Colony Size Research Articles

Protective covers impact honey bee colony performance and access to outside resources

Protective crop covers are used extensively to protect high-value crops from bird and hail damage, however, these structures may present challenges for honey bees (Apis mellifera L.), the main pollinators in these systems. Some studies have indicated that protective covers result in declines in colony size and resource storage, but few replicated field trials exist. To determine the impact of protective cropping structures on honey bee brood production and resource storage, 14 honey bee colonies were placed inside and outside of protective covers on four blueberry (Vaccinium corymbosum and V. virgatum) farms in northern New South Wales, Australia. We measured changes in brood production, pollen and honey storage, hive weight and ambient hive temperature fortnightly over a 12-week period. Brood production, pollen and honey storage, and hive weight all displayed greater reductions within four weeks of placement under net cover, compared to hives outside of net cover. Although brood and honey metrics gradually increased in all hives during the remainder of the 12-week monitoring period, hives located under protective netting had relatively smaller gains in brood production and pollen storage when compared to hives located outside the protective covering. Hives under protective netting that were in the shade and/or whose entrances were facing south were most impacted by the end of the monitoring period. Our findings highlight the need for protected crop management strategies to consider pollinator health as well as crop pollination needs so that both bee health and pollination services are maintained in these systems.

Rapid flotation of Microcystis wesenbergii mediated by high light exposure: implications for surface scum formation and cyanobacterial species succession.

Increasing occurrences of Microcystis surface scum have been observed in the context of global climate change and the increase in anthropogenic pollution, causing deteriorating water quality in aquatic ecosystems. Previous studies on scum formation mainly focus on the buoyancy-driven floating process of larger Microcystis colonies, neglecting other potential mechanisms. To study the non-buoyancy-driven rapid flotation of Microcystis, we here investigate the floating processes of two strains of single-cell species (Microcystis aeruginosa and Microcystis wesenbergii), which are typically buoyant, under light conditions (150 μmol photons s-1 m-2). Our results showed that M. wesenbergii exhibited fast upward migration and formed surface scum within 4 hours, while M. aeruginosa did not form visible scum throughout the experiments. To further explore the underlying mechanism of these processes, we compared the dissolved oxygen (DO), extracellular polymeric substance (EPS) content, and colony size of Microcystis in different treatments. We found supersaturated DO and the formation of micro-bubbles (50-200 µm in diameter) in M. wesenbergii treatments. M. aeruginosa produces bubbles in small quantities and small sizes. Additionally, M. wesenbergii produced more EPS and tended to aggregate into larger colonies. M. wesenbergii had much more derived-soluble extracellular proteins and polysaccharides compared to M. aeruginosa. At the same time, M. wesenbergii contains abundant functional groups, which was beneficial to the formation of agglomerates. The surface scum observed in M. wesenbergii is likely due to micro-bubbles attaching to the surface of cell aggregates or becoming trapped within the colony. Our study reveals a species-specific mechanism for the rapid floatation of Microcystis, providing novel insights into surface scum formation as well as succession of cyanobacterial species.

Roles of DJ41_1407 and DJ41_1408 in Acinetobacter baumannii ATCC19606 Virulence and Antibiotic Response.

Acinetobacter baumannii is a major cause of nosocomial infections, and its highly adaptive nature and broad range of antibiotic resistance enable it to persist in hospital environments. A. baumannii often employs two-component systems (TCSs) to regulate adaptive responses and virulence-related traits. This study describes a previously uncharacterized TCS in the A. baumannii ATCC19606 strain, consisting of a transcriptional sensor, DJ41_1407, and its regulator, DJ41_1408, located adjacent to GacA of the GacSA TCS. Markerless mutagenesis was performed to construct DJ41_1407 and DJ41_1408 single and double mutants. DJ41_1408 was found to upregulate 49 genes and downregulate 43 genes, most of which were associated with carbon metabolism and other metabolic pathways, such as benzoate degradation. MEME analysis revealed a putative binding box for DJ41_1408, 5'TGTAAATRATTAYCAWTWAT3'. Colony size, motility, biofilm-forming ability, virulence, and antibiotic resistance of DJ41_1407 and DJ41_1408 single and double mutant strains were assessed against wild type. DJ41_1407 was found to enhance motility, while DJ41_1408 was found to upregulate biofilm-forming ability, and may also modulate antibiotic response. Both DJ41_1407 and DJ41_1408 suppressed virulence, based on results from a G. mellonella infection assay. These results showcase a novel A. baumannii TCS involved in metabolism, with effects on motility, biofilm-forming ability, virulence, and antibiotic response.

