Abstract
Bee foraging patterns for honey production show regional variation across India’s flora. This study examined pollen composition in 18 honey samples from five districts of Central Uttar Pradesh-Lucknow, Barabanki, Hardoi, Unnao, and Raebareli. The analysis identified 38 distinct pollen species, with 16 samples being multifloral and two monofloral. The predominant pollen type includes Holoptelea integrifolia, Brassica campestris, Solanaceae, and Moringa oleifera, while 14 species were classified into secondary, 20 important minor pollen types, and 26 minor pollen types. The pollen analysis aimed to identify the floral sources visited by honeybees in Lucknow and adjacent districts. The findings correlated with the vegetation patterns observed near beehive locations during honey production.
INTRODUCTION
Pollen are unicellular male gametophytes abundantly produced by flowering plants (Ellison, 2008; Trivedi et al., 2024a). Melissopalynology, the study of pollen in honey, provides valuable insights into bee foraging behaviour and floral diversity (Jones et al., 2021). This field has recently gained importance due to its applications in honey authentication, environmental monitoring, and biodiversity assessment (Smith & Weis, 2020). The co-evolutionary relationship between insect pollinators and angiosperms represents one of the most crucial biotic coexistences driving ecosystem function and stability (Carnell et al., 2020). In terrestrial ecosystems, insect pollinators comprise the largest and most species-rich group of pollen vectors, with honeybees demonstrating exceptional pollination efficiency and ecological dominance (Carnell et al., 2020; Kevan & Baker, 1983).
Honeybees gather both nectar and pollen from flowers, which furnish the essential nutrients required for the sustenance and growth of honeybee colonies (Shukla et al., 2022). Unlike flies and wasps that visit flowers occasionally, bees depend entirely on floral resources throughout their lives (Carnell et al., 2020). The diversity of plant species and their propensity to forage within their flight range in the area are characteristics of the pollen in honey (Shukla et al., 2022; Sniderman et al., 2018; Verma et al., 1988). The honey pollen spectrum reflects the floral composition of the surrounding landscape, offering a unique perspective on plant-pollinator interactions (Brown et al., 2020).
Insect pollination is vital for sustaining ecosystem health and biodiversity. Insects are responsible for pollinating approximately 75% of globally important food crops (Klein et al., 2007). Humans rapidly alter plant diversity in urban settings for survivability and sustenance (Sponsel, 2013). In recent decades, the emphasis on creating aesthetically pleasing developments in metropolitan areas has led to the extinction of indigenous plant species in favour of exotic plant species (Hitchmough, 2011; Peretti, 1998). Recent research has highlighted a significant change in the diversity of plants that honey bees forage over time, reflecting a shift in their preferences (Chauhan et al., 2017; Jato et al., 1994; Ponnuchamy et al., 2014; Seijo et al., 1992). The shift in agricultural practices and urbanisation highlights the decline of local ecosystems, creating nutritional challenges that contribute to bee decline (Carnell et al., 2020; Ollerton et al., 2014). These include diminishing quantity and diversity of suitable foraging habitats, exposure to agrochemicals, improper apicultural management practices, and increased susceptibility to pests and diseases.
Uttar Pradesh (UP) is one of the largest states in India and has a high floral diversity in both agricultural and urban areas. UP has received little attention, with only a few reports published from Lucknow (Chaturvedi, 1976; Chaturvedi & Sharma, 1973; Chauhan & Trivedi, 2011; Chauhan et al., 2013, 2017; Farooqui & Farooqui, 2020), Unnao (Chauhan & Singh, 2010) and other districts of UP (Chauhan et al., 2015). Melissopalynology studies conducted in several parts of India have also been documented, including Andhra Pradesh (Jhansi et al., 1994; Kalpana et al.,1990; Lakshmi & Suryanarayan, 2004; Ramanujam & Kalpana, 1993; Ramanujam & Khatija, 1992; Ramanujam et al., 1992); Karnataka (Agashe & Ramaswamy, 1997; Bhargava et al., 2009; Chauhan & Murthy, 2010; Seethalakshmi, 1980), West Bengal (Bera et al., 2004; Jana & Bera, 2004), Maharashtra (Chaubal & Kotmire, 1985; Deodikar et al., 1958), Himachal Pradesh (Sharma, 1970; Sharma & Raj, 1985), Kumaon (Garg & Nair, 1994; Verma, 1988), Bihar (Suryanarayan et al., 1994), Madhya Pradesh (Quamar & Chauhan, 2011), and UP (Chaturvedi, 1976; Chaturvedi & Sharma, 1973; Chauhan & Singh, 2010; Chauhan & Trivedi, 2011; Chauhan et al., 2013; Farooqui et al., 2023).
