Social Insects Research Articles

From Nature to UAV - A Study on Collision Avoidance in Bee Congregation

Insects engage in a variety of survival-related activities, including feeding, mating, and communication, which are frequently motivated by innate impulses and environmental signals. Social insects, such as ants and bees, exhibit complex collective behaviors. They carry out well-organized duties, including defense, nursing, and foraging, inside their colonies. For analyzing the behavior of any living entity, we selected honeybees (Apis Mellifera) and worked on a small portion of it. We have captured the video of honeybees flying close to a hive (human-made artificial hive) while the entrance was temporarily sealed which resulted in the” bee cloud”. An exploration of the flight trajectories executed and a 3D view of the” bee cloud” constructed. We analyzed the behaviors of honeybees, especially on their speed and distance. The results showed that the loitering honeybees performed turns that are fully coordinated, and free of sideslips so thus they made no collision between themselves which inspired us to propose a method for avoiding collision in unmanned aerial vehicle. This paper gives the collective behavioral information and analysis report of the small portion of data set (honeybees), that bee maintains a safe distance (35mm) to avoid collision.

The recovery and resilience facility as a new legal technology of European governance

ABSTRACT This article examines the innovative legal technology of European governance introduced by the Recovery & Resilience Facility (RRF) and its growing diffusion to a plurality of internal and external EU programs. It argues that the RRF created a new governance model, based on a 5-step process: definition of EU priorities, design of national plans, EU assessment of national plans, national implementation of the plans, and EU monitoring. Since 2021, the RRF legal technology has been replicated in a half dozen contexts – including RePowerEU, the EU Social Climate Fund, the Macro-Financial Assistance+ Instrument for Ukraine 2023, the Ukraine Facility and even the new Stability and Growth Pact. The RRF model has several legitimacy advantages, because it favors national ownership, while still endowing the EU institutions with significant leeway to shape national policy-making. Moreover, as a performance-based arrangement, it has effectiveness advantages too. Yet this model also has drawbacks worth exploring.

Test of the negative feedback hypothesis of colony size sensing in social insects.

Social insects can sense colony size-even without visual information in a dark environment. How they achieve this is yet largely unknown. We empirically tested a hypothesis on the proximate mechanism using ant colonies. In Diacamma colonies, the monogynous queen is known to increase the effort devoted to queen pheromone transmission behaviour (patrolling) as the colony grows, as if she perceives colony size. The negative feedback hypothesis assumes that, through repeated physical contact with workers, the queen monitors the physiological state (fertility) of workers and increases her patrolling effort when she encounters more fertile workers. Supporting this hypothesis, we found that the queen increased her patrolling effort in response to a higher ratio of fertile workers under the experimental condition of constant colony size. Furthermore, chemical analyses and bioassays suggested that cuticular hydrocarbons have queen pheromone activity and can mediate the observed queen-worker communication of fertility state. Such a self-organizing mechanism of sensing colony size may also operate in other social insects living in small colonies.

The diversity of social complexity in termites.

Sociality underpins major evolutionary transitions and significantly influences the structure and function of complex ecosystems. Social insects, seen as the pinnacle of sociality, have traits like obligate sterility that are considered 'master traits', used as single phenotypic measures of this complexity. However, evidence is mounting that completely aligning both phenotypic and evolutionary social complexity, and having obligate sterility central to both, is erroneous. We hypothesize that obligate and functional sterility are insufficient in explaining the diversity of phenotypic social complexity in social insects. To test this, we explore the relative importance of these sterility traits in an understudied but diverse taxon: the termites. We compile the largest termite social complexity dataset to date, using specimen and literature data. We find that although functional and obligate sterility explain a significant proportion of variance, neither trait is an adequate singular proxy for the phenotypic social complexity of termites. Further, we show both traits have only a weak association with the other social complexity traits within termites. These findings have ramifications for our general comprehension of the frameworks of phenotypic and evolutionary social complexity, and their relationship with sterility.

Financial report: international union for the study of social insects 2023

Financial report: international union for the study of social insects 2023

The genomic and cellular basis of biosynthetic innovation in rove beetles

How evolution at the cellular level potentiates macroevolutionary change is central to understanding biological diversification. The >66,000 rove beetle species (Staphylinidae) form the largest metazoan family. Combining genomic and cell type transcriptomic insights spanning the largest clade, Aleocharinae, we retrace evolution of two cell types comprising a defensive gland-a putative catalyst behind staphylinid megadiversity. We identify molecular evolutionary steps leading to benzoquinone production by one cell type via a mechanism convergent with plant toxin release systems, and synthesis by the second cell type of a solvent that weaponizes the total secretion. This cooperative system has been conserved since the Early Cretaceous as Aleocharinae radiated into tens of thousands of lineages. Reprogramming each cell type yielded biochemical novelties enabling ecological specialization-most dramatically in symbionts that infiltrate social insect colonies via host-manipulating secretions. Our findings uncover cell type evolutionary processes underlying the origin and evolvability of a beetle chemical innovation.

