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The Bee Community of Cannabis sativa and Corresponding Effects of Landscape Composition



Industrial hemp, Cannabis sativa (Cannabaceae), is a newly introduced and rapidly expanding crop in the American agricultural landscape. As an exclusively wind-pollinated crop, hemp lacks nectar but produces an abundance of pollen during a period of floral dearth in agricultural landscapes. These pollen resources are attractive to a range of bee species but the diversity of floral visitors and their use of hemp across a range of agricultural contexts remains unclear. We made repeated sweep net collections of bees visiting hemp flowers on farms in New York, which varied in both landscape context and phenotypic traits of hemp varieties. We identified all bee visitors to the species level and found that hemp supported 16 different bee species. Landscape simplification negatively impacted the abundance of bees visiting hemp flowers but did not affect the species richness of the community. Plant height, on the other hand, was strongly correlated with bee species richness and abundance for hemp plots with taller varieties attracting a broader diversity of bee species. Because of its temporally unique flowering phenology, hemp has the potential to provide a critical nutritional resource to a diverse community of bees during a period of floral scarcity and thereby may help to sustain agroecosystem-wide pollination services for other crops in the landscape. As cultivation of hemp increases, growers, land managers, and policy makers should consider its value in supporting bee communities and take its attractiveness to bees into account when developing pest management strategies.
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Pollinator Ecology and Management
The Bee Community of Cannabis sativa and
Corresponding Effects of Landscape Composition
NathanielRyan Flicker, Katja Poveda, and Heather Grab1,
Department of Entomology, Cornell University, Ithaca, NY 14853, and 1Corresponding author, e-mail:
Subject Editor: Theresa Pitts-Singer
Received 24 September 2019; Editorial decision 29 October 2019
Industrial hemp, Cannabis sativa (Cannabaceae), is a newly introduced and rapidly expanding crop in the American
agricultural landscape. As an exclusively wind-pollinated crop, hemp lacks nectar but produces an abundance of
pollen during a period of floral dearth in agricultural landscapes. These pollen resources are attractive to a range of
bee species but the diversity of floral visitors and their use of hemp across a range of agricultural contexts remains
unclear. We made repeated sweep net collections of bees visiting hemp flowers on farms in New York, which varied
in both landscape context and phenotypic traits of hemp varieties. We identified all bee visitors to the species
level and found that hemp supported 16 different bee species. Landscape simplification negatively impacted the
abundance of bees visiting hemp flowers but did not affect the species richness of the community. Plant height, on
the other hand, was strongly correlated with bee species richness and abundance for hemp plots with taller varieties
attracting a broader diversity of bee species. Because of its temporally unique flowering phenology, hemp has the
potential to provide a critical nutritional resource to a diverse community of bees during a period of floral scarcity
and thereby may help to sustain agroecosystem-wide pollination services for other crops in the landscape. As
cultivation of hemp increases, growers, land managers, and policy makers should consider its value in supporting
bee communities and take its attractiveness to bees into account when developing pest management strategies.
Key words: hemp, wild bees, honey bees, landscape simplification, plant traits
Bees provide essential pollination services in both natural and
agricultural systems; yet, both wild and managed bees have been
adversely impacted by numerous characteristics of large-scale, in-
tensied agriculture, including the widespread use of chemical pes-
ticides and insecticides, persistent pathogens and parasites, and the
loss of seminatural nesting habitat and plant diversity (Goulson etal.
2015, Dicks etal. 2016). Landscape-scale loss of natural areas and
plant diversity, a dening characteristic of intensive agriculture, oc-
curs as a consequence of the increased size and connectivity of areas
devoted to agricultural production (Meehan et al. 2011). Habitat
loss associated with agricultural land-use change imposes nutritional
stress on bee communities (Naug 2009) by reducing the diversity of
oral resources and imposing temporal gaps in resource availability
(Di Pasquale et al. 2016). Changing land use patterns, therefore,
threaten the sustainability of the pollination services that our agri-
cultural systems relyupon.
The recent federal legalization and agricultural expansion of in-
dustrial hemp, Cannabis sativa (Schluttenhofer and Yuan 2017), may
inuence the spatial and temporal distribution of pollen resources
for bee communities in the United States. Industrial hemp offers
a unique oral resource to bees in agricultural landscapes. Hemp
owers late in the summer releasing an abundance of pollen during
a period of native and agricultural oral dearth (Dalio 2012, Koh
etal. 2016). As a result, hemp pollen may offer a vital subsistence re-
source to bees at a point in the season when they are resource-limited
(Dalio 2012), thereby helping to alleviate the pressures imposed by
spatial and temporal variation in resource availability that is charac-
teristic of simplied agricultural landscapes (Schellhorn etal. 2015).
Recent studies have documented the importance of hemp pollen
in supporting a diverse community of bees during periods of oral
resource scarcity (O’Brien and Arathi 2019). Hemp visitor commu-
nities may vary across the season (O’Brien and Arathi 2019) poten-
tially reecting changes in landscape-level oral resources over time.
Specically, hemp’s pollinator community may vary temporally as
bees respond to local declines in the availability of oral resources
when the owers of other late-season crops in the landscape senesce
(Grab etal. 2017). Additionally, we know little about the effects of
varietal traits, like plant height, which have been previously shown
to alter visitor preference in other systems (Parsche et al. 2011).
Plant height in hemp is highly variable and determined by both gen-
etic and environmental factors (Campbell etal. 2019). Furthermore,
ower visitors may respond to land use change not only in terms of
Environmental Entomology, 49(1), 2020, 197–202
doi: 10.1093/ee/nvz141
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abundance and species richness but also in community composition
(Rollin etal. 2015). By exploring changes in composition, we can
detect more subtle changes in community structure including species
turnover whereby the identity of the species and their relative abun-
dances change across the landscape gradient. However, prior studies
have been limited in both their spatial and taxonomic resolution.
