Effective Pollinators Research Articles

The role of plant diversity and density in the availability of floral resources for effective pollination and honey production by the honey bee (Apis mellifera) in arid areas

Plants are vital for honey production, supplying nectar and pollen that honey bees (Apis mellifera) use for nutrition and honey production. This study assessed the role of plant diversity and abundance in honey bee foraging in the semi-arid Dodoma region, Tanzania. Sampling plots were set up at 500 m intervals from beehives and observed for foraging bees from January to December 2023. I used negative binomial mixed-effect models to identify the factors influencing bee foraging and the number of flowers per plant. Bees were observed foraging on 21 plant species during the study period, with the majority being non-native shrubs and herbs. The number of foraging bees differed between plant species (χ221,347= 55.843, p < 0.001), where species that produce many flowers had more foraging bees. The number of foraging bees also varied between months (χ29,347= 80.22, p < 0.001), corresponding to the abundance of flowers in each month. Further, the number of foraging bees increased with plant diversity (χ21,347, = 11.847, p = 0.008) per plot. The study underscores the importance of plant diversity in providing a continuous supply of floral resources that sustain bee foraging activities and honey production. A diverse community of native and non-native flowering plants provides consistent foraging opportunities throughout the year. Thus, afforestation programs in the Dodoma region should prioritise the conservation of key plant species to support pollinators and enhance honey production.

A Comparison of Pollination Efficiency Between Wild Bumble Bees and Introduced Honey Bees on Polygonatum cyrtonema

To clarify the pollination contributions of introduced honey bees and native wild bees, we compared their pollination efficiency on a perennial herb, Polygonatum cyrtonema Hua. The flower’s traits and bees’ body traits were measured to quantify the mechanical fit between the bee species and flower. Pollen removal and deposition per visit, visit frequency, and visit duration per flower were investigated. The results show that both native bumble bees (worker bees of Bombus trifasciatus Smith) and introduced honey bees (Apis mellifera L.) are effective pollinators, but bumble bees play a more important role in pollination, due to their higher visit frequency and slightly higher pollen transfer efficiency. The bumble bees removed and deposited significantly more pollen grains per visit than the honey bees (both p &lt; 0.001). The faster visiting speed and shorter visit duration of the bumble bees, combined with their larger body size and longer proboscises, may have contributed to their higher pollen transfer efficiency. The pollination success of P. cyrtonema depends on its pollinators. This study is the first to report on the pollination efficiency of floral visitors on P. cyrtonema. Our findings highlight the importance of conserving native bumble bee populations to ensure the reproductive success of P. cyrtonema. Future studies should focus on their management to minimize potential disruptions to native pollination contribution.

Costs of floral larceny: A meta-analytical evaluation of nectar robbing and nectar theft on animal-pollinated plants.

Mutualistic interactions are biological markets in which different species exchange commodities to mutual benefit. Mutualisms are, however, susceptible to exploitation, with some individuals taking without reciprocating. While it is generally assumed that exploiters will inflict fitness costs, evidence for such costs is mixed and difficult to generalize due to their context-dependent nature. Animal-pollinated flowers are commonly exploited by larcenists, non-pollinating animals that consume floral rewards often without transferring pollen. The impacts of larcenists on plant reproduction vary widely, suggesting they inflict differing costs on plants, but which types of floral larceny are most and least costly, and why, has received little attention. We employed a meta-analytical approach to explore the effects of flower larceny on nectar traits, pollinator visitation, and plant reproduction. We focused on the effects of two contrasting forms of larceny: primary nectar robbing-nectar consumption through holes constructed in the corolla rather than entering flowers legitimately-and nectar theft-nectar consumption by entering flowers but with no pollen transfer. We found that both robbing and theft had negative impacts on nectar quantity and quality, but that only theft negatively affected pollinator visitation rates. Similarly, robbers had no impact on either female or male reproductive success, whereas thieves consistently reduced both male and female reproductive success. These effects were not associated with plant mating systems nor with the identities of robbers and effective pollinators, challenging previous generalizations. This study provides a comprehensive evaluation of larcenists' costs to animal-pollinated plants, revealing that nectar theft is more detrimental to plant reproduction than nectar robbing. These results enhance our understanding of the intricate dynamics of mutualism exploitation in ecological and evolutionary contexts.

