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Stingless bee

Stingless bees, belonging to the tribe Meliponini within the family (order ), are a diverse group of highly social characterized by their vestigial, non-functional stings and reliance on alternative defense mechanisms such as biting or chemical secretions. Comprising over 600 extant species across 45 genera, they form perennial colonies that produce , , and other hive products, making them vital pollinators in tropical ecosystems. These bees exhibit advanced social organization, with division of labor among queens, workers, and drones, and they transport using corbiculae (pollen baskets) on their hind legs. Distributed pantropically, stingless bees achieve their highest diversity in the Neotropics, where approximately 474 species occur across 26 genera, spanning latitudes from 34.89°S to 27.03°N. Smaller populations inhabit the Afrotropics (33 species in 8 genera, from to and ), the Indo-Malayan region, and , with limited presence in subtropical areas. Their nesting biology is remarkably varied, including subterranean nests, cavities in trees or , and exposed structures, often constructed with cerumen (a of and resin). Colony sizes range from a few dozen to tens of thousands of workers, and some display unique behaviors such as cleptobiosis (hive robbing) or necrophagy (feeding on dead ). Stingless bees hold significant economic and cultural value, particularly through meliponiculture, the practice of managing colonies for , , and services, which supports livelihoods in rural tropical communities. In Mesoamerican cultures, such as among the , these bees have been revered for millennia, with serving as a , energy source, and medicinal agent in traditional practices. Their products are used in ethno-medicine for treating ailments like wounds and respiratory issues, while their enhances and crop yields in agroecosystems. Despite these benefits, habitat loss and overharvesting threaten many species, underscoring the need for efforts.

Taxonomy and Phylogeny

Taxonomy

Stingless bees, known scientifically as the tribe , are classified within the order , family , subfamily . This placement situates them among the corbiculate bees, which include honey bees (Apini), bumble bees (), and orchid bees (), distinguished by their pollen-transporting corbicula on the hind legs. The tribe encompasses approximately 605 described extant distributed across 45 genera, predominantly in tropical and subtropical regions worldwide. Key genera include (primarily Neotropical, with around 60 noted for their economic importance in production), (pantropical, representing the most speciose genus with over 140 ), and Plebeia (Neotropical, comprising about 30 small-bodied adapted to diverse habitats). These genera highlight the tribe's diversity, with the majority of species concentrated in the Neotropics. Historical taxonomic revisions have significantly shaped the understanding of Meliponini classification. Pioneering work by Jesus S. Moure in the mid- (e.g., 1946, 1951) proposed a system emphasizing natural groupings, elevating several subgenera to full generic status and refining boundaries based on shared morphological traits. Collaborating closely, João M.F. de Camargo extended these efforts through the late (e.g., 1980, 1996), describing numerous new taxa, particularly in the Neotropics, and establishing subgeneric divisions within major genera like to better reflect evolutionary lineages. Their combined contributions form the backbone of modern meliponine . Species delineation within Meliponini relies primarily on morphological criteria, focusing on differences in structures such as mandibles (e.g., number and shape of teeth) and wings (e.g., venation patterns and cell configurations). Additional features include metatibial morphology for corbicula shape, texture, and setal arrangements on the body, which help distinguish closely related in identification keys. These traits provide a robust framework for , though ongoing revisions incorporate molecular data to resolve cryptic diversity.

Phylogeny

Stingless bees belong to the tribe Meliponini within the subfamily Apinae of the family Apidae, forming one of the four extant tribes of corbiculate bees alongside Apini (honey bees), (bumble bees), and (orchid bees). Phylogenetic analyses based on and molecular data consistently recover Meliponini as the to Apini, with this (Apini + Meliponini) being sister to , and positioned as the basal tribe among corbiculates. This supports a single origin of advanced in corbiculate bees, distinguishing them from the primitively eusocial or solitary behaviors in and . The divergence of Meliponini is estimated to have occurred in the , approximately 80 million years ago, coinciding with the breakup of the . Key evolutionary adaptations defining the include the complete loss of a functional —reducing the to a non-defensive structure—and the development of specialized behaviors for collecting and using plant resins to construct nests, deter pathogens, and defend colonies. These traits likely evolved in response to tropical environments, enabling Meliponini to thrive without reliance on stinging for protection. Molecular phylogenies, constructed using mitochondrial genes such as subunit I () and 16S rDNA, have elucidated intra-tribal relationships and highlighted extensive diversification, particularly in the Neotropics. For instance, -based analyses of genera like reveal deep divergences and rapid speciation events in South American lineages, driven by and climatic shifts during the . Phylogenomic studies incorporating thousands of ultra-conserved elements across hundreds of delineate three major corresponding to biogeographic realms: a diverse Neotropical lineage encompassing over 75% of all Meliponini , an Afrotropical , and an Indo-Australasian . The (Afrotropical and Indo-Australasian) form a to the Neotropical radiation, with evidence of Gondwanan vicariance shaping their early divergence around 73–71 million years ago, followed by long-distance dispersal events. This pattern underscores the ancient Gondwanan origins of the tribe, with subsequent radiations in fragmented tropical habitats.