Therefore, hemp’s ability to support a diverse bee community across
a variety of contexts remains unresolved.
While it is apparent that hemp, as a widely expanding, pol-
len-abundant crop, can provide resources for bees, the bee commu-
nity visiting hemp has not yet been identied in the northeastern
U.S. agricultural landscape. In this study, we characterize the bee
community visiting hemp along a landscape gradient to determine
how shift in landscape composition affects hemp’s bee community.
Furthermore, we investigate the effects of plant height and sam-
pling date on the abundance and species richness of the hemp bee
Hemp is a dioecious, wind-pollinated crop. It lacks brightly colored
owers, extraoral nectaries, and sweet aromas, adaptations char-
acteristic of most insect-pollinated crops (Small and Marcus 2002).
Male plants grow taller than females and release mass quantities of
pollen for several weeks until they senesce. Bees visit male owers
to collect pollen; however, bees do not visit female owers because
they lack oral nectar and, therefore, they do not contribute to hemp
Data were collected at 11 hemp farms in the summer of 2018 in
the Finger Lakes region of New York. This region is characterized by
a wide array of agricultural and natural land uses, including dairy,
eld crop, fruit, and vegetable production as well as deciduous for-
ests, woodlots, and old eld pastures. In the Finger Lakes region,
industrial hemp is produced for grain, ber, and cannabidiol (CBD)
extraction. Cannabidiol is a nonpsychoactive phytocannabinoid
produced by female hemp plants that is used in the manufacturing
of Epidiolex, a pure concentrate of CBD used to treat severe forms of
Epilepsy, as well as in the herbal supplements industry (Hilderbrand
2018). However, because CBD production only utilizes female
plants, all bee sampling was conducted on plots producing hemp for
grain and ber, which offer both male and female plants.
The hemp elds involved in this study varied in size, with the
smallest plot being ~317 m2 (<0.1 acres) and the largest operation
cultivating roughly 42,262 m2 (>11 acres). Hemp cultivars varied
across sites, depending upon whether the plot was being culti-
vated for ber, grain, or dual-purpose production. Fields generally
contained a single variety; however, when multiple varieties were
present, they were grown in separate areas and we focused our sam-
pling efforts on the variety with the greatest bee activity. The average
height of hemp plants was estimated as tall (≥2 m), medium (1–2 m),
or short (≤1 m).
Landscape Analysis
Measures of landscape composition were used to assess the inuence
of habitat characteristics on the abundance and diversity of bees
visiting hemp plots. Using the 2018 National Agricultural Statistics
Service Cropland Data Layer for New York State in ArcGIS, we es-
timated the proportion of land in agricultural uses (row crops, or-
chards, fruit and vegetable elds) at radii of 500 and 1,000 m.The
cover of forests (wooded wetlands, deciduous, coniferous, and
mixed forest stands), seminatural habitats (fallow elds, shrublands,
hay elds, and wetlands), and urban lands were also quantied at
each scale.
Bee Community ofHemp
Bees were netted from the owers of male plants in 20-min sam-
pling transects through hemp plots and around plot perimeters.
Twenty-minute sampling periods were roughly split between tran-
sects through the eld and walks around plot perimeters, depending
on the farm and eld layout. Any bee seen landing on or collecting
pollen from a male hemp ower was collected. Sampling was fo-
cused on areas of the eld that had the greatest prevalence of open
owers and accessible pollen. Each of the sites were visited four
separate times over the course of the sampling period, amounting
to a total of 80 min of sweep-netting per site throughout hemp’s
owering period. All sampling were conducted between July 30 and
September 15 of2018.
Dry ice was used to freeze captured bees on site, and collected
bees were cleaned and pinned for ease of identication. All pinned
bees were identied to the species level using the
keys, published revisions (Gibbs 2011, Gibbs etal. 2013), and refer-
ence materials maintained in the Cornell University Insect Collection
Statistical Methods
Total abundance and species richness of wild bees through time
was calculated for each sampling site and date across the sampling
period. The European honey bee, Apis mellifera L.(Hymenoptera:
Apidae), is a nonnative, highly managed species and their abun-
dance on hemp is likely to represent local hive density rather than
landscape context. Consequently, we evaluated the effects of land-
scape composition, sampling date, and plant height on honey bees
and wild bees separately. Although the common eastern bumble
bee, Bombus impatiens Cresson (Hymenoptera: Apidae), can also
be commercially managed, use of managed colonies in this region is
uncommon and we did not observe managed bumble bee colonies at
any of our eld sites. The effects of variation in landscape compos-
ition at each spatial scale on the abundance, and diversity of hemp’s
bee community were analyzed using generalized linear models with
Poisson error structures as implemented in the lme4 package (Bates
etal. 2015). Separate models were t for each land cover type and
scale and ranked based on Akaike Information Criterion scores cor-
rected for small sample size (AICc). The effects of plant height and
sampling date were included in each model as separate xed effects.
We then used model averaging to calculate estimates and P-values
across models with a cumulative weight ≥0.95. Post-hoc Tukey tests
were used to evaluate whether signicance of differences among
plant height categories. Additionally, we evaluated the variation in
the composition of the community using NMDS based on Gower
distances and tested whether community dissimilarity was explained
by gradients in land cover variables by permutational multivariate
analysis of variance (Oksanen etal. 2018) with 1,000 permutations.
The Bee Community ofHemp
Throughout the sampling period, hemp supported a total of 16 bee
species (Table 1) and 355 individuals were captured from the 11 sites
over the sampling period. The most abundant species were A.mellif-
era, constituting nearly 60% of all captured individuals, and B.impa-
tiens, which constituted nearly 30% of hemp’s bee community (Fig. 1).
