Juvenile temperature regulation in Apis mellifera (Honey bee) and the impacts of brood temperature requirements on the colony

Little is known about the energetic costs to insects of raising young. Honey bees collectively raise young, or brood, through a series of complex behaviors that appear to accelerate and synchronize the timing of brood maturation. These include maintaining the brood nest at warmer and consistent temperatures and the exceptional activity of heater bees. The temperature at which juvenile insects are raised can profoundly affect their development. Apis mellifera (Honey bees) cope with temperature-dependent development via social behavior that maintains the relatively high and constant temperatures within the nest where the brood are raised. Yet juvenile honey bee development is complex and can be categorized into egg, larvae, pupating juveniles, and pupae. Honey bees use passive and active behaviors to maintain remarkably constant brood nest temperatures, from 33 to 35°C, across a wide range of ambient temperatures. In addition to these colony-scale behaviors, a small subset of nurse bees behaves as heater bees. Heater bees contract thoracic flight muscles to generate heat, but their thoraxes reach much higher temperatures than other bees responsible for brood care, ranging between 42 and 47°C. Heater bees focus their attention on incubating individual cells by moving among brood cells and regulating the temperatures of individual eggs, larvae, and pupae. We constructed four sets of experimental hives to explore the developmental temperatures at which each juvenile stage is maintained, the energetic costs of raising juveniles, and the cost of heater bees. One set allowed us to record the temperatures of undisturbed young in the brood nest area established by the colony. The second set was designed to estimate the numerical allocation of individuals to the heater bee task. The third set was intended to contain only brood, which eliminated foraging and allowed us to quantify stored honey use when rearing juveniles at 10 and 30°C. The final set was used to measure the respiration rates and energy expenditure of individual bees displaying resting, walking, heating, and agitated behavior. We first discovered that instead of simply maintaining brood nest areas at 33-35°C, honey bees provide extraordinarily precise but different temperatures for larvae and pupae. We found that the temperature at which heater bees regulate cells is above the overall average temperature range of the brood nest. Honey bees raised larvae at 36.38±0.02°C, substantially higher and with a narrower range than what has been reported for the brood nest, 33-35°C. Honey bees raised pupae at 35.18±0.04°C, also higher than the reported temperatures for the brood nest. We further explored brood development by characterizing the developing juveniles\u27 temperature profile throughout their entire 21-day developmental cycle. We found that eggs were maintained at 36.1 ± 0.03°C, larvae at 36.2 ± 0.02°C, pupating juveniles at 35.9 ± 0.03°C, and pupae at 35.8 ± 0.03°C. All stages were significantly different from all other stages, but importantly larvae were only 0.4°C different from pupae. We then conducted another experiment with brood frames without mature bees and in incubators at 34.5°C. Without nurse bees, the temperatures of eggs, larvae, and pupae were 34.4 ± 0.04°C, 34.7 ± 0.05°C, and 34.3 ± 0.04°C, with larvae different from all other stages, and a 0.3°C difference between larvae and pupae. When compared to the 1.2°C in Chapter 1, this 0.3°C difference suggests that heater bees may be a major driver of the differences between pupae and larvae. However, the 0.4°C difference between larvae and pupae in the second experiment reported in chapter 2, vs. the 0.3°C difference, suggests that the larvae themselves may be the major contributor to the temperature difference between the life stages. Either way, our results suggest honey bee development may involve far more precise temperature during the development of juveniles than previously known. And finally, to determine the cost of maintaining juveniles at these warmer and more consistent temperatures, we compared the honey used by brood-only experimental colonies with whole-colony measurements of honey storage in the literature. We estimated that raising brood costs colonies half of their annual energy budgets stored as honey, or approximately 43.7±0.9 kg·yr-1. We estimated that roughly 2% of colony individuals perform the task of heater bee. Respiration rates of heater bees (19 mW) were more than those of resting bees (8 mW) but similar to those of walking bees (20 mW) and about half of those that were agitated (46 mW). The energetic cost of heating was more than an order of magnitude lower than reported values for the energetic cost of flying. By integrating data from our experimental hives, we estimate that the annual cost of raising brood is quite high; however, we estimate that heater bee behavior and physiology, though extreme, may require only about 7% of the annual honey stored by a colony. Instead of simply maintaining brood nest areas at 33-35°C, honey bees provide extraordinarily precise but different temperatures for larvae and pupae. We do not know if these differences ultimately affect development, but they suggest that honey bees may exert far more precise control over the temperatures of their juveniles than previously known, which comes at a high cost at the colony level (macroeconomic), but a surprisingly low cost at the individual (microeconomic) heater bee level