Fossil Record

The fossil record of stingless bees (tribe Meliponini) provides evidence of their ancient origins and historical distribution, with the earliest known specimens preserved in deposits dating back to the . The oldest described is Cretotrigona prisca, a small approximately 5 mm in length, discovered in Turonian from , USA, dated to approximately 90 million years ago. This specimen, initially described as Trigona prisca, exhibits morphological features typical of modern Meliponini, including reduced wing venation and corbicular adaptations for transport, suggesting that advanced social behaviors and were already established in the lineage by the late . Eocene amber from the yields several additional Meliponini fossils, indicating a broader diversity in subtropical environments. Notable examples include Melissites and Roussyana palmnickenensis from deposits near , , dated to around 44 million years ago, as well as Kelneriapis eocenica and the newly described Liotrigonopsis rozeni. These fossils, preserved in Lutetian-stage , display traits such as open marginal cells and simplified submarginal cells in the wings, aligning closely with extant and Asian genera and supporting an early diversification of the tribe. Miocene amber sites further document Meliponini presence across multiple continents, with species like Proplebeia dominicana from amber (approximately 15–20 million years old), Tetragonula and Austroplebeia from Zhangpu, China, and Liotrigona from Ethiopian amber. These finds span , , , and , corroborating biogeographic models that posit an African origin for the tribe during the breakup of , followed by dispersal to other regions. Fossils from temperate-associated amber deposits highlight a historically wider latitudinal range than the current distribution of living species. Despite this record, significant gaps persist, primarily due to the challenges of preservation in the tropical habitats where most Meliponini occur. formation is rarer in humid, low-latitude environments compared to subtropical or temperate zones, resulting in underrepresentation of early tropical forms and limiting insights into pre-Cretaceous evolution or intra-continental diversification. These biases underscore the reliance on exceptional sites for understanding the tribe's .

Description and Biology

Physical Characteristics

Stingless bees (tribe Meliponini) exhibit a wide range of body sizes, typically measuring 2 to 15 mm in length, with smaller species such as those in the genus Trigonisca reaching only 2–4 mm and larger ones like Melipona up to 8–15 mm. Some species display worker polymorphism, where individuals vary significantly in size and morphology, such as larger "soldier" workers in Tetragonisca angustula that exceed foragers in body dimensions. Unlike many other bees, stingless bees lack a functional sting, possessing instead a vestigial in workers that renders stinging impossible. This adaptation is compensated by robust mandibles capable of inflicting bites and the collection of from plants, which workers use to smear on intruders as a defensive coating. For transport, stingless bees feature corbiculae on their hind legs, consisting of a smooth, concave area on the outer surface of the metatibia fringed by long setae that form a basket-like structure similar to that in honey bees. Variations occur in the scopae, the dense fringes of hairs surrounding the corbicula, which differ in length and density across species to accommodate diverse types and loads. Sensory adaptations in stingless bees include large compound eyes that provide wide-field , often with setose surfaces in certain genera for enhanced environmental detection. Their antennae serve as primary chemosensory organs, equipped with sensilla for detecting pheromones and floral odors essential for navigation and communication. Additionally, workers possess glands on the ventral , which secrete cerumen—a mixture of and —used in nest construction. Caste-specific morphological variations exist, such as larger body sizes and modified abdomens in compared to workers.