Human alterations to the Earth’s terrestrial surface are unprecedented in terms of pace, magnitude, and spatial extent (Lambin et al., 2001). The transformation of land use (reflecting human intent or purpose) and the modification of land cover (representing the biophysical attributes of the Earth’s surface) stand out as two of the most consequential factors (Goudie et al., 1993; Lambin, 1999). Land use and Land Cover (LULC) maps of a region provide essential insights for understanding the features of the region’s terrain and their implications for ecological and environmental stability (Twisa & Buchroithner, 2019). The investigation of LULC change is increasingly recognised as an essential component of contemporary approaches for monitoring environmental shifts and effectively managing natural resources (Kumar et al., 2014; Rawat et al., 2013). Large-scale changes in the Earth’s land surface are being brought about by an increase in anthropogenic activity worldwide, which impacts the functioning of global systems. Additionally, human exploitation of land use and land-cover resources for various purposes has brought about notable transformations (Birhane et al., 2019; Lambin et al., 2001).
This article focuses on a melissopalynological investigation to understand the impact of LULC changes on honey bees’ foraging patterns and proposes strategies to overcome these challenges. This article also aims to characterise the pollen profile of honey collected from Central UP, to elucidate patterns in bee foraging preferences and their implications for health and honey production (Garcia-Martinez et al., 2022).
STUDY AREA
The honey samples were collected from Central UP, covering Barabanki, Hardoi, Unnao, Lucknow, and Raebareli (Figure 1) districts. Eighteen samples were collected, 11 of which were from Lucknow, two each from Hardoi, Barabanki, and Unnao, and one from Raebareli (Table 1). These study areas are marked by widespread agriculture and urbanisation with sparse, moist, and dry deciduous forests. The study area lies within the Central Ganga Plain (CGP), a geologically significant segment of the Indo-Gangetic foreland basin (Goswami & Yhokha, 2010). Its present-day geomorphology has developed through prolonged interactions among tectonic forces, climatic variability, and eustatic sea-level fluctuations during the Quaternary period (Saxena et al., 2015). Although it appears as a flat alluvial expanse, the CGP is characterised by a shallow, asymmetrical depression with a gentle easterly slope (Singh et al., 2007). Composed predominantly of sandy and silty alluvial deposits (Goswami & Yhokha, 2010), this region forms part of the extensive Ganga Plain, which is among the largest alluvial systems globally and hosts numerous lakes and sediment archives valuable for Quaternary palaeoclimatic investigations (Singh, 1996; Srivastava et al., 2003).
Digital Elevation Model (DEM) showing the location of the study sites in Central Uttar Pradesh, India.
Geographical coordinates of Honey samples collection localities in Central Uttar Pradesh, India.
Central UP is influenced by the South West (SW) monsoon, which has a humid subtropical climate. These areas experience three distinct seasons: a hot and dry summer, a warm and humid monsoon, and a cold and dry winter. The summer months, spanning from April through June, are characterised by intense, dry, hot winds, with the average minimum temperature during this period being 27°C and a maximum of 32.5°C. June is the hottest month, with temperatures soaring to 48°C (Chauhan et al., 2017; Mehndi et al., 2023; Shukla et al., 2022). The rainy season typically spans from late June or early July to the end of September, with humidity levels peaking during the monsoon. In contrast, the winter months, extending from November to February, typically feature average minimum temperatures of 7.6°C and a maximum of 21°C (Chauhan et al., 2017; Mehndi et al., 2023; Shukla & Rao, 2021; Shukla et al., 2022).
VEGETATION
The vegetational composition and biodiversity patterns of the CGP are governed by the intricate interactions among climatic variables, ecosystem dynamics, topographical elements, and anthropogenic modifications, particularly agricultural intensification and urbanisation.
