Colony Life Cycle Research Articles

Ten‐a‐day: Bumblebee pollen loads reveal high consistency in foraging breadth among species, sites and seasons

Abstract Pollen and nectar are crucial resources for bees but vary greatly among plant species in their quantity, nutritional quality and timing of availability. This makes it challenging to identify an appropriate range of plants to meet the nutritional needs of bees throughout the year, though this information is important in the design of pollinator conservation schemes. Using DNA metabarcoding of pollen loads, we record the floral resource use of UK farmland bumblebees at different stages of their colony lifecycle, and compare this with null models of ‘expected’ resource use based on landscape‐scale resource availability (pollen and nectar), to identify foraging priorities and preferences. We use this approach to ask three main questions: (i) what is the foraging breadth of individual bumblebees?; (ii) do bumblebees utilise a greater or lesser diversity of plant species than expected if they foraged in proportion to resource availability?; (iii) which plant species do bumblebees preferentially utilise? Individual bumblebees foraged from a highly consistent number of different plant taxa (mean: 10 ± 0.37 SE per bee), regardless of their species, sampling site or time of year. This high consistency in foraging breadth, despite large changes in the quantity, identity and diversity of resource availability, implies a strong behavioural tendency towards a fixed range of foraging resources. This effect was most striking in April when foraging diversity was maintained despite very low landscape‐level resource diversity. Bumblebees used some plant taxa significantly more than predicted from their landscape‐level floral abundance, nectar or pollen supply, implying certain desirable characteristics beyond the mere quantity of resource. These included Allium spp. and Vicia spp. in April; Trifolium repens and Lotus corniculatus in July and Cardueae spp. (thistles) and Taraxacum officinale in September. Practical implication: Our results strongly indicate that resource quantity is not the only factor driving bumblebee foraging patterns and that resource diversity and quality are also important factors. Thus, in addition to providing large quantities of floral resources, we recommend that pollinator conservation schemes also focus on providing a sufficient diversity of preferred floral resources, enabling pollinators to self‐select a diverse and nutritious diet.

Assessing the effects of cold storage regimes of North American Bombus Gynes

AbstractBumble bees are the primary commercial pollinators for greenhouse‐grown crops and managing them requires insight into the Bombus life cycle. However, some aspects of the life cycle are not fully understood. Once mated, adult Bombus gynes can be stored for a short term at a constant low temperature (CLT). However, survival rates for some species are low during CLT, particularly when storage periods exceed a month. To address this, we tested the hypothesis that Bombus gynes stored in a fluctuating thermal regime (FTR) have increased survival compared to gynes stored in CLT. Specifically, the FTR had a baseline temperature of 2°C, with a daily fluctuation to 20°C relative to the CLT of 2°C with no warming pulse. We tested the effects of FTR on gyne survival and post‐cold storage lipid content in three species used for commercial pollination in North America: B. vosnesenskii, B. huntii and B. impatiens. We further assessed how additional factors influence cold storage survival, including gyne body weight, body size and colony age. Survival responses varied among species. Bombus vosnesenskii and B. huntii had a lower survival rate in FTR compared to CLT, but B. impatiens gynes had a significantly higher survival rate in FTR. We did not observe significant effects of FTR on lipid stores for any species, but survival increased with an increasing initial weight prior to cold storage. Moreover, gynes produced later in the colony life cycle had lower body weight and decreased survival compared to early emerging gynes. Our study provides insight into how cold storage conditions interact with colony and gyne characteristics to influence captive overwintering survival. Our findings have economic applications for improving commercial rearing and efforts for conservation rearing of at‐risk Bombus species.

It is buzziness time: rearing, mating, and overwintering Bombus vosnesenskii (Hymenoptera: Apidae).

