Identification and Evaluation of Factors Affecting Nectar Volume and Concentrations of Croton Macrostachyus Hochst.ex Delile

Background: Secretion of nectar is highly influenced by many factors and the objective of the study was also to evaluate factors affecting concentrations of nectar of Croton macrostachyus Hochst.ex Delile. Age of plants highly affect nectar concentration and volume. Honey quality and its medicinal values depends on plants species variety and their sucrose concentration quality and quantity which is governed by many biotic and abiotic factors as well micro climate of the area. Wholesale of nectar and concentration of tend to show more differences in time of day for species study undertaken.Results: As results publicized that nectar concentration and volume of youngest age was not more affected by temperature and relative humidity like that of medium and oldest ages. Temperature and age have significant effect on volume (p = 0.0001) and their interactions is also significant (p = 0.01145). Temperature has significant effects on nectar concentration (p = 0.000). Interaction of relative humidity, time, and layers has significant effects on nectar concentration (p = 0.0024012). The oldest plants had the highest concentration of 10.1 w/w mornings and afternoon 36.5 w/w at 4:00 PM for whereas medium plants had nectar concentration of 5.7 w/w morning and afternoon 16.7 w/w and the smaller or younger plants had nectar concentration of 2.7 w/w mornings and afternoon 9.1 w/w and this shows age significantly affect nectar concentration and volume.Conclusions:Concentration and volume were affected by many biotic and abiotic factors. I conclude imminent fever intensification could harm nectar production since for croton also no nectar could be collected at 30 C⁰ and no nectar recreation was observed after this peak temperature this indicates environmental change can increase the temperature which will have negative influences on honey production in the future unless we combat against climate change which will affect honey production and productivity for the country and we will lose honey and its medicinal values also.

Extreme Drought Affects Visitation and Seed Set in a Plant Species in the Central Chilean Andes Heavily Dependent on Hummingbird Pollination

Rising temperatures and increasing drought in Mediterranean-type climate areas are expected to affect plant–pollinator interactions, especially in plant species with specialised pollination. Central Chile experienced a mega drought between 2010 and 2020 which reached an extreme in the austral summer of 2019–2020. Based on intensive pollinator sampling and floral studies we show that the subalpine form of Mutisia subulata (Asteraceae) is a specialised hummingbird-pollinated species. In a two-year study which included the severest drought year, we quantified visitation frequency, flower-head density, flower-head visitation rates, two measures of floral longevity, nectar characteristics and seed set and monitored climatic variables to detect direct and indirect climate-related effects on pollinator visitation. Flower-head density, nectar standing crop and seed set were significantly reduced in the severest drought year while nectar concentration increased. The best model to explain visitation frequency included flower-head density, relative humidity, temperature, and nectar standing crop with highly significant effects of the first three variables. Results for flower-head density suggest hummingbirds were able to associate visual signals with reduced resource availability and/or were less abundant. The negative effect of lower relative humidity suggests the birds were able to perceive differences in nectar concentration. Reduced seed set per flower-head together with the availability of far fewer ovules in the 2019–2020 austral summer would have resulted in a major reduction in seed set. Longer and more intense droughts in this century could threaten local population persistence in M. subulata.

Floral biology and pollination strategy of Durio (Malvaceae) in Sarawak, Malaysian Borneo

Ng WS, Mohd-Azlan J, Wong SY. 2020. Floral biology and pollination strategy of Durio (Malvaceae) in Sarawak, Malaysian Borneo. Biodiversitas 21: 5579-5594. This study was carried out to investigate on the flowering mechanisms of four Durio species in Sarawak. The anthesis started in the afternoon (D. graveolens and D. zibethinus), evening (D. kutejensis) or midnight (D. griffithii); and lasted between 11.5 hours (D. griffithii) to 20 hours (D. graveolens). All four Durio species are generalists. Individuals of a fruit bat (Eonycteris spelaea, Pteropodidae) are considered as the main pollinator for D. graveolens, D. kutejensis, and D. zibethinus while spiderhunter (Arachnothera, Nectariniidae) is also proposed as a primary pollinator for D. kutejensis. Five invertebrate taxa were observed as secondary or inadvertent pollinators of Durio spp.: honeybee, Apis sp. (Apidae), stingless bee, Tetrigona sp. (Apidae), nocturnal wasp, Provespa sp. (Vespidae), pollen beetle (Nitidulidae), and thrip (Thysanoptera). Honey bees and stingless bees pollinated all four Durio species. Pollen beetles were found to pollinate D. griffithii and D. graveolens while nocturnal wasps were found to pollinate D. kutejensis and D. zibethinus. Thrips were found to pollinate D. griffithii only. Floral rewards include nectar, pollen and staminodes. The nectar production of D. graveolens, D. kutejensis, and D. zibethinus increased from the start of anthesis until just after midnight but decreased from then onwards. Durio griffithii produced consistent nectar concentration with inconsistent volume. Durio graveolens, D. griffithii, and D. zibethinus are partially self-incompatible.

