Pollen Availability Research Articles

More isn’t always better – The effect of environmental nutritional richness on male reproduction of Taxus baccata L.

Limited pollen availability contributes to lower seed production, especially in dioecious species. It can result from a lower quantity and/or a lower quality of pollen grains. Since the environment can impact pollen development, the effect of long-term nutritional availability on the male parameters of the dioecious, long-lived plant, Taxus baccata was investigated. The quantity (production of male flowers) and quality (pollen viability and germination under in vitro conditions, pollen volume, morphology, carbon and nitrogen content) of pollen grains collected from plants growing under different nutritional conditions were analyzed in a long-term pot experiment. Although plants grown in a poorer nutritional environment produced fewer male flowers, they produced pollen grains with greater viability and longevity (e.g. better morphology after in vitro incubation, higher germination rate). Pollen grains also exhibited differential morphology and chemical composition in different nutritional environments. Moreover, it was found that the C: N ratio can be used as a potential marker of pollen viability. Collectively, these results clearly demonstrate the impact of the nutritional environment on pollen grain development. In summary, male plants growing in poor nutritional environments produced a lower number of pollen grains because they produced fewer male flowers, but the pollen produced had much better quality, relative to pollen grains produced in much richer nutritional conditions.

Pollen foraging behaviour of honey bee (Apis mellifera L.) in southern West Bengal, India

Pollen loads of Apis mellifera were analysed to assess their daily pollen collection, polleniferous flora and their pollen biomass contribution in southern West Bengal, India. After that, the pollen host selection and pollen foraging activity of the bee species were also determined. The average daily harvest of pollen loads per honey bee colony was 8.5 g to 127.2 g. The pollen flow through the colonies was the highest during spring, followed by winter and summer, whereas during the monsoon it was the lowest. The weight of a single pollen load ranged from 3.22 mg to 11.73 mg and greatly varied within each season, but seasonal average values do not statistically differ. Families that contributed major amount of biomass were Arecaceae, Myrtaceae, Brassicaceae, Fabaceae, Pedaliaceae and Apiaceae. Taxa providing large amounts of biomass were Brassica nigra, Eucalyptus globulus, Borassus flabellifer, Sesamum indicum, Acacia auriculiformis, Coriandrum sativum, Cocos nucifera, Phoenix sylvestris and Mikania scandens (Asteraceae). As the bee species foraged on 26.32% (80 plant taxa) of the local angiosperm flora, the broad polylecty category was inferred. The pollen host selection by the bee species significantly depends on the flower availability index (FAi) and pollen availability index (PAi) rather than on an individual flower’s pollen quality (in term of pollen morphological characteristics and crude protein content) and pollen quantity (number of pollen grains/flower and amount of pollen biomass/flower). The pollen foraging activity of the bee species varied according to time as well as season. The activity was higher between 9.00 and 10.00 am. Seasonally, the highest activity was observed in spring and the lowest during the monsoon. Furthermore, the ratio of pollen foragers to total incoming foragers also varied according to the time of day as well as the season, and was largely dependent of resource availability.

A decade of flowering phenology of the keystone saguaro cactus (Carnegiea gigantea).

Phenology is the study of biological life cycle events, such as flowering and migration. Climate patterns can alter these life history events, having ecosystem-wide ramifications. For example, warmer springs are associated with earlier leaf-out for many species, impacting species interactions and growing-season carbon dynamics. While phenological research has been conducted extensively in temperate regions, relatively little is known about the phenological responses in arid and semi-arid regions. In this study we looked at the flowering phenology of a keystone species in the Sonoran Desert, the saguaro cactus (Carnegiea gigantea). The timing and abundance of flowering was observed on 151 individuals for 10 years at a site near Tucson, Arizona, USA. Using six phenological traits, we explored the relationship between saguaro size and flowering and the climatic drivers of flowering. Our analyses demonstrated how the calculation of phenological traits at the individual versus the population level can yield differing responses to climate variability, suggesting that not all studies examining the same trait (e.g., first day of bloom) are directly comparable. We found that larger cacti began flowering earlier, flowered for longer, and produced more flowers. Warmer temperatures were correlated with advanced onset and higher bloom yields, while increased precipitation appeared to delay onset and reduce bloom yields. Given that climate models predict that the Southwestern USA will become increasingly warmer with more variable precipitation, saguaros may begin flowering earlier in the season and flower more intensely, which could impact pollen availability and population dynamics.

