Xylocopa Virginica Research Articles

Pesticide risk during commercial apple pollination is greater for honeybees than other managed and wild bees

Abstract Most pesticide research has focussed on risk to managed honeybees, but other managed and wild bees are also exposed to pesticides. Critically, we know little about the magnitude and sources of risk to honeybees compared with other bees during crop pollination. To compare pesticide exposure and risk across wild and managed bees, we sampled the main bee groups present during bloom in 20 apple orchards, including managed honeybees (Apis mellifera), managed bumblebee workers (Bombus impatiens), wild mining bees (Andrena spp. and Andrena [Melandrena] spp.), bumblebee foundress queens (Bombus impatiens) and eastern carpenter bees (Xylocopa virginica). We screened all bees for 92 pesticides and computed a Risk Quotient using available toxicity data (honeybee LD50s), adjusting for differences in toxicity known to scale with body mass. To gain insight into exposure origin, we compared residues in bees to those in focal orchard apple and dandelion flowers. Nearly all bee samples contained pesticides (95%), with the average contamination level ranging from 7.1 ± 2.8 parts per billion (ppb) in B. impatiens workers to 388.4 ± 146.2 ppb in Andrena. Exposure profiles were similar for all bees except A. mellifera, whose unique exposure profile included high levels of the neonicotinoid insecticide thiamethoxam. All bee groups except wild B. impatiens queens had at least one sample exceeding a US Environmental Protection Agency or European Food Safety Authority exposure level of concern. Apis mellifera experienced significantly greater risk than other bee groups, with 63% and 81% of samples exceeding an acute or chronic exposure level of concern, respectively. Risk to honeybees was driven primarily by high thiamethoxam levels not found in focal orchard flowers and likely originating outside the orchard. Synthesis and applications: We find that pesticide exposure and risk differ between honeybees and other managed and wild bees during apple pollination. Furthermore, pesticide exposure is a landscape‐scale phenomenon and therefore measures to reduce exposure must consider the surroundings beyond focal farms. Limiting orchard sprays, while reducing on‐farm exposures, will not protect far‐foraging bees from off‐farm exposures such as thiamethoxam, which we hypothesize is coming from nearby seed‐treated corn fields planted during apple bloom.

The “Carpenter,” a substrate for green synthesis: Biosynthesis and antimicrobial potential

The frequent use of antibiotics has created favorable conditions for bacteria to develop resistance. Bacterial resistance is an issue for global health killing at least 1 million people worldwide annually. The quest for new and effective antimicrobials with activities against resistance bacteria demands immediate attention. The use of nanoparticles as antimicrobials alternatives to conventional antibiotics may have the potential to combat bacterial resistance. Silver nanoparticles, silver nanoparticles have captivated the interest of most researchers by virtue of their broad-range antimicrobial activity against bacteria due to their strong biocidal effect against microorganisms. Silver nanoparticles have been traditionally synthesized by physical chemical and biological process. However, biosynthesis of silver nanoparticles from wings of carpenter bees Xylocopa virginica, which is abundantly available in summer in the United States of America, is yet to be explored. Herein, we report the synthesis of silver nanoparticles using wing extract of carpenter bees X. virginica. Subsequently the biosynthesized nanoparticles were characterized by UV–Visible absorption spectroscopy and scanning electron microscopy (SEM). Furthermore, the antimicrobial activity of the biosynthesized nanoparticles was investigated against two common Gram-negative and Gram-positive pathogenic bacteria viz Klebsiella pneumonia, Escherichia coli, Micrococcus luteus and Staphylococcus aureus using microdilution method. The results of this study indicate that biosynthesized silver nanoparticles from X. virginica wing extract showed an absorption band at 440 nm and SEM revealed spherical nanoparticles 20- 60 nm in size. Additionally, biosynthesizes silver nanoparticles from the wings of X. virginica exhibited antimicrobial activity against all the tested bacteria signifying their biomedical, pharmaceutical, and agricultural potential.