Task specific behavior of Indian honey bee (Apis cerana indica) workers

The success of honey bees living in a colony is due to well-organized interaction among morphologically similar castes, the workers. Here, we investigated the behavior of marked worker bees (Apis cerana indica Fab.) after emergence. To have a distinct difference in behavior between early- and middle-adult bees, worker bees were divided into two groups: young-aged bees (YAB) and middle-aged bees (MAB). Four castes i.e., “cell cleaner”, “nurse bee” (YAB), “MAB”, and “forager bees” were identified in A. c. indica. Seventeen distinct behavioral tasks performed by the worker caste with advancing age were recorded. YAB were observed to be engaged in taking care of the brood, such as “capping”, “inspecting”, and “feeding the brood”, while MAB were observed to be engaged in “honey processing”, “building combs”, “guarding”, and other tasks. There were no significant differences in “inspecting cells” and “walking” between YAB and MAB. YAB were seen “In cell” comparatively higher on the combs. Tasks like “capping” are done only by YAB, while tasks like “head inside honey cells”, “building comb”, and “chewing wood” are performed by MAB. Except for a brief orientation flight, YAB never performed “guarding” or “foraging” outside the colony. Data indicated that MAB is also involved in feeding the broods. The transition from within-colony to outside-colony tasks was observed when workers were 18-20 days old. Additionally, worker bees performed a variety of duties concurrently on the same day. Thus, the worker caste of A. c. indica, which lacks physical difference, can organize and divide colony responsibilities.

Are ants not only ‘social insects’, but also ‘nomic insects’? In search of clues of normativity in the ant world

Abstract Recently, various philosophers and ethologists have argued or hypothesised that, in addition to humans, there are also non-human animals that are capable of following rules and implementing normative behaviours. The investigation of animal normativity until now, however, has been almost exclusively focused on mammals and, in particular, non-human primates and cetaceans. In contrast, this work aims to extend this research to the world of invertebrates and, more specifically, to the world of eusocial insects. For the purpose of investigating whether there are clues of normativity in the world of eusocial insects, we will inquire into the question of whether certain behaviours of ants can be considered normatively conditioned behaviours.

Intercolony Avoidance Optimizes Foraging in Eciton burchellii Army Ants

Foraging individuals optimize spatial movement to maximize resource use in heterogeneous environments. Colonies of Eciton burchellii, a neotropical species of army ant, forage as an army, consuming broad arrays of arthropod and social insect prey. Prey depletion in foraging paths exacerbates resource heterogeneity for E. burchellii and may encourage colonies to avoid contact with recently raided areas. Colonies are known to turn in opposite directions more often than random from previous days’ foraging paths, which increases distances between recently raided areas. However, no evidence of colony avoidance of areas recently foraged by a conspecific colony has been presented. In this study, we analyze data collected in the Peruvian Amazon between 1998 and 2008 to examine colony spatial distribution using nearest-neighbor distance data. We found that colonies optimize movement by choosing foraging angles that deflect away from areas recently raided by conspecific colonies. In addition, we found that the observed nearest neighbor distance between E. burchellii colonies was more significant than expected if colonies were dispersed randomly. This dispersion pattern increases the distance between colonies and contributes to a spatial movement that optimizes foraging and decreases colony interactions at recently raided areas.

Colony environment and absence of brood enhance tolerance to a neonicotinoid in winter honey bee workers, Apis mellifera

