Effect of weather factors and nitrogen application on nectar secretion and honey production potential in sunflower

Sunflower is a highly important bee floral crop. The nectar secretion governs this parameter and is greatly influenced by cultivar, environmental factors and fertilizer application. Studies were conducted at Punjab Agricultural University, Ludhiana on sunflower hybrids (PSH 996 and PSH 1962) sown on different dates (January 31, February 10, February 20 and March 2) with three levels of nitrogen (45, 60 and 75 kg ha-1). Delay in sowing from January 31 to March 2 caused significant reduction in nectar secretion (12.66%) and increase in its concentration (5.38%). The daily mean temperature had significant positive (R2 = 0.52 and 0.54) while mean relative humidity had negative (R2 = 0.55 and 0.37) correlation with nectar total soluble solids (TSS).Nectar secretion and its TSS increased significantly only at nitrogen dose of 60 kg ha-1 as compared to 45 kg ha-1.Weather parameters have more pronounced effects on TSSat 45 kg ha-1.Delay in sowing by one month resulted in reduction in honey production potential by 1.5- 1.8 kg ha-1. In addition to this, the reduced nectar availability due to delay in sowing may negatively effect in attracting and sustaining pollinators’ populations and crop yield.

Nectar secretion in a dry habitat: structure of the nectary in two endangered Mexican species of Barkeria (Orchidaceae)

Barkeria scandens and B. whartoniana are endangered, endemic taxa from Mexico. They are epiphytes adapted to dry habitats. Since these plants are xerophytic, their flowers were investigated for structural adaptations to nectar secretion. The flowers of both species are structurally similar, and contrary to most claims for the genus, have functional floral nectaries comprising a nectary chamber and a narrow tubular cuniculus. Nectar is present in both these structures, and contains sugars and lipid-like compounds. The nectary tissue is composed of a single-layered epidermis overlying 1–2 layers of subepidermal secretory parenchyma. The outer tangential wall of the epidermal cells is thick and multi-layered, whereas the cuticle, which often shows blistering, is lamellate and possesses micro-channels. Lipid-like material occurs both between the microfibrils of the cell wall and in the micro-channels. Robust secretory tissue, thick cell walls, and lipid-like nectar components limit nectar evaporation. Moreover, the rigidity of the nectary potentially makes it possible for red-flowered B. scandens to switch from entomophily to ornithophily.

Nectar secretion of Callistemon citrinus (Curtis) Skeels, Myrtaceae: Potential for honey production

The honey production capacity of bee flora is used to estimate the optimum colony carrying capacity of given area that helps to harvest the best honey yield. The research was conducted to quantify the nectar secretion pattern, the effect of temperature and humidity on dynamics of nectar secretion, and honey production capacity of Callistemon citrinus. One day before nectar collection, five inflorescences were enclosed with mesh bags on different branches of the tree. From these, twenty flowers were randomly selected per tree for the measurement of nectar volume. Additionally, nectar volume and concentration, temperature, and air humidity were measured with an interval of one hour. One way ANOVA and linear regression were used for data analysis. The average amount of nectar and its concentration were different significantly within the time of the day. Nectar amount was correlated positively with humidity while concentration was negatively correlated with temperature. The average nectar volume (µl) per flower in 24 hours, sugar amount per tree (kg), honey yield per individual tree (kg) and honey production capacity of Callistemon citrinus per hectare were 10.9+0.4, 0.65, 0.79, and 1264 kg (46-3808 kg), respectively. The real expected honey yield was 632 kg ha-1. Total financial return was estimated to be $4424 based on a value of $7 kg-1 of Callistemon citrinus honey. Therefore, the multiplication and plantation of this plant are suggested for honey production.

Temporal Memory in Foraging of the Stingless Bee Melipona subnitida (Hymenoptera: Apidae: Meliponini)

Bees feed on nectar and pollen, however these resources are often available to floral visitors during restricted temporal windows. The presence of temporal memory is an advantage, as foragers can save energy by scheduling their flight activity to coincide with peaks of nectar secretion in the flowers or at times of higher sugar concentration in the nectar. Thus, the objectives of this study were (i) to investigate whether Melipona subnitida has temporal memory, and evaluate whether it becomes more accurate over the days, and (ii) to determine whether the behavior of anticipating the offered resource presents intra-individual consistency in the behavior of foragers. The visitation of the bees was high before and during the opening interval of the food resource, but rare after the closing, suggesting that M. subnitida has the ability to memorize the time of availability of the resource, increasing the accuracy over the days, with bees anticipating their visits in relation to the time they discovered the resource, and the opening time of the resource. There was individual consistency in the behavior of food-anticipatory activity, with the presence of bees that consistently anticipated in relation to the opening time of the resource (inspectors) and bees that consistently did not anticipate (reactivated forager) . By anticipating the search for a resource, foragers allow the group to exploit it effectively, as they exploit it in the first hours of its opening, and foragers that never anticipate avoid unnecessary risks of predation and energy expenditure.

Phosphorus fertilization induces nectar secretion for honeybee visitation and cross-pollination of almond trees

Precise phosphorus (P) application requires a mechanistic understanding of mineral effects on crop biology and physiology. Photosynthate assimilation, metabolism, and transport require phosphorylation, and we postulated that P is critical for the bloom and fruit-set of almond trees that rely on stored carbohydrate reserves. Hence, we studied the growth, physiology and carbohydrate dynamics in 2-year-old almond trees irrigated with P concentrations between 1 mg l−1 and 20 mg l−1. Almond trees attained maximal photosynthesis, transpiration, and growth by 6 mg P l−1 irrigation. Nevertheless, almond trees continued to extract P in 10 mg P l−1 and 15 mg P l−1 irrigations, which corresponded to larger yields. We attributed the augmented productivity to increased fruit-set (59% between 6 mg P l−1 and 15 mg P l−1), caused by more frequent (29%) honeybee visits. High P improved pollinator visitation by enabling almond trees to utilize more of their starch reserves for nectar secretion (which increased by ~140% between 6 mg P l−1 and 15 mg P l−1). This work elucidates the benefits of P fertilization to plant–pollinator mutualism, critical to almond productivity, and reveals novel indices for optimal P application in almond orchards.

Foraging Behavior of Apis mellifera Linn. Visiting Some Plant Flowers in Aljabal Alakhder Region –Libya

The study aimed to investigate the effects of nectar secretion and climate conditions on the number of honeybee workers foraging on flowers of three different plant species. Nectar samples were taken at different hours of the day. Handling and traveling time of each bee per flower were recorded. The results showed a significant difference during daylight hours on nectar volume (P>0.05). The highest amount of nectar was recorded at 10 am on a Prunus domestica flower plant (0.5± 0.2) and the lowest on a Pyrus communis flower plant at 8:00 am with (0.0132 ± 0.008). Also, the highest recorded handling time was on a Malus domestica flower plant at 10 am with (6.1± 1.7 Sec). And while there was an absence of mean handling time at 4:00 pm on the P. communis flower plant, The results showed that the highest traveling time recorded was on a M. domestica flower plant at 12 am with (2.2 ± 0.1 Sec) compared with the P. communis flower plant that recorded the lowest traveling time at 4:00 pm with (0.1± 0.1 Sec). Furthermore, the results revealed that the preference of Apis mellifera was the M. domestica flower plant. The findings showed a significance (P>0.05) between the effects of climate conditions on the number of bees during visits, while also revealing that there was a relationship between high temperatures and an increase in the number of visiting bees. Meanwhile, the number of visits decreased during the hours of observation with lower humidity.