Bombus vosnesenskii Radowszkowski, 1862 is one of three bumble bee species commercially available for pollination services in North America; however, little is documented about B. vosnesenskii colony life cycle or the establishment of ex situ rearing, mating, and overwintering practices. In this study, we documented nest success, colony size, and gyne production; recorded the duration of mating events; assessed overwintering survival of mated gynes; and evaluated second-generation nest success for colonies established from low- and high-elevation wild-caught B. vosnesenskii gynes. Of the 125 gynes installed, 62.4% produced brood cells (nest initiation) and 43.2% had at least 1 worker eclose (nest establishment). High-elevation B. vosnesenskii gynes had significantly higher nest initiation and establishment success than low-elevation gynes. However, low-elevation colonies were significantly larger with queens producing more gynes on average. Mating was recorded for 200 low-elevation and 37 high-elevation gynes, resulting in a mean duration of 62 and 51 min, respectively. Mated gynes were then placed into cold storage for 54 days to simulate overwintering, which resulted in 59.1% of low-elevation gynes surviving and 91.9% of high-elevation gynes surviving. For second-generation low-elevation gynes, 26.4% initiated nesting and 14.3% established nesting. Second-generation high-elevation gynes did not initiate nesting despite CO2 narcosis treatments. Overall, these results increase our understanding of B. vosnesenskii nesting, mating, and overwintering biology from 2 elevations. Furthermore, this study provides information on successful husbandry practices that can be used by researchers and conservationists to address knowledge gaps and enhance the captive rearing of bumble bees.

Development, behaviour, productivity, and health status of the native honey bee Apis mellifera ruttneri vs. the introduced A. m. ligustica in Malta

The tiny population of the endemic Maltese honey bee (A. m. ruttneri) is threatened by anthropogenic influences, such as urbanisation, habitat loss, and unsustainable agricultural practices, but most prominently by the importation of commercially important non-native stock. To obtain data on the colony life cycle parameters of A. m. ruttneri and to measure its apicultural performance in relation to imported A. m. ligustica under Maltese conditions, we conducted a comparative study between mid-2017 and early 2020. Over one full season, colonies of both subspecies (A. m. ruttneri (n = 15) vs. A. m. ligustica (n = 18)) were regularly assessed for survival, colony size, behaviour, and presence of diseases. The comparative assessments were completed in September 2018, but monitoring and sampling of the surviving colonies of A. m. ruttneri continued until March 2020. Our results clearly indicate that the tested group of sister queens of A. m. ruttneri is well adapted to the prevailing environmental conditions in Malta. The colonies survived significantly longer compared to the tested group of sister queens of A. m. ligustica and performed better in several parameters measured, their colony development, and health being well in tune with the environment. A. m. ruttneri received acceptable scores for behavioural traits (gentleness and calmness on the comb), showing potential for improvement by breeding. The results from this pioneering study clearly indicate that A. m. ruttneri, with its superior adaptation to Maltese conditions and the potential to improve by breeding, represents a prime option towards economically sound beekeeping on the Maltese archipelago.

Variation in North American bumble bee nest success and colony sizes under captive rearing conditions.

Of the 265 known bumble bee (Bombus) species, knowledge of colony lifecycle is derived from relatively few species. As interest in Bombus commercialization and conservation grows, it is becoming increasingly important to understand colony growth dynamics across a variety of species since variation exists in nest success, colony growth, and reproductive output. In this study, we reported successful nest initiation and establishment rates of colonies and generated a timeline of colony development for 15 western North American Bombus species, which were captively reared from wild-caught gynes from 2009 to 2019. Additionally, we assessed variation in colony size among 5 western North American Bombus species from 2015 to 2018. Nest initiation and establishment rates varied greatly among species, ranging from 5-76.1% and 0-54.6%, respectively. Bombus griseocollis had the highest rates of nest success across the 11-yr period, followed by B. occidentalis, B. vosnesenskii, and B. huntii. Furthermore, days to nest initiation and days to nest establishment varied among species, ranging from 8.4 to 27.7 days and 32.7 to 47 days. Colony size also differed significantly among species with B. huntii and B. vosnesenskii producing more worker/drone cells than B. griseocollis, B. occidentalis, and B. vancouverensis. Additionally, gyne production differed significantly among species with B. huntii colonies producing more gynes than B. vosnesenskii. Results from this study increase knowledge of systematic nesting biology for numerous western North American Bombus species under captive rearing conditions, which can further improve rearing techniques available to conservationists and researchers.

The shifting importance of abiotic and biotic factors across the life cycles of wild pollinators.