Native ants vary in their use of seeds from a recently introduced myrmecochorous exotic plant

AbstractMyrmecochory is a common mutualism between ants and plants benefiting both partners: ants obtain a nutrient-rich food source, while plants enjoy a host of benefits ranging from enhanced dispersal to protected germination sites. However, this mutualism can be exploited by invasive myrmecochores, where native ants spread invasive plant seeds, possibly to the detriment of native plant assemblages. With the recent introduction of a potentially invasive myrmecochorous plant (Thesium ramosum) in Alberta, Canada, we tested ant interest in T. ramosum. To evaluate both general interest in T. ramosum as a food source, and preference for T. ramosum over other food sources, we collected colonies of four commonly occurring native Formica species and conducted seed removal trials and food preference trials. We then evaluated interest in and preference for T. ramosum seeds through assessing mean rate of seed removal and food item removal, total number of seeds and food items removed, and trends in seed and food item removal through time. We found that while all ant species tested showed interest in T. ramosum, interest level varied among species, and additional factors such as colony size and presence of host species in socially parasitic species influenced interest in T. ramosum. Considering native ant interest in T. ramosum as a food source, it seems plausible that Formica species may act as a dispersal vector for T. ramosum, potentially enhancing its invasiveness.

Abstract 6967: Role of CXCL7 in colon cancer cell proliferation

Abstract Chemokine (C-X-C motif) ligand 7 (CXCL7) - a protein product of the pro platelet basic protein (PPBP) gene - is a potential biomarker for colorectal cancer (CRC) diagnosis. However, its role in CRC progression is not known. Hence, we examined the role of CXCL7 in colon cancer cell proliferation through enhanced aerobic glycolysis. We first examined the effect of CXCL7 on cellular proliferation and glycolytic flux using human colon cancer (HT-29) cells transfected with CXCL7 or an empty vector as a control. Stable CXCL7- and vector-expressing cells were selected using hygromycin B. In addition, we treated HT-29 cells with CXCL7 obtained from the conditioned media (CM) from CXCL7-transfected HEK-293T cells or CM from vector-transfected (control) cells. CXCL7 expression was confirmed by analyzing PPBP expression using RT-qPCR, and CXCL7 level in the conditioned media was quantified by ELISA. The specificity of CXCL7 actions were examined using a CXCL7 neutralizing antibody (R&D Systems) and an antagonist (SB225002) to C-X-C motif chemokine receptor 2 (CXCR2). Cancer cell proliferation was assessed by measuring DNA synthesis (EdU incorporation). Glycolytic flux was monitored by measuring glucose uptake using a fluorescent derivative of 2-deoxyglucose (2-NBDG), Seahorse glycolysis stress test analysis, lactate accumulation in the cultured cell’s media, and Western blotting for glycolytic enzyme protein expression. To further investigate CXCL7-mediated proliferation, we examined EdU incorporation and colony size in 3D engineered tissues and tumor xenograft growth in nude mice injected with CXCL7- and vector-expressing HT29 cells. The proliferation rate in CXCL7-expressing HT-29 cells and HT-29 cells treated with the CXCL7-CM were significantly higher (1.2-fold and 1.8-fold, respectively) compared to controls (p<0.01). Consistently, the proliferation rate in CXCL7-expressing HT-29 3D engineered tissues was significantly enhanced compared to vector-expressing tissues (p<0.05). Importantly, blocking the CXCL7/CXCR2 axis using a CXCL7 neutralizing antibody and a CXCR2 inhibitor abrogated CXCL7-stimulated proliferation. Lactate levels were two-fold higher in the culture media from both CXCL7-expressing HT-29 cells and HT-29 cells treated with CXCL7-CM compared to the controls (p<0.05). Glucose uptake was also greater in CXCL7-overexpressing cells and CXCL7-CM treated cells compared to vector controls. Data from Seahorse assay and Western blots confirmed that CXCL7-expressing HT-29 cells and HT-29 cells treated with CXCL7-CM have higher glycolytic capacity and increased glycolytic enzymes’ protein expression compared to the controls, respectively. In vivo, CXCL7-expressing HT-29 xenograft tumor weight and PCNA protein levels were 100% and 60% greater, respectively, than vector-expressing tumors (p<0.05). Our study for the first time showed that CXCL7 stimulates colon cancer cell proliferation and enhances aerobic glycolysis. Citation Format: Hadeel Aldhowayan, Jannatul F. Nipa, Lauren Jun, Ifeoluwa Odeniyi, Parker L. Jones, Ramesh Jeganathan, Elizabeth A. Lipke, Michael W. Greene. Role of CXCL7 in colon cancer cell proliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6967.