The arboreal vegetation in the region, though sparsely distributed, is characterised by diverse tree species, including Abrus precatorius, Acacia nilotica, Acacia arabica, Adhatoda vasica, Adina cordifolia, Ageratum conyzoides, Ailanthus excelsa, Bauhinia variegata, Benincasa hispida, Brassica campestris, Butea monosperma, Callistemon citrinus, Capparis decidua, Carica papaya, Cordia dichotoma, Coriandrum sativum, Dalbergia sissoo, Emblica officinalis, Eucalyptus globulus, Holoptelea integrifolia, Madhuca indica, Melia azadirachta, Moringa oleifera, Prosopis juliflora, and Syzygium cumini (Manju et al., 2016; Trivedi et al., 2014, 2016).
Among shrubs, Vitex negundo, Carissa opaca, Rhamnus spp., Ziziphus mauritiana, and ground flora, Parthenium hysterophorus, Polygonum aviculare, and Crotalaria juncea are common. The herbaceous vegetation is dominated by members of several families, including Poaceae, with significant representation from Brassica campestris, as well as members of Chenopodiaceae, Euphorbiaceae, Asteraceae, Solanaceae, and Ranunculaceae (Saxena & Trivedi, 2017; Saxena et al., 2015, 2017; Shukla et al., 2022; Tripathi et al., 2016; Trivedi & Chauhan, 2011; Trivedi et al., 2012, 2013, 2014, 2016, Trivedi 2024a).
MATERIALS AND METHODS
Pollen Analysis
Eighteen squeezed honey samples were collected from the natural beehives in the different localities of Central UP. A systematic sampling approach was employed across four distinct land-use categories: densely populated urban centres, moderate-density residential areas, protected conservation zones, and agricultural landscapes surrounding these regions.
Honey samples (5 grams each) were dissolved in 50 mL of distilled water, stirred gently to ensure homogeneity, and then centrifuged. After centrifugation, the sample is treated with glacial acetic acid to dehydrate. This process is followed by acetolysis (9:1, acetic acid, and concentrated sulphuric acid) (Erdtman, 1943). Samples were again treated with glacial acetic acid, followed by washing them three times with distilled water using centrifugation and decantation. Permanent slides were prepared using glycerin gel and Canada Balsam for microscopic analysis, and further identification of pollen and spores was carried out using an Olympus BX52 microscope equipped with an Olympus DP23 camera at a magnification of ×400.
Pollen types were identified using reference slides available at the BSIP sporothek, along with published literature (Chaturvedi, 1976; Chaturvedi & Sharma, 1973; Chauhan & Singh, 2010; Chauhan & Trivedi, 2011).
Land use and Land cover (LULC)
Our research utilised LULC mapping techniques to enhance our understanding of the study area. LULC mapping provides researchers with comprehensive insights into regional terrain characteristics and landscape patterns (Twisa & Buchroithner, 2019). This methodology is particularly valuable for examining the intricate relationships between climatic factors, human activities, and environmental conditions (Chen, 2002; Gómez et al., 2016; Trivedi et al., 2024b). As environmental monitoring and natural resource management have become increasingly sophisticated, LULC change analysis has become a crucial component of modern research strategies (Kumar et al., 2014).
For our analysis, we employed Sentinel-2 Multi-Spectral Instrument (MSI) data collected during the post-monsoon period. The satellite’s 10-metre spatial resolution capability allowed us to detect and analyse subtle landscape features with high precision. This detailed resolution enabled us to create accurate LULC maps that both validated our field observations and provided a deeper understanding of the area’s landscape dynamics, supporting more effective decision-making processes (Karra et al., 2021).
RESULTS
The melissopalynological analysis of 18 honey samples revealed a diverse floral composition and foraging patterns of honey bees within both urban and rural ecosystems, elucidating the botanical origins and nectar sources across the study sites. Following the International Commission for Bee Botany (1970) guidelines (Louveaux et al., 1978), pollen frequencies were classified into four distinct categories: predominant pollen types (>45%), secondary pollen types (16%–45%), important minor pollen types (3%–15%), and minor pollen types (<3%). This systematic categorisation enabled a comprehensive assessment of the relative contribution of different floral sources to honey production across the study sites.
Spatial distribution of Melissopalynological profiles across districts
Lucknow District
A total of 11 honey samples were collected from various locations across the districts (Table 1). Of the recovered pollen taxa, approximately 40% are trees, 49% are herbs, and 6% are shrubs (Figure 2).
Plant distribution pattern of various honey samples of Central Uttar Pradesh, India.