Organisms living in seasonal environments are exposed to different environmental conditions as they transition from one life stage to the next across their life cycle. How different life stages respond to these varying conditions, and the extent to which different life stages are linked, are fundamental components of the ecology of an organism. Nevertheless, the influence of abiotic and biotic factors on different parts of an organism's life cycle is often not accounted for, which limits our understanding of the ecological consequences of environmental change. We investigated the relative importance of climate conditions, food availability, and previous life-stage abundance in an assemblage of seven wild bumble bee species, asking: how do these three factors directly influence bee abundance at each life stage? To do so, we used a 7-year dataset where we monitored climate conditions, floral resources, and abundances of bees in each life stage across the active colony life cycle in a highly seasonal subalpine ecosystem in the Colorado Rocky Mountains, USA. Bee abundance at different life stages responded to abiotic and biotic conditions in a broadly consistent manner across the seven species: the survival and recruitment stage of the life cycle (overwintered queens) responded negatively to longer winters; the growth stage (workers) responded positively to floral resource availability; and the reproductive stage (males) was positively related to the abundance of the previous life stage (workers). Most species also exhibited some idiosyncratic responses. Our long-term examination of annual bumble bees reveals a general set of responses in the abundance of each life stage to climate conditions, floral resource availability, and previous life stage. Across species, these three factors each directly influenced a distinct life stage, illustrating how their relative importance can shift throughout the life cycle. The life-cycle approach that we have taken highlights that important details about demography can be overlooked without considering life-stage-specific responses. Ultimately, it is these life-stage-specific responses that shape population outcomes, not only for animal pollinators but also for many organisms living in seasonal environments.

Nitrogen fixation by diverse diazotrophic communities can support population growth of arboreal ants

BackgroundSymbiotic ant-plant associations, in which ants live on plants, feed on plant-provided food, and protect host trees against threats, are ubiquitous across the tropics, with the Azteca-Cecropia associations being amongst the most widespread interactions in the Neotropics. Upon colonization of Cecropia’s hollow internodes, Azteca queens form small patches with plant parenchyma, which are then used as waste piles when the colony grows. Patches—found in many ant-plant mutualisms—are present throughout the colony life cycle and may supplement larval food. Despite their initial nitrogen (N)-poor substrate, patches in Cecropia accommodate fungi, nematodes, and bacteria. In this study, we investigated the atmospheric N2 fixation as an N source in patches of early and established ant colonies.ResultsVia 15N2 tracer assays, N2 fixation was frequently detected in all investigated patch types formed by three Azteca ant species. Quantified fixation rates were similar in early and established ant colonies and higher than in various tropical habitats. Based on amplicon sequencing, the identified microbial functional guild—the diazotrophs—harboring and transcribing the dinitrogenase reductase (nifH) gene was highly diverse and heterogeneous across Azteca colonies. The community composition differed between early and established ant colonies and partly between the ant species.ConclusionsOur data show that N2 fixation can result in reasonable amounts of N in ant colonies, which might not only enable bacterial, fungal, and nematode growth in the patch ecosystems but according to our calculations can even support the growth of ant populations. The diverse and heterogeneous diazotrophic community implies a functional redundancy, which could provide the ant-plant-patch system with a higher resilience towards changing environmental conditions. Hence, we propose that N2 fixation represents a previously unknown potential to overcome N limitations in arboreal ant colonies.

Honey bee hive covers reduce food consumption and colony mortality during overwintering.

Beekeepers regularly employ management practices to mitigate losses during the winter, often considered the most difficult time during a colony life cycle. Management recommendations involving covering or wrapping hives in insulation during winter have a long history; over 100 years ago, most recommendations for overwintering in cold climates involved heavy insulation wraps or moving hives indoors. These recommendations began to change in the mid-20th century, but hive covers are still considered useful and are described in contemporary beekeeping manuals and cooperative extension materials. However, most of the data supporting their use is published primarily in non-peer reviewed trade journals and was collected >40 years ago. In this time, the beekeeping environment has changed substantially, with new pressures from pathogens, agrochemicals, and land use changes. Here, we provide an update to the historical literature, reporting a randomized experiment testing the effectiveness of a common honey bee hive cover system across eight apiaries in central Illinois, USA, a temperate region dominated by conventional annual agriculture. We found that, when other recommended overwintering preparations are performed, covered colonies consumed less food stores and survived better than uncovered controls (22.5% higher survival). This study highlights the value of hive covers, even in an area not subject to extremely cold winter conditions, and these data can aid the production of evidence-based extension recommendations for beekeepers.

