Nectar Resources Research Articles

Nectar and pollen sources for honeybees in Kafrelsheikh province of northern Egypt.

This study was conducted at the apiary of the Beekeeping Research Section at the Sakha Agricultural Research Station, ARC, Kafrelsheikh, and other apiaries in Kafrelsheikh province, during two successive years 2015 and 2016. The study aimed to survey nectar and pollen floral resources in Kafrelsheikh province. Ninty seven plant species belonging to 33 families were recorded as nectar sources, and 82 plant species belonging to 36 families were recorded as pollen sources during the whole year. The largest amount of monthly trapped pollen was obtained during May followed by August. It can be concluded that, beekeepers in Kafrelsheikh province can harvest good honey yield at the end of blooming seasons of citrus (Citrus spp.) during March and April, Egyptian clover (Trifolium alexandrinum L.) during May and June, loofah (Luffa aegyptiaca Mill.) during June to October, cotton (Gossypium spp.) during July and August, and banana (Musa spp.) during August and September. They also, could be trapping pollen loads collected from faba bean (Vicia faba L.) and flax (Linum usitatissimum L.) during January to March, date palm (Phoenix dactylifera L.) during March and April, Egyptian clover during May and June, summer seed watermelon (Citrullus lanatus var. colothynthoides L.) during June and July, loofah and maize (Zea mays L.) during June to November.

Local and landscape drivers of butterfly richness and abundance in a human-dominated area

In Europe, butterflies have declined over the last decades mainly because of the increasing urbanization and the agricultural intensification occurred in lowlands areas. Drivers of butterfly decline were identified in changes of both local scale habitat characteristics and landscape-scale land-use coverage. Thus, to counteract the negative trend of butterfly populations, management actions that simultaneously have an effect on local and landscape scale environments are needed.The present research was performed in northern Italy, in a human-dominated area of about 170 km2. From April to September 2014 and 2015, we surveyed butterflies in 494 50-m sections, grouped into 44 line transects. First, using a multi-scale GAMM, we analysed the simultaneous effect of local (nectar index, crop type, presence of woodlands and hedgerows and degree of shelter) and landscape (fractional cover in 500-m buffer of arable lands, meadows, woodlands and artificial surfaces) variables on butterfly richness and abundance. We evaluated the contribution of local and landscape variables by a variation partitioning approach. Second, we performed a GAMM to investigate the effect of specific management practices adopted in meadows, hedgerows and field margins on butterfly communities. Our results showed that the evaluation of the effect of local scale characteristics on butterfly communities definitely cannot disregard the landscape context. We thus suggest maintaining urban and agricultural areas alternated by a mosaic of nectar-rich land-covers, such as meadows and alfalfa, forest patches and hedgerows.Our study also allowed to formulate management guidelines of specific habitats. Accordingly, meadows should be managed by reducing the number of cuts, while wide herbaceous margins, characterised by a high grass layer rich in dicots, should be maintained in arable lands. To avoid a barrier effect and to guarantee the presence of a well-developed shrub layer, which provides high nectar resources, it is also necessary to avoid an excessive growth in hedgerows height. Results evidence that the adoption of these management guidelines and of a proper landscape planning strategy, can lead to play an important role in butterfly conservation even within human dominated areas.

Validation of floral food resources for pollinators in agricultural landscape in SE Poland.

Proper management of bee pastures is considered an important activity for diversity of pollinators and conservation of the population size. In the present study, the floral composition and diversity, flowering spectrum and availability of food resources in natural and man-made habitats in four rural municipalities in Lublin Upland, SE Poland were evaluated. The connection between pollinator-friendly biotopes was also determined and some suggestions are made on creation/supplementation of bee pastures adapted to the arable land structure in eastern Poland (mean acreage 7.65 ha). Forage species richness (S) differed among vegetation types: the highest S value was found in field margins, while mixed forests represented the lowest species richness (mean ± standard deviation = 37.8 ± 9.5 vs 16.5 ± 2.3). In all habitats, the most abundant flowering was recorded in May. Then the blooming abundance decreased until a complete decline at the end of summer. The mean distance between pollinator-friendly biotopes is 2.4 ± 1.53 km, which is out of the flying range/foraging distance of most pollinators. Shortages of nectar and pollen resources in the agricultural landscape of SE Poland are evident. Therefore it is assumed that the landscape structure requires support in terms of food niches for pollinators and creation/supplementation of bee pastures is necessary, e.g. six to nine patches of 0.025-0.3 ha each within an area of 100 ha. © 2017 Society of Chemical Industry.