Castes

Stingless bee colonies are organized into three primary : workers, , and males (drones). Workers are the smallest , typically measuring 2–10 mm in length, and are responsible for , nest , and brood . represent the largest , often up to 15–20 mm in length in some , and are dedicated to , laying thousands of eggs throughout their lifespan. Males, or drones, are similar in size to workers but often have slightly larger eyes and are around 3–12 mm. A defining feature of stingless bee queens is physogastry, a physiological enlargement of the abdomen that accommodates the production and storage of numerous eggs, causing the queen's body to swell to 1.5–1.8 times the size of workers in many species. This condition arises post-mating and enhances the queen's reproductive capacity but limits her mobility within the colony. In contrast, males develop from unfertilized eggs through , a common to , resulting in their haploid genetic makeup and lack of a father. This haploidy contributes to males' distinct morphology, including larger eyes and testes adapted for nuptial flights, and distinguishes them from diploid females (workers and queens). Worker polymorphism occurs in several stingless bee , leading to morphological variation within the caste that supports specialized tasks. For instance, in scutellaris, workers exhibit size dimorphism, with smaller individuals performing general duties and larger "soldiers" featuring broader heads and stronger mandibles for enhanced defense against intruders. These soldiers can be up to 30% larger than foragers, with head width correlating to improved sensory capabilities, such as more antennal sensilla for enemy recognition. Similar polymorphism appears in other genera like Tetragonisca, where guards show bimodal size distributions for nest protection. Caste development in stingless bees is regulated by physiological factors, particularly endocrine signals like (). Elevated levels during the larval spinning phase promote queen differentiation by delaying and inducing physogastry, while lower levels favor worker . Application of JH analogs to female larvae can shift them toward queen-like traits in up to 100% of cases, underscoring JH's pivotal role in caste specification. These hormonal differences, combined with nutritional inputs during larval stages, ensure the precise morphological and physiological divergence among castes.

Reproduction and Life Cycle

Stingless bee typically emerge from specially provisioned brood cells and undertake a single shortly after eclosion, during which they generally mate with one male attracted by pheromonal cues from male aggregation sites near colonies, though has been documented in some . The mated stores the received sperm in her , a specialized that allows her to fertilize eggs throughout her reproductive lifespan without further mating in most cases. This generally monandrous contrasts with the observed in honey bees, resulting in high genetic relatedness among workers (r=0.75) but lower colony-level . Brood cells are mass-provisioned by workers, who deposit a mixture of pollen, nectar (or honey), and glandular secretions into each cell before the queen lays a single egg upright on the food mass. This provisioning occurs individually for each cell, with the quantity and quality of food influencing larval development and caste determination; for instance, larger provisions in certain species like Melipona promote queen production via genetic mechanisms, while in others it is trophic. Once sealed with cerumen, the cell provides all necessary sustenance for the larva's complete development, distinguishing this from the progressive feeding seen in honey bees. Colonies reproduce through , a process where a group of workers prepares a new nest site before a virgin and a swarm of workers depart the parent colony to establish it. The virgin then undertakes her from the new site, and returning to initiate egg-laying, while the parent colony may produce additional queens for further . This gradual fission maintains connections between mother and daughter colonies for weeks to months, facilitating resource sharing until independence. The of stingless bees encompasses four stages: , , , and . The stage lasts 3–7 days, hatching into a that consumes the provisioned food mass over 5–20 days, depending on and . Pupation follows, lasting 10–40 days as the spins a and undergoes , with total development time varying from 20 to 60 days across ; for example, in Tetragonula iridipennis, it averages about 53 days. emerge fully formed, ready to assume colony roles, with queens capable of living several years and workers 30–90 days.

Behavior and Ecology

Social Organization

Stingless bees (tribe Meliponini) exhibit advanced eusociality, characterized by overlapping generations within perennial colonies, cooperative brood care among non-reproductive workers, and a reproductive division of labor where a single queen monopolizes egg-laying while workers perform all other tasks. This social structure enhances inclusive fitness by promoting the survival and reproduction of close kin, as workers are more related to their sisters (produced by the queen) than to their own potential offspring due to haplodiploid sex determination. Division of labor in stingless bee colonies follows age-based polyethism, where young workers focus on nursing tasks such as brood care, food processing, and nest maintenance, transitioning to foraging and guarding as they age, typically after 10–30 days depending on the species. Spatial polyethism also occurs, with workers specializing in specific nest areas—such as the brood chamber for nursing or storage pots for provisioning—based on their position within the colony structure, which optimizes efficiency in the confined nest environment. For example, in Melipona marginata, workers show temporal polyethism with early-age individuals handling internal duties and older ones venturing outside, though this pattern can be influenced by colony needs or individual experience. Communication in stingless bee societies relies heavily on pheromones and acoustic signals to coordinate colony activities. Queen mandibular gland pheromones, including fatty acids like (Z)-9-hexadecenoic acid, signal the queen's presence, suppress worker ovarian development, and maintain social cohesion by eliciting retinue behavior among workers. Acoustic communication involves vibratory signals produced by thoracic muscles, such as pulsed buzzes that serve as alarm signals to alert the colony to threats, increasing defensive readiness and foraging cessation at risky sites. Colony sizes in stingless bees vary widely, from a few hundred individuals in smaller species like Plebeia minima to tens of thousands in larger ones like Scaptotrigona aff. postica, reflecting adaptations to environmental resources and nest architecture. This variation contributes to queen-worker conflict over male production, as workers in singly mated colonies are genetically inclined to lay unfertilized eggs that develop into males, potentially competing with the queen's reproduction; however, workers produce males in many species while queens retain partial control through policing or suppression.