Pollen morphology and availability of pollen and stigma in Syzygium (Myrtaceae)

Abstract The present study aimed to describe the pollen morphology in three species of Syzygium, to test pollen availability and stigma receptivity. The pollen was analyzed by light and scanning microscopy to show the detailed ornamentation of the pollen grains. Pollen availability was measured according to two protocols. Stigmatic receptivity was tested at different stages of flower development. There are differences among the pollen morphology for the species studied; when the polar and equatorial diameters are measured in the equatorial view of the pollen grains, it is observed that S. jambos is the largest species concerning the two values of the diameters, S. malaccense is the smallest species and S. aqueum, the largest species in relation to the polar diameter in the equatorial view. For the equatorial diameter in equatorial view, S. aqueum showed the smallest diameters and S. malaccense, the major diameters, but the two species overlap in the values of the measured diameters. There are variations in the number of apertures in the pollen grains. Alexander’s stain is more sensitive to estimate pollen availability and the species S. aqueum and S. jambos have the same schedules of pollen availability and stigma receptivity.

Diet and nutritional status during early adult life have immediate and persistent effects on queen bumble bees.

Many insects sequester nutrients during developmentally programmed periods, which they metabolize during subsequent life history stages. During these periods, failure to store adequate nutrients can have persistent effects on fitness. Here, we examined a critical but under-studied nutrient storage period in queen bumble bees: the first days of adult life, which are followed by a diapause period typically coinciding with winter. We experimentally manipulated availability of pollen (the primary dietary source of lipids and protein) and the sugar concentration of artificial nectar (the primary source of carbohydrates) for laboratory-reared queens during this period and examined three nutritional phenomena: (i) diet impacts on nutritional status, (ii) the timescale upon which nutrient sequestration occurs and (iii) the fitness consequences of nutrient sequestration, specifically related to survival across the life cycle. We found evidence that pollen and nectar starvation negatively impact lipid storage, whereas nectar sugar concentration impacts stored carbohydrates. The majority of nutrients were stored during the first ~ 3days of adult life. Nutrients derived from pollen during this period appear to be more critical for surviving earlier life stages, whereas nutrients sequestered from nectar become more important for surviving the diapause and post-diapause periods. Negative impacts of a poor diet during early life persisted in our experiment, even when pollen and a relatively high (50%) nectar sugar concentration were provided post-diapause. Based on these findings, we posit that the nutritional environment during the early adult life of queens has both immediate and persistent impacts on fitness. These findings underscore the importance of examining effects of stage-specific nutritional limitations on physiology and life history traits in this social insect group. Moreover, the findings may shed light on how declining food resources are contributing to the decline of wild bumble bee populations.

Predation efficiency and preference of lab-reared and field-collected populations of predatory mite Cydnoseius negevi (Acari: Phytoseiidae) on two mite pest species Oligonychus afrasiaticus and Tetranychus urticae (Acari: Tetranychidae)

The predatory mite Cydnoseius negevi (Swirski and Amitai) is mostly found in association with the old world date mite (OWDM), Oligonychus afrasiaticus (McGregor) and occasionally with the two spotted spider mite (TSSM), Tetranychus urticae Koch. We evaluated the predation efficiency and preference of lab-reared (LR) and field-collected (FC) populations of C. negevi on larvae and nymphs (juveniles) of OWDM and TSSM. No significant effect of long-term pollen feeding on predation efficiency or prey-stage preference was observed when comparing LR and FC populations of C. negevi. However, significant differences were observed between LR and FC populations of C. negevi for prey species preference, the LR population of C. negevi significantly preferred OWDM over TSSM. Maximum predation efficiency was observed in prey species preference tests (average 29–31 juveniles of OWDM and TSSM together) as compared to predation efficiency/prey stage preference tests (average 20–24 and 16-22 juveniles of OWDM and TSSM, respectively) within 24 h. The results revealed that C. negevi somewhat preferred OWDM than TSSM. The availability of pollen did not affect the predation efficiency of C. negevi against both pest species.