Abstract 6773: Tissue engineered colorectal cancer microspheres for drug screening

Abstract Three-dimensional (3D) disease models have garnered widespread interest for use in later stages of the drug discovery process, such as preclinical efficacy and toxicology studies, due to their pathophysiologically relevant properties. However, there is a need and opportunity for 3D cancer models to be used earlier in the drug screening process. To meet this need, the 3D models must strike a balance between throughput, which includes scalability and uniformity, and physiological relevance, such as the ability to modulate key attribute of the tumor microenvironment. Here we report the creation of 3D colorectal cancer (CRC) tissue models, referred to as VivoSpheres, and demonstrated their relevance to cancer drug screening. The VivoSphere production platform couples tissue engineering toolkits with microfluidics, enabling the scalable production of engineered cancer microspheres. The model supports the long-term maintenance of the cancer cell phenotype. In a preliminary study, we were able to generate more physiologically relevant drug responses. We formed CRC VivoSpheres by encapsulating HT-29 CRC cells within poly(ethylene glycol)-fibrinogen hydrogel microspheres using our previously developed microfluidic platform. CRC VivoSpheres were rapidly produced with high cell densities (20 × 106 cells/ml) and high uniformity on day 0 with a coefficient of variation (COV) < 7%. This high uniformity was maintained for 15 days (COV ≤ 10%), which is critical for long-term dose studies. The cells maintained high viability and showed high proliferative capability with a significant increase in colony size and expression of Ki67 up to day 29. The encapsulated cells maintained the CRC phenotype over time with the expression of CD44 (cancer stem cell marker) and CK20 (CRC marker). After establishing shipping conditions that maintained cell viability for remote use, the HT-29 VivoSpheres were shipped to the oncology team at Southern Research for drug testing. The CRC VivoSpheres were treated with DMSO, GANT61, and SRI-38832, the latter two of which are GLI1 inhibitors. Phase contrast images and western blot were used to assess the response of CRC VivoSpheres to the treatments. Oncogenic GLI1 transcription activity and NBS1 overexpression have been found to contribute to chemotherapeutic resistance, negating the anti-tumor effects of 5-fluorouracil. While 2D cultured HT-29s responded to treatment with GANT61, HT-29 VivoSpheres continued to express NBS1 following GANT1 treatment, but downregulated NBS1 in response to the GLI1 inhibitor SRI-38832, which is the same response Southern Research has seen in in vivo tumor models. In conclusion, we have developed tissue-engineered 3D CRC models that hold promise for use in drug screening. These models have demonstrated an initial capability to reproduce the CRC phenotype and mimic in vivo drug response. Citation Format: Yuan Tian, Mohammadjafar Hashemi, Benjamin Anbiah, Ruowen Zhang, Iman Hassani, Rebecca Boohaker, Elizabeth Lipke. Tissue engineered colorectal cancer microspheres for drug screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6773.