Reproductive biology of three co-occurring, primarily small-mammal pollinated Protea species (Proteaceae)

This study investigated the role of vertebrates in the reproductive biology of a community of three co-occurring Protea species (Protea canaliculata, Protea sulphurea and Protea humiflora, Proteaceae) at Kraggashoek in the Western Cape, South Africa. Live-trapping, measures of facial and faecal pollen loads, and footage from remote cameras facing the inflorescences confirmed that all three are visited by small mammals and specialist nectarivorous birds. These plant species have bowl-shaped inflorescences that produce highly concentrated (34.1–42.9%) sucrose-rich nectar and a “yeasty” scent, typical traits of small-mammal pollinated plants. Camera footage indicated that 140 visits were made by eight small mammal species to an accumulative 19 inflorescences of the three Protea species. Small mammals thus made up 69% of total visits by all vertebrate species. Camera footage revealed that Micaelamys namaquensis visited flowers more frequently than any other vertebrate visitor (41% of total visitations by birds and mammals) but Elephantulus edwardii (10% of total visitations by birds and mammals) spent the longest time foraging on inflorescences (~28s per inflorescence). The ‘trap shy’ species, Graphiurus ocularis, was observed for the first time on camera, visiting Protea humiflora and Protea sulphurea inflorescences. Galerella pulverulenta (Cape gray mongoose) also visited inflorescences of P. canaliculata. The remaining 31% of total vertebrate visits, primarily to Protea humiflora, were by three species of specialist nectarivorous birds (the Cape sugarbird Promerops cafer, and the shorter-billed sunbirds, Anthobaphes violacea and Cinnyris chalybeus). Breeding system experiments with Protea sulphurea revealed that pollinators are needed for seed set, although exclusion of vertebrate pollinators only marginally lowered seed set of this partially self-incompatible species. These three Protea species had asynchronous flowering periods, supporting a wide range and relative abundance (overall live mammal trapping success rate of 22.7% nocturnal and 5.7% diurnal species) of vertebrate pollinators over a three month period in winter. That these Protea species co-occur suggests there is a community of vertebrate flower visitor species and primarily small mammal-pollinated plant species. The partitioning of nectar resources over a long period has conservation implications for both the plants and animals.

Anthropogenic Impacts on Mortality and Population Viability of the Monarch Butterfly.

Monarch butterflies (Danaus plexippus) are familiar herbivores of milkweeds of the genus Asclepias, and most monarchs migrate each year to locate these host plants across North American ecosystems now dominated by agriculture. Eastern migrants overwinter in high-elevation forests in Mexico, and western monarchs overwinter in trees on the coast of California. Both populations face three primary threats to their viability: (a) loss of milkweed resources for larvae due to genetically modified crops, pesticides, and fertilizers; (b) loss of nectar resources from flowering plants; and (c) degraded overwintering forest habitats due to commercially motivated deforestation and other economic activities. Secondary threats to population viability include (d) climate change effects on milkweed host plants and the dynamics of breeding, overwintering, and migration; (e) the influence of invasive plants and natural enemies; (f) habitat fragmentation and coalescence that promote homogeneous, species-depleted landscapes; and (g) deliberate culture and release of monarchs and invasive milkweeds.

Flower resource and land management drives hoverfly communities and bee abundance in seminatural and agricultural grasslands.

