Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees

Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial “flowers” that provided a sucrose reward, we compared species’ dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines.     

Microsatellite loci for the stingless bee Melipona rufiventris (Hymenoptera: Apidae)

Eight microsatellite primers were developed from ISSR (intersimple sequence repeats) markers for the stingless bee Melipona rufiventris. These primers were tested in 20 M. rufiventris workers, representing a single population from Minas Gerais state. The number of alleles per locus ranged from 2 to 5 (mean = 2.63) and the observed and expected heterozygosity values ranged from 0.00 to 0.44 (mean = 0.20) and from 0.05 to 0.68 (mean = 0.31), respectively. Several loci were also polymorphic in M. quadrifasciata, M. bicolor, M. mandacaia and Partamona helleri and should prove useful in population studies of other stingless bees.     

Landscape genetics of a tropical rescue pollinator

Pollination services are increasingly threatened by the loss and modification of natural habitats, posing a risk to the maintenance of both native plant biodiversity and agricultural production. In order to safeguard pollination services, it is essential to examine the impacts of habitat degradation on the population dynamics of key pollinators and identify potential “rescue pollinators” capable of persisting in these human-altered landscapes. Using a landscape genetic approach, we assessed the impact of landscape structure on genetic differentiation in the widely-distributed tropical stingless bee Trigona spinipes (Apidae: Meliponini) across agricultural landscape mosaics composed of coffee plantations and Atlantic forest fragments in southeastern Brazil. We genotyped 115 bees at 16 specific and highly polymorphic microsatellite loci, developed using next-generation sequencing. Our results reveal that T. spinipes is capable of dispersing across remarkably long distances, as we did not find genetic differentiation across a 200 km range, nor fine-scale spatial genetic structure. Furthermore, gene flow was not affected by forest cover, land cover, or elevation, indicating that reproductive individuals are able to disperse well through agricultural landscapes and across altitudinal gradients. We also found evidence of a recent population expansion, suggesting that this opportunistic stingless bee is capable of colonizing degraded habitats. Our results thus suggest that T. spinipes can persist in heavily-altered landscapes and can be regarded as a rescue pollinator, potentially compensating for the decline of other native pollinators in degraded tropical landscapes.     

Preference in flower visits and partitioning in pollen diets of stingless bees in an Asian tropical rain forest

Floral resource partitioning among stingless bees (Trigona, Meliponini, Apidae) in a lowland rain forest in Sarawak, Malaysia, was investigated using tree towers and walkways in a 4-year study that included a general flowering period. We obtained 100 collections of insect visitors to flowers of varying floral location and shape representing 81 plant species. The tendency of 11 species of stingless bees to visit specific flowers with a particular floral location and shape was analyzed by logistic regression analysis. This analysis showed that the proportion of flower visitor collections containing Trigona fuscobalteata and T. melanocephala differed according to floral location. The former was frequently collected at canopy and gap flowers, whereas the latter was most often collected at understory flowers. The analysis also suggested that T. erythrogastra was more rarely collected at shallow flowers than at deep flowers. Analysis of the pollen diets of T. collina, T. fuscobalteata, T. melanocephala, and T. melina revealed that similarity of pollen sources differed among the six permutated pairs of the four species. The lowest mean rank of similarity found was between T. fuscobalteata and T. melanocephala. This result supports the hypothesis that preference in visiting flowers in different locations leads to pollen resource partitioning. Received: May 14, 1997 / Accepted: April 23, 1999     

Microsatellite loci to assess genetic variation in Tor putitora

Seven polymorphic microsatellite DNA loci were identified in golden mahseer, Tor putitora, through cross‐species amplification. Thirty‐two primers developed for three cyprinid fishes were tested in the study. The genetic variation detected at each microsatellite locus in T. putitora specimens (n = 107), collected from three different rivers and one lake was assessed. The allele frequencies deviated significantly from that expected under Hardy–Weinberg equilibrium. The mean observed heterozygosity values ranged from 0.29 to 0.40. Significant genotype heterogeneity indicated that the samples were not drawn from the same gene pool. The results indicate that the identified microsatellite loci exhibit promise for use in fine scale population structure analyses of T. putitora.     

