emotional distress and/ or suicidal crisis. This study will also contribute to a growing body of research on the role and benefits of peer support and provide critical new knowledge on the successes and challenges of service co-design to inform future practice