Discussion in 'Environment' started by jjl, Feb 18, 2016.
For more of her creations go to: http://www.aganethadyck.ca/
I don't know how I missed this :
Connecticut Continues To Suffer Massive Loss of Honeybees
Connecticut beekeepers reported losing nearly half of their honeybees during the summer and winter of 2015-16, according to a new report, a die-off rate even higher than the national average of 44 percent.
State and national experts call the continuing losses of honeybees — which are essential for pollinating crops humans depend on — a major concern and unsustainable in the long run.
"It's a significant loss," Michael Creighton, the state bee inspector and a staff member at the Connecticut Agricultural Experiment Station (CAES), said Wednesday. He said state bee losses were "close to 50 percent."
"I would agree that it's unsustainable," said Richard Cowles, a CAES scientist working on genetic bee research to improve honeybee resistance to diseases. Cowles said agricultural experiment station experts are also looking at ways to improve habitats for pollinators.
Bee Protection Bill Wins Final Approval
Most scientists studying the problems of honeybee die-offs agree that these extraordinary death rates are the result of a combination of poor bee nutrition due to loss of habitat, disease, and pesticides. Bees that lack a variety of flowers to feed on end up with poor diets, leaving them vulnerable to parasites such as the Varroa mite and diseases, and some pesticides may also weaken bee colonies.
A new historical study released last month also indicates that climate change and rising levels of carbon dioxide in the atmosphere may also be involved in the bee decline. The report by the U.S. Department of Agriculture research service found that higher carbon dioxide levels in the atmosphere appear to have reduced the amount of protein in the pollen bees feed on, particularly in plants like goldenrod, which is a key food source for many wild and domestic bees late in the year.
Connecticut's Wild Bees May Be In Trouble
The Bee Informed Partnership's 2015-16 survey indicates that the die-off of honeybees in Connecticut, while still higher than the national average, was somewhat better than during the prior year. Connecticut honeybee losses hit 57.5 percent in 2014-15, a period that included severe winter weather.
"We had a milder winter [for 2015-16], and that probably helped us out a little," Creighton said of the difference in bee death rates between the two years.
Creighton said beekeepers are able to keep replacing some portion of their losses, splitting up remaining hives to create new ones. "But that also puts added stress on these colonies, and affects honey production as well," he said.
Connecticut's General Assembly just approved legislation aimed at helping the state's bees and other pollinators such as butterflies.
The measure restricts the use of certain types of pesticides called neonicotinoids that have been linked to bee population declines, calls for development of statewide plans to improve bee health, and ordering the state Department of Transportation to plant pollinator-friendly flowers and bushes along state highways.
One provision in the new law calls for CAES scientists to develop a "best practices" plan to direct the DOT's pollinator plantings and to improve beekeeping procedures.
Cowles said all kinds of issues are involved in the bee die-offs, including things like the overpopulation of white tail deer.
Too many deer in an area results in "degradation of low-growing vegetation in woodlands," Cowles said. He said the result is often devastating for wild bees, which are also important crop pollinators.
Many of Connecticut's more than 300 wild bee species feed on the low-growth vegetation that is vanishing because there are too many deer. Cowles said studies have found those types of woodland plants "are absolutely essential for solitary wild bees… who are left with nothing to feed on."
Fat Bees – Part 1 (A)
What if I told you that there was one amazing molecule in the honeybees’ bodies that allows them to store protein reserves, make royal jelly, promotes the longevity of queen and “winter” bees, is a part of their immune system, allows them to brood up in spring in the absence of pollen, and has an effect upon their foraging behavior? Surely you’d want to be familiar with such an important molecule!
Its name? Vitellogenin
This spring I was in the beeyard showing a class of kids a beautiful comb of very young brood. Every cell was glistening with “brood food.” I explained to the students the significance of that wonderous liquid, in that it was akin to the milk with which mammals nourish their young. Nearly all other animals on earth (with the exception of the nonsocial insects) either abandon their young to fare for themselves, or (in the case of birds) feed them the same food that the adults eat. Honeybees have the wondrous ability to feed their larvae with milklike secretions from their own bodies—royal jelly and “bee milk.”