Bombus terrestris in a mass-flowering pollinator-dependent crop: A mutualistic relationship?

Bumblebees (Bombus spp.) rely on an abundant and diverse selection of floral resources to meet their nutritional requirements. In farmed landscapes, mass‐flowering crops can provide an important forage resource for bumblebees, with increased visitation from bumblebees into mass‐flowering crops having an additional benefit to growers who require pollination services. This study explores the mutualistic relationship between Bombus terrestris L. (buff‐tailed bumblebee), a common species in European farmland, and the mass‐flowering crop courgette (Cucurbita pepo L.) to see how effective B. terrestris is at pollinating courgette and in return how courgette may affect B. terrestris colony dynamics. By combining empirical data on nectar and pollen availability with model simulations using the novel bumblebee model Bumble‐BEEHAVE, we were able to quantify and simulate for the first time, the importance of courgette as a mass‐flowering forage resource for bumblebees. Courgette provides vast quantities of nectar to ensure a high visitation rate, which combined with abundant pollen grains, enables B. terrestris to have a high pollination potential. While B. terrestris showed a strong fidelity to courgette flowers for nectar, courgette pollen was not found in any pollen loads from returning foragers. Nonetheless, model simulations showed that early season courgette (nectar) increased the number of hibernating queens, colonies, and adult workers in the modeled landscapes. Synthesis and applications. Courgette has the potential to improve bumblebee population dynamics; however, the lack of evidence of the bees collecting courgette pollen in this study suggests that bees can only benefit from this transient nectar source if alternative floral resources, particularly pollen, are also available to fulfill bees’ nutritional requirements in space and time. Therefore, providing additional forage resources could simultaneously improve pollination services and bumblebee populations.

Flower closure enhances pollen viability in Crocus discolor G. Reuss

Repetitive flower closure (nyctinasty) is influenced by various regulatory mechanisms, but its ultimate function remains unclear. It is hypothesized that closed corolla may protect a plant's reproductive organs against various unfavourable environmental conditions. We investigated if repetitive flower closure enhances pollen viability and prevents pollen loss in an early spring flowering species, Crocus discolor, occurring in open grasslands of submontane to subalpine zones of the Western Carpathian Mountains. Artificially interrupted temporal petal closure resulted in lower pollen viability, but it had no effect on the pollen availability in flowers. The latter result suggests that wind did not cause pollen loss from open flowers, but whether closed corolla may protect reproductive organs from being damaged by hail or rain remains to be tested. Closing corolla may serve as a pollen protection mechanism, particularly in early flowering plants facing harsh environmental conditions.

Pollination of Peltogyne chrysopis: an endemic tree of the Atlantic Forest

ABSTRACT Peltogyne chrysopis is an arboreal legume endemic to the Atlantic Forest and known only from the state of Bahia, Brazil. Focal observations were made of anthesis, pollen availability, stigma receptivity, nectar production, and the presence of osmophores and UV-reflective pigments for the species. Floral visitors were also observed and classified based on the timing and frequency of their visits and their foraging behavior. The breeding system was inferred from the pollen-ovule ratio and pollen tube growth after pollination treatments. Peltogyne chrysopis was found to be melittophilous, with anthesis occurring from 02h00min to 05h00min, and protogynous and xenogamous, with flower scent emission and pollen release before sunrise. Xenochlora nigrofemorata was the main pollinator, as it effectively collected and transferred pollen grains. Nectar production appears to be a secondary resource to ensure the attraction of a diversity of floral visitors and potential pollinators in the absence of effective pollinators. The results of the present study contribute to understanding the pollination mechanisms of Peltogyne, a genus that has been neglected with regard to its reproductive mechanism, and documents, for the first time, the role of the bee genus Xenochlora in plant pollination.