Salvage of floral resources through re-absorption before flower abscission

Plants invest floral resources, including nectar and pigment, with likely consequent reproductive costs. We hypothesized that plants, whose flowers abscise with age, reabsorb nectar and pigment before abscission. This was tested with flowers of Rhododendron decorum, which has large, conspicuous white flowers that increasingly abscise corollas as flowers age. As this species is pollinated by bees, we also hypothesized that nectar concentration would be relatively high (i.e., > 30% wt/vol) and petals would contain UV-absorbing pigment. Floral nectar volume and concentration were sampled on successive days until abscission (up to ten days old, peak at five days) and for sub-sample of four-day-old flowers. Flowers just abscised were similarly sampled. Flower colours were measured using a modified camera, with recordings of spectral reflectance for abscised and open non-abscised flowers. Pigment content was summed values of red, green, blue channels of false color photos. As expected, flowers reabsorbed almost all nectar before abscission, separately reabsorbing nectar-sugar and nectar-water, and petals contained UV-absorbing pigment. However, flowers did not reabsorb pigment and nectar-concentration was < 30% wt/vol. That flowers reabsorb nectar, not pigment, remains unexplained, though possibly pigment reabsorption is uneconomical. Understanding floral resource reabsorption therefore requires determination of biochemical mechanisms, plus costs/benefits for individual plants.

Nectar, humidity, honey bees ( Apis mellifera ) and varroa in summer: a theoretical thermofluid analysis of the fate of water vapour from honey ripening and its implications on the control of Varroa destructor

This theoretical thermofluid analysis investigates the relationships between honey production rate, nectar concentration and the parameters of entrance size, nest thermal conductance, brood nest humidity and the temperatures needed for nectar to honey conversion. It quantifies and shows that nest humidity is positively related to the amount, and water content of the nectar being desiccated into honey and negatively with respect to nest thermal conductance and entrance size. It is highly likely that honeybees, in temperate climates and in their natural home, with much smaller thermal conductance and entrance, can achieve higher humidities more easily and more frequently than in man-made hives. As a consequence, it is possible that Varroa destructor , a parasite implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm −3 ) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests. This study provides the theoretical basis for new avenues of research into the control of varroa, via the modification of beekeeping practices to help maintain higher hive humidities.

Thermal efficiency extends distance and variety for honeybee foragers: analysis of the energetics of nectar collection and desiccation by Apis mellifera

The desiccation of nectar to produce honey by honeybees ( Apis mellifera L.) is an energy-intensive process, as it involves a quasi-isothermal change in the concentration of sugars from typically 20 to 80% by vaporization (honey ripening). This analysis creates mathematical models for: the collected nectar to honey ratio; energy recovery ratio; honey energy margin; and the break-even distance, which includes the factors of nectar concentration and the distance to the nectar from the nest; energetics of desiccation and a new factor, thermal energy efficiency (TEE) of nectar desiccation. These models show a significant proportion of delivered energy in the nectar must be used in desiccation, and that there is a strong connection between TEE and nest lumped thermal conductance with colony behaviour. They show the connection between TEE and honeybee colony success, or failure, in the rate of return, in terms of distance or quality of foraging. Consequently, TEE is a key parameter in honeybee populations and foraging modelling. For bee keeping, it quantifies the summer benefits of a key hive design parameter, hive thermal conductance and gives a sound theoretical basis for improving honey yields, as seen in expanded polystyrene hives.

Food Reward and Distance Influence the Foraging Pattern of Stingless Bee, Heterotrigona itama

Beekeeping with stingless bee provides new opportunities to improve the incomes of many households in Malaysia through the sale of honey and other bee products. While Heterotrigona itama is one of the most commonly cultured species of stingless bees, its behavior is not very well understood. Hence, we conducted this study to investigate the behavior of H. itama in exploiting food sources by ascertaining the nectar sugar concentration preferred by the bee. We also aimed to determine the preferred distance of food source from the beehive. Our results suggest that H. itama prefers high sugar concentrations of 35% and above, and most of the bees preferred to forage close to their hive to collect food. We discuss how nectar concentration, food distance, and abiotic factors influence the number of bees exploiting food sources and the overall foraging pattern of H. itama.

Food Reward and Distance Influence the Foraging Pattern of Stingless Bee, Heterotrigona itama

Stingless bee beekeeping provides new opportunities to improve the incomes of many households in Malaysia through the sale of honey and other bee products. While Heterotrigona itama is one of the most commonly cultured species of stingless bees, its behavior is not very well understood. Hence, we conducted this study to investigate the behavior of H. itama in exploiting food sources by ascertaining the nectar sugar concentration preferred by the bee. We also aimed to determine the preferred distance of food source from the bee hive. Our results suggest that H. itama prefers high sugar concentrations of 35% and above, and they would fly up to 7 m from the hive to collect food. We discuss how nectar concentration and food distance influence the number of bees exploiting food sources and the overall foraging pattern of H. itama.