198 Environmental Entomology, 2020, Vol. 49, No. 1
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Effect of Landscape, Plant Height, and
The proportion of agricultural land cover had the strongest effect on
the bee community visiting hemp (conditional model-averaged esti-
mate=−0.66, z= 2.779, P=0.005). Specically, increased agricul-
tural cover at the 1,000-m scale reduced the average number of wild
bees visiting hemp owers by as much as 76% (Fig. 2a, Supp Table 1
[online only]). Urban cover at the 1,000-m scale was associated with
an increase in bee visitation (estimate=7.41, z=2.285, P=0.022);
however, the model including urban cover was not different from a
model without any land cover variables (ΔAICc=1.27, Supp Table 1
[online only]). The height of hemp plants also had a strong inuence
on the abundance of wild bees visiting hemp owers, with tall plants
attracting nearly 17 times the number of visits compared to short
plants (estimate= −3.49, z=4.139, P<0.005, Fig. 2a, Supp Table
1 [online only]). Additionally, the average number of wild bee vis-
its increased across the sampling period (estimate=0.46, z=2.908,
P=0.003, Supp Table 1 [online only], Fig. 2b).
Abundance of A.mellifera did not vary with landscape compos-
ition (Supp Table 2 [online only]) but, similar to wild bees, increased
with plant height (conditional model-averaged estimate = −2.88,
z=2.80, P=0.005, Supp Table 2 [online only]) and sampling date
(estimate=0.48, z=2.84, P=0.004, Supp Table 2 [online only]).
The species richness of hemp visitors was greatest on tall plants
(conditional model-averaged estimate=−1.16, z=2.25, P=0.023,
Fig. 3, Supp Table 3 [online only],) but was not inuenced by sam-
pling date (estimate = −0.01, z = 0.102, P =0.918, Supp Table 3
[online only]). Landscape composition also did not have a signi-
cant effect on the bee species richness of hemp ower visitors (Supp
Table 3 [online only]). However, both forest cover (F(1,28) = 2.76,
P=0.05) and seminatural habitat cover (F(1,28)=4.38, P =0.014)
at the 1,000-m scale were associated with variation in community
composition (Fig. 4).
Crops serve as critical resources for pollinators in agricultural land-
scapes (Westphal etal. 2003, Le Feon etal. 2010). Hemp, a newly
introduced and rapidly expanding crop in U.S. agricultural land-
scapes, offers an abundance of pollen resources to bees during a
period of oral resource scarcity in agricultural landscapes (Dalio
2012). In this study, we sought to identify the bee community vis-
iting hemp and to analyze the effects of landscape composition on
bee visitation to hemp. Hemp supported a total of 16 different social
species of bee pollinators. We found a negative impact of agricul-
tural cover on the abundance of wild bees visiting hemp. The average
number of bees visiting hemp owers increased across the sampling
period and both the abundance and diversity of the bee community
visiting hemp increased with plant height.
Table 1. Species visiting male hemp flowers in New York and
counts for each species observed
Species Count
Apis mellifera 210
Bombus impatiens 105
Lasioglossum hitchensi 11
Augochlora pura 5
Xylocopa virginica 4
Lasioglossum ephialtum 4
Lasioglossum spp. (male) 3
Lasioglossum zonulum 2
Lasioglossum paradmirandum 2
Lasioglossum zephyrum 2
Halictus confusus 1
Lasioglossum imitatum 1
Lasioglossum laevissimum 1
Lasioglossum planatum 1
Lasioglossum versatum 1
Lasioglossum oblongum 1
Lasioglossum perpunctatum 1
Fig. 1. Honey bees, Apis mellifera (a and b) and bumble bees, Bombus impatiens (c and d) collecting pollen from male hemp flowers.
Environmental Entomology, 2020, Vol. 49, No. 1 199
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Hemp provided pollen resources to important pollinators
in the NYS agricultural landscape. Overall, the community was
not dissimilar to prior work describing hemp visitors in northern
Mississippi (Lago and Stanford 1989), which reported primarily
A. mellifera, B. impatiens, and Lasioglossum (Dialictus) spp.
(Hymenoptera: Halictidae) but did contrast with recent work in
Colorado (O’Brien and Arathi 2019) which found a large number
of Melissodes bimaculata Lepeletier (Hymenoptera: Apidae) and the
cucurbit specialist, Eucera (Peponapis) pruinosa Say (Hymenoptera:
Apidae). In New York, nearly 60% of hemp’s bee community was
represented by A.mellifera, which may be considered the most im-
portant and widely relied-upon species for agricultural pollination
services in the United States (Morse and Calderone 2000). Nearly,
30% of the visitors captured on hemp were B.impatiens, a generalist
pollinator that, like A.mellifera, is intensively relied upon in wild
and managed contexts for agricultural pollination services (Kleijn
etal. 2015). Hemp also supported a diverse community of nonman-
aged bee pollinators. Wild pollinators enhance the effectiveness of
pollination services through functional complementarity with man-
aged species (Chagnon etal. 1993, Hoehn etal. 2008, Frund etal.
2013) and have become increasingly important in buffering the im-
pacts of widespread declines in managed A.mellifera populations on
agricultural pollination services (Kremen etal. 2007, Garibaldi etal.
2011, Brittain etal. 2013). As a late-season crop that blooms during
a critical period of oral resource scarcity in agricultural landscapes,
hemp may facilitate pollination services for crops in the following
year by lling periods of late-season resource scarcity (Waser and
Real 1979, Moeller 2004, Riedinger et al. 2014, Grab etal. 2017)
and reducing the spatial and temporal variation in oral resources in
agricultural landscapes (Schellhorn etal. 2015).
The height of hemp plants provided a strong indicator for both
the diversity and abundance of hemp’s bee community. In addition
to potentially providing a greater overall amount of pollen, tall
plants are more apparent than shorter varieties, which may explain
why they attracted a more abundant and species rich community of
pollinators (Russo and Shea 2017). The abundance of bees visiting
Fig. 3. The average species richness of bees sampled from hemp varied with
plant height. Letter values indicate significant differences (P<0.05) based on
post hoc contrasts with a Tukey correction.