Scale-dependent effects of conspecific flower availability on pollination quantity and quality in an invasive shrub.

Pollen limitation can strongly influence reproduction of pollinator-dependent plants. Flower abundance can affect pollination 'quantity' and 'quality' due to its influence on pollen availability and foraging patterns of pollinators, ultimately impacting on seed production. We complemented individual-based measurements with landscape-level metrics to assess the influence of conspecific flower availability at different spatial scales on the quantity and quality components of pollination, and their impact on seed production in the invasive shrub Cytisus scoparius. In 2013-2014, we sampled 40 C. scoparius populations in Nahuel Huapi National Park, Patagonia (Argentina). In each population, we estimated the proportion of tripped flowers, fruit- and seed-set in five randomly selected individuals. The proportion of tripped flowers and the proportion of them setting fruit were used as proxies of pollination quantity and quality, respectively. Conspecific flower availability at distinct spatial scales (5-1000m) was estimated as the area covered by flowering C. scoparius from color aerial photographs. Flower availability influenced seed output due to contrasting scale-dependent effects on pollination quantity and quality. Increasing flower availability at the landscape-scale reduced pollination quantity, whereas at the neighborhood-scale it increased pollination quality. The overall positive effect of flower availability on seed output at the neighborhood scale was slightly higher than the overall negative effect at the landscape scale. Moreover, pollination quality had a higher positive effect on seed output than pollination quantity. Our results demonstrate that pollination quality may severely limit plant reproduction. Pollination quality limitation can act independently of pollination quantity limitation because these factors operateat different spatial scales.

Pollen Collection, Honey Production, and Pollination Services: Managing Honey Bees in an Agricultural Setting.

Hybrid canola seed production is an important pollination market in Canada; typically both honey bees (Apis mellifera L. (Hymenoptera: Apidae)) and Alfalfa Leafcutting bees (Megachile rotundata Fab. (Hymenoptera: Megachilidae)) are concurrently managed to ensure pollination in this high-value crop. Beekeepers are paid to provide pollination services, and the colonies also produce a honey crop from the canola. Pollen availability from male-fertile plants is carefully managed in this crop to provide an abundance of pollen to fertilize male-sterile (‘female’) plants. This abundance of pollen represents an underutilized resource for beekeepers, and an opportunity to diversify the hive-products produced for market in this management system. We used a commercial-style pollen trap to collect pollen from colonies twice weekly for the duration of canola pollination, and compared the honey production and amount of sealed brood in colonies with pollen traps to those without pollen traps. We found that while pollen trapping reduced honey production, there was no negative impact on brood production, and at current market prices, the per-hive revenue was higher in colonies from which pollen was trapped. Pollen trapping honey bee colonies in the context of hybrid canola pollination, therefore, offers beekeepers an opportunity to diversify their products and increase their revenue.

Pollen Availability and Behavior of Visiting Bees of Solanum lycocarpum A. St. Hill (Solanaceae)

This study aimed to assess the pollen availability and foraging behavior of visiting bees to identify the effective pollinators of Solanum lycocarpum at a forest fragment. Five flowers of each of two floral morphs were used to determine pollen viability using optical microscopy. Bees were collected during the first 15 minutes of every hour of collection and classified into large, medium and small. Behavioral observations were performed during the remaining 45 minutes. Both floral morphs presented high percentage of viable pollen, without much difference between them. A total of 322 bees from 12 species were collected. Visits were more frequent when the anthers were maintained. Epi charis flava, Centris scopipes and Oxaea flavescens, along with Centris analis had large body size and, due to the behavior presented, were considered effective pollinators of S. lycocarpum. The intense intraspecific and interspecific competition observed among visiting bees may be advantageous for S. lycocarpum reproduction.