Potential gap in understanding cyanoHABs: Light-dependent morphological variations in colonial cyanobacterium Microcystis

Colony formation is a crucial characteristic of Microcystis, a cyanobacterium known for causing cyanobacterial harmful algal blooms (cyanoHABs). It has been observed that as Microcystis colonies grow larger, they often become less densely packed, which correlates with a decrease in light penetration. The objective of this study was to investigate the effects of light limitation on the morphological variations in Microcystis, particularly in relation to the crowded cellular environment. The results indicated that when there was sufficient light (transmittance = 100 %) to support a growth rate of 0.11±0.01 day−1, a significant increase in colony size was found, from 466±15 μm to 1030±111 μm. However, under light limitation (transmittance = 50 % – 1 %) where the growth rate was lower than 0, there was no significant improvement in colony size. Microcystis in the light limitation groups exhibited a loose cell arrangement and even the presence of holes or pores within the colony, confirming the negative correlation between colony size and cell arrangement. This pattern is driven by regional differences in growth within the colony, as internal cells have a significantly lower frequency of division compared to peripheral cells, due to intra-colony self-shading (ICSS). The research demonstrates that Microcystis can adjust its cell arrangement to avoid excessive self-shading, which has implications for predicting and controlling cyanoHABs. These findings also contribute to the understanding of cyanobacterial variations and can potentially inform future research on the diverse phycosphere.

Dissecting coral recovery: bleaching reduces reproductive output in Acropora millepora

AbstractIncreasingly frequent and severe bleaching events driven by climate change are decreasing coral populations worldwide. Recovery of these populations relies on reproduction by the survivors of such events including local and upstream larval sources. Yet, corals that survive bleaching may be impaired by sublethal effects that suppress reproduction, reducing larval input to reefs, and consequently impeding recovery. We investigated the impact of the 2020 mass-bleaching event on Acropora millepora reproduction on inshore, turbid reefs in Woppaburra sea Country (the Keppel Islands), to improve our understanding of the effects of bleaching on coral populations. A. millepora experienced high bleaching incidence but low mortality across the island group during this event and thus constituted an ideal population to investigate potential sublethal effects on reproductive output. Six months after the heat wave, and just prior to spawning, we collected, decalcified, and dissected samples from 94 tagged A. millepora colonies with a known 2020 bleaching response, to investigate the relationships between stress severity and reproduction. Despite having regained their pigmentation, we detected a significant reduction in fecundity in colonies that had bleached severely. Considering the impact of the bleaching event on the coral population sampled (i.e., mortality, bleaching severity and colony size), coupled with reductions in fecundity, we estimated a total decrease in population-level reproductive output of 21%. These results suggest that reduced reproductive output may impact recovery of coral populations following bleaching and should be considered alongside traditional estimates of coral mortality.

Application of ant algorithm in solving TSP problems

Ant colony system algorithms, as a new class of global search algorithms, can solve the TSP (Traveling Salesman Problem). At the same time, the TSP problem is a classical NP-C problem, the solution of TSP problem involves many fields, such as network routing, vehicle routing, logistics and transportation, so it is very important to solve TSP problem effectively. In this experiment, the ant colony optimization algorithm is simulated and experimented using Matlab software on bayg29 dataset and the algorithm strategy is improved by controlling different parameters. Our main goal is to improve the performance of the algorithm through meticulous parameter fine-tuning and policy improvement. We explored a range of parameter adjustments, including variables such as pheromone evaporation rate, ant colony size, etc. By undertaking this comprehensive investigation, we aspire to push the boundaries of ant colony optimization, unlocking its potential to deliver highly efficient solutions for complex TSP instances. This research holds promise for revolutionizing the efficiency and cost-effectiveness of solutions across a wide range of practical applications.