Sexual dimorphism in excess power index of four North American native bees (Hymenoptera, Andrenidae, Apidae, and Halictidae)

A multitude of hymenopteran species exhibit sexual dimorphism for simple traits, such as color, size, or antennal segment number. These differences can reflect selection for specialized biological roles, many of which have not been documented for the majority of bee and wasp species. The excess power index (EPI) is an estimate of insect flight performance that is inferred by the combination of several morphological characteristics. We compared the female and male EPIs in four species of native bees: Agapostemon virescens Fabricius, Andrena carlini Cockerell, Melissodes bimaculata Lepeletier and Xylocopa virginica L.. While females of each species had a significantly larger whole body mass, males had a significantly larger EPI. A larger body mass for females is associated with egg laying abilities and foraging behavior. Male fitness may be dependent on EPI; males that have greater flight capacity can travel further or remain in flight for longer time periods in search of mates.

The Prevalence and Manifestation of Wing De-melanization in the Eastern Carpenter Bee (Hymenoptera, Apidae Xylocopa virginica) Associated with Urban Areas

Animals that live in urban environments face unique stressors due to increased temperatures associated with these novel ecosystems. Large bees in the family Apidae thermoregulate in a variety of fashions including wing muscle vibrations, basking, and collecting heat with the wings. Thus, the coloration of the wing will impact the degree of heat absorption. The eastern carpenter bee, Xylocopa virginica Linnaeus, is a widespread, univoltine species found throughout eastern North America. Typically, X. virginica has solid dark brown to black wings. We report on a newly discovered wing phenotype in which the wing has lost significant amounts of coloration, making them nearly transparent. Using specimens from St. Louis, MO, we found that the de-melanization is usually restricted to the distal portions of the wing, yet the coverage differs between individuals. The proportion of individuals exhibiting pigment loss is similar between males and females. We examined observations on the iNaturalist platform and found that the phenotype is found in urban areas throughout the species range. We hypothesize that de-melanization could be an adaptation to heat stress, however more research is needed.

Evidence for multiple mating by female eastern carpenter bees, Xylocopa virginica (Hymenoptera: Apidae)

Abstract Relatedness within groups is influenced by the mating patterns of founders: the more parents that contribute to a group, the lower the relatedness of their offspring. Xylocopa virginica (Hymenoptera: Apidae) is a facultatively social bee in which low relatedness is influenced by sequential maternity. We investigated whether multiple paternity, which would occur if egg-laying females mate multiple times, might also contribute to low relatedness among female nestmates. We used two approaches to investigate how frequently females mate polyandrously. First, we used visual observations of mating behaviour to estimate mating frequencies and to evaluate evidence for temporal variation in female receptivity to mates. Second, we used a data set of microsatellite genotypes to evaluate evidence for multiple paternity based on inferred proportions of full and half sisters. Based on visual observations, we inferred a female mating frequency of 1.1 (harmonic mean). Females were more receptive early in their first nestmate provisioning phase and less receptive in their second brood provisioning phase. Based on microsatellite genotypes analysed with COLONY software, we inferred that 5–44% of female sibships included maternal half sisters, implying female mating frequencies between 1.13 and 1.41 (harmonic means). Thus, multiple mating contributes to the low group relatedness found in Xylocopa virginica.

Competition Drives Group Formation and Reduces Within Nest Relatedness in a Facultatively Social Carpenter Bee

Animals respond to competition among kin for critical breeding resources in two ways: avoidance of direct fitness costs via dispersal of siblings to breed separately, and formation of kin-based societies in which subordinates offset direct fitness costs of breeding competition via altruism and increased indirect fitness. In the facultatively social eastern carpenter bee, nests are a critical breeding resource in perpetually short supply, leading to strong competition among females. Observations of individually marked and genotyped females in conditions of high and low resource competition demonstrate that competition leads to resource sharing and group nesting. However, in contrast to almost all known animal societies, females avoid nesting with relatives, and disperse from their natal nests to join social groups of non-relatives. This is the first example of a structured insect society with cooperation nestmates, the majority of which are unrelated; thus cooperation is more likely based on selection for direct, rather than indirect fitness. By forming social groups of non-kin, females avoid the indirect fitness costs of kin competition among sisters, yet increase their chances of successful reproduction, and thus direct fitness, when forming colonies of non-relatives.