B chromosomes and fertility in a native population of Hymenachne amplexicaulis (Poaceae: Panicoideae: Paspaleae)

Fertility is a measure of reproductive success, defined as the capacity of an individual to reproduce and generate offspring, and has been identified as an important trait correlating to the invasive ability of a species. Hymenachne amplexicaulis (Rudge) Nees is a grass native to South America of high bromatological quality, making it a species with good forage potential. In the places where it was introduced it is now considered an invasive weed due to its dominance over native vegetation. In this work, individuals of H. amplexicaulis were analyzed from a native population in its southernmost native range, situated on Yacyretá reservoir dam. All individuals show a diploid cytotype with two B chromosomes (2n = 2x = 20 + 2B). This is the first chromosome count recording B chromosomes for the genus, and a new cytotype for the species. The karyotype was found to be symmetrical and unimodal, composed by 20 metacentric chromosomes and two small B chromosomes. Pollen viability was tested at 90.6%, seed set production of population reaches 18.65%, and the viable seeds presented a germination power of 41%. The reproductive performance is less than expected with respect to the mean amount of spikelets that a single inflorescence possesses and notwithstanding optimal conditions of supply and availability of viable pollen for fecundation. Germination test indicate good seed quality and viability in native range. In H. amplexicaulis effective fertility is lower than its potential fertility, but it is not an indicator of absence of invasive threat. Reproductive performance of B host plants indicates sufficient invasive potential.

The Type of Honeybees Forages in District of Pakem Sleman and Nglipar Gunungkidul Yogyakarta

This research aimed to investigate the type of plants for honeybees forages in Pakem Sleman and Nglipar Gunungkidul. This research was conducted from 16 March to 12 May 2016. The method used was direct observation in the plantations, fields, and forests. The type of plants observed were dominant plants, so can be developed beekeeping, honey. To determine the type of plants that produce nectar and pollen, one or two samples of flower in each plant were taken, then the availability of nectar and pollen was checked. The data of honeybees forage types were analyzed descriptively. The results showed that the type of honeybees forages in Pakem Sleman consisted of coconut, coffee, banana, calliandra, avocado, rice, albizia, chili, tomato, long beans, mustard green, maize, cucumber, melinjo, mahogany, cassava, and cherry. Honeybees forages in Nglipar Gunungkidul consisted of coconut, albizia, acacia, banana, peanuts, tamarind, eucalyptus, rambutan, sorghum, cacao, soybeans, cassava, maize, rice, rose wood, mahogany, and cherry. Thus, Pakem Sleman and Nglipar Gunungkidul have great potential for development of beekeeping honey.

Reproductive Biology of Varronia curassavica Jacq. (Boraginaceae)

Varronia curassavica, a subshrubby medicinal species associated with restinga in the Atlantic Forest, has been exploited by local people and the pharmaceutical industry. Indeed, restingas have experienced a continuous process of degradation, and thus, with species and ecosystem both at risk, efforts to support conservation actions are required. The present study aimed to evaluate aspects of V. curassavica reproductive biology. To accomplish this, morphological characterization was performed by monitoring flowering events. The availability of nectar and pollen, as well as the frequency and behavior of floral visitors and dispersers, was also evaluated. This species exhibits both heterostyly and protogyny. Anthesis is diurnal, and flowers last less than a day. The high number of flower and fruit abortions suggests that mechanisms, such as self-incompatibility intra-morphs and easily detached flowers, contribute to reduced fruit production. The high diversity of floral visitors indicate a generalist pollination syndrome. Diptera, Hymenoptera and Lepidoptera were the main pollinators, and nectar was the main resource sought by these insects. Fruits were dispersed by birds and ants. It can be concluded that the interaction of V. curassavica with several species is a key factor in its own survival and for maintaining the biological diversity of restinga.

Small and surrounded: population size and land use intensity interact to determine reliance on autonomous selfing in a monocarpic plant.