In eusocial insects, worker longevity is essential to ensure colony survival in brood-free periods. Trade-offs between longevity and other traits may render long-living workers in brood-free periods more susceptible to pesticides compared to short-lived ones. Further, colony environment (e.g., adequate nutrition) may enable workers to better cope with pesticides, yet data comparing long vs. short-living workers and the role of the colony environment for pesticide tolerance are scarce. Here, we show that long-living honey bee workers, Apis mellifera, are less susceptible to the neonicotinoid thiamethoxam than short-lived workers, and that susceptibility was further reduced when workers were acclimatized under colony compared to laboratory conditions. Following an OECD protocol, freshly-emerged workers were exposed to thiamethoxam in summer and winter and either acclimatized within their colony or in the laboratory. Mortality and sucrose consumption were measured daily and revealed that winter workers were significantly less susceptible than summer workers, despite being exposed to higher thiamethoxam dosages due to increased food consumption. Disparencies in fat body activity, which is key for detoxification, may explain why winter bees were less susceptible. Furthermore, colony acclimatization significantly reduced susceptibility towards thiamethoxam in winter workers likely due to enhanced protein nutrition. Brood absence and colony environment seem to govern workers’ ability to cope with pesticides, which should be considered in risk assessments. Since honey bee colony losses occur mostly over winter, long-term studies assessing the effects of pesticide exposure on winter bees are required to better understand the underlying mechanisms.

The Worker Flow at the Hive Entrance Predicts When Nest Cleaning is Intensified in Stingless Bees

Waste produced by living organisms is commonly disposed of as a prophylactic measure to avoid the spread of diseases and parasite infestation. For social insects, a proportion of workers is allocated to dispose the waste material outside the colony’s nest. However, most nests of social insects have a single entrance, where a high flow of individuals may create congestion, potentially compromising normal foraging activities and colony growth/health. Here, we investigated how two species of stingless bees (Tetragonisca fiebrigi and Plebeia droryana) deal with waste disposal and regular foraging activities, and the impacts of these activities on traffic flow at nest entrances. First, we compared the average traffic of bees assigned to waste removal activities. Following this, we investigated probabilities for waste removal as bee traffic increases. Then, we estimated a cutoff value to predict the likelihood that waste removal activities will be intensified over foraging trips. We found that, on average, the number of bees performing waste removal activities was lower than those undertaking foraging trips for both species. In addition, we observed that as overall bee traffic increases, the number of workers engaged in waste removal reduces or even ceases. Our models indicate that bee traffic of approximately 15 individuals/time is a cutoff score, below which, colonies invest in waste removal and above which, foraging trips are increased. It suggests that both species use the entrances of their colonies in an optimized way by adjusting which tasks should be intensified as the traffic of individuals increases.

Experimental queen removal stimulates caste flexibility of females in Neotropical social wasps (Vespidae Polistinae Epiponini)

Caste plasticity is an essential trait in social insects, and it facilitates the allocation of individuals in different tasks according to population demands in the colony (e.g. workers can become queens upon loss or death of their “original queen”). The process of caste determination can take place in immature stages (preimaginal) or through adult stages (imaginal). Neotropical social wasp tribe Epiponini has both types of caste determination process and is thus a fascinating group to study caste plasticity. We performed queen removal tests in five Epiponini species with preimaginal and imaginal caste determination to better understand caste plasticity and queen selection processes. Queen absence stimulates the establishment of new reproductive females in Chartergellus and Metapolybia (imaginal), while females in Protopolybia (preimaginal) attempt to lay eggs even in the presence of their “original queen”. Contrary to what has been hypothesized, we found that age is not a predictive factor in the female’s potential to become a queen. Caste flexibility seems to be a crucial trait which aids Epiponini tropical colonies to survive, as it allows the colony to replace lost workers and queens promptly until a new generation of wasps can emerge.

Establishment of a reverse transcription-recombinase polymerase amplification-lateral flow dipstick method for the dual detection of Israeli acute paralysis virus and chronic bee paralysis virus.

As an important social insect, honey bees play crucial roles in agricultural production, sustainable development of agricultural production, and the balance of the natural environment. However, in recent years, Israeli acute paralysis virus (IAPV) and chronic bee paralysis virus (CBPV), the main pathogens of bee paralysis, have continuously harmed bee colonies and caused certain losses to the beekeeping industry. Some beekeeping farms are located in wild or remote mountainous areas, and samples from these farms cannot be sent to the laboratory for testing in a timely manner, thereby limiting the accurate and rapid diagnosis of the disease. In this study, we used a reverse transcription-recombinase polymerase amplification-lateral flow dipstick (RT-RPA-LFD) method for the dual detection of IAPV and CBPV. RPA primers and LFD detection probes were designed separately for their conserved genes. Primers and probes were screened, and the forward and reverse primer ratios, reaction times, and temperatures were optimized. According to the results of the optimization tests, the optimal reaction temperature for RT-RPA is 37°C, and when combined with LFD, detection with the naked eye requires <20 min. The developed RPA-LFD method specifically targets IAPV and CBPV and has no cross-reactivity with other common bee viruses. In addition, the minimum detection limit of the RT-RPA-LFD method is 101 copies/μL. Based this study, this method is suitable for the detection of clinical samples and can be used for field detection of IAPV and CBPV.