Agriculture (1000m)
Agriculture (500m)
Forest (1000m)
Forest (500m)
Urban (1000m)
Urban (500m)
Seminatural (1000m)
Seminatural (500m)
−0.25 0.00 0.25 0.50
Land cover
Fig. 4. Ordination plot showing the position of hemp visiting species (points)
relative to the vectors of environmental variables (lines). Solid lines indicate
that the environmental variable was significantly associated with variation
in the community.
Fig. 2. The average number of wild bees visiting hemp flowers varies depending on a) plant height, the proportion of agricultural land cover at 1,000 m
surrounding the field and b) the sampling date.
200 Environmental Entomology, 2020, Vol. 49, No. 1
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hemp plants also increased throughout the sampling period, which
may reect the increasing importance of hemp as a pollen-forage
resource as the owers of other late-season crops senesce at the end
of the summer. Hemp varieties that are taller and later owering
varieties may therefore better support the pollinator communities of
other crops in the agroecosystem.
At the landscape level, hemp plantings located at sites with mod-
erate agricultural cover are also likely to support a more abundant
population of crop pollinators, as we found that the number of wild
bees visiting hemp declined as the proportion of agricultural cover
in the landscape increased. Landscape simplication has been shown
to restrict the availability of foraging and nesting resources for pol-
linators in agricultural landscapes through reduced diversity of oral
resources and seasonal periods of resource scarcity (Di Pasquale
et al. 2016), which imposes nutritional stress on bee populations
(Naug 2009). Our ndings conrm the negative impacts of agricul-
tural land use change on the abundance of wild bees visiting crop
owers. Because high agricultural land cover negatively impacts the
abundance of hemp’s bee community, hemp may provide a more ef-
fective resource for bees in more complex landscapes, where it is
utilized by a greater number of bees. However, the average number
of species utilizing hemp did not vary with landscape context sug-
gesting that hemp will support a broad array of crop pollinators
across a range of landscape contexts. We observed shifts in commu-
nity composition that were driven mainly by differences in forest and
seminatural habitat cover. These patterns are likely due to the avail-
ability of suitable nesting habitat as species like Augochlora pura Say
(Hymenoptera: Halictidae), which nest in rotting logs (Stockhammer
1966), were associated with forest cover and species like Xylocopa
virginica L.(Hymenoptera: Apidae), which often nest in man-made
wooden structures (Gerling and Hermann 1978), were associated
with urban cover. These ndings suggest that hemp will support a
different suite of species in landscapes with more open natural habi-
tats, such as meadows and shrublands, compared with landscapes
with greater forested cover, reecting variation in habitat require-
ments, and life cycle characteristics of different bee species.
An important consideration that should be addressed in future
research is the relative value of hemp pollen in supporting bee repro-
duction. Mass owering crops can support pollinator populations
(Westphal etal. 2003, Jauker etal. 2012), but the incorporation of
novel pollens into the diets of generalist bees has been shown to
have detrimental effects on larval development (Williams 2003). The
presence of cannabinoids, particularly tetrahydrocannabinol (THC),
in hemp pollen (York etal. 1975) is not likely to have an impact on
bee development due to the loss of cannabinoid receptors in insects
(McPartland etal. 2001).
Hemp is a high pollen producing crop owering during a period
of oral resource scarcity and supports a diverse array of bees in
the northeastern U.S.landscape. The rapid expansion of hemp pro-
duction in the United States (Schluttenhofer and Yuan 2017) may
have signicant implications for agroecosystem-wide pollination dy-
namics. The potential for hemp to serve as a oral resource for bees
is inuenced by landscape composition, the height of hemp plants,
and temporal factors. Growers, extension agents and policy makers
should consider risks to bees as pest management practices are de-
veloped for this crop (Cranshaw etal. 2019). As a late-season crop
owering during a period of seasonal oral dearth, hemp may have
a particularly strong potential to enhance pollinator populations and
subsequent pollination services for crops in the following year by
lling gaps in late-season resource scarcity.
Supplementary data are available at Environmental
We would like to gratefully acknowledge the hemp farmers who participated
in this study and to Dr. Larry Smart of the Cornell Hemp Research Program
for allowing pollinator sampling at Cornell research sites. N.F.would espe-
cially like to acknowledge the CALS Charitable Trust research support pro-
gram, which provided grant funding to support this research project.
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... In total, we counted 1826 pollinators during the study, representing three types of bees, namely honey bees, bumble bees, and sweat bees. The community of bees documented here was similar to that of previous work with the same bee types (honey bees, bumble bees, and sweat bees) [47,48]. However, another study [7] indicated additional bee species, including the longhorn bee, miner bee, and leafcutter bee. ...
... Sweat bees were the most abundant bees in our study, accounting for 84.7% of the bee community on all four hemp varieties (Figure 4). In other studies, the honey bee was the most abundant, comprising nearly 60% [7] and 30% [48] of the bee community on industrial hemp. Several factors could have played a role in influencing the abundance and type of bee recorded. ...
... However, the experimental field in the study by [7] was located near active honey bee colonies. Additionally, both studies by [7,48] were conducted in regions where agriculture is intensive and may have had fields with sunflower and cucurbits in the nearby vicinity. These plants shed large amounts of pollen and also attract bees and other pollinators. ...