Spatial partitioning of floral volatiles provides a "chemosensory roadmap" for bumblebee pollinators.

Spatial partitioning of floral volatiles provides a "chemosensory roadmap" for bumblebee pollinators.

Vapor pressure deficit control and mechanical vibration techniques to induce self-pollination in strawberry flowers

BackgroundPollination strategies to supplement or replace insect pollinators are needed to produce marketable strawberry fruits in indoor vertical farms. To ensure the self-pollination of strawberry flowers, anther dehiscence, and pollen attachment were investigated under different vapor pressure deficit (VPD) conditions and external mechanical wave vibrations.ResultsThe proportion of dehisced anthers was examined under VPDs of 2.06, 1.58, and 0.33 kPa, and the projected area of pollen clumps was assessed under VPDs of 2.06 and 0.33 kPa. After exposing flowers to a VPD of 2.06 kPa, vibrations with various frequency (Hz) and root mean square acceleration (m s−2) combinations were used to evaluate pollination effectiveness. The anthers underwent complete dehiscence at VPDs of 2.06, 1.58, and 0.33 kPa. The pollen clump ejection index was highest at a VPD of 2.06 kPa. Pollen clump detachment was effective at 800 Hz with 40 m s−2, while pollen attachment to the stigma was most effective at 100 Hz with 30 and 40 m s−2.ConclusionsThese findings demonstrate that high VPD promotes anther dehiscence timing and facilitates pollen clump formation, while specific vibration frequencies with high acceleration optimize pollen detachment and stigma attachment, offering an effective strategy for controlled strawberry pollination in vertical farming.

Pistil Development Delay Limits Seed Set in Protandrous Onion (Allium cepa L.)

Onion (Allium cepa L.) plants produce umbellate inflorescences that bear dozens of hermaphrodite flowers. Outcrossing is encouraged by a strong protandrous dichogamy. Honeybees are reported as the most suitable pollinator for this crop due to their efficiency in pollen transfer. However, bee activity does not always guarantee pollination success and an adequate seed set. This work aimed to analyze the developmental changes of the pistil along the flower lifespan to determine the reasons for common failures in the onion seed set. Studies were carried out in two productive seasons, in a male sterile line and a fertile line, using two different pollination procedures. The results showed that the stigma papillae did not fully develop until 4 days after anthesis (DAA), reducing the stigma receptivity to only 4 days. The style did not reach its maximum length until 8 DAA, when ovule fertility was achieved. Eight days were needed for the pollen tube to grow, reach, and fertilize the ovules. The results were consistent over two consecutive years. The short period of stigmatic receptivity and strong protandrous dichogamy limit the duration of the effective pollination period and could explain the poor cropping performance in obtaining seeds from some onion hybrid lines.

The effectiveness of pollinators and their foraging behavior on Neustanthus phaseoloides (Fabaceae).

Insect pollination is critical for the reproduction of crops and wild plants, yet the efficiency of pollinators varies widely across species. Hence, it is essential to study the visitation behavior and pollination effectiveness of the floral visitors. Neustanthus phaseoloides is an agro-ecologically and medicinally important plant occurring in Tripura, Northeast India. We selected it for the present investigation as its distinct floral morphology might impact the pollinator visitation behaviors and subsequent pollination success. A total of 12 insect foragers visited the flowers of N. phaseoloides. Among them, 10 generalist pollinators were observed depositing conspecific pollen along with some amount of heterospecific pollen grains on the stigma. Although the pollen deposition efficiency varied significantly among pollinator species, the bees were the most effective in pollen deposition and subsequent reproductive outputs. All pollinators contributed to the fruit and seed production at varying degrees, indicating their effectiveness in reproductive success. The mating system studies indicated that the species was self-compatible and dependent on pollinators for increased reproductive success. Furthermore, some degree of pollination deficit was detected in our study population, suggesting that the increased visitation of effective pollinators might enhance the reproductive outputs. Overall, this first report on the pollination effectiveness of N. phaseoloides will improve our understanding of the reproductive success in a medicinally useful wild plant.