These amazing products are actually a continuum of mixtures of glandular secretions, and of the nectar-rich contents of the honey sacks of nurse bees of the right age. Worker larvae receive “worker jelly” for the first two days, consisting of a white, lipid-rich secretion from the mandibular glands, and a clear, protein-rich secretion from the hypomandibular glands. After the first two days, the food for worker larvae shifts to “bee milk”–a mixture of “jelly” from the hypomandibular glands, and nectar from the honey sac. The food may also contain up to 5% pollen, but it appears to be an inadvertent “contaminant” from the nurses’ mouthparts or honey sacs. Worker jelly is low in sugar at first (with the sugar being mostly glucose), then increases in sugar content for older larvae (with the sugar type shifting to fructose).
Larvae floating in jelly. Similarly to mammals, honey bees feed their young a perfect food–a glandularly-secreted “milk.”
Queen larvae, on the other hand, are fed royal jelly continuously. This jelly consists of roughly equal amounts of secretions from both glands, has a higher sugar content, and different vitamin content than worker food. Surprisingly, queens are the default product of every fertilized egg! Only by reducing the amount of food fed, the type of food, and the size and orientation of the cell, can the colony suppress “normal” queen development, in order to produce nominally sterile workers.
Royal jelly is the most perfect food on earth—for queen bees. Queen larvae are fed lavishly, and float in a pool of creamy white jelly, from which they feed like Sumo wrestlers, gorging themselves to the excess needed to become the shapely beauties we prize (bee larvae do not defecate until their final moult, and thus do not foul their food). Queens are then fed royal jelly for the rest of their lives, by nurse bees in the brood nest. The queen must again eat amazing quantities—she lays nearly her body weight in eggs every day during peak colony buildup, which requires a prodigious amount of nutrition!
So far I’ve only discussed the food requirements of larvae and queens. Adult worker bees also need to eat, and they are “born” hungry! As soon as they hatch, they head for the feed trough, first for a shot of sugar to give them energy. The brood combs are ringed by cells of open nectar or honey, readily available for the ravenous nurse bees, who are producing all the brood food to feed the larvae. Of course, everyone knows that you can’t raise kids on sugar alone, but that’s about all that nectar or honey provide. So our newly-hatched bee then seeks out cells of stored pollen next to the brood, and begins the process of building up her body protein level. She eats a little within the first several hours after emergence, really starts packing it in by two days, and tanks out around day five. At this point, her brood food glands and fat bodies are fully developed (provided that adequate pollen is available), and she can produce royal jelly. She will continue to consume pollen only if needed for further broodrearing, or to “fatten up” for winter. Once she becomes a forager, she will satisfy her protein requirements by soliciting protein-rich jelly from younger nurse bees (Crailsheim 1990).
The point that every beekeeper needs to understand is that the real nutrition for the colony comes from pollen. Specifically, a mixture of various and appropriate plant pollens, gathered by foragers, and carried back to the hive in the specialized pollen baskets on their hind legs. Pollen is synonymous with “bee food”—it provides the protein, lipids (fats), vitamins, sterols, minerals, and micronutrients that bees need for growth and health. Honeybee colonies require pollen in a big way—to the tune of 30-100 lbs a year! The stimulus for pollen foraging is largely the presence of brood pheremones produced by young larvae—hence, beekeepers who see pollen loads coming in at the entrance generally assume that the colony is queenright with brood present.
Nurse bees consuming pollen (yellow) and beebread (orange), in order to convert it into jelly.
Fat Bees – Part 1 (B)
Pollen foragers carry their pollen loads directly to the brood nest, and use their heads to pack it into cells adjacent to larvae. This pollen is generally consumed quickly by nurse bees. The dynamics of pollen storage and consumption produce the typical ring of pollen around the brood. Pollen that remains stored for longer periods may undergo lactic acid fermentation in the cell–this likely preserves it, much as similar fermentation does sauerkraut or yogurt. Cells of pollen may be covered with honey in fall to be used the next spring as the colony expands the broodnest prior to early pollen flows. This last point is a big one! Honeybees are tropical insects that need a warm environment and constant feeding (similar to humans). Similarly to humans, when they migrated from the tropics to more temperate climates, they “learned” to create dry homes (a cluster in a cavity) that they can heat to comfortable temperatures during winter, and to store food in their larders for lean times (i.e., any time that plants aren’t flowering).