Investigating the structural basis of piperine targeting AKT1 against prostate cancer through in vitro and molecular dynamics simulations

AkT1, significantly impacts many tumours cell functions, like transcription, apoptosis, glucose metabolism, cell proliferation, and cell migration. For tumours to develop and spread, aberrant activation of AKT1 is essential. Therefore, a major focus of molecularly targeted PCa treatment is AKT1. The present study investigates the effect of piperine compared to SDF using in-vitro studies, viz colony formation assay, comet assay and AKT1 gene expression studies using human PCa cell line PC3. A cluster of approximately at least 50 cells constitutes a colony. The clonogenic assay showed that the number and size of colonies significantly decreased when treated with compounds (SDF and piperine) in comparison to the untreated cells which effectively proliferated to form more colonies. Piperine treatment showed significant inhibition of colony formation than SDF. Effective genotoxicity was observed in piperine-treated PC3 cells with an increased Tail length of 120 µm and it was moderately observed in SDF with a Tail length of 30 µm treated on PC3 cells. The control group did not show any considerable genotoxicity with a Tail length of 6 µm. Our data, both in vitro and in silico, suggested that piperine would be a good starting point for developing novel drugs for the treatment of PCa. The downstream functions of Akt1 may be inhibited by these effects, which could impede the proliferation of PCa cells. High stability of the piperine-AKT1 complex was found by the MD simulation. Higher hydrophilic residues like Lys268 and Ser205 at the active pocket may be the cause of the binding stability. Overall, the observed results confirmed the anti-PCa effect of piperine by causing effective DNA damage and proved to be genotoxic in nature against the human PCa. These effects may impede the downstream activities of Akt1 and result in PCa cell growth regression. Communicated by Ramaswamy H. Sarma

Evidence of promoting effects of 6:2 Cl-PFESA on hepatocellular carcinoma proliferation in humans: An ideal alternative for PFOS in terms of environmental health?

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic chemicals, encompassing compounds like perfluorooctane sulfonate (PFOS), which have widespread applications across various industries, including food packaging and firefighting. In recent years, China has increasingly employed 6:2 Cl-PFESA as an alternative to PFOS. Although the association between PFAS exposure and hepatocellular carcinoma (HCC) has been demonstrated, the underlying mechanisms that promote HCC proliferation are uncleared. Therefore, we aimed to investigate the effects and differences of PFOS and 6:2 Cl-PFESA on HCC proliferation through in vivo and in vitro tumor models. Our results reveal that both PFOS and 6:2 Cl-PFESA significantly contribute to HCC proliferation in vitro and in vivo. Exposure led to reduced population doubling times, enlarged cell colony sizes, enhanced DNA synthesis efficiency, and a higher proportion of cells undergoing mitosis. Furthermore, both PFOS and 6:2 Cl-PFES) have been shown to activate the PI3K/AKT/mTOR signaling pathway and inhibit necroptosis. This action consequently enhances the proliferation of HCC cells. Our phenotypic assay findings suggest that the tumorigenic potential of 6:2 Cl-PFESA surpasses that of PFOS; in a subcutaneous tumor model using nude mice, the mean tumor weight for the 6:2 Cl-PFESA-treated cohort was 2.33 times that observed in the PFOS cohort (p < 0.01). Despite 6:2 Cl-PFESA being considered a safer substitute for PFOS, the pronounced effects of this chemical on HCC cell growth warrant a thorough assessment of hepatotoxicity risks linked to its usage.

In-vitro queen rearing protocol for stingless bee, Tetragonula iridipennis Smith

South-East Asia falls behind in comparison to South America and Australia in beekeeping with stingless bees. This is partly contributed by the lack of proper management techniques and slow rate of natural colony multiplication in different bee species found in this part of the world. Production of natural queen bees in stingless bee colonies depends upon several factors, such as adequate nutrition, temperature regulation, seasonality, colony size, natural enemies among many others. The capacity to produce a large number of queen bees without depending upon the production of natural queen inside colonies makes in vitro rearing of stingless bee as a good help for the problem of slow colony multiplication. The present study describes in vitro queen rearing protocol for the Asian stingless bee, Tetragonula iridipennis Smith. The larval provision required for producing a queen bee was three times more than a natural worker bee. The in vitro queen bees were morphologically similar to the natural queens. The reproductive success of these in vitro queen bees also supported the proposed protocol. The technique would be useful in colony multiplication of this species at a faster rate and in developing management tactics for large-scale adoption in Indo-Malayan and Australasia regions.