Wasp pollination and pollinator filtering by dense hairs at the floral tube entrance in Marsdenia tinctoria (Apocynaceae).

The physical filtering of pollinators is an important factor influencing pollination effectiveness. This study explored the potential functions of dense hairs that completely obstruct the entrance of floral tube in Marsdenia tinctoria by characterizing the flowers of this species, as well as its pollinators and their behavior. The corolla was white upon blooming in the morning, then turned yellow at night, and the flower finally dropped by the third morning. The hairs tended to be disheveled in yellow-petaled flowers. Pollination success increased with floral age. Direct observations of flowers in natural M. tinctoria populations over a period of 32h recorded 126 visitors, of which 70% were wasps. We observed pollinia attached to the mouthparts of wasps, carpenter bees, and honeybees, but not to those of butterflies, moths, flies, or ants. Detailed examination of insect mouthparts and floral morphology indicated that insect visitors that acted as pollinators had mouthparts longer than the floral tubes, equipped with hairs to which pollinia could attach. The mouthparts of potter wasps were often covered with pollinaria, carrying on average 30-75 pollinia. The dense floral hairs were penetrated by large-bodied visitors, and blocked smaller visitors. Disturbance of these floral hairs allowed smaller insects to access nectar, suggesting that the hairs function in preventing nectar theft by smaller insects. This study presents the first case of wasp pollination in the genus Marsdenia and provides insights into the potential function of its dense floral hairs, a synapomorphy of this genus, in filtering floral visitors.

Cockroach pollination ensures sexual reproduction in the non-photosynthetic plant Balanophora tobiracola.

While Coleoptera, Diptera, Hymenoptera, and Lepidoptera have traditionally been recognized as key pollinators, recent studies suggest that other insect groups, such as Blattodea (cockroaches), may also play a significant role. However, direct evidence of fruit set resulting from cockroach pollination remains limited, even in plants presumed to rely on this mode of pollination. This study investigated the breeding system of the non-photosynthetic plant Balanophora tobiracola on Yakushima Island, Japan, with a particular focus on the potential occurrence of agamospermy. Additionally, the research rigorously evaluates the pollination effectiveness of cockroaches and ants in B. tobiracola by assessing reproductive success exclusively through their visits. Pollination experiments revealed high fruit set even under emasculation, indicating that agamospermy ensures seed production. However, B. tobiracola still relies heavily on pollinator activity for sexual reproduction. Ants and cockroaches were identified as effective pollinators, whereas contributions of pyralid moths, crane flies, and nitidulid beetles-whose larvae consume B. tobiracola infructescences-were negligible. Notably, a single visit from certain cockroach species significantly enhanced pollination. The above findings demonstrate that B. tobiracola is effectively pollinated by cockroaches and ants. Combining unusual pollinators with agamospermy likely facilitates the reproductive success of B. tobiracola in dense forest understories where typical pollinators, like bees, are scarce. Our results underscore the need to reassess the role of agamospermy as reproductive assurance and the significance of cockroaches and ants as pollinators, particularly for plants in shaded understory habitats.

Effect of Nitrophos Fertilizer on Pollinator Dynamics and Onion Seed Yield.

The yield of flowering crops depends on multiple factors, with pollination and the availability of nutrients being particularly crucial. However, fewer studies have explored the combined effects of nutrients and insect-mediated pollination on onions (Allium cepa L.). Here, we studied how different levels of insect pollination (0%, 25%, 50%, and 100%) and nitrophos fertilizer application (188, 375, and 750 kg/hectare) affect onion seed yield. We found that pollination benefits to yield were maximum at intermediate levels of nitrophos availability. A higher pollinator abundance was recorded at a high nitrophos level, followed by intermediate and low levels. Syrphid flies and honey bees were the most abundant insect pollinators. The abundance of honey bees was higher at a low nitrophos level, while syrphid flies were more abundant at a higher nitrophos level. Moreover, the umbel weight and seed number were higher at the intermediate fertilizer level. Also, single visits by insect pollinators were observed, and the highest umbel weight was found at the intermediate fertilizer level with a single visit from A. florea. This finding provides evidence that resource and pollination availability have interactive, nonlinear effects on seed production. Our results also support ecological intensification as a reliable strategy for sustainable agro-ecosystem management.