Biomarkers in a socially exchanged /fluid reflect colony maturity, behavior, and distributed metabolism.

In cooperative systems exhibiting division of labor, such as microbial communities, multicellular organisms, and social insect colonies, individual units share costs and benefits through both task specialization and exchanged materials. Socially exchanged fluids, like seminal fluid and milk, allow individuals to molecularly influence conspecifics. Many social insects have a social circulatory system, where food and endogenously produced molecules are transferred mouth-to-mouth (stomodeal trophallaxis), connecting all the individuals in the society. To understand how these endogenous molecules relate to colony life, we used quantitative proteomics to investigate the trophallactic fluid within colonies of the carpenter ant Camponotus floridanus. We show that different stages of the colony life cycle circulate different types of proteins: young colonies prioritize direct carbohydrate processing; mature colonies prioritize accumulation and transmission of stored resources. Further, colonies circulate proteins implicated in oxidative stress, ageing, and social insect caste determination, potentially acting as superorganismal hormones. Brood-caring individuals that are also closer to the queen in the social network (nurses) showed higher abundance of oxidative stress-related proteins. Thus, trophallaxis behavior could provide a mechanism for distributed metabolism in social insect societies. The ability to thoroughly analyze the materials exchanged between cooperative units makes social insect colonies useful models to understand the evolution and consequences of metabolic division of labor at other scales.

Onset of morning activity in bumblebee foragers under natural low light conditions.

Foraging on flowers in low light at dusk and dawn comes at an additional cost for insect pollinators with diurnal vision. Nevertheless, some species are known to be frequently active at these times. To explore how early and under which light levels colonies of bumblebees, Bombus terrestris, initiate their foraging activity, we tracked foragers of different body sizes using RFID over 5 consecutive days during warm periods of the flowering season. Bees that left the colony at lower light levels and earlier in the day were larger in size. This result extends the evidence for alloethism in bumblebees and shows that foragers differ in their task specialization depending on body size. By leaving the colony earlier to find and exploit flowers in low light, larger‐sized foragers are aided by their more sensitive eyes and can effectively increase their contributions to the colony's food influx. The decision to leave the colony early seems to be further facilitated by knowledge about profitable food resources in specific locations. We observed that experience accrued over many foraging flights determined whether a bee started foraging under lower light levels and earlier in the morning. Larger‐sized bees were not more experienced than smaller‐sized bees, confirming earlier observations of wide size ranges among active foragers. Overall, we found that most foragers left at higher light levels when they could see well and fly faster. Nevertheless, a small proportion of foragers left the colony shortly after the onset of dawn when light levels were below 10 lux. Our observations suggest that bumblebee colonies have the potential to balance the benefits of deploying large‐sized or experienced foragers during dawn against the risks and costs of foraging under low light by regulating the onset of their activity at different stages of the colony's life cycle and in changing environmental conditions.

The hybrid bacterial foraging algorithm based on many-objective optimizer.

A new multi-objective optimized bacterial foraging algorithm - Hybrid Multi-Objective Optimized Bacterial Foraging Algorithm (HMOBFA) is presented in this article. The proposed algorithm combines the crossover-archives strategy and the life-cycle optimization strategy, look for the best method through research area. The crossover-archive strategy with an external archive and internal archive is assigned to different selection principles to focus on diversity and convergence separately. Additionally, according to the local landscape to satisfy population diversity and variability as well as avoiding redundant local searches, individuals can switch their states periodically throughout the colony lifecycle with the life-cycle optimization strategy. all of which may perform significantly well. The performance of the algorithm was examined with several standard criterion functions and compared with other classical multi-objective majorization methods. The examiner results show that the HMOBFA algorithm can achieve a significant enhancement in performance compare with other method and handles many-objective issues with solid complexity, convergence as well as diversity. The HMOBFA algorithm has been proven to be an excellent alternative to past methods for solving the improvement of many-objective problems.