Isolation and characterization of microsatellite markers in Labiotermes labralis (Isoptera,Termitidae, Nasutitermitinae)

We report here on the development of six polymorphic microsatellite loci for Labiotermes labralis. This soil‐feeding species is restricted to the Neotropical rainforest and then could represent a major candidate for being a bio‐indicator of anthropic disturbance resulting in the forest fragmentation. The microsatellite loci were isolated and characterized using a microsatellite‐enriched genomic library. The primers were tested on a French Guyanese population of L. labralis, represented by the sampling of one soldier in 22 nests. The primers were also tested against nine species of the same Nasutitermitinae subfamily and were successfully amplified at five loci in Armitermes minutus.     

Nest architecture and genetic differentiation in a species complex of Australian stingless bees

We investigated the taxonomic significance of nest shape and its putative role in speciation in Trigona (Heterotrigona) carbonaria and T. (H.) hockingsi, two sibling species of stingless bee species from eastern Australia. These species are primarily distinguished by their nest architecture, as in all other respects they are nearly identical. We genotyped 130 colonies from six locations in Queensland at 13 microsatellite loci together with 106 additional colonies from six other Indo-Pacific Trigona species. Whether they were present in allopatry or in sympatry, colonies that displayed the T. carbonaria or the T. hockingsi nest architecture could be unambiguously differentiated at the genetic level. However, T. hockingsi colonies were classifiable into two highly differentiated paraphyletic and geographically separate populations, one in northern and one in southern Queensland. These two populations probably belong to two distinct species, T. hockingsi and T. davenporti nov. sp. Our results suggest that nest architecture characters are relevant but not sufficient criteria to identify species in this group. Consequently, modifications of nest architecture are probably not of prime importance in the speciation process of Australian stingless bees, although nest architecture differences probably result from relatively simple mechanisms. The rare interspecific hybrid colonies detected did not display a nest with an intermediate form between T. hockingsi and T. carbonaria.     

Cross-species amplification of 44 microsatellite loci developed for Chaetodon trifascialis, C. lunulatus and C. vagabundus in 22 related butterflyfish species

Forty‐four microsatellite primers developed for three species of butterflyfish were cross‐tested against 22 related confamilial species. Amplification success and cross‐species transferability of these markers were moderately high. Between 24 and 37 loci were amplified successfully in each species, with a mean success rate per species of 71.7% (± 1.8 SE). Rates of amplification success were comparable among primers designed for the three source species, ranging from a mean success rate per species of 16.9 loci (± 0.8 SE) for Chaetodon trifascialis source loci to 13.7 loci (± 1.5 SE) for C. vagabundus source loci. Polymorphism rates were high (76.1%± 3.1 SE of all successfully amplified loci), and 10 loci were polymorphic in all successfully amplified species (Tri14, B11, C5, D3, D113, D6, D117, D120, D111, D118). The number of alleles per polymorphic locus ranged from 2 to 8, and the average number of alleles across all polymorphic loci and all species was 3.6 (± 0.07 SE). Polymorphism rates were higher overall in primers designed for C. vagabundus (89.9%± 3.9 SE). Overall cross‐testing success was lowest for Heniochus chrysostomus, the most phylogenetically divergent species. The significant cross‐testing reported here provides a valuable resource that will enable population genetics studies to be undertaken on a range of butterflyfishes without the need for expensive and time‐consuming de novo microsatellite development.     

Microsatellite loci isolated from narrow‐leaved cattail Typha angustifolia

We present 11 dinucleotide microsatellite DNA loci isolated from the narrow‐leaved cattail (Typha angustifolia) and describe conditions for their amplification. The PCR primers were tested on at least 20 individuals of Typha angustifolia and T. latifolia from two Ukrainian populations per species. The primers amplify loci with relatively high numbers of alleles (averaging 7.22 and 4.95 alleles per locus in T. angustifolia and T. latifolia, respectively), and polymorphic information content (averaging 0.61 and 0.46 in T. angustifolia and T. latifolia, respectively).     