Habitat fragmentation has transformed landscapes globally, leaving remnants embedded within a complex matrix that is rapidly becoming more developed. For many plant populations, the associated factors of decreased size and intensification of land use surrounding them are expected to increase pollen limitation ('PL'), unless autonomous self-pollination provides reproductive assurance ('RA'). Decreased pollinator visitation is often assumed to drive these patterns, but other, less studied mechanisms might include increased heterospecific pollen transfer or decreased conspecific pollen availability via florivory. I investigate how PL and RA and their potential underlying mechanisms vary with population size and land use intensity surrounding populations in the biennial Sabatia angularis (Gentianaceae). I estimated the capacity for seed production via autonomous self-pollination (i.e. autofertility). Over 2 years in 22 S. angularis populations across a fragmented landscape, I performed emasculation and pollen supplementation experiments measuring RA and PL, and quantified visitation rates of potential pollinators and a pollen consumer, conspecific pollen loads and rates of heterospecific pollen deposition. Autofertility based on fruit mass was 93 % under PL but only 51.6 % relative to maximal conditions. PL and RA were significant on average across populations in the first year of study. Variation in RA was significantly influenced by the interaction between population size and land use intensity, which in turn rendered PL independent of these factors. Visitation and heterospecific pollen deposition rates were greatest in small populations and declined with population size, while conspecific pollen loads were greatest in intermediate sized populations. Increased reliance on RA is predicted in small S. angularis populations surrounded by intense development, which can explain elevated selfing rates in fragmented populations of plant species more generally. Results from this study point toward forces such as heterospecific pollen transfer, self-pollen limitation or resource availability influencing the need and ability to rely on RA.

THE IMPACT OF FOOD RESOURCES ON FITNESS OF EPISYRPHUS BALTEATUS

Syrphids effectiveness as predators of aphids depends on the supply and quality of pollen and nectar. Pollen is required for reproduction and nectar for survival. Most investigations have focused on the interaction between prey and the predator while overlooking the importance of food foraging and supply during the different physiological phases. It is important to know how pollen and nectar supply affects the overall fitness of hoverflies. We investigated the impact of resource availability on the fitness of E. balteatus. Individual mated female syrphids were released in net cages with rape plant infested with Brevicoryne brassicae. Pollen and sugar supply was manipulated to simulate limitation in food resources. As a control, pollen and sugar were provided throughout the lifespan while the treatments included: pollen only, sugar only, withdraw of pollen during pre-oviposition and oviposition period. Oviposited eggs were counted daily and foraging patterns recorded with a video observation system. Feeding on pollen and sugar throughoutresulted in a 2 fold the number of eggs compared to different shortage treatments. Lack of pollen during pre-oviposition and feeding on sugar only lead to a complete lack of egg laying. The highest longevity occurred if pollen and sugar were available throughout being twice as long as if feeding on sugar only.Feeding on pollen alone resulted in same longevity as when feeding pollen and sugar throughout. Syrphids contacted the food patch containing pollen quite often and for longer durations during the pre-oviposition period. The number of visits and durations then decreased during oviposition period.  These results demonstrate that pollen availability is not only essential for oviposition but also enhanced survival.Consequently, lack of pollen sources during pre-oviposition has a negative impact on egg output and longevity.

Floral visits of the wild bee, <i>Lithurgus atratus</i>, impact yield and seed germinability of okra, <i>Abelmoschus esculentus</i>, in Sri Lanka