The effects of protein supplementation, fumagillin treatment, and colony management on the productivity and long-term survival of honey bee (Apis mellifera) colonies.

In this study, we intensively measured the longitudinal productivity and survival of 362 commercially managed honey bee colonies in Canada, over a two-year period. A full factorial experimental design was used, whereby two treatments were repeated across apiaries situated in three distinct geographic regions: Northern Alberta, Southern Alberta and Prince Edward Island, each having unique bee management strategies. In the protein supplemented treatment, colonies were continuously provided a commercial protein supplement containing 25% w/w pollen, in addition to any feed normally provided by beekeepers in that region. In the fumagillin treatment, colonies were treated with the label dose of Fumagilin-B® each year during the fall. Neither treatment provided consistent benefits across all sites and dates. Fumagillin was associated with a large increase in honey production only at the Northern Alberta site, while protein supplementation produced an early season increase in brood production only at the Southern Alberta site. The protein supplement provided no long-lasting benefit at any site and was also associated with an increased risk of death and decreased colony size later in the study. Differences in colony survival and productivity among regions, and among colonies within beekeeping operations, were far larger than the effects of either treatment, suggesting that returns from extra feed supplements and fumagillin were highly contextually dependent. We conclude that use of fumagillin is safe and sometimes beneficial, but that beekeepers should only consider excess protein supplementation when natural forage is limiting.

Measuring coral disease lesions: a comparison of methodologies

The presence of stressors, particularly disease, on corals necessitates assessments of their severity in order to compare threat levels and to plan for impacts. Diseases in particular are often measured via the rate at which a lesion moves across a coral (lesion progression rate) to determine the impact of those lesions and also to compare virulence across species, regions, and disease types. Lesion progression can even be used as a field indicator for disease identification. Many different methodologies have been used to measure lesion progression rates. These may be field-based or photographic measurements, and they include linear progression rates as well as areal progression rates. All methods have pros and cons, including varying levels of accuracy and repeatability, variability with respect to colony and lesion sizes, and time and computational requirements. Additionally, not all metrics can be directly compared, and so experiments done with the intent to compare with previous work must consider methodologies used in former studies. Areal progression rates have high variability, but can provide impressive information on overall tissue loss. Overall, linear lesion progression rates provide more accurate and less variable assessments of loss, and are better used for comparisons. Using the average of multiple linear measurements may further increase precision. Measuring from photographs rather than direct field measurements provides a more permanent and repeatable record, but outside of directly planar surfaces is likely to yield inaccuracies. The emerging use of 3-D photogrammetry can overcome many of these limitations, but the methods require considerable time and computational power. The pros and cons of each methodology should be assessed during experimental design to best answer the hypotheses in question as well as consider whether comparisons to other studies are valid.

Social foraging and the associated benefits of group-living in Cliff Swallows decrease over 40 years.