Pollination is a key ecosystem service, and appropriate management, particularly in agricultural systems, is essential to maintain a diversity of pollinator guilds. However, management recommendations frequently focus on maintaining plant communities, with the assumption that associated invertebrate populations will be sustained. We tested whether plant community, flower resources, and soil moisture would influence hoverfly (Syrphidae) abundance and species richness in floristically‐rich seminatural and floristically impoverished agricultural grassland communities in Wales (U.K.) and compared these to two Hymenoptera genera, Bombus, and Lasioglossum. Interactions between environmental variables were tested using generalized linear modeling, and hoverfly community composition examined using canonical correspondence analysis. There was no difference in hoverfly abundance, species richness, or bee abundance, between grassland types. There was a positive association between hoverfly abundance, species richness, and flower abundance in unimproved grasslands. However, this was not evident in agriculturally improved grassland, possibly reflecting intrinsically low flower resource in these habitats, or the presence of plant species with low or relatively inaccessible nectar resources. There was no association between soil moisture content and hoverfly abundance or species richness. Hoverfly community composition was influenced by agricultural improvement and the amount of flower resource. Hoverfly species with semiaquatic larvae were associated with both seminatural and agricultural wet grasslands, possibly because of localized larval habitat. Despite the absence of differences in hoverfly abundance and species richness, distinct hoverfly communities are associated with marshy grasslands, agriculturally improved marshy grasslands, and unimproved dry grasslands, but not with improved dry grasslands. Grassland plant community cannot be used as a proxy for pollinator community. Management of grasslands should aim to maximize the pollinator feeding resource, as well as maintain plant communities. Retaining waterlogged ground may enhance the number of hoverflies with semiaquatic larvae.

Do linden trees kill bees? Reviewing the causes of bee deaths on silver linden (Tilia tomentosa).

For decades, linden trees (basswoods or lime trees), and particularly silver linden (Tilia tomentosa), have been linked to mass bee deaths. This phenomenon is often attributed to the purported occurrence of the carbohydrate mannose, which is toxic to bees, in Tilia nectar. In this review, however, we conclude that from existing literature there is no experimental evidence for toxicity to bees in linden nectar. Bee deaths on Tilia probably result from starvation, owing to insufficient nectar resources late in the tree's flowering period. We recommend ensuring sufficient alternative food sources in cities during late summer to reduce bee deaths on silver linden. Silver linden metabolites such as floral volatiles, pollen chemistry and nectar secondary compounds remain underexplored, particularly their toxic or behavioural effects on bees. Some evidence for the presence of caffeine in linden nectar may mean that linden trees can chemically deceive foraging bees to make sub-optimal foraging decisions, in some cases leading to their starvation.

Pollinators shift to nectar robbers when florivory occurs, with effects on reproductive success in Iris bulleyana (Iridaceae).

Studies have indicated that florivory and nectar robbing may reduce reproductive success of host plants. However, whether and how these effects might interact when plants are simultaneously attacked by both florivores and nectar robbers still needs further investigation. We used Iris bulleyana to detect the interactions among florivory, nectar robbing and pollination, and moreover, their effects on plant reproductive success. Field investigations and hand-pollination treatments were conducted on two experimental plots from a natural population, in which Experimental plot was protected from florivores and Control plot was not manipulated. The flower calyx was bitten by sawflies to consume the nectary, and three bumblebee species were pollinators. In addition, the short-tongued pollinator, Bombus friseanus, was the only robber when there was a hole made by a sawfly. The bumblebee had significantly shortened flower handling time when robbing, as compared to legitimate visits. Pollinator visitation and seed production decreased significantly in damaged flowers. However, seed production per flower after supplementary hand-pollination did not differ significantly between damaged and undamaged flowers. Compared to the Experimental plot, bumblebees visited fewer flowers per plant in a foraging bout in the Control plot. The flowers damaged by florivory allowed B.friseanus to shift to a nectar robber. Florivory and nectar robbing collectively decreased plant reproductive success by consuming nectar resources, which may reduce attractiveness to pollinators of the damaged flowers. However, the changes in pollinator behaviour might be beneficial to the plant by reducing the risk of geitonogamous mating.