Bee-pollinated crops in landscapes with a low abundance of bees suffer from insufficient pollination. The present study investigates the effect of wild bee pollination on fruit and seed production in okra, Abelmoschus esculentus (L.) Moench. The study was conducted in a home garden, where an okra field was established for three pollination trials each to include 40 okra plants. For each trial, three sets of 25 flower buds were selected and tagged. One set was covered to deter bees, another set was kept open to enable bee visits and the other set was cross-pollinated by hand. Of the two species of bees, Tetragonula iridipennis (Smith) visited flowers for nectar while Lithurgus atratus Smith collected and carried pollen grains. The period of stigma receptivity and pollen availability coincided with the highest activity of L. atratus from 10.00 a.m. to 12.20 p.m. Bee-pollinated flowers had significantly enhanced okra pod length and diameter, seed number and seed germinability compared to the trial with flowers covered to deter bees. Hand pollinated flowers also produced significantly longer pods and a higher number of seeds with higher germinability. Although there was no significant difference in pod length and diameter and seed number between hand pollination trial and bee-pollinated trial, germinability of bee-pollinated seeds was significantly higher. Present study highlights the importance of the wild bee, L. atratus to enhance pod size, seed number and seed germinability in okra in Kurunegala, Sri Lanka.

VARIATION OF HONEYBEES FORAGES AS SOURCE OF NECTAR AND POLLEN BASED ON ALTITUDE IN YOGYAKARTA

The latitude will influence plant type that growth, water availability, soil nutrients, temperature, humidity, rainfall, and sunlight, so that impact on the ability of plant for flowering. This research was aimed to determine the types of honeybees forages as the source of nectar, pollen and the both based on the latitude in Yogyakarta. The Research has been conducted in District of Cangkringan and Turi Sleman and Patuk Gunungkidul, Yogyakarta. The research used methods directly survey to observe in plantation area, field, and forest. Identification of plant type for produce nectar and pollen was taken one or two samples, then check the availability of nectar and pollen. The data of type of bee forage were analyzed by descriptive analysis. The results of research showed that the type of bee forage in Cangkringan with latitude of 500 – 900 and > 1000 m asl were 23 plants consisted of coconut, sugarcane, rice, sengon, chili, tomato, bean, banana, corn, cucumber, melinjo, mahogany, walnut, durian, sesbania grandiflora, cocoa, cherry, eggplant, sweet potato, cassava and acacia. The District of Turi with latitude of 500 – 900 and > 1000 m asl were 18 plants consisted of coconut, calliandra, rice, tomato, banana, corn, mahogany, rambutan, durian, mango, papaya, avocado, jackfruit, guava, melinjo, kapok, sweet potato and cocoa. The District of Patuk with latitude of 200 – 700 m asl were 28 plants consisted of cacao, rice, corn, cassava, peanut, soybean, chili, eggplant, melinjo, orange, guava, durian, avocado, mango, rambutan, starfruit, sapodilla, papaya, banana, jackfruit, breadfruit, leucaena, rosewood, acacia, mahogany, albizzia, sweet potato and coconut. The type of bee forage as the source of nectar and pollen in Yogyakarta is varied so is potential for the development beekeeping honeybees.

Mitigating effects of pollen during paraquat exposure on gene expression and pathogen prevalence in Apis mellifera L

Honey bee (Apis mellifera L.) populations have been experiencing notable mortality in Europe and North America. No single cause has been identified for these dramatic losses, but rather multiple interacting factors are likely responsible (such as pesticides, malnutrition, habitat loss, and pathogens). Paraquat is one of the most widely used non-selective herbicides, especially in developing countries. This herbicide is considered slightly toxic to honey bees, despite being reported as a highly effective inducer of oxidative stress in a wide range of living systems. Here, we test the effects of paraquat on the expression of detoxification and antioxidant-related genes, as well as on the dynamics of pathogen titers. Moreover, we tested the effects of pollen as mitigating factor to paraquat exposure. Our results show significant changes in the expression of several antioxidant-related and detoxification-related genes in the presence of paraquat, as well as an increase of pathogens titers. Finally, we demonstrate a mitigating effect of pollen through the up-regulation of specific genes and improvement of survival of bees exposed to paraquat. The presence of pollen in the diet was also correlated with a reduced prevalence of Nosema and viral pathogens. We discuss the importance of honey bees' nutrition, especially the availability of pollen, on colony losses chronically reported in the USA and Europe.