Development of microsatellite markers for the endangered semi‐shrub Chimaphila umbellata (Ericaceae)

Based on the DNA sequencing reads obtained using 454 pyrosequencing, primers amplifying 16 microsatellite loci were developed for the endangered semi‐shrub Chimaphila umbellata, which occurs sporadically in the Japanese Archipelago. These 16 loci were polymorphic in the populations sampled from the Hokkaido and Tohoku Districts; the mean number of alleles was 3.31 and 3.44, and the mean expected heterozygosity was 0.42 and 0.44, respectively. These loci were not linked to each other and contained no null alleles. Amplification using these primers was also tested in the congeneric species C. japonica, but only three of them successfully amplified DNA of the species. These markers will be used to examine genetic diversity and genetic differentiation in populations of C. umbellata.     

Spectral sensitivity of photoreceptors in the compound eye of stingless tropical bees

The spectral sensitivity of photoreceptors of the tropical bees Melipona quadrifasciata, M. marginata, and Trigona spinipes were measured on-line with a rapid constant response amplitude method. The results indicate that although these bees forage in different habitats they have the same set of photoreceptors with sensitivity maxima in ultra-violet, blue and green.     

Development of a Species-Diagnostic Marker for Identification of the Stingless Bee Trigona pagdeni in Thailand

A species-diagnostic SCAR marker for identification of the stingless bee (Trigona pagdeni Schwarz) was successfully developed. Initially, amplified fragment length polymorphism analysis was carried out across representatives of 12 stingless bee species using 64 primer combinations. A 284 bp band restrictively found in T. pagdeni was cloned and sequenced. A primer pair (CUTP1-F/R) was designed and tested for species-specificity in 15 stingless bees. The expected 163 bp fragment was successfully amplified in all examined individuals of T. pagdeni (129/129). Nevertheless, cross-species amplification was also observed in T. fimbriata (1/3), T. collina (11/112), T. laeviceps (1/12), and T. fuscobalteata (15/15), but not in other species. SSCP analysis of CUTP1 further differentiated T. fuscobalteata and T. collina from T. pagdeni. Although T. laeviceps, T. fimbriata, and T. pagdeni shared an identical SSCP genotype, they are not taxonomically problematic species.     

Microsatellite loci transferability from Theobroma cacao to Theobroma grandiflorum

Theobroma grandiflorum (cupuassu) is an important fruit tree native to the Brazilian Amazon. Forty‐eight microsatellite loci developed for the congener Theobroma cacao were tested in cupuassu, and 29 (60.4%) produced robust alleles. The analyses of 216 cupuassu accessions using the 21 polymorphic microsatellite loci revealed a total of 113 alleles. The number of alleles per polymorphic locus ranged from two to 11, with an average of 5.38 alleles per locus. The average observed heterozygosity was 0.343, while the mean expected heterozygosity was 0.614. The successful transferability of T. cacao microsatellite primers to cupuassu was consistent with currently accepted phylogeny.     

Effect of group size on the aggression strategy of an extirpating stingless bee, Trigona spinipes

Summary. Group aggression influences communication and defense strategies in many social insect communities. Such aggression plays a particularly significant role in the lives of stingless bees, important native Neotropical pollinators, in which the battle for food resources can be deadly and critical to colony survival. However, the effects of group size on individual aggression levels and the spatio-temporal aggression strategy of communal aggressors have not been fully explored. We therefore investigated how group size affects the aggression levels and the spatio-temporal attack strategy (which body parts, and the amount of time spent in attacking each part) in close combats between Trigona spinipes foragers and a natural competitor, Melipona rufiventris. In all trials, T. spinipes foragers competitively excluded M. rufiventris foragers from nearby feeders, exhibiting four levels of aggressive behavior ranging from threat displays to prolonged grappling and decapitation. Surprisingly, aggression levels and spatial strategy corresponded to the size of group attacks. Larger groups of attackers used individually lower aggression levels than small groups of attackers. Smaller groups also attacked appendages linked to escape (legs and wings) with greater frequency than larger groups, which focused on vital central body areas (abdomen, thorax, and head). Increased aggression corresponded to increased risks for attackers and the attacked. All combatants engaging at the highest level of aggression died (100% mortality). Thus the dominance style of T. spinipes may minimize attack risk and maximize victim harm with finely tuned hostility.Received 22 May 2004; revised 18 August 2004; accepted 26 October 2004.     