Nectar sampling for prairie and oak savanna butterfly restoration.

Premise of the study:Understanding floral resources is vital for restoring pollinators in habitats affected by anthropogenic development and climate change. As the primary adult food, nectar can limit butterfly longevity and reproduction. For pollinator restoration, it would therefore be useful to examine nectar resources. However, because many flowers preferred by butterflies are too small for microcapillary sampling and the potential for nectar contamination can make accurate measurement difficult, we developed a modified centrifugation method to extract and separate nectar and pollen.Methods:We sampled nectar from 19 forbs using a glass wool filter to exclude potentially contaminating pollen during centrifugation. To minimize costs, we measured sugar concentration by refractometry and simple ninhydrin tests for amino acids and improved test accuracy by subsequent image analysis. Artificial nectars were used to verify the new techniques.Results:This method eliminated pollen from samples, while only slightly increasing sugar concentrations. Some amino acids were lost during centrifugation, but only samples with high concentrations exhibited substantial loss. We found significant differences in nectar quality among species, as well as an unexpected inverse relationship between amino acid and sugar concentrations.Discussion:This modified centrifugation technique is an efficient, less damaging, inexpensive approach for collecting nectar from small flowers while eliminating pollen contamination, and will facilitate restoration of declining pollinators and thereby the plants they service.

Altitudinal migration and the future of an iconic Hawaiian honeycreeper in response to climate change and management

AbstractAltitudinal movement by tropical birds to track seasonally variable resources can move them from protected areas to areas of increased vulnerability. In Hawaiʻi, historical reports suggest that many Hawaiian honeycreepers such as the ‘I‘iwi (Drepanis coccinea) once undertook seasonal migrations, but the existence of such movements today is unclear. Because Hawaiian honeycreepers are highly susceptible to avian malaria, currently minimal in high‐elevation forests, understanding the degree to which honeycreepers visit lower elevation forests may be critical to predict the current impact of malaria on population dynamics and how susceptible bird populations may respond to climate change and mitigation scenarios. Using radio telemetry data, we demonstrate for the first time that a large fraction of breeding adult and juvenile ‘I‘iwi originating from an upper‐elevation (1,920 m) population at Hakalau Forest National Wildlife Refuge exhibit post‐breeding movements well below the upper elevational limit for mosquitoes. Bloom data suggest seasonal variation in floral resources is the primary driver of seasonal movement for ‘I‘iwi. To understand the demographic implications of such movement, we developed a spatial individual‐based model calibrated using previously published and original data. ʻI‘iwi dynamics were simulated backward in time, to estimate population levels in the absence of avian malaria, and forward in time, to assess the impact of climate warming as well as two potential mitigation actions. Even in disease‐free ‘refuge’ populations, we found that breeding densities failed to reach the estimated carrying capacity, suggesting the existence of a seasonal “migration load” as a result of travel to disease‐prevalent areas. We predict that ‘I‘iwi may be on the verge of extinction in 2100, with the total number of pairs reaching only ~ 0.2–12.3% of the estimated pre‐malaria density, based on an optimistic climate change scenario. The probability of extinction of ‘I‘iwi populations, as measured by population estimates for 2100, is strongly related to their estimated migration propensity. Long‐term conservation strategies likely will require a multi‐pronged response including a reduction of malaria threats, habitat restoration and continued landscape‐level access to seasonally variable nectar resources.

Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems.