First Records of Xylocopa virginica (Linnaeus) (Hymenoptera: Apidae) in Montana and Idaho

A species of large carpenter bee, Xylocopa virginica virginica (Linnaeus, 1771), is reported from Montana and Idaho, USA for the first time. This new Montana distribution record adds to a growing list of bee species found in the state and contributes to an ongoing inventory of the bees of Montana. The Montana collection likely does not represent an established population but a transient accidental introduction resulting from human transportation since Montana is considerably geographically separated from the published distribution of this species and no additional adults have been found. The Idaho collections may represent an established local population as there are several specimens and online records in or near Boise on multiple dates and years. An online record of a specimen of X. californica arizonensis Cresson, 1879 from Montana proved to be erroneous. The distribution of X. virginica is reviewed and the economic, social, and ecological implications of the occurrence or establishment of this species in Montana and Idaho are discussed.

Genetic structure across urban and agricultural landscapes reveals evidence of resource specialization and philopatry in the Eastern carpenter bee, Xylocopa virginica L.

Human activity continues to impact global ecosystems, often by altering the habitat suitability, persistence, and movement of native species. It is thus critical to examine the population genetic structure of key ecosystemservice providers across human‐altered landscapes to provide insight into the forces that limit wildlife persistence and movement across multiple spatial scales. While some studies have documented declines of bee pollinators as a result of human‐mediated habitat alteration, others suggest that some bee species may benefit from altered land use due to increased food or nesting resource availability; however, detailed population and dispersal studies have been lacking. We investigated the population genetic structure of the Eastern carpenter bee, Xylocopa virginica, across 14 sites spanning more than 450 km, including dense urban areas and intensive agricultural habitat. X. virginica is a large bee which constructs nests in natural and human‐associated wooden substrates, and is hypothesized to disperse broadly across urbanizing areas. Using 10 microsatellite loci, we detected significant genetic isolation by geographic distance and significant isolation by land use, where urban and cultivated landscapes were most conducive to gene flow. This is one of the first population genetic analyses to provide evidence of enhanced insect dispersal in human‐altered areas as compared to semi‐natural landscapes. We found moderate levels of regional‐scale population structure across the study system (GʹST = 0.146) and substantial co‐ancestry between the sampling regions, where co‐ancestry patterns align with major human transportation corridors, suggesting that human‐mediated movement may be influencing regional dispersal processes. Additionally, we found a signature of strong site‐level philopatry where our analyses revealed significant levels of high genetic relatedness at very fine scales (<1 km), surprising given X. virginica's large body size. These results provide unique genetic evidence that insects can simultaneously exhibit substantial regional dispersal as well as high local nesting fidelity in landscapes dominated by human activity.

Xylocopa sonorina Smith, 1874 from Vancouver, British Columbia, Canada (Hymenoptera: Apidae, Xylocopinae) with comments on its taxonomy.

BackgroundOnly one species of large carpenter bee, Xylocopa virginica (Linnaeus, 1771), has been recorded from Canada, albeit restricted to southern Ontario and Quebec. However, a single female specimen identified by Hurd in 1954 as X. varipuncta Patton, 1879 from British Columbia is in the C.A. Triplehorn Insect Collection at The Ohio State University (OSUC), suggesting that this species was accidentally introduced into coastal western Canada. As wood-nesters, many large carpenter bees are likely capable of expanding their range great distances by natural and unnatural transport methods while nesting inside suitable substrates, the presumed mode of transport into western Canada, and likely elsewhere. The ease at which the nests are transported has likely contributed to the nomenclatural and distributional ambiguity surrounding this species due to morphological similarities of specimens from North America, Hawaii, and several South Pacific islands.New informationBy comparing DNA barcodes of specimens from the western United States to specimens from Hawaii, we confirm the early opinion of P.H. Timberlake (Timberlake 1922) that specimens long established on the Hawaiian Islands are the same X. varipuncta from continental North America. Furthermore, these DNA barcode sequences also match those of specimens identified as X. sonorina Smith, 1874 from the French Polynesian and Samoan Islands, thus fully supporting the opinion of Groom et al. (2017) that all are likely conspecific. As X. sonorina, a species described from and likely introduced to Hawaii is the oldest name available, X. varipuncta is here placed into synonymy. Additional research will be needed to trace the timing and pathway of introduction and establishment of X. sonorina; it is presumed that the species is native to the southwestern United States but has been established in Hawaii since the mid-1800s. It is also established in French Polynesia, the Samoan Islands, and likely other south Pacific islands, with additional records of occurrence from Java, New Zealand, and now Canada.