Nesting Habits

Stingless bees, belonging to the tribe Meliponini, construct nests that vary widely in architecture and location, reflecting adaptations to diverse tropical and subtropical environments. These nests serve as permanent structures, often lasting for years, and are built using a of glandular secretions and collected materials to , , and efficient brood development. The primary material is cerumen, a malleable mixture of produced by workers and gathered from the environment, which allows for flexible shaping of nest components such as walls, pots, and brood cells. Additional materials include geopropolis, formed by combining with or particles like and stones, often used to reinforce nest entrances or outer layers in species like ; and batumen, a hardened composite of , wax, and debris or , applied as thick coatings to seal cavities or create structural pillars. These materials provide antimicrobial properties and structural integrity, essential for maintaining nest hygiene in humid conditions. Nest types among stingless bees encompass exposed, cavity-dwelling, subterranean, and associative forms. Exposed nests are constructed openly on branches, tree trunks, or artificial substrates, as seen in genera such as Trigona and Tetragonisca, where they are enveloped in layers of cerumen for protection. Cavity nests, the most common, occupy tree hollows, rock fissures, or human-made structures, with species like Plebeia and Scaptotrigona lining the interior with batumen and cerumen sheets. Subterranean nests occur in soil or underground cavities, exemplified by Geotrigona species, while some, like Partamona, build within abandoned termite mounds, utilizing the pre-existing structure. Many nests feature involucre sheets—concentric layers of thin cerumen envelopes surrounding the brood area—to enhance thermal insulation and deter intruders, particularly in exposed or cavity types. Brood arrangement in stingless bees differs markedly from the vertical wax combs of honey bees, typically forming horizontal clusters or irregular combs of individual cells rather than interconnected hexagonal structures. In species like , brood cells are arranged in stacked horizontal layers or spirals within the nest core, while smaller genera such as Plebeia and Scaura organize them in loose, clustered chains without combs, allowing for progressive construction as the colony expands. This arrangement facilitates compact space use in irregular nest cavities and supports the mass-provisioning strategy unique to Meliponini. Brood rearing involves a coordinated process where workers first construct and provision individual cells with a mixture of and , forming a mass sufficient for complete larval development. The queen then oviposits a single onto this provisioned mass, after which workers rapidly seal the cell with a cerumen cap, preventing further access. Workers maintain optimal conditions inside sealed cells by regulating (typically –34°C) and (around 80–90%) through fanning and nest , ensuring larval survival until eclosion after 20–50 days, depending on the . This sealed, mass-provisioned minimizes risks and contrasts with the progressive provisioning seen in other bees. Recent studies indicate stingless bees face challenges from rising temperatures affecting brood (range –35°C).

Foraging and Pollination

Stingless bees exhibit behaviors adapted to tropical environments, typically ranging up to 500 meters from their nests, though some species like Melipona panamica can forage over 2 kilometers in native habitats. These bees employ mass recruitment strategies, where successful use pheromones from glands such as the labial or mandibular to guide nestmates to profitable food sources, enabling rapid mobilization of workers to ephemeral resources. This communication is often species-specific and can involve scent trails or pulsed signals that direct recruits precisely in time and space. Stingless bees maintain a polylectic , collecting resources from a diverse array of , including and from flowers as primary food sources, as well as resins from trees for nest construction and defense. is gathered using corbiculae, or pollen baskets on the hind legs, where workers moisten and pack floral into compact loads for transport back to the . , serving as an source, is stored in the bees' crop during trips, with volumes decreasing as they return to the nest. Resin involves mandibular collection from plant exudates or wounds, often from in genera like , and is transported similarly on the legs or body. These bees rarely collect fungi as a primary dietary component, though some associate with fungal in their nests. In pollination, stingless bees demonstrate high efficiency, particularly through in families like , where they vibrate their thoracic muscles to dislodge pollen from poricidal anthers, as observed in species such as Melipona fasciculata. They exhibit strong floral , or constancy, during individual trips, preferring to exploit one plant species until depleted before switching. However, over multiple trips, they follow trap-lining routes—stable, linear paths revisiting dispersed flower patches—which optimizes energy use in patchy tropical habitats. Ecologically, stingless bees are key pollinators in tropical forests, comprising up to 70% of bee visitors to canopy flowers in regions like the , where they support mass-flowering trees and maintain . Stingless bees visit flowers of from over 200 families, contributing to of diverse tropical despite varying colony sizes influencing overall foraging output.