Oilseed rape (OSR; Brassica napus L.) is a major crop in temperate regions and provides an important source of nutrition to many of the yield‐enhancing insect flower visitors that consume floral nectar. The manipulation of mechanisms that control various crop plant traits for the benefit of pollinators has been suggested in the bid to increase food security, but little is known about inherent floral trait expression in contemporary OSR varieties or the breeding systems used in OSR breeding programmes. We studied a range of floral traits in glasshouse‐grown, certified conventional varieties of winter OSR to test for variation among and within breeding systems. We measured 24‐h nectar secretion rate, amount, concentration and ratio of nectar sugars per flower, and sizes and number of flowers produced per plant from 24 varieties of OSR representing open‐pollinated (OP), genic male sterility (GMS) hybrid and cytoplasmic male sterility (CMS) hybrid breeding systems. Sugar concentration was consistent among and within the breeding systems; however, GMS hybrids produced more nectar and more sugar per flower than CMS hybrid or OP varieties. With the exception of ratio of fructose/glucose in OP varieties, we found that nectar traits were consistent within all the breeding systems. When scaled, GMS hybrids produced 1.73 times more nectar resource per plant than OP varieties. Nectar production and amount of nectar sugar in OSR plants were independent of number and size of flowers. Our data show that floral traits of glasshouse‐grown OSR differed among breeding systems, suggesting that manipulation and enhancement of nectar rewards for insect flower visitors, including pollinators, could be included in future OSR breeding programmes.

Laboratory Evaluations of the Foraging Success ofTamarixia radiata(Hymenoptera: Eulophidae) on Flowers and Extrafloral Nectaries: Potential use of Nectar Plants for Conservation Biological Control of Asian Citrus Psyllid (Hemiptera: Liviidae)

Tamarixia radiata (Waterson) (Hymenoptera: Eulophidae) is a specialist parasitoid of late-instar nymphs of Asian citrus psyllid, Diaphorina citri (Kuwayama) (Hemiptera: Liviidae), a vector of the causal agent of huanglongbing disease of citrus (Sapindales: Rutaceae). Tamarixia radiata is mass reared; however, parasitism levels following inundative releases have remained relatively low. One possible explanation for the low parasitism levels is the lack of sugar resources available for adult wasps in targeted release landscapes, such as abandoned commercial citrus groves and residential areas. Establishing nectar plants can be an effective means of increasing nutritional resources in targeted sites for biocontrol agents. Some eulophids forage effectively only on fully exposed nectaries, i.e., those unobstructed by other floral parts. Therefore, care must be taken to select plants that possess nectary architecture compatible with parasitoid morphology and foraging ability. A series of laboratory studies were undertaken as a first step to determine the potential for T. radiata to obtain sugar from natural sources in target landscapes. Following contact with a sugar spot on filter paper, the wasps engaged in stereotypical zigzagging movements, demonstrating that contact with sugar induced arrestment and induction of localized searching behavior. Tamarixia radiata fed on sugars found in nectar (sucrose, glucose, fructose) and honeydew (melizitose, raffinose), indicating that it should feed well on both nectar and honeydew resources. At the highest concentration tested (1 M), it preferred sucrose and melizitose, whereas at the lowest concentration tested (0.1 M), it preferred sucrose and glucose. There was no preference among sugars when tested at the 0.5 M concentration. Choice tests with wasps previously exposed to scented sucrose solution showed that the wasps were stimulated and attracted by nectar odor and could learn to associate a particular odor with the presence of nectar. Observations conducted with starved wasps on freshly cut sprigs of nectar plants showed that foraging success was highest on extrafloral nectaries and flowers with exposed nectaries. The wasps readily located the extrafloral nectaries on snap bean and cowpea, and fed on them for the majority of the observation periods. Likewise, they quickly located the fully exposed nectaries in the inflorescences of euphorbiaceous plants, such as Euphorbia heterophylla L. (Malpighiales: Euphorbiaceae). Foraging success declined in flowers with nectaries that were only partially exposed; the wasps' movements were deterred by floral parts or trichomes that obstructed the nectary. The wasps were unable to obtain nectar from composites and other plants with hidden nectaries. Overall, the results of these laboratory evaluations showed that T. radiata responds to sugars and chemical cues associated with nectaries and is capable of foraging on extrafloral nectaries and flowers with exposed nectaries.

Asymmetric competition for nectar between a large nectar thief and a small pollinator: an energetic point of view.