Investigating the effects of diurnal and nocturnal pollinators on male and female reproductive success and on floral trait selection in Silene dioica

Investigating the effects of diurnal and nocturnal pollinators on male and female reproductive success and on floral trait selection in Silene dioica

Impact of Seasonal Atmospheric Factors and Photoperiod on Floral Biology, Plant-Pollinator Interactions, and Plant Reproduction on Turnera ulmifolia L. (Passifloraceae).

Reproductive traits and plant-pollinator interactions largely depend on seasonal weather conditions, which are species-specific. Turnera ulmifolia is an ornamental plant distributed worldwide. There is little information about plant species' reproductive ecology and environmental factors' impact on it. Here, we aimed to examine the effects of seasonal atmospheric factors (e.g., temperature, light, relative humidity, rainfall) and photoperiod on flowering, interactions with flower visitors, and the reproductive success of Turnera ulmifolia in West Bengal, India. Flowering intensity peaked in hot summers and dropped in cold winters, correlating positively with temperature and humidity. Flower opening and closing occurred earlier on hot days, while flower longevity increased in winter, showing a negative correlation with temperature and humidity. Pollen and ovule production were lower in cold weather, positively linked to temperature and humidity. The self-compatible plant was moderately dependent on pollinators and had no pollination deficit in open conditions. Visitor abundance, richness, and diversity varied season-wise, with higher values during spring-summer. Based on pollinating agents, the plant showed multiple pollination modes (e.g., melittophily, myophily, myrmecophily, and psychophily). Effective pollinators were Amegilla zonata, Borbo cinnara, Halictus acrocephalus, Nomia (Curvinomia) strigata, and Tetragonula iridipennis. The fruit set (%) did not differ significantly season-wise, but the seed set remained higher in the hot days of summer than in cold winter. Therefore, it can be concluded that atmospheric factors and photoperiod significantly impact floral traits, plant-pollinator interactions, and plant reproduction.

An AI-Based Digital Scanner for Varroa destructor Detection in Beekeeping.

Beekeeping is a crucial agricultural practice that significantly enhances environmental health and food production through effective pollination by honey bees. However, honey bees face numerous threats, including exotic parasites, large-scale transportation, and common agricultural practices that may increase the risk of parasite and pathogen transmission. A major threat is the Varroa destructor mite, which feeds on honey bee fat bodies and transmits viruses, leading to significant colony losses. Detecting the parasite and defining the intervention thresholds for effective treatment is a difficult and time-consuming task; different detection methods exist, but they are mainly based on human eye observations, resulting in low accuracy. This study introduces a digital portable scanner coupled with an AI algorithm (BeeVS) used to detect Varroa mites. The device works through image analysis of a sticky sheet previously placed under the beehive for some days, intercepting the Varroa mites that naturally fall. In this study, the scanner was tested for 17 weeks, receiving sheets from 5 beehives every week, and checking the accuracy, reliability, and speed of the method compared to conventional human visual inspection. The results highlighted the high repeatability of the measurements (R2 ≥ 0.998) and the high accuracy of the BeeVS device; when at least 10 mites per sheet were present, the device showed a cumulative percentage error below 1%, compared to approximately 20% for human visual observation. Given its repeatability and reliability, the device can be considered a valid tool for beekeepers and scientists, offering the opportunity to monitor many beehives in a short time, unlike visual counting, which is done on a sample basis.

Pollination effectiveness affects the level of generalisation of a plant species with phenotypically plastic flowers

Pollination effectiveness affects the level of generalisation of a plant species with phenotypically plastic flowers

Transcriptomic reprogramming and epigenetic regulation underlying pollination-dependent and auxin-induced fruit set in tomato.