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Simple Summary Research on nutritional requirements in combination with improving bee protection has recently increased because of the continuous global decline in the abundance and diversity of bees. The decline is currently attributed to several stressors, including climate change, diminishing forage resources, and pesticide use, among other factors. Industrial hemp (Cannabis sativa L.) is a new crop that is grown over a wide geographic area in the United States, providing economic and nutritional benefits to humans. However, the contribution of hemp floral resources (pollen) to bee nutrition is not well understood. We investigated the chemical composition of pollen from four industrial hemp varieties (Canda, CFX-2, Henola, and Joey) and documented the abundance and diversity of bees on the crop using two sampling methods. Results showed differences in composition among the four hemp varieties. Overall, the Joey variety was the most preferred by bees, despite expressing lower protein, amino acid, and saturated and monosaturated fatty acid content. Based on our findings, we concluded that industrial hemp pollen provides some nutritional benefits to bees. However, it is important to understand that multiple sources of pollen are needed for sustained bee survival. Abstract Apart from its economic value, industrial hemp (Cannabis sativa L.) is a prolific pollen producer, serving as a food source for bees. However, little is known regarding the extent to which varietal differences in hemp pollen chemistry influences bee preference. Here, we report the chemical profile of pollen from four hemp varieties (Canda, CFX-2, Henola, and Joey) and bee abundance and diversity, using direct visual counts and pan traps. The number and type of bees on each variety was recorded and the chemical composition (proximate analysis and mineral, amino, and fatty acid profiles) of pollen from each hemp variety was determined. During the entire sampling period, three bee types (bumble bees, honey bees, and sweat bees) were recorded, with a combined total of 1826. Among these, sweat bees and bumble bees were the most prevalent and were highest on the Joey variety. The four varieties expressed protein content ranging from 6.05% to 6.89% and the highest in Henola. Seventeen amino acids were expressed in all varieties, with leucine recording the highest content ranging from 4.00 mg/g in Canda to 4.54 mg/g in Henola. In general, Henola expressed high protein, amino acid, and saturated and monosaturated fatty acid contents and recorded significantly fewer bees compared with Joey, which had a low content of these components and a high content of polyunsaturated fatty acids. Our findings suggest that, while industrial hemp offers abundant and accessible pollen that would promote bee health and sustainability of their ecosystem services, the nutritional quality may not be adequate for bee growth and development as an exclusive pollen source.
... Hemp is typically a dioecious annual (Ainsworth 2000, Divashuk et al. 2014, Davidson et al. 2018. The female and male plants exhibit separate growth forms, with the males being taller and lankier, and the females being shorter and denser (Ainsworth 2000, Davidson et al. 2018, Flicker et al. 2020). ...
... Alcohol extraction is completed by chilling ethanol, pumping it into a container of Cannabis sativa L. plant material, and letting it soak (Fenili 2019). The extract is then distilled to remove the alcohol, leaving a mixture of cannabinoids for suspension in oils or use in other applications. ...
... Supercritical CO2 pressurizes carbon dioxide and puts it in a chamber with the plant material (Fenili 2019). The distillate is found by evaporating off the CO2; this method gives the cleanest 8 chemical profile (Fenili 2019). ...
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Cannabis sativa L. is a crop plant that is native to Asia. It is a primarily dioecious annual agriculturally used for its seed, fiber, and flowers. After recent legislative action legalized hemp nationally for research and cultivation in the US, distinct classifications had to be made. Cannabis sativa L. cultivars are presently separated into two major categories by the FDA: medical marihuana and hemp. Within the hemp classification, there is CBD-type hemp and industrial hemp. These classifications are based on Cannabis sativa L.’s chemical composition, which varies throughout the plant’s tissue. The desired cannabinoid chemicals for CBD-type hemp and medical Cannabis (high THC) are found in high concentrations in the female flowers. To differentiate CBD-type hemp from medical marihuana, the USDA’s current regulations limit tetrahydrocannabinol (THC) concentration to no more than 0.3% total. Genetic research on the plant has been, until recently, limited to legal applications of differentiating industrial hemp from medical marihuana. This study has been completed to ascertain Cannabis sativa L.’s current chemical composition and genetic diversity among Maryland growers. Hemp growers located across Maryland provided the field sites and samples. Chemical composition was determined from an analysis of flowers through a partnership with a Morgan State University chemistry lab. The determination of genetic diversity was completed on hemp leaves through the analysis of 12 standard and novel microsatellites. Cannabis sativa L. samples were taken from eight field sites across twenty eight distinct cultivars. Cultivars #5 and Cherry had the highest CBDA content among the strains studied. Microsatellite analysis determined that the most genetically variable cultivars were A-B1 and #5. With this research, CBDA type hemp growers in Maryland will be able to determine some strains which have high concentrations of their desired cannabinoids and which cultivars are more genetically variable.
... The plant blooms at different times and provides ample pollen, making it an important source of food for bees (Balcke et al., 2014). By creating a microclimate that is beneficial for pollinators, Cannabis contributes to the conservation of biodiversity, which is essential to the health of the planet (Flicker et al., 2020). Another potential application of Cannabis is a bioremediation crop that can absorb and store heavy metals from the soil, making it effective in cleaning contaminated soil (McPartland and McKernan, 2017). ...
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Cannabis sativa , also known as “hemp” or “weed,” is a versatile plant with various uses in medicine, agriculture, food, and cosmetics. This review attempts to evaluate the available literature on the ecology, chemical composition, phytochemistry, pharmacology, traditional uses, industrial uses, and toxicology of Cannabis sativa . So far, 566 chemical compounds have been isolated from Cannabis , including 125 cannabinoids and 198 non-cannabinoids. The psychoactive and physiologically active part of the plant is a cannabinoid, mostly found in the flowers, but also present in smaller amounts in the leaves, stems, and seeds. Of all phytochemicals, terpenes form the largest composition in the plant. Pharmacological evidence reveals that the plants contain cannabinoids which exhibit potential as antioxidants, antibacterial agents, anticancer agents, and anti-inflammatory agents. Furthermore, the compounds in the plants have reported applications in the food and cosmetic industries. Significantly, Cannabis cultivation has a minimal negative impact on the environment in terms of cultivation. Most of the studies focused on the chemical make-up, phytochemistry, and pharmacological effects, but not much is known about the toxic effects. Overall, the Cannabis plant has enormous potential for biological and industrial uses, as well as traditional and other medicinal uses. However, further research is necessary to fully understand and explore the uses and beneficial properties of Cannabis sativa .