An antifungal compound secreted by termite workers, phenylacetic acid, inhibits the growth of both termite egg-mimicking fungus and entomopathogenic fungi

Social insects live in closely related family groups but face risks of intrusion and infection by pathogenic and parasitic microbes. To cope with the microbes invading their nests and feeding sites, social insects produce various types of antimicrobial substances. Subterranean termites occupy microbe-rich decaying wood and soil at high density, expanding their nest area by exploring and feeding on wood outward from the royal chamber (room for kings and queens). Although antimicrobial agents have been identified in many termite species, few studies have investigated those used by foraging workers in decaying wood under development, which is richer in microbes than the well-sterilized royal chamber and its surroundings. Here, we report that phenylacetic acid, an antifungal aromatic compound, is secreted by foraging workers of the Japanese subterranean termite Reticulitermes speratus. The compound was detected by gas chromatography–mass spectrometry analysis of ethyl acetate extracts of shelter papers infested with the workers, and antimicrobial tests demonstrated that it inhibits the germination and/or mycelial growth of the entomopathogenic fungi (Metarhizium anisopliae and Beauveria bassiana) and the termite egg-mimicking fungus Athelia termitophila. Our study provides new insights into the antimicrobial defense mechanisms of termites, including by combining different types of antimicrobial substances secreted by different castes, and thus the survival strategy of entomopathogenic and parasitic fungi in termite nests.

Stingless bee foragers experience more thermally stressful microclimates and have wider thermal tolerance breadths than other worker subcastes

IntroductionThe current state of anthropogenic climate change is particularly concerning for tropical insects, species predicted to be the most negatively affected. Researching climatic tolerance in social insects is challenging because adaptations exist at both individual and societal levels. Division of labor research helps to bridge the gap between our understanding of these adaptations at different scales, which is important because social insects comprise a tremendous portion of global animal biomass, biodiversity, and ecosystem services. Considering how individual physiologies construct group-level adaptations can improve climate change impact assessments for social species. Tetragonisca angustula is a neotropical stingless bee species that exhibits high worker subcaste specialization with a morphologically distinct soldier caste.MethodsWe used this species to investigate 1) whether age- and size-differentiated subcastes differ in thermal tolerance, 2) which worker subcaste operates closest to their thermal limits, and 3) the extent to which this species selects active foraging times to offset thermal stress. We measured the thermal tolerance (CTmax and CTmin) of small-bodied foragers and two soldier subcastes (hovering guards and standing guards) in T. angustula.Results and discussionDespite body size differences between foragers and guards, no differences in the upper or lower thermal limits were observed. However, the average thermal tolerance breadth of foragers was significantly larger than that of guards, and foraging sites were more thermally variable than nest sites, supporting the Climatic Variability Hypothesis at a microclimate scale and in the context of division of labor. Warming tolerance was significantly lower among small-bodied foragers compared to hovering and standing guards. The magnitude of warming tolerances indicated low risk of imminent climate change impacts in this environment but suggests that increasing temperatures and heatwave prevalence may cause foragers to meet their upper thermal limits before other subcastes. Foraging occurred at a narrower range of temperatures than would challenge critical temperatures, with higher morning activity. Directionally increasing temperatures will likely confine these preferred foraging temperatures to a narrower time window. Further study is needed to elucidate how foragers may shift times of activity in response to anthropogenic warming, but changing climates may impact plant pollination rates in natural and agricultural systems.

HIVE TEMPERATURE REGULATION BY HONEYBEES IN RESPONSE TO EXTREME CONDITIONS

Honeybees are considered the primary pollinators of agricultural crops. However, climate change, pesticide use, disease transmission and pests all have an impact on their survival. Temperature is an important consideration, especially when bees are subjected to harsh conditions as a result of the effort required to regulate them within their hives. The brood chamber should be kept between 33 and 35 °C. The recognized temperature thresholds are 6 and 38 °C; deviations above or below these values cause metabolic damage in honeybees; the larger the difference, the greater the stress. These eusocial insects have developed thermoregulating mechanisms in response to adverse environmental conditions; the colony compensates for this difference by either fanning their wings to create air circulation and cause evaporative cooling or raising the temperature by generating endothermic heat to raise the temperature of the breeding chamber. This review brings together the most important and updated references on how to improve colony thermoregulation and its relationship to climate change.