The palynological analysis of L1 revealed a diverse assemblage of pollen types. Holoptelea integrifolia emerged as the predominant pollen type, constituting 75.3% of the total pollen count (Table 2). Ageratum conyzoides represented an important minor pollen type at 4.7%, accompanied by Eucalyptus and Poaceae (2.9% each). The minor pollen types represented by Myrtaceae, Prosopis juliflora (1.5%), Meliaceae, Moraceae, Malvaceae (1.2% each), Ricinus communis, and Blumea (0.9% each) (Figure 3).
Diagram representing the frequency distribution of the pollen taxa recovered in the honey samples from Central Uttar Pradesh.
Types of honey from Central Uttar Pradesh, based on pollen class.
L2 revealed the presence of secondary pollen types, characterised by Prosopis juliflora (37.5%) and Brassica campestris (31.3%) (Plate 1). Among important minor pollen types, Schleichera oleosa contributed 14.3%, along with Artemisia and Helianthus at 12.5% and 6.3%, respectively, of the total pollen content in the honey sample.
L3 exhibited a unique monofloral characteristic, containing Brassica campestris pollen at 100% abundance. This predominance of a single taxon establishes it as monofloral honey, representing the predominant pollen type.
The samples collected from L4 and L5 demonstrated a diverse pollen spectrum, with secondary pollen types represented by Brassica campestris (37.3%) and Apiaceae (~37%). The minor pollen types of importance included Cerealia (8.8%), Ageratum conyzoides (8.4%), Eucalyptus (~3.7%), and Syzygium cumini (~4.2%). The minor pollen types comprise Schleichera oleosa, Bombax ceiba (~0.4% each), and Ricinus communis (~0.3%).
The sample from L6 revealed the presence of nectarless Poaceae (21.4%) together with Prosopis juliflora (17.9%), representing a secondary pollen type. The pollen spectrum also included Citrus and Moringa oleifera (1.8% each) as minor pollen types, while Artemisia (3.6%) constituted an important minor pollen type.
Four honey samples (L7‒L10) were collected from proximate locations within the same area. In L7, Solanaceae (47.1%) was the predominant pollen type recovered. Secondary pollen types included Mangifera indica (17.6%) and Prosopis spicigera (23.5%) in L7; Moraceae (40.5%), Tinospora cordifolia (23.8%), Ageratum conyzoides (27.4%), and Brassica campestris (17.9%) in L8; Moraceae (20.5%) and Brassica campestris (16.2%) in L9; and Brassica campestris (22.7%) in L10. Important minor pollen types recorded in samples L7–L10 comprise Prosopis juliflora (5.4%–11.8%), Bombax ceiba (6.8%–13.1%), Moraceae (11.9%), Cerealia (13.5%), Eucalyptus (5.4%–6.8%), Mangifera indica (3.4-5.4%), Ageratum conyzoides (11.4%), Tinospora cordifolia (9.1%), and Syzygium cumini (3.4%) (Table 2). Minor pollen types consist of Holoptelea integrifolia, Myrtaceae (1.2%–2.3% each), Eucalyptus,* Malvaceae (2.4% each), Syzygium cumini (2.7%) and Poaceae (1.1%).
The honey sample from L11 revealed secondary pollen types comprising Syzygium cumini (21.9%), Malvaceae and Brassica campestris (15.6% each). Important minor pollen types included Moringa oleifera (10.9%), Eucalyptus, Tinospora cordifolia (9.4% each), Bombax ceiba and Cerealia (7.8% each). Holoptelea integrifolia (1.6%) was classified as a minor pollen type.
Hardoi District
The pollen taxa recovered from samples H1 and H2 comprised approximately 78% trees, ~26% shrubs and only ~0.5% herbs (Figure 2). Moringa oleifera (53.3%) in H1 and Holoptelea integrifolia (42.2%) in H2 were classified as predominant pollen types. Secondary pollen types included Mangifera indica (17.6%) and Solanaceae in both H1 (15.4%) and H2 (27.2%). Important minor pollen types comprised Holoptelea integrifolia, Myrtaceae (7.5% each), Mangifera indica (9.9%), Prosopis spicigera (6.9%), Ageratum conyzoides (5.5%) (Plate 1). Minor pollen types consist of Emblica officinalis (1.7%) along with Terminalia spp., Madhuca indica, Moraceae (0.5% each), Prosopis juliflora, P. spicigera, Meliaceae, Eucalyptus, Punica, Brassica campestris, Apiaceae, Boraginaceae (0.1% each), Tinospora cordifolia, Ageratum conyzoides (0.8% each), Schleichera oleosa (2.0%), Syzygium cumini (0.3%–1.5%), Moringa oleifera (0.8%), Tubliflorae (0.2%), Poaceae and Chenopodiaceae (0.2% each) (Figure 3).