There are two alternative hypotheses related to body size and competition for restricted food sources. The first one supposes that larger animals are superior competitors because of their increased feeding abilities, whereas the second one assumes superiority of smaller animals because of their lower food requirements. We examined the relationship between two unrelated species of different size, drinking technique, energy requirements and roles in plant pollination system, to reveal the features of their competitive interaction and mechanisms enabling their co-existence while utilising the same nectar source. We observed diurnal feeding behaviour of the main pollinator, the carpenter bee Xylocopa caffra and a nectar thief, the northern double-collared sunbird Cinnyris reichenowi on 19 clumps of Hypoestes aristata (Acanthaceae) in Bamenda Highlands, Cameroon. For comparative purpose, we established a simplistic model of daily energy expenditure and daily energy intake by both visitor species assuming that they spend all available daytime feeding on H. aristata. We revealed the energetic gain-expenditure balance of the studied visitor species in relation to diurnal changes in nectar quality and quantity. In general, smaller energy requirements and related ability to utilise smaller resources made the main pollinator X. caffra competitively superior to the larger nectar thief C. reichenowi. Nevertheless, sunbirds are endowed with several mechanisms to reduce asymmetry in exploitative competition, such as the use of nectar resources in times of the day when rivals are inactive, aggressive attacks on carpenter bees while defending the nectar plants, and higher speed of nectar consumption.

Potential impacts ofTuberolachnus salignus(giant willow aphid) in New Zealand and options for control

The giant willow aphid Tuberolachnus salignus was discovered in New Zealand in late 2013. Despite being a recent addition to the New Zealand fauna, the aphid is already widespread and abundant throughout the country. The giant willow aphid is expected to have negative impacts on host trees, primarily willows (Salix spp.), as has been observed elsewhere. All willows are exotic to New Zealand and a few have formal weed status, however many species are valued for multiple purposes, including flood protection, land stabilization, shelterbelts, and as early season pollen and nectar resources for honey bees. Tuberolachnus salignus presents a unique problem for New Zealand's thriving honey and honey products industries. Bees readily forage on the vast quantities of honeydew secreted by the aphid, however the honeydew contains melezitose sugar. The low solubility of this sugar results in honey crystallizing in the comb, making it difficult to extract and thereby reducing yield. It is also considered to be poor food for bees, and has been linked to bee dysentery and low overwintering survival. We elaborate on the potential complications for New Zealand as a result of the arrival of this new species and present options for its control and management.

Spatial segregation of the endemic versus non-endemic hummingbird on Robinson Crusoe Island, Chile: the effect of competitor abundance but not resources or habitat

Competitive pressure from invasive species tends to have a particularly strong impact on remote islands, and knowledge of such phenomena can be crucial to the conservation of endemic biodiversity. Of the two hummingbird species inhabiting Robinson Crusoe Island, Juan Fernandez Archipelago, Chile, one (Green-backed Firecrown, Sephanoides sephaniodes) has a wide mainland distribution while the other (Juan Fernandez Firecrown, Sephanoides fernandensis) is endemic and critically endangered. Even though habitat degradation and predation by exotic mammal species are known to pose major threats, little attention has been given to the influence of interspecific competition for floral nectar resources. In this study, we investigated the existence of interspecific competition by testing for spatial segregation of the two species using point counts dispersed within their suitable habitats. We additionally considered the influence of habitat type and flower abundance, which could also cause spatial segregation between the species. We found a negative association between the point count abundance of the two hummingbirds species, which remained consistent when accounting for the role of habitat type and flower abundance. Together, this could be an indication of interspecific competition in which individuals of S. fernandensis may benefit from aggregation by sharing the individual costs of chasing the vastly more abundant S. sephaniodes.

富士山麓・上ノ原草原における人為的管理が吸蜜植物の開花とチョウ類(成虫)の種組成に与える影響

富士山麓・上ノ原草原における人為的管理が吸蜜植物の開花とチョウ類(成虫)の種組成に与える影響

Improving vegetation quality for the restoration of pollinators – the relevance of co-flowering species in space and time

Pollination is a key ecosystem function that directly and indirectly provides food for all organisms – regardless of the trophic level. In degraded ecosystems, installing plant and habitat resources for pollinators starts with an understanding of the temporal and spatial habitat needs of pollinators, and the augmentations, the co-factors and conditions required for pollinator populations. These co-factors, not immediately recognised as linked to the provision of pollination services, are critical for complexity and include a diverse array of resources such as food plants for larvae, shelter and temporal legacies of earlier flowering species. Practical steps for restoration include the installation of an array of plant species that provide a staggered supply of flowers and this can be refined to include specific floral types that are the mega supermarkets for nectar and pollen resources in them.