Individual and combined impacts of sulfoxaflor and Nosema bombi on bumblebee (Bombus terrestris) larval growth.

Sulfoxaflor is a globally important novel insecticide that can have negative impacts on the reproductive output of bumblebee (Bombus terrestris) colonies. However, it remains unclear as to which life-history stage is critically affected by exposure. One hypothesis is that sulfoxaflor exposure early in the colony's life cycle can impair larval development, reducing the number of workers produced and ultimately lowering colony reproductive output. Here we assess the influence of sulfoxaflor exposure on bumblebee larval mortality and growth both when tested in insolation and when in combination with the common fungal parasite Nosema bombi, following a pre-registered design. We found no significant impact of sulfoxaflor (5 ppb) or N. bombi exposure (50 000 spores) on larval mortality when tested in isolation but found an additive, negative effect when larvae received both stressors in combination. Individually, sulfoxaflor and N. bombi exposure each impaired larval growth, although the impact of combined exposure fell significantly short of the predicted sum of the individual effects (i.e. they interacted antagonistically). Ultimately, our results suggest that colony-level consequences of sulfoxaflor exposure for bumblebees may be mediated through direct effects on larvae. As sulfoxaflor is licensed for use globally, our findings highlight the need to understand how novel insecticides impact non-target insects at various stages of their development.

Wolbachia-infected ant colonies have increased reproductive investment and an accelerated life cycle.

Wolbachia is a widespread genus of maternally transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its hosts to favor its own transmission. Wolbachia-mediated phenotypic effects are well characterized in solitary hosts, but effects in social hosts are unclear. The invasive pharaoh ant, Monomorium pharaonis, shows natural variation in Wolbachia infection between colonies and can be readily bred under laboratory conditions. We previously showed that Wolbachia-infected pharaoh ant colonies had more queen-biased sex ratios than uninfected colonies, which is expected to favor the spread of maternally transmitted Wolbachia Here, we further characterize the effects of Wolbachia on the short- and longer-term reproductive and life history traits of pharaoh ant colonies. First, we characterized the reproductive differences between naturally infected and uninfected colonies at three discrete time points and found that infected colonies had higher reproductive investment (i.e. infected colonies produced more new queens), particularly when existing colony queens were 3 months old. Next, we compared the long-term growth and reproduction dynamics of infected and uninfected colonies across their whole life cycle. Infected colonies had increased colony-level growth and early colony reproduction, resulting in a shorter colony life cycle, when compared with uninfected colonies.

Habitat Preference and Phenology of Nest Seeking and Foraging Spring Bumble Bee Queens in Northeastern North America (Hymenoptera: Apidae: Bombus)

Bumble bees are among the most abundant and important wild pollinators in North America. Spring nest establishment is a brief and vulnerable stage in the colony life cycle that is poorly understood. Bumble bee nesting activity in temperate North America has received little recent attention, and this knowledge gap is a barrier to conservation efforts. The aim of this study was to investigate the habitat use, nesting phenology, and key food plants of spring bumble bee queens. Through 108 nonlethal surveys of bumble bee queens in spring 2018, researchers observed 451 nest seeking and 555 foraging queens of nine species in Ohio, U.S.A. Spring queen activity began in mid-April and peaked in mid-May, although nest seekers were observed into late June. Nest seeking queens favored woody transitional habitats over open habitats. In accordance queen abundance and diversity increased with the proportion of forest in the surrounding landscape. The proportion of row crops and urban areas negatively influenced queen diversity and the number of nest seekers, respectively. Through a literature review, the earliest emergence dates for each species were compared for 12 datasets to establish an order of species emergence in northeastern North America. Forty-seven species of flowering plants were used by foraging queens. Highly visited food plants included both native and nonnatives(*): Lupinus perennis, Malus spp., Taraxacum officinale*, Lonicera spp.*, Lamium purpureum*, Glechoma hederacea*, Trifolium pratense*, and Mertensia virginica. Systematic field surveys are needed by state to document the timing of spring queen emergence and nesting activities to inform conservation efforts.

