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.

The dominant axes of lifetime behavioral variation in honey bees

Insect colonies are decentralized systems that employ task allocation, whereby individuals undertake different roles to fulfill colony needs, such as honey bee "nurses", "nest workers", and "foragers". However, the extent to which individuals can be well-classified by discrete "roles", how they change behavior from day-to-day, over entire lifetimes, and with environmental conditions, is poorly understood. Using long-term automated tracking of over 4,200 individually-identified bees (Apis mellifera), we use behavioral metrics to quantify and compare behavior. We show that individuals exhibit behavioral variation along two dominant axes that represent nest substrate use and movement within the nest. Across lifetimes, we find that individuals differ in foraging onset, and that certain bees exhibit lifelong consistencies in their movement patterns. Furthermore, we examine a period of sudden nectar availability where the honey stores tripled over 6 days, and see that the colony exhibits a distributed shift in activity that did not require a large-scale colony reorganization. Our quantitative approach shows how collective units differ over days and lifetimes, and how sources of variation and variability contribute to the colony's robust yet flexible response.

Diel scent and nectar rhythms of an African orchid in relation to bimodal activity patterns of hawkmoth pollinators

Background and Aims The temporal dimensions of floral adaptation to pollinators are not yet well understood, partly because we lack accurate information on the diel rhythms of flower visitation for many pollinators. We investigated whether diel patterns of pollinator visitation to flowers of the African woodland orchid Bonatea polypodantha are synchronized with rhythms of floral anthesis, scent emission and nectar availability. Methods Direct observations and motion-activated cameras were used to identify pollinators of B. polypodantha and to document their activity periods. The timing of pollinaria removal from flowers, emission of scent and availability of nectar was also measured. Results We found that B. polypodantha is pollinated exclusively by short-tongued hawkmoths. Pollinaria of the orchid are affixed between the labial palps of the moths and brush over the protruding stigmatic arms. The flowers also receive visits by long-tongued hawkmoths, but these act as nectar thieves. Tracking of pollinaria removal from flowers confirmed that pollination occurs only at night. Camera footage revealed a striking crepuscular pattern of foraging by short-tongued hawkmoths with peaks of activity during the twilight periods at dusk and at dawn. In contrast, long-tongued hawkmoths were found to visit flowers throughout the night. Flowers of B. polypodantha exhibit unimodal peaks of anthesis, scent emission (dominated by nitrogenous aromatics) and nectar availability before or around dusk. Conclusions Flowers of B. polypodantha are pollinated exclusively by short-tongued hawkmoths, which show crepuscular foraging activity at dusk and dawn. Floral phenophases of the orchid are closely synchronized with the peak of pollinator activity at dusk.

Introduced social bees reduce nectar availability during the breeding season of the swift parrot (Lathamus discolor)

Numerous pollinators are declining across the world. One of these, the swift parrot (Lathamus discolor) is a critically endangered Australian bird that feeds largely on the nectar and pollen of Eucalyptus trees. The Swift Parrot Recovery Plan includes competition for food from introduced social bees as a threatening process, although little evidence exists in support of this. Here, we present the strongest evidence yet to support this theory. We examined nectar standing crops in the species of trees that are important to swift parrots during their breeding season, Tasmanian blue gum (Eucalyptus globulus) and black gum (E. ovata). By comparing the amounts of nectar between flowers exposed to visitors and those bagged to exclude visitors throughout the day, we discovered that introduced honey bees (Apis mellifera) and bumble bees (Bombus terrestris) consumed most of the nectar and that exposed flowers often contained little nectar. Honey bees were the more common species, but bumble bees had greater per capita rates of nectar consumption. However, at low densities these bees had no effect on standing crops of nectar, and in such situations some nectar could be harvested by managed honey bees without reducing nectar availability for swift parrots. Although this study suggests that introduced social bees may pose a threat to swift parrots, further work is needed to determine whether our results are indicative of the impacts of bees across greater scales of time and space and whether these affect the reproductive success and conservation status of the swift parrot.

Plant-hummingbird interactions and temporal nectar availability in arestinga from Brazil

ABSTRACT Hummingbirds are the most important and specialized group of pollinating birds in the Neotropics and their interactions with plants are key components to many communities. In the present study we identified the assemblage of plants visited by hummingbirds and investigated the temporal availability of floral resources in an area of restinga, sandy plain coastal vegetation associated with the Atlantic forest, in Southeastern Brazil. We recorded flower and nectar features, flowering phenology and interactions between plants and hummingbirds and estimated the amount of calories produced per hectare from June 2005 to August 2006. Ten plant species were visited by two hummingbirds,Amazilia fimbriata and Eupetomena macroura. Resource availability was highly variable among plant species and over time. Nectar volume and concentration per flower were similar to other Neotropical hummingbird-visited plant assemblages. The estimated nectar resource availability between months varied from 0.85 to 5.97 Kcal per hectare/day, demanding an area between one and 6.8 ha to support a single hummingbird. Our study reports an unusual tropical setting where almost all interactions between hummingbirds and plants were performed by a single hummingbird species,A. fimbriata. Hence, the variable nectar availability is probably influencing hummingbird movements, its foraging area, and consequently plant pollination.