Corrigendum to: Improving vegetation quality for the restoration of pollinators – the relevance of co-flowering species in space and time

Pollination is a key ecosystem function that directly and indirectly provides food for all organisms – regardless of the trophic level. In degraded ecosystems, installing plant and habitat resources for pollinators starts with an understanding of the temporal and spatial habitat needs of pollinators, and the augmentations, the co-factors and conditions required for pollinator populations. These co-factors, not immediately recognised as linked to the provision of pollination services, are critical for complexity and include a diverse array of resources such as food plants for larvae, shelter and temporal legacies of earlier flowering species. Practical steps for restoration include the installation of an array of plant species that provide a staggered supply of flowers and this can be refined to include specific floral types that are the mega supermarkets for nectar and pollen resources in them.

POLLINATOR DIVERSITY AND FORAGING DYNAMICS ON MONSOON CROP OF CUCURBITS IN A TRADITIONAL LANDSCAPE OF SOUTH INDIAN WEST COAST

Studies on insect pollinator ecology and dynamics are very rarely carried out in traditional Indian agriculture landscapes. Indiscriminate landscape changes in the rural areas and tendencies towards crop monocultures can have significant effects on pollinator habitats and effectiveness. This study was aimed at observing insect pollinators, their visitation frequencies and timings on monsoon cucurbit crops such as Cucumis sativus L., C. pubescens Willd., Momordica charantia L., Trichonsanthes anguina L. and Luffa acutangula L. (Roxb.), in a coastal Karnataka Village.  This study was also aimed at covering the significance of the surrounding landscape elements in sustaining pollinator elements. Bees, such as Apis dorsata, A. cerana and Trigona sp., were major visitors on all cucurbits, except snake gourd which was pollinated mainly by lepidopterans. Insect species were found to partition floral resources of any given crops between them by minimal overlapping in their visitation timings. Natural elements of the landscape around, mainly a village forest and rocky savanna furnished habitats for bees and lepidopterans. Prolifically blooming monsoon herbs on lateritic plateaus, by providing nectar resources for pollinators, presumably play key role in making the case study village well known for monsoon vegetables.

Potential supply of floral resources to managed honey bees in natural mistbelt forests

Honey bees play a vital role in the pollination of flowers in many agricultural systems, while providing honey through well managed beekeeping activities. Managed honey bees rely on the provision of pollen and nectar for their survival and productivity. Using data from field plot inventories in natural mistbelt forests, we (1) assessed the diversity and relative importance of honey bee plants, (2) explored the temporal availability of honey bee forage (nectar and pollen resources), and (3) elucidated how plant diversity (bee plant richness and overall plant richness) influenced the amount of forage available (production). A forage value index was defined on the basis of species-specific nectar and pollen values, and expected flowering period.Up to 50% of the overall woody plant richness were found to be honey bee plant species, with varying flowering period. As expected, bee plant richness increased with overall plant richness. Interestingly, bee plants’ flowering period was spread widely over a year, although the highest potential of forage supply was observed during the last quarter. We also found that only few honey bee plant species contributed 90 percent of the available forage. Surprisingly, overall plant richness did not significantly influence the bee forage value. Rather, bee plant species richness showed significant and greater effect. The results of this study suggest that mistbelt forests can contribute to increase the spatial and temporal availability of diverse floral resources for managed honey bees. Conservation efforts must be specifically oriented towards honey bee plant species in mistbelt forests to preserve and enhance their potential to help maintain honey bee colonies. The implications for forest management, beekeeping activities and pollination-based agriculture were discussed.