Animals that feed socially can sometimes better locate prey, often by transferring information about food that is patchy, dense, and temporally and spatially unpredictable. Information transfer is a potential benefit of living in breeding colonies where unsuccessful foragers can more readily locate successful ones and thereby improve feeding efficiency. Most studies on social foraging have been short-term, and how long-term environmental change affects both foraging strategies and the associated benefits of coloniality is generally unknown. In the colonial Cliff Swallow (Petrochelidon pyrrhonota), we examined how social foraging, information transfer, and feeding ecology changed over a 40-year period in western Nebraska. Relative to the 1980's, Cliff Swallows in 2016-2022 were more likely to forage solitarily or in smaller groups, spent less time foraging, were more successful as solitaries, fed in more variable locations, and engaged less in information transfer at the colony site. The total mass of insects brought back to nestlings per parental visit declined over the study. The diversity of insect families captured increased over time, and some insect taxa dropped out of the diet, although the three most common insect families remained the same among the decades. Nestling Cliff Swallow body mass at 10 days of age and the number of nestlings surviving per nest declined more sharply with colony size in 2015-2022 than in 1984-1991 at sites where the confounding effects of ectoparasites were removed. Adult body mass during provisioning of nestlings was lower in more recent years, but the change did not vary with colony size. The reason(s) for the reduction in social foraging and information transfer over time are unclear, but the consequence is that colonial nesting may no longer offer the same fitness advantages for Cliff Swallows as in the 1980's. The results illustrate flexibility of foraging behavior and dynamic shifts in the potential selective pressures for group-living.

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface.

Due to climate change, Microcystis blooms occur at increasing frequencies in aquatic ecosystems worldwide. Wind-generated turbulence is a crucial environmental stressor that can vertically disperse the Microcystis surface scum, reducing its light availability. Yet, the interactions of Microcystis scum with the wind-generated hydrodynamic processes, particularly those at the air-water interface, remain poorly understood. Here, we explore the response of Microcystis (including colony size and migration dynamics) to varying magnitudes and durations of intermittent wind disturbances in a mesocosm system. The flow velocities, size of Microcystis colonies, and the areal coverage of the water surface by scum were measured through video observations. Our results demonstrate that low wind speeds increase colony size by providing a stable condition where Microcystis forms a scum layer and aggregates into large colonies at the air-water interface. In contrast, wind disturbances disperse scum and generate turbulence, resulting in smaller colonies with higher magnitudes of wind disturbance. We observed that surface scum can form rapidly following a long period (6h) of high-magnitude (4.5m s-1) wind disturbance. Furthermore, our results indicate reduced water surface tension caused by the presence of Microcystis, which can decrease surface flow velocity and counteract wind-driven mixing. The reduced surface tension may also drive lateral convection at the water surface. These findings suggest that Microcystis reduces surface tension, likely by releasing surface-active materials, as an adaptive response to various wind conditions. This could result in an increased rate of surface scum re-formation under wind conditions and potentially facilitate the lateral expansion of scum patches during weak wind periods. This study reveals new insights into how Microcystis copes with different wind conditions and highlights the importance of the air-water interface for Microcystis scum dynamics.

Colony size of amazonian stingless bees and its assessment through intrinsic parameters

Stingless bees live in populous colonies that vary in size from a few hundred individuals to tens of thousands, although information on actual colony size is limited. The objectives of this study were to determine the colony size of five Amazonian stingless bee species (Melipona flavolineata, Melipona fasciculata, Scaptotrigona aff. postica, Frieseomelitta longipes, and Plebeia minima), and to identify biological parameters that covary with colony size. The number of brood cells, adult bees, and food stocks were counted under laboratory conditions, alongside field assessments of egg-laying rate and external activity of adult workers. To identify covariates of colony size, the number of adult bees was regressed against the number of brood cells, egg-laying rate, external activity of adult workers, and food stocks, and the best candidate models were ranked using the Akaike Information Criterion. Mean (±s.d.) adult populations were: in M. flavolineata, 1046 ± 185; in M. fasciculata, 593 ± 300; in S. aff. postica, 7404 ± 1391; in F. longipes, 2425 ± 1000 and in P. minima, 405 ± 254. Thus, we showed that the external activity is the biological parameter, after the number of brood cells, that presents the best relationship with the number of adult bees, which can be easily evaluated in the field. Determining colony sizes using easily measurable biological parameters are important steps to understanding stingless bee’s life histories, ecology, and evolution, and to ease their keeping and utilization for pollination.

Effect of extracellular polymeric substances on the colony size and morphological changes of Microcystis.