Defense and Natural Enemies

Stingless bees ( Meliponini) lack functional stings, having evolutionarily reduced cornicles that cannot penetrate threats, and instead employ diverse non-stinging defenses to safeguard colonies from intruders. These mechanisms encompass physical , chemical repellents derived from sources, and coordinated behavioral responses that deter or eliminate predators and parasites. Such adaptations are crucial for their survival in tropical environments where nests face frequent raids. Individual workers utilize mandibular biting as a frontline physical , often engaging in prolonged or suicidal attacks by latching onto invaders and inflicting damage until the bee dies or the threat retreats. In species like those in the genus , this biting targets soft tissues of or other arthropods, effectively disrupting raids despite the high cost to the defender. Chemical defenses complement biting, with some species, such as those in the genus Oxytrigona, secreting caustic substances such as from cephalic glands to irritate and repel attackers. Additionally, collected plant resins are smeared directly onto intruders or applied to nest surfaces, forming geopropolis that provides barriers and deters foraging pests through sticky, toxic properties. At the colony level, specialized guard bees station themselves at nest entrances—often tubular structures built from cerumen—to monitor and intercept threats, releasing alarm pheromones to recruit reinforcements. In several species, such as Tetragonisca angustula, a polymorphic soldier caste emerges, consisting of larger workers (up to 30% heavier than foragers) that physically remove or harass intruders more effectively than standard guards. Hovering guards patrol the vicinity, enabling rapid detection and coordinated attacks that minimize intrusion success. Stingless bee colonies face predation from various , including that attempt to breach nests for brood and provisions, often countered by resin-based deterrence. Cleptobiotic bees of the genus Lestrimelitta represent a specialized threat, raiding host colonies to steal larval food, , and through chemical that evades initial detection. Phoretic mites, such as those in the families Carpoglyphidae and , hitch rides on bees or reside in nests, feeding on provisions or without the severe impacts seen in honey bee infestations, though diverse acarine species can elevate with host density. Vertebrate predators target stingless bee nests for and brood, with birds such as jacamars (Galbulidae) capturing foraging workers mid-flight and mammals like kinkajous (Potos flavus) excavating arboreal nests at night using their prehensile tails and strong claws. These raids can devastate colonies, prompting bees to rely on fortified entrance designs and mass mobbing to disrupt access. Parasitic threats include fungal pathogens that infect brood, with species of Aspergillus—such as A. caelatus—causing high mortality in larvae of hosts like Heterotrigona itama by invading provisions and producing mycotoxins. Unlike honey bees, stingless bees lack mites but harbor other parasitic or commensal mites that may weaken colonies under stress, highlighting the role of in suppressing fungal growth within nests.

Distribution and Diversity

Geographical Range

Stingless bees (Apidae: Meliponini) are distributed pantropically, inhabiting tropical and subtropical regions worldwide but absent from temperate zones. Their range spans the Neotropics from central southward to northern , the Afrotropical region across , the Indo-Malayan realm in , and the Australasian region including and nearby islands. They are notably absent from higher-latitude areas such as and , where cooler climates prevail. These bees occupy a variety of tropical habitats, including rainforests, savannas, mangroves, and dry forests, adapting to both humid and seasonally dry environments within their range. Altitudinally, they extend from up to approximately 3,000 meters in the , where some species thrive in montane cloud forests and premontane zones. This elevational tolerance allows them to exploit diverse ecosystems, though abundance typically decreases at higher altitudes due to cooler conditions. Introductions of stingless bees outside their native ranges are uncommon and generally limited to controlled settings, such as greenhouses for crop pollination. For instance, species like Trigona minangkabau have been introduced into Japanese greenhouses to pollinate strawberries, demonstrating potential for managed use but not widespread naturalization. Such efforts remain rare, with most populations confined to their indigenous tropical distributions to avoid ecological risks. Stingless bees depend on stable warm temperatures exceeding 15°C and high levels for nesting and brood development, reflecting their to consistently tropical conditions. Nests maintain internal around 80-90% and temperatures between 28-34°C, making them vulnerable to fluctuations below these thresholds that can halt and colony growth. These requirements reinforce their restriction to non-temperate zones.