... In the months of May and June, periods of floral scarcity are often observed, and Cannabis plants become an important source of pollen for the colonies of Apis mellifera, which seeing the possible alternative choices decrease, resort to foraging of hemp fields to compensate for the lack of nutrients, as has been observed by various beekeepers (Dalio, 2012;Flicker, Poveda, & Grab, 2020). It has been noted that, even though bees are found in the presence of fields with wide choices of flowers, they still collect significant amounts of hemp pollen to carry to the hive as deposits of food (Dalio, 2012). ...
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Cannabis sativa L. belongs to the Cannabaceae family and includes annual, robust, fast-growing and generally dioecious plants. Industrial hemp, and particularly the inflorescences, has been recently recognized as important source of bioactive extracts with antioxidant and antimicrobial effects. The goal of the present study was to explore botanical, phytochemical, and biological properties of water and hydroalcoholic hemp pollen extracts from male inflorescences. The extracts from hemp pollen were found rich in phenolic compounds, such as hydroxytyrosol, coumaric acid, and hesperitin. The phenolic profile was also consistent with the observed scavenging/reducing, enzyme inhibitory, and antimicrobial properties of the extracts. Regarding the antimicrobial effects, Escherichia coli, Trycophyton rubrum, and T. tonsurans were the most sensitive to growth inhibitory effects (MIC values: 9.92-79.37 µg/mL) of the extracts. Whereas, null effects on prostate PC3 and myocyte C2C12 cell viability, in the range 1-1000 µg/mL, are consistent with MIC values and suggest extracts’ biocompatibility. The experimental data obtained, which are not reflected in the literature as the topic of hemp pollen is almost completely unexplored, confirm the innovativeness of a product obtained directly from bees, which in the face of greater variability and complexity can reserve promising applications in food, pharmaceutical and cosmetic sectors.
... Bees have been observed in hemp, but these reports have been from pollen producing fiber or grain varieties of the crop (O'Brien and Arathi, 2019;Flicker et al., 2020). The floral/ cannabinoid varieties sampled in this study do not produce pollen. ...
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Hemp is a newly (re)introduced crop to United States and California agriculture. A study was initiated in the summer of 2021 to survey the arthropods present in hemp in two regions of California: Fresno County in the Central Valley and Ventura County along the Central Coast. Eight hemp plots were sampled every two weeks from August to mid-October using a combination of D-vac samples, leaf collections, and visual observations. All samples were processed and ultimately recorded as the total number of specimens collected per morphospecies across all sampling dates, further broken down to express the number of specimens collected from the Central Valley and the Central Coast. D-vac sampling was the most reliable method for specimen collection and led to the recovery of arthropods from 11 orders, 69 families, and 157 morphospecies. Approximately 13,000 specimens were collected and processed, half of which were whiteflies (Hemiptera: Aleyrodidae). Of the specimens recovered, Hemiptera was the most representative order (with and without whiteflies), followed by Thysanoptera and then Hymenoptera. The most frequently collected specimen was Engytatus modestus (Hemiptera: Miridae). Very few pest species were recovered, cannabis aphid (Phorodon cannabis) being the only one that was observed in any noticeable density. Many generalist predators and parasitoid wasps were also collected. Findings from this survey provide baseline information on the arthropod species present in California hemp. This survey will be repeated and expanded in future growing seasons.
... As a prolific pollen producer, hemp may serve as an excellent food resource, particularly for bees (Hymenoptera) (Fig. 3). The potential benefit likely will be greatest with fiber hemp grown in more varied landscapes, as bees make greater use of hemp when plants are taller and in locales with greater diversity (O'Brien and Arathi 2019; Flicker et al. 2020). ...
Industrial hemp (Cannabis sativa L.) has considerable potential as a sustainable crop for numerous existing industrial and consumer products, with many more likely still to be realized. Much early excitement about this ancient crop arose from its assumed capacity to supply renewable feedstocks (e.g., fibers, grain, biomolecules) for numerous uses, both with little environmental “footprint” and the ability to be recycled or upcycled. Although many tout hemp as the solution for all things, such enthusiasm should be tempered by issues of historical precedent and of scale. First, the lack of research investment during the decades-long restriction in the West ensures that time will be needed to develop sustainable hemp production systems. Even as these systems are developed, there are questions about the capacity to grow sufficient amounts of hemp to meet the needs for an array—and large volume—of products. Still, there is room for guarded optimism that as the crop comes “on line,” it will receive the research needed to make the plant a viable resource for farmers and society. This review explores hemp sustainability issues in agronomic and systems contexts and touches on some of the attendant challenges to scale-up.
... A very recent research conducted in the USA has highlighted that hemp, thanks to its flowering cycle that occurs at a different time compared to other species and also to the abundant pollen produced, has favored the nutrition of various species of bees, increasing their biodiversity. Thanks to the increase in pollination with other crops in the area, the biodiversity of the entire agro-ecosystem under study has also been increased (Flicker et al. 2020). The beneficial effects of hemp on the environment are shown in Fig. 1. ...
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The Italian Law of 22 November 2016 has legalized the cultivation of hemp, which drives the development of sustainable agriculture by generating new products with high added value in the new context of circular economy. Hemp cultivation is known for its low environmental impact, as hemp grows fast, suppresses weeds and does not need pesticides. It has no specialized parasites, favors pollination and improves the physical and chemical soil fertility. Recently, many countries have increased their interest in hemp ( Cannabis Sativa L.), considering it as a climate-friendly crop that can mitigate climate change and desertification. For these reasons, hemp can be a new protagonist of Italian agriculture already oriented towards the objectives of EU 2030 which predicts 40% decrease in greenhouse gas emissions compared to 1990. The hemp cultivation can activate a new supply chain by allowing using different parts of the plant, benefiting farmers, environment, and human health. Indeed, although a very old plant, hemp will be one of the main protagonists of the green economy in the near future. Its seeds can be used by agri-food industry to produce flour, pasta, pastry and oil, while the stem through canapulo (woody part of stem) in green building sector. Its fiber (external part of stem) will find new applications in textile industry. As for its inflorescences and roots, thanks to the extraction of bioactive molecules, they will play an important role in the pharmaceutical and parapharmaceutical industry. Finally, only the medical sector with Δ ⁹ ‐tetrahydrocannabinol (THC) extraction from inflorescence is not yet regulated by the aforementioned Italian Law.