Optimal foraging and the information theory of gambling.

At a macroscopic level, part of the ant colony life cycle is simple: a colony collects resources; these resources are converted into more ants, and these ants in turn collect more resources. Because more ants collect more resources, this is a multiplicative process, and the expected logarithm of the amount of resources determines how successful the colony will be in the long run. Over 60 years ago, Kelly showed, using information theoretic techniques, that the rate of growth of resources for such a situation is optimized by a strategy of betting in proportion to the probability of pay-off. Thus, in the case of ants, the fraction of the colony foraging at a given location should be proportional to the probability that resources will be found there, a result widely applied in the mathematics of gambling. This theoretical optimum leads to predictions as to which collective ant movement strategies might have evolved. Here, we show how colony-level optimal foraging behaviour can be achieved by mapping movement to Markov chain Monte Carlo (MCMC) methods, specifically Hamiltonian Monte Carlo (HMC). This can be done by the ants following a (noisy) local measurement of the (logarithm of) resource probability gradient (possibly supplemented with momentum, i.e. a propensity to move in the same direction). This maps the problem of foraging (via the information theory of gambling, stochastic dynamics and techniques employed within Bayesian statistics to efficiently sample from probability distributions) to simple models of ant foraging behaviour. This identification has broad applicability, facilitates the application of information theory approaches to understand movement ecology and unifies insights from existing biomechanical, cognitive, random and optimality movement paradigms. At the cost of requiring ants to obtain (noisy) resource gradient information, we show that this model is both efficient and matches a number of characteristics of real ant exploration.

Transmission of fungal partners to incipient Cecropia-tree ant colonies.

Ascomycete fungi in the nests of ants inhabiting plants (= myrmecophytes) are very often cultivated by the ants in small patches and used as food source. Where these fungi come from is not known yet. Two scenarios of fungus recruitment are possible: (1) random infection through spores or hyphal fragments from the environment, or (2) transmission from mother to daughter colonies by the foundress queen. It is also not known at which stage of the colony life cycle fungiculture is initiated, and whether the- symbiont fungi serve as food for the ant queen. To clarify these questions, we investigated four Azteca ant species inhabiting three different Cecropia species (C. insignis, C. obtusifolia, and C. peltata). We analysed an rRNA gene fragment from 52 fungal patches produced by founding queens and compared them with those from established Azteca colonies (n = 54). The infrabuccal pockets of winged queens were dissected to investigate whether young queens carry fungi from their mother colony. Additionally, 15N labelling experiments were done to verify whether the queen feeds on the patches until she is nourished by her first worker offspring. We infer from the results that the fungi cultivated in hollow plant structures are transferred from the parental colony of the young queen. First, fungal genotypes/OTU diversity was not significantly different between foundress queen patches and established colonies, and second, hyphal parts were discovered in the infrabuccal pockets of female alates. We could show that fungiculture already starts before queens lay their eggs, and that the queens do not feed on fungal patch material but feed it to the larvae. Our findings suggest that fungiculture may be crucial for successful colony founding of arboreal ants in the tropics.

Dispersal and mating strategies in two neotropical soil-feeding termites, Embiratermes neotenicus and Silvestritermes minutus (Termitidae, Syntermitinae)

Colony breeding systems and dispersal strategies of eusocial insects shape the genetic structure at the colony, but also at the population level. Most of the few molecular studies dedicated to termites suggest that winged reproductives disperse far enough to secure the formation of outbred founding pairs. However, these studies almost exclusively focused on wood-feeding termites and knowledge about the dispersal potential of winged reproductives is missing for soil-feeding termites. We investigated the dispersal and mating strategies of Embiratermes neotenicus and Silvestritermes minutus (Termitidae, Syntermitinae), two very abundant soil-feeding species from the Neotropics. In both species, analysis of microsatellite markers indicated low genetic similarity between closely located colonies and low genetic differentiation between populations separated by less than 10 km. Each of the 39 E. neotenicus colonies originated from a single pair of primary reproductives and the mean inbreeding coefficient of sterile castes was only slightly different from that expected in offspring of an outbred pair. Most S. minutus colonies (34/41) were consistent with outbred biparental foundation. In three mature colonies, the genotypes of sterile castes suggested their origin by mixing of multiple related reproductives. Finally, four colonies in late stage of the colony life cycle contained sterile populations originating from multiple unrelated reproductives. We conclude that long-distance flights resulting in outbred reproduction are common in these soil-feeding species in pristine habitats but that other factors, such as mating preferences, could increase relatedness between founders.