Primers from the orders Osteoglossiform and Siluriform detect polymorphic microsatellite loci in sun-catfish, Horabagrus brachysoma (Teleostei: Bagridae)

Horabagrus brachysoma (sun‐catfish, Bagridae, Siluriformes) is a valuable ornamental and food fish. The stock structure of H. brachysoma, necessary to conserve its declining natural populations, is not known. Twenty‐five primers developed for four fish species belonging to the orders Siluriform (3) and Osteoglossiform (1) were tested and eight primers amplified microsatellite loci in H. brachysoma. The results demonstrate that cross‐priming between fish species belonging to different families and even to different orders can yield microsatellite loci. Five of eight primers each amplified two loci. However, the loci that had repeat motifs after sequencing were considered only for genotyping. Finally, eight loci were polymorphic with hree to seven alleles. Individual fish genotype data (n = 42; 21 each in two rivers) at each locus was analysed. Significant genetic heterogeneity was detected at six loci. The identified loci exhibited potential for use in population genetics application in H. brachysoma.     

Signals and cues in the recruitment behavior of stingless bees (Meliponini)

Since the seminal work of Lindauer and Kerr (1958), many stingless bees have been known to effectively recruit nestmates to food sources. Recent research clarified properties of several signals and cues used by stingless bees when exploiting food sources. Thus, the main source of the trail pheromone in Trigona are the labial, not however the mandibular glands. In T. recursa and T. spinipes, the first stingless bee trail pheromones were identified as hexyl decanoate and octyl decanoate, respectively. The attractant footprints left by foragers at the food source are secreted by glandular epithelia of the claw retractor tendon, not however by the tarsal gland. Regarding intranidal communication, the correlation between a forager’s jostling rate and recruitment success stresses the importance of agitated running and jostling. There is no evidence for a “dance” indicating food source location, however, whereas the jostling rate depends on food quality. Thoracic vibrations, another intranidal signal well known in Melipona, were analyzed using modern technology and distinguishing substrate vibrations from airborne sound. Quantitative data now permit estimates of signal and potential communication ranges. Airflow jets as described for the honeybee were not found, and thoracic vibrations do not “symbolically” encode visually measured distance in M. seminigra. We dedicate this review to Martin Lindauer and Warwick Kerr who pioneered research on the communication and recruitment in stingless bees by studies reported in a seminal paper published in this Journal half a century ago in 1958.     

Effect of Biotic Factors on the Spatial Distribution of Stingless Bees (Hymenoptera: Apidae, Meliponini) in Fragmented Neotropical Habitats

We recorded stingless bee colony abundance and nesting habits in three sites with different anthropogenic activities in the Soconusco region of Chiapas, Mexico: (1) agroforestry (7 hacacao crop), (2) grassland (12?ha), and (3) urban area (3?ha). A total of 67 nests were found, representing five stingless bee species, Tetragonisca angustula angustula (Lepeletier), Trigona fulviventris (Guérin), Scaptotrigona mexicana (Guérin), Scaptotrigona pectoralis (Dalla Torre), and Oxytrigona mediorufa (Cockerell). The most abundant stingless bee in each site was T. angustula angustula (>50%). The primary tree species used by the bees were Ficus spp. (Moraceae, 37.8%) and Cordia alliodora (Boraginaceae, 13.5%). The nest entrance height of T. angustula angustula (96?±?19?cm) was different than the other species, and this bee was the only one that used all different nesting sites. Volatiles analyzed by gas chromatography from pollen collected by the stingless bees differed between bee species, but were highly similar in respect to the fragrances of the pollen collected by the same species at any site. Our data indicate that T. angustula angustula experienced low heterospecific and high intraspecific foraging overlap especially in the urban site. We observed cluster spatial distribution in grassland and in agroforestry sites. In the urban site, T. angustula angustula presented random distribution tended to disperse. Trigona fulviventris was the only overdispersed and solitary species.     