Barabanki District
Palynological analysis of honey samples (B1 and B2), collected from Dikoliya Village, revealed distinct taxonomic distributions. The pollen spectrum was predominantly characterised by herbaceous taxa, which constituted 92% of the total pollen content, while arboreal taxa accounted for only 8%, and shrub representation was minimal (Figure 2). Brassica campestris emerged as the dominant pollen taxon, with relative frequencies of 57% and 98.7% in samples B1 and B2, respectively. Secondary pollen types included Eucalyptus (16%) and Apiaceae (26.8%) in B1. Minor pollen types comprised Eucalyptus and Ageratum conyzoides (0.6% each) among herbs.
Unnao District
Among the two samples (U1 and U2), approximately 50% of the recovered pollen taxa were recovered from trees, ~44% from shrubs, and ~6.5% from herbs (Figure 2). U1 has a secondary pollen type including Syzygium cumini (21.7%), Eucalyptus (17.4%), and Brassica campestris (21.7%), whereas in U2, B. campestris (48.4%) was classified as the predominant pollen type. In U2, secondary pollen types comprised Myrtaceae (30.6%) and Poaceae (16.1%). Important minor pollen types consist of Delonix regia, Malvaceae (13% each), Moringa oleifera (8.7%), and Schleichera oleosa (4.3%). Minor pollen types include Syzygium cumini (2.6%) and Artemisia (1.6%) (Table 2).
Raebareli District
Sample R1 contained approximately 42% tree taxa and 19% herbaceous taxa. Secondary pollen types included Prosopis juliflora (38.5%) and Poaceae (15.4%). Important minor pollen types comprised Ziziphus (3.8%) and Tubliflorae (3.8%) (Table 2).
DISCUSSION
The analysis of pollen composition in honey samples from Lucknow and its neighbouring districts provides valuable insights into the foraging patterns of honeybees in Central UP. The recovered pollen spectrum reflects the diversity of available floral resources, with foraging patterns primarily influenced by regional climate and anthropogenic factors shaping the local vegetation. The composition of these plant communities plays a crucial role in determining honey characteristics, while the retrieved pollen spectra serve as an effective indicator of recent changes in vegetation patterns (Chauhan et al., 2017).
Pollen analysis identified 38 distinct plant species (Table 3) across 18 sampling locations, enabling classification of honey samples as monofloral or multifloral. Among all samples, only L3 and B2 were characterised as monofloral, with the remaining 16 samples identified as multifloral in nature.
Pollen Taxa recovered from honey samples collected in localities of Central Uttar Pradesh, India.
The pollen spectra demonstrated that honey bees in the study area foraged from a diverse range of both indigenous flora and cultivated crops. Analysis revealed equivalent proportions of trees and herbs in the Lucknow and Unnao regions, while trees predominated in Hardoi and Raebareli, and herbs dominated in Barabanki. The high pollen frequencies observed can be attributed to the abundance of these taxa in the vicinity of the sampling sites during their peak flowering period (Figure 4), facilitating immediate nectar flow.
Flowering Periods of Plant Species Collected in Central Uttar Pradesh.
LULC analysis (Figure 5) revealed that the landscape is predominantly occupied by cropland, covering approximately 78% of the total area. Built-up areas accounted for 12%, while deciduous forest, range land, and water bodies comprised 4.5%, 3.8% and 1.1% respectively. Barren land and flooded vegetation represented minimal proportions at 0.4% and 0.04%, respectively (Table 4). The findings from both field observations and pollen analysis are in strong agreement with the LULC results, reinforcing the interpretation that anthropogenic land-use changes have significantly altered the indigenous vegetation pattern. This study highlights the growing anthropogenic pressure, as land-use intensification and habitat modification directly alter bee foraging dynamics, with cascading effects on local biodiversity and disrupting ecosystem stability.
Land Use Land Cover (LULC) map of Central Uttar Pradesh using Sentinel-2, Multi-Spectral Instrument (MSI) bands with spatial resolution of 10 m.