The transition from flower to fruit, naturally triggered by flower pollination and known as fruit set, is instrumental for plant reproduction, seed formation, and crop yield. Notably, this developmental process can also proceed in the absence of flower fertilization, although it remains unclear whether pollination-dependent and pollination-independent fruit sets undergo similar transcriptomic reprogramming. Genome-wide transcriptomic profiling of the flower-to-fruit transition, either pollination-induced or triggered by auxin treatment, shows that both types of triggers modulate the expression of a common large set of genes primarily expressed in maternal tissues. These include genes related to auxin, gibberellin, brassinosteroid, and ethylene signaling. Furthermore, analysis of changes in histone marking during this transition phase indicated that gene reprogramming underlying both types of fruit set primarily correlated with dynamic changes in H3K9ac and H3K4me3 histone marks. Notably, MCM1, AG, DEFA and SRF (MADS)-box and NAM, ATAF1/2, and CUC2 (NAC) genes were extensively downregulated during the transition from flower to fruit, suggesting their negative roles in fruit initiation. In contrast, Teosinte branched1/Cincinnata/proliferating cell factor (TCP), SQUAMOSA -promoter binding proteins (SBP), Sucrose nonfermenting 2 (SNF2), Growth-regulating factor (GRF), and Su (var)3-9, Enhancer-of-zeste and Trithorax (SET) family genes were significantly upregulated in both pollinated and auxin-treated young developing fruits, suggesting their active roles in promoting fruit sets. Despite these similarities, a comparative analysis of the effects of natural pollination and auxin treatment revealed several differences, primarily related to seed development and hormone signaling. Taken together, the data support the idea that auxin serves as the central hormone orchestrating the extensive gene reprogramming associated with fruit initiation in tomato.

Effects of Pollination of Some Stigmas in Kiwifruit Flowers on Seed Distribution and Fruit Quality

Effects of Pollination of Some Stigmas in Kiwifruit Flowers on Seed Distribution and Fruit Quality

Managed honeybees and soil nitrogen availability interactively modulate sunflower production in intensive agricultural landscapes of China.

Insects provide important pollination services for cops. While land use intensification has resulted in steep declines of wild pollinator diversity across agricultural landscapes, releasing managed honeybees has been proposed as a countermeasure. However, it remains uncertain whether managed honeybees can close the pollination gap of sunflower (Helianthus annuus L. [Asterales: Asteraceae]) in areas lacking wild pollinators, and how the benefits of honeybees to sunflower production are modulated by soil nutrients. We investigated the effects of 3 pollination treatments (open, self and hand pollination) on sunflower yield parameters. We also estimated the pollination efficiency of managed honeybees (Apis mellifera L. [Hymenoptera: Apidae]), and analyzed the effects of honeybee visitation and soil nitrogen on sunflower yield parameters. Insect pollinators contributed 73% of seed set and 69% of the weight of filled seeds per head in the open pollination of sunflowers, but large pollination deficits still existed. Insect pollination may enhance sunflower yield by augmenting the number and weight of filled seeds per head, but not by altering the total number of seeds. Except for the total number of seeds per head, yield parameters increased significantly with the number of honeybee visits. Low nitrogen accelerated the positive effect of honeybee pollination on sunflowers, and alleviated the negative effect of distance of beehives on honeybee visitation rate. We conclude that managed honeybees could be used to pollinate sunflowers in areas with the shortage of wild pollinators, and sunflower production may benefit from shortening the distance of beehives and lowing of nitrogen fertilizer inputs.

Assessment of Self-incompatibility and the Different Modes of Pollination on Seed Set and Yield of Buckwheat (Fagopyrum esculentum M.)