Minimizing Bee (Hymenoptera: Apoidea) Bycatch in Japanese Beetle Traps.

Native and introduced bees were attracted to and captured in commercially available Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae), traps baited with floral lure components: geraniol, eugenol, and phenethyl propionate [PEP] in Rhode Island, Ohio, and Tennessee. Studies in Rhode Island showed that Bombus impatiens Cresson (Hymenoptera: Apidae) was significantly more attracted to geraniol alone and as a component in floral lure blends than to either eugenol or PEP alone. Xylocopa virginica (L.) (Hymenoptera: Apidae) was more selective in being primarily attracted to traps baited with higher amounts of geraniol in 2016. Removing geraniol from the floral lure blend did not significantly reduce Japanese beetle captures in 2017 and 2018 in Rhode Island and Ohio but did significantly reduce bee captures in Rhode Island in 2017 and 2018. Green, black, brown, and red traps captured significantly fewer bees than clear or standard yellow vane and green cage traps in 2018 in Rhode Island and Tennessee; however, there were no significant differences between Japanese beetle captures in any of the colored or clear traps. Our results show that using all green traps with a lure composed of eugenol and PEP and the Japanese beetle female produced sex pheromone can effectively capture Japanese beetles while minimizing bycatch of bees.

Effect of Corolla Slitting and Nectar Robbery by the Eastern Carpenter Bee (Hymenoptera: Apidae) on Fruit Quality of Vaccinium corymbosum L. (Ericales: Ericaceae).

Eastern carpenter bees, Xylocopa virginica (L.) (Hymenoptera: Apidae), are among the most abundant native bee visitors to highbush blueberry, Vaccinium corymbosum L., flowers in the northeastern United States, and they sometimes display corolla-slitting behavior to rob nectar. We studied foraging behavior of X. virginica on 14 blueberry cultivars in an experimental planting in Rhode Island, and assessed factors related to slitting frequency, and the effects of slitting on fruit set and blueberry quality. Among 14 cultivars in bloom, an average of 35% (range 16-67%) of flowers were slit in 2017, and 39% (range 20-62%) in 2018. Factors that affected the proportion of corollas slit included cultivar, anther length, flower volume, and number of days in bloom at or above 15°C. Corolla slitting did not affect fruit set. Average weight and percent soluble solids of fruit resulting from slit and non-slit corollas did not differ significantly in two early- ('Bluehaven', 'Earliblue'), two mid- ('Collins', 'Bluecrop'), and two late-season ('Herbert', 'Lateblue') ripening cultivars in 2017. In 2018, average fruit weight and percent soluble solids resulting from slit and non-slit flowers did not differ significantly in most cultivars, but slit corollas resulted in berries with greater mass in two cultivars, 'Bluehaven' and 'Collins'. 'Collins' fruit from non-slit corollas had a significantly higher percentage of soluble solids at maturity than fruit from slit corollas in 2018. Corolla slitting and nectar robbery by X. virginica did not have a significant negative effect on fruit quality under the described growing conditions and pollinator community.

Eastern Carpenter Bee (Hymenoptera: Apidae): Nest Structure, Nest Cell Provisions, and Trap Nest Acceptance in Rhode Island.