1. Cluster of Pollen, 2. Delonix regia, 3. Moringa oleifera, 4. Bombax ceiba, 5. Holoptelea integrifolia, 6. Peltophorum spp., 7. Madhuca indica, 8. Mangifera indica, 9. Terminalia spp., 10. Myrtaceae, 11. Meliaceae, 12. Schleichera oleosa, 13. Eucalyptus spp., 14. Prosopis juliflora, 15. Prosopis spicigera, 16. Moraceae, 17. Ricinus communis, 18. Punica spp., 19. Solanaceae, 20. Malvaceae, 21. Chenopodeaceae, 22. Cerealia, 23. Tinospora cordifolia, 24. Helianthus spp., 25. Brassica campestris, 26. Apiaceae, 27. Ageratum conyzoides, 28. Tubuliflorae, 29. Poaceae and 30. Artemisia.
Land Use Land Cover distribution in Central Uttar Pradesh, India.
In Lucknow, predominant pollen types are found at sites L1, L3, and L7, represented by Holoptelea integrifolia, Brassica campestris, and Solanaceae, respectively. Barabanki (B1, B2) and Unnao (U2) have Brassica campestris as the dominant pollen, while Hardoi H1 and H2 show the predominance of Moringa oleifera and Holoptelea integrifolia, respectively. The pollen spectra of the Raebareli district do not show any predominant pollen types. Among secondary pollen types, Lucknow shows the presence of Prosopis juliflora, Prosopis spicigera, Brassica campestris, Apiaceae, Poaceae, Mangifera indica, Moraceae, Tinospora cordifolia, Ageratum conyzoides, Syzygium cumini, and Malvaceae. Hardoi has a secondary pollen type of Mangifera indica and Solanaceae, while Barabanki shows Eucalyptus and Apiaceae. Syzygium cumini, Eucalyptus, Brassica campestris, Myrtaceae, and Poaceae are recorded as secondary pollen types in Unnao, whereas Raebareli has Prosopis juliflora and Poaceae.
Melissopalynological analysis of honey samples from Lucknow conducted by Chauhan and Trivedi (2011) identified Syzygium cumini as the dominant pollen type, indicating its significance as a nectar source and foraging plant for bees in the region. A later study by Chauhan et al. (2017) reported S. cumini, contributing 16% and 14% of the pollen content in honey from semi-urban and urban areas, respectively. However, more recent findings documented only 2%–3% representation, suggesting a decline in the plantation of this slow-growing yet economically and medicinally important species (Farooqui & Farooqui, 2020). In addition to S. cumini, Chauhan et al. (2017) also recorded various secondary pollen types such as Prosopis spicigera and Ageratum conyzoides, along with several minor types including Bombax ceiba, Ailanthus excelsa, Tinospora cordifolia, Moringa oleifera, Eucalyptus globulus, and Aegle marmelos.
Over the past decade, honey bees in residential areas of Lucknow have shown a marked preference for Ageratum conyzoides, a common weed, as a primary or secondary forage source (Chauhan et al., 2017). However, this species, along with other members of Asteraceae such as Artemisia, Tubuliflorae, and grasses like Poaceae, is associated with 60%–75% of cases of seasonal rhinosinusitis, asthma, and dermatitis (Ghosh et al., 2017; Singh, 2017). The pollen composition in honey samples thus reflects temporal shifts in bee foraging behaviour, corresponding to changes in local plant diversity (Chauhan & Singh, 2010; Chauhan & Trivedi, 2011).
Recent studies from the Prayagraj region reveal distinct patterns in honey production sources. In the northern areas, unifloral honey was predominantly derived from plant species such as Brassica campestris, Dalbergia sissoo, Eucalyptus spp., Helianthus annuus, Peltophorum pterocarpum, and Sesamum indicum, with B. campestris being particularly dominant due to its widespread cultivation. In contrast, southern areas yielded unifloral honey primarily composed of pollen from Ageratum conyzoides, Madhuca longifolia, Tamarindus indica, and Parthenium hysterophorus (Shukla et al., 2022). In urban zones of Prayagraj, Brassica campestris remains the predominant pollen type, while Ageratum conyzoides, Psidium spp., and Corymbia citriodora occur as secondary pollen types (Mehndi et al., 2023).
Supporting evidence from the Upper Gangetic Plains, encompassing regions of Uttarakhand and Uttar Pradesh, further underscores the widespread foraging of B. campestris by honeybees. According to Datta et al. (2008), this taxon was recorded as the predominant pollen type in seven honey samples, secondary in 14, and as an important minor type in seven samples. This broad representation suggests that B. campestris remains a key apicultural resource throughout the region, influenced by both ecological availability and agricultural practices.