Colony identity clues for Syntermes grandis (Blattodea: Termitidae) individuals using near-infrared spectroscopy and PLS-DA approach.

Termites are social insects with high species diversity in tropical ecosystems. Multivariate analysis with near-infrared spectroscopy (NIRS) and data interpretation can separate social insects belonging to different colonies of the same species. The objective of this study was to propose the use of discriminant analysis by partial least squares (PLS-DA) combined with NIRS to identify the colonial origin of the Syntermes grandis (Rambur, 1842) (Blattodea: Termitidae) in 2 castes. Six ground S. grandis colonies were identified and mapped; 30 workers and 30 soldier termites in each colony were submitted to spectral measurement with NIRS. PLS-DA applied to the termites' spectral absorbance was used to detect a spectral pattern per S. grandis colony by caste. PLS-DA regression with NIRS proved to be an approach with 99.9% accuracy for identifying the colonial origin of S. grandis workers and 98.3% for soldiers. The methodology showed the importance of qualitatively characterizing the colonial phenotypic response of this species. NIRS is a high-precision approach to identifying the colony origin of S. grandis workers and soldiers. The PLS-DA can be used to design ecological field studies to identify colony territorial competition and foraging behavior of subterranean termite species.

Pervasive relaxed selection in termite genomes.

Genetic changes that enabled the evolution of eusociality have long captivated biologists. More recently, attention has focussed on the consequences of eusociality on genome evolution. Studies have reported higher molecular evolutionary rates in eusocial hymenopteran insects compared with their solitary relatives. To investigate the genomic consequences of eusociality in termites, we analysed nine genomes, including newly sequenced genomes from three non-eusocial cockroaches. Using a phylogenomic approach, we found that termite genomes have experienced lower rates of synonymous substitutions than those of cockroaches, possibly as a result of longer generation times. We identified higher rates of non-synonymous substitutions in termite genomes than in cockroach genomes, and identified pervasive relaxed selection in the former (24-31% of the genes analysed) compared with the latter (2-4%). We infer that this is due to reductions in effective population size, rather than gene-specific effects (e.g. indirect selection of caste-biased genes). We found no obvious signature of increased genetic load in termites, and postulate efficient purging of deleterious alleles at the colony level. Additionally, we identified genomic adaptations that may underpin caste differentiation, such as genes involved in post-translational modifications. Our results provide insights into the evolution of termites and the genomic consequences of eusociality more broadly.

Inter-clonal competition over queen succession imposes a cost of parthenogenesis on termite colonies.

In social insect colonies, selfish behaviour due to intracolonial conflict among members can result in colony-level costs despite close relatedness. In certain termite species, queens use asexual reproduction for within-colony queen succession but rely on sexual reproduction for worker and alate production, resulting in multiple half-clones of a single primary queen competing for personal reproduction. Our study demonstrates that competition over asexual queen succession among different clone types leads to the overproduction of parthenogenetic offspring, resulting in the production of dysfunctional parthenogenetic alates. By genotyping the queens of 23 field colonies of Reticulitermes speratus, we found that clone variation in the queen population reduces as colonies develop. Field sampling of alates and primary reproductives of incipient colonies showed that overproduced parthenogenetic offspring develop into alates that have significantly smaller body sizes and much lower survivorship than sexually produced alates. Our results indicate that while the production of earlier and more parthenogenetic eggs is advantageous for winning the competition for personal reproduction, it comes at a great cost to the colony. Thus, this study highlights the evolutionary interplay between individual-level and colony-level selection on parthenogenesis by queens.

Serial founder effects slow range expansion in an invasive social insect

Invasive populations often experience founder effects: a loss of genetic diversity relative to the source population, due to a small number of founders. Even where these founder effects do not impact colonization success, theory predicts they might affect the rate at which invasive populations expand. This is because secondary founder effects are generated at advancing population edges, further reducing local genetic diversity and elevating genetic load. We show that in an expanding invasive population of the Asian honey bee (Apis cerana), genetic diversity is indeed lowest at range edges, including at the complementary sex determiner, csd, a locus that is homozygous-lethal. Consistent with lower local csd diversity, range edge colonies had lower brood viability than colonies in the range centre. Further, simulations of a newly-founded and expanding honey bee population corroborate the spatial patterns in mean colony fitness observed in our empirical data and show that such genetic load at range edges will slow the rate of population expansion.