... Choosing flowers which are very morphologically and/or phylogenetically distinct from the crop may also reduce crop/wildflower competition (Carvalheiro et al. 2014), but might also mean that the plantings support fewer effective pollinators. The flowering phenologies of cover crops and even crops themselves can play an important role in an integrated pollinator plan; for example, hemp has been touted as a valuable agroecological landscape ingredient, because its late flowering helps support pollinators during a time of lower flower availability (Flicker et al. 2019). This project has sought to answer a series of questions in the context of the mid-Hudson Valley: Could NRCSrecommended (and potentially supported) wildflower seed mixes be established organically? ...
Technical Report
Full-text available
Report on several years of agroecological study of the effects of perennial wildflowers and forest edge on insects and spiders on a Mid-Hudson Valley Farm.
After decades of prohibition of the cultivation and breeding of hemp ( Cannabis sativa < 0.3% ∆9‐tetrahydrocannabinol [THC]), there is untapped potential for genetic improvement of this crop to provide food, feed, fiber, and medicinal compounds. Successful breeding efforts will require the development and characterization of germplasm resources, optimization of crossing methods, better understanding of sex determination, high‐throughput phenotyping platforms, and deployment of genomic tools for rapid selection. This review provides a brief overview of these topics and some key opportunities for genetic improvement of hemp to support an emerging industry utilizing this newly legalized crop.
Growers have increasingly expressed frustration over the negative externalities created by their neighbor's production practices. These spatial agricultural network problems include issues such as cross‐pollination and herbicide drift. We develop novel methods for estimating parameters that allow us to adapt and apply general network diffusion models to these spatial agricultural network problems. Doing so allows us to calculate externality damage within a region and calculate cost‐effective policies for alleviating that externality. We empirically illustrate, motivate, and test this approach by applying it to hemp. We find that network structure is an important factor in externality size and cost‐effective policy response for spatial agricultural network problems. We also find that policies that are implemented early and proactively are more likely to be successful and cost effective than policies implemented retroactively. Finally, we find that in our application of limiting the cross‐pollination damage experienced by growers of feminized hemp from non‐feminized hemp growers, the most cost‐effective policy is to establish a regional quota on non‐feminized production combined with intertemporal cultivar spacing. This policy response will likely change across time and region as economic and network variables evolve.
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Hemp (Cannabis sativa L.) is now being grown within the United States over a much broader geographic area and for different uses than during its last period of significant production that ended after World War II. Within the past 3 yr, a large number of arthropod species have been documented to feed on hemp in the United States. Among key pest species, corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), has demonstrated greatest potential for crop injury, being particularly damaging to flower buds. Hemp russet mite, Aculops cannibicola (Farkas), and cannabis aphid, Phorodon cannabis Passerini, are the two species observed most damaging among those that suck plant fluids. Eurasian hemp borer, Grapholita delineana Walker, is widely present east of the Rocky Mountains and appears to have potential to significantly damage both flower buds and developing seeds. Numerous species of caterpillars, grasshoppers, and beetles chew hemp foliage; the severity of these defoliation injuries appears to be minimal, but needs further study. Similarly, numerous seed feeding hemipterans, most notably stink bugs and Lygus bugs, are regularly found in the crop but injury potential remains unclear. Some preliminary efforts have been made to develop integrated pest management strategies for these insects, particularly for corn earworm. Future research can be expected to rapidly resolve many of the data gaps that presently restrict advancing pest management on the crop. However, a major confounding issue involves the use of pesticides on hemp. Federal agencies have not yet provided clear direction on this issue, and regulatory decisions have subsequently devolved to the states.
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Core Ideas Some hemp traits are more strongly affected by environmental factors than others. Multi‐environment testing is an integral part of hemp cultivar development. Water availability can have a significant impact on yield and other traits. Starting with the 2014 Farm Bill, hemp (Cannabis sativa L.) is being re‐introduced as an industrial crop in the United States. Since the crop has been absent for over 70 yr, little is known regarding the genetic mechanisms controlling economically relevant traits. Particularly, with federal legality of the crop hinging on a stringent tetrahydrocannabinol (THC) content of 0.3% or less, it is necessary to assess variance in this trait due to environmental effects and genotype × environment interactions (GEI) to avoid running afoul of federal law. Understanding how physical and biochemical traits respond to the environment also plays a strong role in selecting and developing appropriate cultivars for production in diverse growing regions. In 2016 we performed cultivar trials in multiple environments in Colorado to assess performance characteristics of a diverse set of germplasm from breeding programs across Europe and Asia. From these data, we were able to identify traits nearly entirely controlled by genetic factors, like days to maturity and THC and cannabidiol (CBD) production. We also identified traits strongly influenced by the environment and GEI, like grain yield, plant height, and water use. Individual cultivars also exhibited widely varying degrees of sensitivity to the environment. This underscores the importance of continued work to characterize genetic control of hemp traits to expedite breeding of cultivars that are well‐adapted to target growing regions.
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The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for the analysis of dissimilarities. Together with the labdsv package, the vegan package provides most standard tools of descriptive community analysis. Package ade4 provides an alternative comprehensive package, and several other packages complement vegan and provide tools for deeper analysis in specific fields. Package provides a Graphical User Interface (GUI) for a large subset of vegan functionality. The vegan package is developed at GitHub ( GitHub provides up-to-date information and forums for bug reports. Most important changes in vegan documents can be read with news(package="vegan") and vignettes can be browsed with browseVignettes("vegan"). The vignettes include a vegan FAQ, discussion on design decisions, short introduction to ordination and discussion on diversity methods. A tutorial of the package at provides a more thorough introduction to the package. To see the preferable citation of the package, type citation("vegan").