Melissopalynological investigations across various regions of India highlight significant floral diversity in honey samples. In the Paderu forest division of Andhra Pradesh, analysis of 17 honey samples revealed six unifloral types, three dominated by Ageratum conyzoides and one each by Schleichera oleosa, Psidium guajava, and Mimosa pudica. The remaining 11 samples were classified as multifloral, with Mimosa pudica, Syzygium cumini, and Centipeda minima as dominant taxa (Devender et al., 2020). In Guntur district, predominant pollen types included Helianthus annuus, Guazuma ulmifolia, and Borassus flabellifer (Rebolledo Ranz, 2020). Multifloral honey samples from Hingoli district, Maharashtra, were characterised by a diverse pollen assemblage dominated by Moringa oleifera, Pongamia pinnata, Syzygium cumini, Tamarindus indica, and Terminalia spp., along with other significant taxa such as Aegle marmelos, Albizia spp., Bauhinia spp., and Brassica campestris (Nagarkar, 2021). In the Chandrapur district, Lathyrus sativus was predominant, accompanied by Cajanus cajan, Celosia argentea, Prosopis juliflora, and Hyptis suaveolens (Laxmikant & Devendra, 2014). A unifloral honey dominated by Coffea spp. (Rubiaceae) was documented from the Nilgiri Biosphere Reserve in Karnataka (Sivaram et al., 2012), while in the Dakshina Kannada district, key pollen taxa included Ixora coccinea, Cocos nucifera, Psidium guajava, and Mimosa pudica (Krishna & Patil, 2019).
Compared to the present dataset from UP, honey from Andhra Pradesh exhibits a higher diversity of arboreal pollen taxa, indicating greater representation of native tree-derived nectar sources. Trees are considered more critical for pollinators, offering stable and nutritionally rich foraging resources compared to herbaceous plants (Geslin et al., 2013). In contrast, honey samples from UP are predominantly composed of herbaceous pollen taxa, many of which are known to be allergenic. Notably, Ageratum conyzoides, an exotic and invasive weed, is a well-documented aeroallergen associated with respiratory conditions such as asthma and rhinitis (Killian & McMichael, 2004). Pollen diagrams from Central UP reveal a high representation of A. conyzoides, highlighting its dual role in supporting apiculture while posing potential health risks to individuals with sensitivities. The limited native vegetation within the foraging range of honeybees in urban areas, such as Lucknow, has likely compelled bees to utilise available floral resources. As a result, exotic A. conyzoides, along with ornamental and fast-growing urban landscape trees such as Eucalyptus, Prosopis, and Holoptelea, have become important contributors to the multifloral honey produced in the region.
CONCLUSIONS
Palynotaxonomy is a growing field that helps in studying the interactions between honey-producing bees, pollen, and vegetation within a specific geographic area. Melissopalynology is also a crucial tool for assessing honey authenticity, detecting adulterations, and differentiating honey types. Along with its applications in the food industry and therapeutic discussions, it plays a critical role in conservation. Identifying plant species utilised by bees through melissopalynology is vital, as conserving plants supports bees and bee conservation promotes plant survival (Anklam, 1998).
Bee populations face numerous threats from human activities, including climate change, land use and land cover changes due to urbanisation, invasive species, monocultures with limited floral diversity, and pesticide use. Seasonal changes in temperature, light, and vegetation also significantly impact bee behaviour and ecosystems. Future research should investigate the impact of climate change on honeybees and compare the pollen in honey from farmed versus wild bees to enhance our understanding of the role of melissopalynology in protecting bees, plants, and ecosystems.
A comparative study over the last 23 years reveals that the growing human population and land-use changes have impacted the natural foraging habits of honeybees. Bees are now forced to depend more on available herbaceous plants and exotic weed species. It is essential to investigate how this shift in pollen sources affects the health, behaviour, and population dynamics of honey bees.
Footnotes
Acknowledgements
The authors express their gratitude to the Director, Professor M.G. Thakkar, Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow, India, for providing the required resources for conducting this research.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was financially supported by the Birbal Sahni Institute of Palaeosciences, Lucknow, for laboratory analyses. Additional funding for the publication of this article was provided through the project CH.B.D.B./747/2025.