Lifecycle coevolution framework for many evolutionary and swarm intelligence algorithms fusion in solving complex optimization problems

Abstract In last few decades, many different evolutionary and swarm intelligence (EA and SI) algorithms have been delicately developed for solving complex optimization problems. However, according to no free lunch theorem (NFL), a general-purpose universal EA or SI algorithm that is efficient for various types of optimization problems is theoretically impossible. The main focus in this research is to prove that there are potential free lunches in coevolutionary optimization mode. The significant improvements in the generality and effectiveness of EA and SI search ability can be achieved by fusing unlimited number of optimization algorithms based on the new concept of Lifecycle Coevolution Framework (LCF). The main innovation of LCF is to run the different SI algorithms simultaneously, in which individuals of each optimizer dynamically shift their states of birth, searching, learning, reproduction, and death throughout the whole colony life cycle. Based on LCF, we instantiate a novel coevolutionary optimization algorithm called a Lifecycle Framework of Multiple Evolution Algorithms (LCFMEAs). For purposes of examining the success of LCFMEAs in solving complex optimization problems, 50 benchmark functions with different specifications are employed. The results show that LCFMEAs provide extremely competitive performance when it is compared with six widely used evolutionary and swarm intelligence algorithms.

Spatial and temporal variations in floral resource availability affect bumblebee communities in heathlands

Modifications of landscape structure and composition can decrease the availability of floral resources, resulting in the decline of many pollinator species, including bumblebees. These declines may have significant ecological consequences, because bumblebees pollinate a large range of plant species. Our study was carried out in heathlands, open semi-natural habitats that have decreased considerably due to human activities. We analysed how floral resources affect bumblebee communities throughout the colony lifetime at three scales: plot scale, heathland patch scale, and landscape scale. Floral density at the plot scale and spruce plantations at the landscape scale influenced bumblebee communities. The abundance of bumblebees on ericaceous species was higher when the landscape included a substantial proportion of unsuitable foraging habitat (i.e., spruce plantations). Both life history traits and colony life cycle stage influenced bumblebee responses to the availability of floral resources. Bumblebees were more affected by floral resources during the colony development phase than during the nest-foundation or mating phases. Moreover, bumblebees of species that form large colonies needed larger quantities of favourable foraging habitat, compared with small-colony bees, and their proportion decreased in habitats dominated by spruce plantations. In conclusion, the conservation of plant–bumblebee interactions will require management at a larger spatial scale than the restricted protected habitats. Moreover, at the landscape scale, both quantity of favourable foraging patches and their ecological continuity are important to conserve both small- and large- colony species.

Artificial Bee Colony Optimizer Based on Bee Life-Cycle for Stationary and Dynamic Optimization

This paper proposes a novel optimization scheme by hybridizing an artificial bee colony optimizer (HABC) with a bee life-cycle mechanism, for both stationary and dynamic optimization problems. The main innovation of the proposed HABC is to develop a cooperative and population-varying scheme, in which individuals can dynamically shift their states of birth, foraging, death, and reproduction throughout the artificial bee colony life cycle. That is, the bee colony size can be adjusted dynamically according to the local fitness landscape during algorithm execution. This new characteristic of HABC helps to avoid redundant search and maintain diversity of population in complex environments. A comprehensive experimental analysis is implemented that the proposed algorithm is benchmarked against several state-of-the-art bio-inspired algorithms on both stationary and dynamic benchmarks. Then the proposed HABC is applied to the real-world applications including data clustering and image segmentation problems. Statistical analysis of all these tests highlights the significant performance improvement due to the life-cycle mechanism and shows that the proposed HABC outperforms the reference algorithms.