Analysis of pollen provisions in Xylocopa virginica (L.) nests in southern Rhode Island showed that this species produced pollen loaves from 21 different genera of plants in 2016, 19 in 2017, and 39 in 2018. Antirrhinium majus L. (garden snapdragon) pollen was the most common type collected in all three years (21.4%). Overall, wind-pollinated tree pollen comprised 22.1% of all pollen loaves. Blueberry pollen was a minor component of pollen loaves (0.1%), despite abundant blueberry plants nearby. Mean values of X. virginica nest measurements (tunnel length 15.4 ± 1.2 cm, width 15.0 ± 0.5 mm, and cell length 17.7 ± 0.3 mm) were similar to those reported in previous studies. Only 2 of the 216 trap nests deployed in 2017 were occupied by 11 X. virginica bees (9 females and 2 males). However, 17 nests contained 230 Osmia taurus Smith, 6 nests contained 73 O. cornifrons (Radoszkowski), and 1 nest contained 8 O. lignaria Say. Thirty-four nests (15.7%) were occupied by 151 grass-carrying wasps, Isodontia sp. and 6 vespid wasps occupied three nests (1.4%) in 2017. In 2018, 4 of 96 trap nests were occupied by carpenter bees. Understanding the nesting and foraging habits of X. virginica will help us to manage natural populations for pollination services.

Association Between Density of Foraging Bees and Fruit Set in Commercial Fields of Rabbiteye Blueberries (Ericales: Ericaceae) in Louisiana and Mississippi.

Field-scale data on the relationship between pollinator activity and fruit set are scarce for rabbiteye blueberries (Vaccinium virgatum Aiton). We measured the densities of Apis mellifera L. (Hymenoptera: Apidae), Habropoda laboriosa F. (Hymenoptera: Apidae), Bombus Latreille (Hymenoptera: Apidae) spp., and Xylocopa virginica L. (Hymenoptera: Apidae) in 7-21 commercial fields during each of 3 yr in Louisiana and Mississippi. Foraging bees were counted on 10 'Tifblue' bushes per field on 2 d during bloom, and the density of bees per flower was calculated based on the number of flowers open during the counts. Fruit set was measured 30 d after bloom. The impact of foraging activity on fruit set was inconsistent when densities of either all foragers or foragers of individual taxa were considered. Strong associations were observed only in 2001, with fruit set increased by H. laboriosa and Bombus and with a weaker contribution by A. mellifera. Floral robbery by X. virginica had no measurable negative effects. Populations of H. laboriosa were more consistent than those of other bees across sites. Managed colonies of A. mellifera were added at two densities (12.5 or 2.5 colonies per hectare) in seven fields each in 2001. These supplemental bees did not result in greater forager densities or fruit set in stocked fields. The observations show the challenge of field-scale pollination tests but provide an initial framework for rabbiteye blueberry growers to assess the availability of foraging bees early in bloom to help decide whether to add supplemental A. mellifera to try to enhance pollination if populations of non-Apis bees are low.

Documenting Potential Sunn Hemp (Crotalaria juncea L.) (Fabaceae) Pollinators in Florida.

Sunn hemp, Crotalaria juncea L., is a warm-season legume that can be planted in rotation to cash crops to add nitrogen and organic matter to the soils, for weed growth prevention, and to suppress nematode populations. Sunn hemp flowers also provide nectar and pollen for pollinators and enhance biological control by furnishing habitat for natural enemies. Experiments were conducted in Northern and North Central Florida to evaluate bee populations that visited flowers within mixed plots of sunn hemp and sorghum-sudangrass and plots of two sunn hemp germplasm lines. Collections of bees that visited 'AU Golden' and Tillage Sunn flowers indicated that Xylocopa virginica (L.) (Hymenoptera: Apidae), Xylocopa micans Lepeletier (Hymenoptera: Apidae), Megachile sculpturalis Smith (Hymenoptera: Megachilidae), Megachile mendica (Cresson) (Hymenoptera: Megachilidae), and Megachile georgica Cresson (Hymenoptera: Megachilidae) were present in large numbers in May through July and then again in October. Although Tillage Sunn seeds planted in March flowered in May, percent bloom and number of bee visits were low. Compared with short day sunn hemp cultivars, 'AU Golden' plants produced flowers early in the season to provide food and habitat for pollinators and have the potential to produce an abundant seed crop in Northern and North Central Florida.