Exotic insect pollinators and native pollination systems

Insect pollinators have been relocated by humans for millennia and are, thus, among the world’s earliest intentional exotic introductions. The introduction of managed bees for crop pollination services remains, to this day, a common and growing practice worldwide and the number of different bee species that are used commercially is increasing. Being generalists and frequently social, these exotic species have the potential to have a wide range of impacts on native bees and plants. Thus, understanding the consequences of introduced species on native pollinator systems is a priority. We generated a global database and evaluated the impacts of the two main groups of invasive bees, Apis mellifera and Bombus spp., on their pollination services to native flora and impacts on native pollinators. In a meta-analysis, we found that per-visit pollination efficiency of exotic pollinators was, on average, 55% less efficient than native pollinators when visiting flowers of native species. In contrast to per-visit pollination efficiency, our meta-analysis showed that visitation frequency by exotic pollinators was, on average, 80% higher than native pollinators. The higher visitation frequency of exotic pollinators overcame deficiencies in pollen removal and transfer resulting in seed/fruit set levels similar to native pollinators. Also, evidence showed that exotic pollinators can displace native insect and bird pollinators. However, the direct effects of exotic insect pollinators on native pollination systems can be context dependent, ranging from mutualism to antagonism.Fil: Debnam, Scott. University of Montana; Estados UnidosFil: Sáez, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Aizen, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Callaway, Ragan M.. University of Montana; Estados Unido

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

Indirect facilitation mediated by pollinators in intermountain prairie

Pollinators can drive indirect facilitative and competitive indirect interactions among plant species. Most work on indirect facilitation via pollinators has focused on “magnet species” which enhance the pollination success of their neighbors because they are disproportionately attractive. However, focusing on magnet species may overestimate the generality of indirect facili- tation and underestimate the occurrence of indirect competition among plant species via pollinators. We used experimental arrangements that included three flowering native intermountain prairie species (Achillea millefolium, Gaillardia aristata, and Linum lewisii), all of which are similarly attractive to pollinators, to explore how variation in species richness and den- sity affected pollinator visitation rates, diversity, and behavior. All three plant species experienced significant increases in pollinator visitation and the species richness of visiting pollinator communities when grown with another species that was in flower at the same time. This “diversity” effect was stronger than the effects of the total density of individual plants in flower in a plot. We also found an increase in visitation time, per flower, for solitary pollinator species in plots with two spe- cies in flower compared to plots with one plant species in flower. Social pollinator species did not increase visitation time in two-species plots. Finally, seed set by Linum was significantly greater in two-species than in one-species plots. Our results indicate that indirect facilitative interactions mediated by pollinators may be common in intermountain prairie plant com- munities and that such indirect interactions do not have to mediated by benefactor species that are strikingly more attractive than their beneficiaries

Bees as Biosensors: Chemosensory Ability, Honey Bee Monitoring Systems, and Emergent Sensor Technologies Derived from the Pollinator Syndrome

This review focuses on critical milestones in the development path for the use of bees, mainly honey bees and bumble bees, as sentinels and biosensors. These keystone species comprise the most abundant pollinators of agro-ecosystems. Pollinating 70%–80% of flowering terrestrial plants, bees and other insects propel the reproduction and survival of plants and themselves, as well as improve the quantity and quality of seeds, nuts, and fruits that feed birds, wildlife, and us. Flowers provide insects with energy, nutrients, and shelter, while pollinators are essential to global ecosystem productivity and stability. A rich and diverse milieu of chemical signals establishes and maintains this intimate partnership. Observations of bee odor search behavior extend back to Aristotle. In the past two decades great strides have been made in methods and instrumentation for the study and exploitation of bee search behavior and for examining intra-organismal chemical communication signals. In particular, bees can be trained to search for and localize sources for a variety of chemicals, which when coupled with emerging tracking and mapping technologies create novel potential for research, as well as bee and crop management

Interstitial ultrasound ablation of vertebral and paraspinal tumours: Parametric and patient-specific simulations

PURPOSE: Theoretical parametric and patient-specific models are applied to assess the feasibility of interstitial ultrasound ablation of tumours in and near the spine and to identify potential treatment delivery strategies. METHODS: 3D patient-specific finite element models (n=11) of interstitial ultrasound ablation of tumours associated with spine were generated. Gaseous nerve insulation and various applicator configurations, frequencies (3 and 7 MHz), placement trajectories, and tumour locations were simulated. Parametric studies with multilayered models investigated the impacts of tumour attenuation, tumour dimension, and the thickness of bone insulating critical structures. Temperature and thermal dose were calculated to define ablation (>240 equivalent minutes at 43°C (EM43°C)) and safety margins (<45°C & <6 EM43°C), and to determine performance and required delivery parameters. RESULTS: Osteolytic tumours (≤44 mm) encapsulated by bone could be successfully ablated with 7 MHz interstitial ultrasound (8.1-16.6 W/cm(2), 120-5900 J, 0.4-15 min). Ablation of tumours (94.6-100% volumetric) 0-14.5 mm from the spinal canal was achieved within 3-15 min without damaging critical nerves. 3 MHz devices provided faster ablation (390 versus 930 s) of an 18 mm diameter osteoblastic (high bone content) volume than 7 MHz devices. Critical anatomy in proximity to the tumour could be protected by selection of appropriate applicator configurations, active sectors, and applied power schemas, and through gaseous insulation. Preferential ultrasound absorption at bone surfaces facilitated faster, more effective ablations in osteolytic tumours and provided isolation of ablative energies and temperatures. CONCLUSIONS: Parametric and patient-specific studies demonstrated the feasibility and potential advantages of interstitial ultrasound ablation treatment of paraspinal and osteolytic vertebral tumours