Native and Non-Native Supergeneralist Bee Species Have Different Effects on Plant-Bee Networks

Supergeneralists, defined as species that interact with multiple groups of species in ecological networks, can act as important connectors of otherwise disconnected species subsets. In Brazil, there are two supergeneralist bees: the honeybee Apis mellifera, a non-native species, and Trigona spinipes, a native stingless bee. We compared the role of both species and the effect of geographic and local factors on networks by addressing three questions: 1) Do both species have similar abundance and interaction patterns (degree and strength) in plant-bee networks? 2) Are both species equally influential to the network structure (nestedness, connectance, and plant and bee niche overlap)? 3) How are these species affected by geographic (altitude, temperature, precipitation) and local (natural vs. disturbed habitat) factors? We analyzed 21 plant-bee weighted interaction networks, encompassing most of the main biomes in Brazil. We found no significant difference between both species in abundance, in the number of plant species with which each bee species interacts (degree), and in the sum of their dependencies (strength). Structural equation models revealed the effect of A. mellifera and T. spinipes, respectively, on the interaction network pattern (nestedness) and in the similarity in bee’s interactive partners (bee niche overlap). It is most likely that the recent invasion of A. mellifera resulted in its rapid settlement inside the core of species that retain the largest number of interactions, resulting in a strong influence on nestedness. However, the long-term interaction between native T. spinipes and other bees most likely has a more direct effect on their interactive behavior. Moreover, temperature negatively affected A. mellifera bees, whereas disturbed habitats positively affected T. spinipes. Conversely, precipitation showed no effect. Being positively (T. spinipes) or indifferently (A. mellifera) affected by disturbed habitats makes these species prone to pollinate plant species in these areas, which are potentially poor in pollinators.     

The cuticular profiles of Australian stingless bees are shaped by resin of the eucalypt tree Corymbia torelliana

Bees are known to collect pollen and nectar to provide their larvae and themselves with food. That bees, especially the tropical stingless bees (Apidae: Meliponini), also collect plant resins has, however, been barely addressed in scientific studies on resource use in bees. Resins are used for nest construction, nest maintenance and nest defence. Furthermore, some South‐East Asian species transfer resin‐derived terpenes to their cuticular profiles. The resin requirement of bees is in turn used by certain plant species, which attract bees either for pollination by providing resin in their inflorescences, or for seed dispersal by providing resin in their seed capsules (mellitochory). Mellitochory is found in the eucalypt tree Corymbia torelliana, the resin of which is collected by Australian stingless bees. We investigated how the interaction between C. torelliana and resin‐collecting bees affects the chemical ecology of two Australian stingless bee genera by comparing the chemical profiles of eight bee species with resin from C. torelliana fruits. The two bee genera differed significantly in their chemical profiles. Similar to South‐East Asian stingless bees, 51% of all compounds on the body surfaces of the five Tetragonula species were most likely derived from plant resins. Up to 32 compounds were identical with compounds from C. torelliana resin, suggesting that Tetragonula species include C. torelliana compounds in their chemical profiles. By contrast, few or none resinous compounds were found on the body surfaces of the three Austroplebeia species sampled. However, one prominent but as yet unknown substance was found in both C. torelliana resin and the chemical profiles of all Tetragonula and four Austroplebeia colonies sampled, suggesting that most colonies (76%) gathered resin from C. torelliana. Hence, C. torelliana resin may be commonly collected by Australian stingless bees and, along with resins from other plant species, shape their chemical ecology.     

Frugivory by a stingless bee (Hymenoptera: Apidae)

Frugivory is not frequent among bees. Although stingless bees visit aged fruits for pulp, the use of fresh fruits is recorded only for Trigona hypogea Silvestri, a species that does not visit flowers. Here we report the occurrence of frugivory in Trigona amazonensis (Ducke), a flower-visiting stingless bee.