Keanekaragaman serangga pengunjung bunga pada tanaman tumpang sari kedelai dengan tanaman orok-orok (Crotalaria juncea)

Tumbuhan berbunga dapat meningkatkan populasi serangga polinator, yang sekaligus berperan penting dalam meningkatkan hasil tanaman. Tujuan penelitian ini untuk mengetahui pengaruh tumpang sari Crotalaria juncea dengan kedelai terhadap keanekaragaman serangga pengunjung bunga dan polinator alami terhadap hasil kedelai. Penelitian dirancang pada petak tunggal, dengan perlakuan: tanpa C. juncea (kontrol), penanaman C. juncea mengelilingi lahan kedelai, penanaman C. juncea setiap 5 baris kedelai, dan penanaman C. juncea setiap 10 baris kedelai. Pengaruh polinator alami terhadap hasil kedelai diamati melalui penyungkupan tanaman dengan jaring serangga. Hasil penelitian menunjukan, bahwa penanaman C. juncea dapat meningkatkan keanekaragaman serangga pengunjung bunga. Indeks keanekaragaman tertinggi 2,37 tercatat pada petak penanaman C. juncea setiap 10 baris kedelai. Keanekaragaman serangga pengunjung bunga terbanyak, yaitu 18 spesies ditemukan pada perlakuan penanaman C. juncea setiap 5 baris kedelai. Serangga pengunjung bunga yang dominan adalah Coccinella transversalis, Apis mellifera, Xylocopa virginica, Megachile parientina, Megachile relativa, Ropalidia fasciata, dan Vespa sp. Polinator alami (tanpa sungkup) dapat meningkatkan jumlah polong 30,11%, jumlah biji 44,63%, dan berat biji per tanaman 15,44% sehingga berperanan penting pada hasil kedelai.

Linear dominance hierarchies and conditional reproductive strategies in a facultatively social carpenter bee

In social groups, dominance rank may have important fitness consequences, as higher ranking individuals tend to have higher overall fitness. In social nests of the eastern carpenter bee, Xylocopa virginica, females in social nests demonstrate a complete division of labour where one female is the dominant egg layer and forager while other females in the nest are non-reproductive. We investigated the nature of reproductive queues in this species by performing removal experiments across 3 years to observe how females respond to new reproductive opportunities in the nest. When a primary female was removed, a secondary female always assumed her position as replacement primary and reproductive queues formed in a linear fashion. A third type of female in the nest, the tertiary female, did not become reproductive, even if she was the only female remaining. In delaying reproduction, tertiary females were able to overwinter a second time and were often successful at becoming reproductive in their second summer. Tertiary females were smaller than primary or secondary females, had higher fat stores and lower ovarian development. When all other females in the nest were removed, tertiary females were observed ejecting the offspring of previous dominant females in the nest. Tertiary females appear to represent a novel reproductive strategy among the Hymenoptera who can drastically alter their physiology and behaviour, essentially doubling their life span to maximize reproductive potential.

New insights into floral morph variation in Passiflora incarnata L. (Passifloraceae) in Tennessee, U.S.A.

Passiflora incarnata is a functionally andromonoecious clonal wildflower, native to the southeastern United States, whose primary pollinator is the carpenter bee, Xylocopa virginica. While recent studies looking at reproductive ecology in P. incarnata have classified flowers as one of two morphs (male or hermaphroditic) based on stylar deflexion, preliminary field studies conducted in Tennessee indicated there were five distinct morphs present (three male, two hermaphroditic), supported by stylar deflexion, floral size, and pistil development. The present study sought to test the hypothesis that five distinct floral morphs are present in P. incarnata by sampling 13 floral characters, and to document variation in nectar constituents, volume, and concentration across the five morphs. Five well-established individual plants were examined at three sites in Cookeville, Tennessee. Two-factor permuted analysis of variance of 13 floral characteristics with floral morph and individual plants as factors suggested that morph:plant interactions explained 6%, individual plant explained 18%, and floral morph explained 36% of variation in floral characteristics. Nectar sampling indicated that all morphs produced nectar comprised exclusively of sucrose. Nectar volume generally increased with floral morph size, while nectar concentration decreased. NMDS analysis indicated that four of the five hypothesized morphs were supported as distinct, with morphs 4a and 4b best classified as submorphs due to substantial overlap. The supported morphs are best distinguished by ovary width, ovary length, style length, and stigma width. These findings support a hypothesis that the morphs result from variation in developmental arrest during floral ontogeny. The ecological implications of the morphs and nectar variation are considered for X. virginica with suggestions for additional studies.