Origin and Dispersion

Stingless bees (tribe Meliponini) are believed to have originated in approximately 100 million years ago during the , coinciding with the early breakup of the supercontinent . This ancient cradle is supported by phylogenetic analyses showing early-diverging lineages, such as the genus Meliponula, confined to the Afrotropical region. The vicariance event driven by 's fragmentation around 100–130 million years ago explains the deep divergence between (African, Asian, and Australian) and (Neotropical) clades, with the separation of from isolating these populations and initiating independent evolutionary trajectories. Fossil evidence, including amber inclusions like prisca from 96–74 million years ago, corroborates this timeline of early diversification. Dispersal from to and likely occurred overland through connected landmasses prior to 30 million years ago, during the Eocene–, when tectonic bridges facilitated migration before the full isolation of continents. Genera such as , now widespread in and , trace their arrival to the Miocene around 20 million years ago, possibly aided by land bridges or rafting across shrinking seaways. To remote islands like those in the Pacific or Oceans, colonization may have involved rare long-distance events, including vegetative rafting on floating debris or, in more recent , inadvertent human-mediated transport via early seafaring cultures, though the former is inferred for ancient distributions. In the Neotropics, stingless bees underwent an explosive radiation following the initial Gondwanan split, with over 400 extant species across 26 genera emerging through adaptive diversification in diverse tropical habitats. This burst intensified post-Pliocene (after ~2.6 million years ago), driven by climatic fluctuations and that promoted , resulting in the highest global diversity concentrated in Central and . Geographic barriers such as vast oceans and expansive deserts have profoundly limited stingless bee dispersal, enforcing by preventing between isolated populations. Ocean separated African and South American lineages irrevocably after Gondwana's breakup, while arid Saharan and Arabian deserts restricted northward expansion from , confining Old World species to humid and leading to distinct regional faunas.

Diversity by Region

Stingless bees exhibit varying levels of across tropical and subtropical regions, influenced by climatic barriers, availability, and historical . In , approximately 30 are documented, primarily in the genera Meliponula and Hypotrigona, with many adapted as specialists that thrive in open woodlands and grasslands. This relatively low diversity compared to other regions stems from arid barriers like the Desert, which limit northward expansion and isolate populations south of the . For instance, Meliponula ferruginea constructs nests in tree cavities within woodlands, demonstrating resilience to seasonal dry periods through efficient resin-based defenses. In , stingless bees are represented by 14 species, mainly in the genera Austroplebeia and , which are well-suited to arid and semi-arid environments with characteristically small colony sizes of 1,000–5,000 individuals. These bees often nest in ground cavities or low shrubs, enabling survival in fragmented habitats like eucalypt savannas, where species such as Austroplebeia australis forage on drought-tolerant . Their adaptations include reduced metabolic rates and opportunistic pollen collection, contributing to their persistence in Australia's variable climate. The Neotropics host the highest diversity of stingless bees, with over 400 species across more than 30 genera, reflecting the region's extensive rainforests and varied microhabitats. Brazil alone accounts for around 300 species, including endemics like those in Melipona and Partamona, where ecological specializations divide communities into canopy foragers targeting epiphytes and understory species exploiting herbaceous plants. For example, Melipona quadrifasciata in Atlantic forests shows vertical stratification in foraging, enhancing pollination efficiency in multilayered canopies, while arid-adapted Tetragonisca angustula dominates in caatinga drylands. This richness underscores the Neotropics' role as a biodiversity hotspot, with ongoing discoveries adding to the tally. Asia supports moderate stingless bee diversity, with about 50 concentrated in , including the genus Heterotrigona known for its -rich nests in humid forests. Island endemics in , such as Wallacetrigona incisa in highlands, exhibit unique adaptations like high-elevation foraging and kleptobiotic behaviors, restricted by oceanic barriers that promote . like Heterotrigona itama in Malaysian dipterocarp forests demonstrate communal collection for nest , supporting moderate sizes in tropical understories. This regional pattern highlights a from lowlands to isolated archipelagos, fostering localized .