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During the growing seasons of 1983 and 1985, a general survey of insects associated with cultivated marijuana, Cannabis sativa, on the University of Mississippi campus was conducted. Of the species collected that were using the plants for food, the majority (43) were sap feeders, 15 were leaf chewers, nine ate or gathered pollen and one was possibly a root feeder. Only sap feeders appeared to be successfully reproducing on the marijuana. Species collected in greatest abundance were Agallia constricta and Graphocephala versuta (Cicadellidae), Spissistillus festinus (Membracidae), Clastoptera xanthocephala (Ceropidae), Halticus bractatus (Miridae), Systena elongata (Chrysomelidae) and Schizocerella pilicornis (Argidae).
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One of the greatest challenges in sustainable agricultural production is managing ecosystem services, such as pollination, in ways that maximize crop yields. Most efforts to increase services by wild pollinators focus on management of natural habitats surrounding farms or non-crop habitats within farms. However, mass flowering crops create resource pulses that may be important determinants of pollinator dynamics. Mass bloom attracts pollinators and it is unclear how this affects the pollination and yields of other co-blooming crops. We investigated the effects of mass flowering apple on the pollinator community and yield of co-blooming strawberry on farms spanning a gradient in cover of apple orchards in the landscape. The effect of mass flowering apple on strawberry was dependent on the stage of apple bloom. During early and peak apple bloom, pollinator abundance and yield were reduced in landscapes with high cover of apple orchards. Following peak apple bloom, pollinator abundance was greater on farms with high apple cover and corresponded with increased yields on these farms. Spatial and temporal overlap between mass flowering and co-blooming crops alters the strength and direction of these dynamics and suggests that yields can be optimized by designing agricultural systems that avoid competition while maximizing facilitation.
Industrial hemp, (Cannabis sativa L.), one of the earliest crops spun for fiber, is now used for a variety of commercial products including paper, textiles, clothing, biodegradable plastics, biofuel, food, animal feed etc., all of which are derived from hemp fiber or seeds. Being wind pollinated, dioecious and staminate hemp plants produce large amounts of pollen that are attractive to bees. Hemp flowering in northern Colorado, where this study was conducted, occurs between the end of July and the end of September. This time period coincides with a dearth of pollinator-friendly crop plants in the region, making hemp flowers a potentially valuable source of pollen for foraging bees. Here we present the diversity and abundance of bees collected in the fields of flowering hemp. A total of 23 different genera of bees were collected of which the European honeybee, Apis mellifera at 38% of the total abundance was the most dominant followed by Melissodes bimaculata at 25% and Peponapis pruinosa at 16%. These three genera made up nearly 80% of the total abundance. While hemp does not produce any nectar, the pollen rich nature of the flowers can make hemp an ecologically valuable crop. As cultivation of hemp continues to expand, we expect insect pests on hemp to also become prevalent. Our results documenting bee diversity in flowering hemp provides the impetus for the development of integrated pest management plans that protect pollinators while controlling pests.
Hemp has been an important crop throughout human history for food, fiber, and medicine. Despite significant progress made by the international research community, the basic biology of hemp plants remains insufficiently understood. Clear objectives are needed to guide future research. As a semi-domesticated plant, hemp has many desirable traits that require improvement, including eliminating seed shattering, enhancing the quantity and quality of stem fiber, and increasing the accumulation of phytocannabinoids. Methods to manipulate the sex of hemp plants will also be important for optimizing yields of seed, fiber, and cannabinoids. Currently, research into trait improvement is hindered by the lack of molecular techniques adapted to hemp. Here we review how addressing these limitations will help advance our knowledge of plant biology and enable us to fully domesticate and maximize the agronomic potential of this promising crop.
Earlier this year, the first global thematic assessment from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) evaluated the state of knowledge about pollinators and pollination ( 1 , 2 ). It confirmed evidence of large-scale wild pollinator declines in northwest Europe and North America and identified data shortfalls and an urgent need for monitoring elsewhere in the world. With high-level political commitments to support pollinators in the United States ( 3 ), the United Kingdom ( 4 ), and France ( 5 ); encouragement from the Convention on Biological Diversity's (CBD's) scientific advice body ( 6 ); and the issue on the agenda for next month's Conference of the Parties to the CBD, we see a chance for global-scale policy change. We extend beyond the IPBES report, which we helped to write, and suggest 10 policies that governments should seriously consider to protect pollinators and secure pollination services. Our suggestions are not the only available responses but are those we consider most likely to succeed, because of synergy with international policy objectives and strategies or formulation of international policy creating opportunities for change. We make these suggestions as independent scientists and not on behalf of IPBES.
Networks are a popular way to visually represent and analyse interactions between species in ecological communities, and there have been several recent calls for interaction network measures to be targets of conservation and management efforts. However, it is challenging to deliberately manipulate empirical network properties. Our objective was to determine whether the network property of connectance could be manipulated in a planned and deliberate fashion, without altering the size of the community. Connectance (proportion of realized interactions out of total number of possible interactions) is often used as a proxy for community complexity, and theory also suggests it is related to community robustness and stability. We designed a field experiment to increase the connectance of a mutualistic community by manipulating the attractiveness of plant species in a bee-plant interaction network. Specifically, we applied a chemical fertilizer to enhance the floral display and resource quality provided by experimental plants, and assessed the effect on bee community structure. We found the connectance was significantly higher in fertilized plots relative to controls. This manipulation was associated with a significant increase in both the species richness (+41%) and abundance (+77%) of pollinators; there were more pollinator species in treatment plots, and these pollinators visited more plant species with a higher frequency. This study shows that a network property can indeed be altered experimentally; here we were able to deliberately increase the connectance of a bee-plant network while keeping constant both the number of plant species and the background community of potential floral visitors. Deliberate manipulation of experimental community structure therefore could be a valuable avenue for future research. Integration of network theory with empirical research also has the potential to inform the design of network control approaches.