Nestmate discrimination based on familiarity but not relatedness in eastern carpenter bees

How animals recognize conspecific individuals has important outcomes in many contexts, but interactions among group members are particularly important. Two recognition criteria are often implicated in these interactions: kin recognition is based on relatedness cues and nestmate recognition is based on familiarity. For social insects, both types of recognition are possible, as many nestmates are close kin and familiarity can develop among individuals that encounter each other repeatedly. To discern whether social insects use kin or nestmate recognition, it is necessary to simultaneously assess how relatedness and familiarity influence behaviour. The facultatively social eastern carpenter bee, Xylocopa virginica, offers an excellent opportunity to study how either nestmate or kin recognition (or both) may influence interactions among nestmates, as many females disperse from their natal nests in spring, and often attempt to join new colonies that may contain unrelated individuals. This leads to frequent behavioural interactions among females that may be related or unrelated, and familiar or unfamiliar. We used observation nests and microsatellite loci to assess the influence of familiarity and relatedness on behavioural interactions during the early phase of colony development, when females establish reproductive queues prior to brood production. Females were more likely to feed and were less aggressive to familiar rather than related nestmates, regardless of their relatedness. This suggests that eastern carpenter bees primarily use learned cues to discriminate among nestmates. Interactions with nestmates were also context-dependent, as females returning to the nest without food were the recipients of more aggression than those returning with food. If spring dispersal leads to reduced relatedness in X. virginica colonies, then nestmate recognition based on familiarity would be an important factor in maintaining group cohesion.

Nesting habits influence population genetic structure of a bee living in anthropogenic disturbance.

While most organisms are negatively affected by anthropogenic disturbance, a few species thrive in landscapes altered by humans. Typically, native bees are negatively impacted by anthropogenic environmental change, including habitat alteration and climate change. Here, we investigate the population structure of the eastern carpenter bee Xylocopa virginica, a generalist pollinator with a broad geographic range spanning eastern North America. Eastern carpenter bees now nest almost exclusively in artificial wooden structures, linking their geographic distribution and population structure to human activities and disturbance. To investigate the population structure of these bees, we sampled females from 16 different populations from across their range. Nine species-specific microsatellite loci showed that almost all populations are genetically distinct, but with high levels of genetic diversity and low levels of inbreeding overall. Broadly speaking, populations clustered into three distinct genetic groups: a northern group, a western group and a core group. The northern group had low effective population sizes, decreased genetic variability and the highest levels of inbreeding in the data set, suggesting that carpenter bees may be expanding their range northward. The western group was genetically distinct, but lacked signals of a recent range expansion. Climatic data showed that summer and winter temperatures explained a significant amount of the genetic differentiation seen among populations, while precipitation did not. Our results indicate that X.virginica may be one of the rare 'anthrophilic' species that thrive in the face of anthropogenic disturbance.

Native Bee Diversity and Pollen Foraging Specificity in Cultivated Highbush Blueberry (Ericaceae: Vaccinium corymbosum) in Rhode Island.

We identified 41 species of native bees from a total of 1,083 specimens collected at cultivated highbush blueberry plantings throughout Rhode Island in 2014 and 2015. Andrena spp., Bombus spp., and Xylocopa virginica (L.) were collected most often. Bombus griseocollis (DeGeer), B. impatiens Cresson, B. bimaculatus Cresson, B. perplexus Cresson, and Andrena vicina Smith collected the largest mean numbers of blueberry pollen tetrads. The largest mean percent blueberry pollen loads were carried by the miner bees Andrena bradleyi Viereck (91%), A. carolina Viereck (90%), and Colletes validus Cresson (87%). The largest mean total pollen grain loads were carried by B. griseocollis (549,844), B. impatiens (389,558), X. virginica (233,500), and B. bimaculatus (193,132). Xylocopa virginica was the fourth and fifth most commonly collected bee species in 2014 and 2015, respectively. They exhibit nectar robbing and females carried relatively low blueberry pollen loads (mean 33%). Overall, we found 10 species of bees to be the primary pollinators of blueberries in Rhode Island.