Human Interactions

Pollination Role

Stingless bees serve as vital pollinators for numerous tropical crops, enhancing fruit set and overall agricultural yields in regions where environmental conditions favor their activity. In crops such as coffee (Coffea arabica), their pollination significantly boosts fruit set, with studies showing increases from approximately 60% under limited bee diversity to 90% with greater pollinator variety, representing up to a 50% improvement over self- or wind-pollination scenarios. For cacao (Theobroma cacao), small Amazonian species like those in the genera Plebeia and Frieseomelitta facilitate cross-pollination, potentially elevating pod yields beyond the low natural rates (around 2–5% fruit set) achieved by primary midges, with studies on hand-pollination showing up to 20% yield gains, suggesting potential benefits for managed systems. Similarly, in macadamia (Macadamia integrifolia) orchards, stingless bees such as Trigona spp. achieve nut set rates equivalent to open-pollinated controls, outperforming self-pollination by 20–40% in controlled trials by ensuring effective pollen transfer to compatible cultivars. Managed pollination programs often involve placing stingless bee hives directly in orchards or fields to optimize crop visitation, a strategy particularly advantageous in hot, humid tropical climates. Unlike temperate-adapted honey bees, which may reduce foraging during extreme heat or humidity, stingless bees maintain high activity levels in temperatures exceeding 30°C and relative humidity above 80%, making them more reliable for year-round pollination in equatorial agriculture. This adaptation allows for consistent service in enclosed systems like greenhouses or shaded agroforests, where hives can be positioned near flowering crops to maximize efficiency without the need for extensive transport. Despite these benefits, stingless bees face limitations in large-scale applications due to their relatively short ranges, typically 500–1,000 m from the , compared to 3–5 km for honey bees, restricting coverage in expansive monocultures and necessitating higher densities. Additionally, competition from , particularly Africanized honey bees (Apis mellifera), can displace stingless bees from floral resources, reducing their contributions in altered landscapes. A notable case study from Brazilian agriculture illustrates these dynamics: in melon (Cucumis melo) fields in northeastern Brazil, introducing stingless bee hives alongside natural insect visitors increased fruit set and yields by approximately 30% over controls reliant on wind or limited self-pollination, highlighting the value of integrated management for cucurbit crops.

Products and Uses

Stingless bees produce honey with a higher moisture content, typically ranging from 20% to 40%, compared to the honey of honeybees (Apis mellifera), which contributes to its distinct texture and shorter shelf life. This elevated moisture level is accompanied by lower sugar concentrations, often around 60–80% total sugars, primarily fructose and glucose, making it less viscous and sweeter in flavor due to its acidic profile. The honey's antibacterial properties stem from incorporated plant resins, phenolic compounds, and other phytochemicals collected during foraging, which inhibit microbial growth and support its use in traditional medicine for treating infections and aiding wound healing. Annual yields per colony vary by species and region but generally range from 0.5 to 5 liters, reflecting the bees' smaller colony sizes and foraging efficiency. Propolis, a resinous collected from and mixed with , exhibits strong activity against and fungi, attributed to its , terpenoids, and phenolic acids, and has been employed in across tropical regions for treating wounds, skin infections, and gastrointestinal issues. Cerumen, the blend of and plant resins used by stingless bees for nest construction, shares similar qualities and is traditionally applied topically in practices to soothe burns, cuts, and inflammatory conditions due to its and regenerative effects. In regions like and , cerumen has been documented for its wound-healing potential, promoting tissue repair while preventing secondary infections. Pollen gathered by stingless bees serves as a nutrient-dense , containing 5–60% proteins, essential , vitamins (such as and E), minerals, and antioxidants like and , which support immune function and overall nutrition in traditional diets. It is consumed fresh or dried in various cultures for its therapeutic benefits, including effects and potential protection against , often mixed into foods or teas for daily supplementation. Beeswax from stingless bees, often in the form of cerumen, is utilized for crafting candles due to its clean-burning properties and natural scent, a practice rooted in indigenous traditions in and where it provides illumination without soot. Additionally, the wax's malleability allows for artistic applications, such as sculpting figurines or modeling in crafts, valued for its durability and aesthetic appeal in cultural artifacts. Geopropolis, a variant of mixed with and produced by certain stingless bee species, is traditionally used in crafts for its qualities as a and construction material, such as or repairing tools in Amazonian communities. This earthy also finds non-commercial applications in sealing cracks in wooden structures or as a in handmade items, leveraging its natural durability and properties to extend the lifespan of crafts.