The movement pattern of Apis species of honey bees Viz., Apis cerana F., Apis florea F. and Apis mellifera L. recorded during their foraging period revealed that they visited either pin or thrum morph, vice-versa thus bringing the effective cross pollination of both the flower morphs. Among the hand cross-pollinated treatments pollen from pin morph to thrum morph and pollen from thrum morph to pin morph was compatible and resulted in 100 per cent seed set. The weight of seed varied among treatments with a maximum when thrum morph was hand cross-pollinated with pollen from pin morph. Effect of different modes of pollination on seed set and yield attributing characters of buckwheat flowers revealed that maximum flower drop was recorded in control and Tetragonula iridipennis Smith pollination as compared to plots of open pollination, A. cerana pollination and A. mellifera pollination. The weight of 1000 seeds were maximum in plots pollinated with A. cerana pollination compared to the plots pollinated by A. mellifera and T. iridipennis Smith. The flower drops and fruit set in the respective treatments proved that, the pollinating agents, especially honey bees, viz., A. cerana, A. mellifera and A. florea are very much essential for effective pollination, fertilization and maximizing seed set and yield attributing parameters.

Seasonal dynamics of arthropods in Lucerne (Medicago sativa L.) and nutritional link to rodent foraging

Lucerne (Medicago sativa L.) is a highly nutritive crop with more vitamins and minerals used as a fodder legume since it is available throughout the year. In the Coimbatore district farmers prefer lucerne as a fodder crop because of its quality, year-round production, and seed yield fetches a high price. The monitoring study on lucerne crop pests, natural enemies and pollinators was conducted at Tamil Nadu Agricultural University, Coimbatore for three seasons from October 2021 to June 2024. The major sucking pests observed in Lucerne were aphids (Aphis craccivora Koch) and stink bugs (Nezara virudula, (L.)) and the natural enemy observed was coccinellid predators (Cheilomenes sexmaculata (Fabricius)). Natural enemies such as the Ladybird beetle (Coccinella repanda Thunberg) and Paper wasp (Polistes exclamans Vierick) were also documented as crucial in regulating these pest populations. The study also observed a diverse range of pollinators including the Alfalfa Leafcutter bee (Megachile rotundata (Fabricius)), various butterflies, and several species of bees that are vital for effective pollination and enhanced crop quality. The population of aphids and stink bugs ranged from 0.00 to 1.47 and from 0.00 to 1.35, respectively, from April to May. In contrast, from November to February, the aphid population varied from 0.07 to 0.45, while the stink bug population ranged from 0.02 to 0.38. The maximum population of coccinellids was recorded at 3.16 in October 2023. The correlation of pest and predator population with weather parameters showed maximum and minimum temperatures favoured the population development while it was negatively correlated with relative humidity and rainfall. Profiling of root nutrients showed lucerne roots contain a significant amount of essential nutrients that meet the dietary requirements of mice.

Effects of Floral Characters on the Pollination Biology and Breeding System of Iris setosa (Iridaceae): A Cold-Tolerant Ornamental Species from Jilin Province.

Floral phenology and features are intricately linked to pollinator behavior and pollination systems. Iris setosa is one of the ornamental irises of the family Iridaceae with beautiful flowers and leaves, and little research has been reported on its pollination biology. This study analyzed how phenology, floral features, breeding systems, and pollinator visits affect reproductive success of I. setosa populations in Jilin Province. Field observations and pollination studies demonstrated that I. setosa reached the bud stage in late May, with an average flowering time of 30 days. The anthers were outwardly dehiscent toward the outer edge of the style branches. In herkogamy, the relative locations of the anthers and stigma remained unchanged during flower opening. The stamens matured first. The pollen was most viable and the stigmas were most receptive on the first day of flowering. The nectar had the maximum sugar content. The sexual reproduction system was mainly outcrossing, with some self-compatibility and a need for pollinators. After artificial self-pollination, fluorescent microscopy revealed the winding of pollen tubes. The predominant flower-visiting insects were Apis mellifera, Megachile sp., Syrphus corollae, Episyrphus balteatus, and Lasioglossum sp., among which A. mellifera, Megachile sp., and Lasioglossum sp. were effective pollinators. Understanding the pollination mechanisms and strategies of I. setosa provides basic reference data on the potential for reproduction, and conservation efforts.