Surface blooms of colony-forming Microcystis are increasingly occurring in aquatic ecosystems on a global scale. Recent studies have found that the Microcystis colonial morphology is a crucial factor in the occurrence, persistence, and dominance of Microcystis blooms, yet the mechanism driving its morphological dynamics has remained unknown. This study conducted a laboratory experiment to test the effect of extracellular polymeric substances on the morphological dynamics of Microcystis. Ultrasound was used to disaggregate colonies, isolating the cells and of the Microcystis suspension. The single cells were then re-cultured under three homologous EPS concentrations: group CK, group Low, and group High. The size, morphology, and EPS [including tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS), bound polysaccharides (B-polysaccharides), and bound proteins (B-proteins)] changes of colonies were closely monitored over a period of 2 months. It was observed that colonies were rapidly formed in group CK, with median colony size (D50) reaching 183 µm on day 12. The proportion of colonies with a size of 150-500 µm increased from 1% to more than 50%. Colony formation was also observed in both groups Low and High, but their D50 increased at a slower rate and remained around 130 µm after day 17. Colonies with a size of 50-150 µm account for more than 50%. Groups CK and Low successively recovered the initial Microcystis morphology, which is a ring structure formed of several small colonies with a D50 of 130 µm. During the recovery of the colony morphology, the EPS per cell increased and then decreased, with TB-EPS and B-polysaccharides constituting the primary components. The results suggest that colony formation transitioned from adhesion driven to being division driven over time. It is suggested that the homologous EPS released into the ambient environment due to the disaggregation of the colony is a chemical cue that can affect the formation of a colony. This plays an important but largely ignored role in the dynamics of Microcystis and surface blooms.

Colonial breeding impacts potentially fitness-relevant cognitive processes in barn swallows

Many animals breed colonially, often in dense clusters, representing a complex social environment with cognitive demands that could ultimately impact individual fitness. However, the effects of social breeding on the evolution of cognitive processes remain largely unknown. We tested the hypothesis that facultative colonial breeding influences attention and decision-making. Barn swallows (Hirundo rustica) breed in solitary pairs or in a range of colony sizes, up to dozens of pairs. We tested for selective attention to social information with playbacks of conspecific alarm calls and for decision-making with simulated predator intrusions, across a range of colony sizes from 1 to 33 pairs. We also evaluated the adaptive value of both processes by measuring seasonal reproductive success. Swallows breeding in larger colonies were more selective in their attention to social information. Birds breeding in larger colonies were also less risk averse, deciding to return more quickly to their nests after a predator approach paradigm. Finally, birds that showed higher selective attention hatched more eggs and birds that returned to their nests more quickly after a predator intrusion had more nestlings. Although we cannot fully attribute these fitness outcomes to the cognitive measures considered in this study, our results suggest that social breeding plays a role in adaptively shaping both the acquisition of social information and decision-making.

Pollen diet diversity across bee lineages varies with lifestyle rather than colony size.

The shift to a pollen diet and the evolution of more highly organized societies, i.e., eusocial, were key milestones in bee diversification over their evolutionary history, culminating in a high dependence on feeding broods with a large variety of floral resources. Here, we hypothesized that obligatory eusocial bees have a wider diet diversity than their relatives with solitary lifestyles, and this would be related to colony size. To test both hypotheses, we surveyed diet breadth data (palynological analysis) based on the Shannon-Wiener index (H') for 85 bee taxa. We also obtained colony size for 47 eusocial bee species. These data were examined using phylogenetic comparative methods. The results support the generalist strategy as a derived trait for the bee taxa evaluated here. The dietary diversity of eusocial bees (H': 2.1, on average) was 67.5% higher than that of noneusocial bees (H': 1.21, on average). There was, however, no relationship between diet breadth and colony size, indicating that smaller colonies can harvest a pollen variety as diverse as larger colonies. Taken together, these results provide new insights into the impact of lifestyle on the diversity of collected pollen. Furthermore, this work sheds light on an advantage of living in more highly structured societies irrespective of the size of the colony.