Meliponiculture

Meliponiculture, the husbandry of stingless bees, traces its origins to ancient Mesoamerican civilizations, particularly the and , where it has been practiced for over 3,000 years in the Yucatan Peninsula. The cultivated species such as , known locally as xunan kab or "lady bee," using traditional log hives called jobones—hollowed sections of wood, typically 50-60 cm long and 30 cm in diameter, suspended horizontally under house and oriented east-west for optimal sun exposure. These hives mimicked natural nesting sites, allowing for colony division and controlled harvesting, often managed by specialized priest-shamans through rituals like u hanli kab to ensure prosperity; production from 3,000-4,000 such hives may have yielded up to 7 tons of annually, supporting , tribute, and medicinal uses. Modern meliponiculture has evolved to incorporate box hives that replicate natural nest structures, facilitating techniques such as colony splitting and queen rearing to propagate colonies sustainably. In colony splitting, a strong hive is divided into two: one retaining the mature queen with young brood, and the other receiving mature brood and virgin queen cells, achieving up to 100% success in producing new queens within 2-3 weeks when hives are placed 5 meters apart during the dry season. Box hives, often compartmentalized with entrance holes of 16 mm and elevated on stands to deter predators, enable easier inspection and management compared to traditional logs. Key challenges include preventing absconding—colony abandonment due to stress—through stable environmental conditions, supplementary feeding, and avoiding pheromone interference from the mature queen during splits, which can inhibit new queen development if hives are inadequately separated. Regional adoption varies, with Brazil hosting over 5,000 meliponiculturists across 20 states, managing diverse species like Tetragonisca angustula and Melipona quadrifasciata through practices emphasizing colony multiplication near native vegetation and pest control via vinegar traps. In Australia, regulations for native species such as Tetragonula carbonaria were strengthened in 2024 when Food Standards Australia New Zealand approved stingless bee honey for commercial sale, provided hygienic practices are followed and production adheres to compositional limits; however, keeping is restricted to suitable climates in northern New South Wales and coastal Queensland to match native ranges. Economically, meliponiculture offers small-scale income for rural keepers, generating approximately $500–$2,000 per year in the through honey sales at $3.11–$49.81 per kg from 0.25–1 kg per colony annually, with 216 producers managing over 3,300 across and . Training programs in , led by academics, government agencies, and cooperatives, provide hands-on courses to rural communities, including women, focusing on management, , and sustainable harvesting to revive and expand the practice.

Conservation Status

Stingless bees (tribe Meliponini) face significant threats from human activities, with habitat loss being the primary driver due to widespread tropical . Since the mid-20th century, tropical forests—critical nesting and habitats for these bees—have experienced substantial declines, with losing over 70 million hectares of forest since 1990 alone, driven by and . This disrupts colony establishment and resource availability, as stingless bees require stable, diverse forest environments for survival. Additionally, use in intensive poses a direct toxic risk, with studies showing that Meliponini species are particularly sensitive to agrochemicals compared to other bees, leading to reduced success and population declines. exacerbates these pressures by altering flowering and increasing events, which can desynchronize bee activity with sources and cause colony . On the , only a small number of the over 600 stingless bee species have been assessed, with most classified as due to limited ecological data and understudied diversity. For instance, , a culturally significant species in , is not globally listed but is considered vulnerable or locally endangered in parts of its range, such as Mexico's , where hive numbers have declined by up to 93% over the past 25 years due to habitat loss and other threats. National assessments in regions like and highlight additional species at risk, including Meliponini in urbanized Southeast Asian contexts, underscoring the need for broader global evaluations. Conservation efforts focus on habitat protection and sustainable management practices. Protected areas, such as Amazonian reserves in and , provide refugia for diverse Meliponini populations by preserving forested ecosystems essential for their persistence. Meliponiculture, the cultivation of stingless bee colonies, supports propagation and maintenance, with initiatives in and integrating traditional practices to bolster wild populations. Emerging genetic banking efforts, including studies on population structure, aim to safeguard lineages against fragmentation, though these remain limited in scope. Despite these measures, substantial gaps persist in conservation, particularly in under-monitored regions like and , where stingless bee diversity is high but research and threat assessments are sparse. In , knowledge gaps hinder domestication and protection of endemic , while Asian landscapes face unique pressures from without adequate species-specific strategies. Addressing these requires expanded , regional IUCN assessments, and integrated policies to mitigate ongoing threats.