O.K., in my roundabout way, I’m finally going to get to my point. Bees not only store pollen and honey in the combs, but they also store food reserves in their bodies. This is done mainly in the form of a compound called “vitellogenin.” vitellogenin is classed as a “glycolipoprotein,” meaning that is has properties of sugar (glyco, 2%), fat (lipo, 7%), and protein (91%) (Wheeler & Kawooya 2005). Vitellogenin is used by other animals as an egg yolk protein precurser, but bees have made it much more important in their physiology and behavior, using it additionally as a food storage reservoir in their bodies, to synthesize royal jelly, as an immune system component, as a “fountain of youth” to prolong queen and forager lifespan, as well as functioning as a hormone that affects future foraging behavior!
This is a great example of the conservatism of evolution. Just as the same genes that code for a fish’s fins also code for a dog’s paw, a human hand, or a bird or bat’s wing, bees have expanded the role of vitellogenin to perform multiple functions in their systems. They are able to do this because most of the bees in a colony are sterile females who rarely lay eggs. Therefore, they have the mechanism to produce this egg yolk precurser, but no use for it. So instead, they deposit it in fat bodies in the abdomen and head.
Fat bodies (white), reduced in a forager (left), fully developed in a “winter bee” (right).
Now, fat bodies aren’t just fat. Putnam & Stanley (2007) put it well: “In addition to its important roles as a storage depot, the fat body of insects functions as a key center of metabolism and biochemistry… fat bodies biosynthesize and accumulate not only lipid reserves, but also carbohydrates, amino acids, proteins and other metabolites. …[F]at bodies respond to physiological and biochemical needs in a number of ways, including very high rates of protein biosynthesis, formation and release of trehalose, release of lipids, detoxification of nitrogenous waste products, and biosynthesis of hormones… Many of the proteins that are crucial in the lives of insects are biosynthesized in fat bodies” (including vitellogenins).
Now here’s where Dr. Gro Amdam comes into the picture. While she was pursuing her thesis at the Norwegian University of Life Science in 2002, she wondered what all the vitellogenin synthesized by bees was doing. She found out that instead of being used for egg yolk protein, it was being fed to queens, larvae, and older workers (Amdam, et al 2003). “The insight that vitellogenin was important during the nest stage, and thus for worker division of labour, led Amdam to speculate that the protein could–directly or indirectly–affect the bees transition from nest tasks to foraging duties. ‘The age at onset of foraging is highly variable, but there was no good physiological model for explaining this variation. One possibility was that the probability of starting foraging was related to the level of the bees’ dynamic vitellogenin stores. This would ensure that vitellogenin-rich bees stayed in the nest as useful nurses of the brood and other bees, whereas vitellogenin-exhausted bees became foragers’” (Anon 2007).
In later research Amdam demonstrated that suppression of vitellogenin leads to high titers of juvenile hormone–a systemic hormone associated with insect development, and honeybee foraging activity. Unlike in other insects, vitellogenin and juvenile hormone now work antagonistically in the honeybee to regulate their development and behavior (Nelson, et al. 2007).
Furthermore, Dr. Amdam showed that vitellogenin scavenged free radicals from the bees’ systems, thereby allowing queens and winter bees to live longer, by suppressing oxidative stress damage (Seehuus, et al. 2006). Vitellogenin is indeed the “Fountain of Youth for the honeybee! Maybe the health claims for royal jelly have merit—if you were to eat enough of it. By implication, since juvenile hormone levels spike in stressed bees, vitellogenin may have a role to play in fighting stress (Lin & Huang 2004).
Schmickl and Crailsheim (2004) have published a most informative review of nutrient flow dynamics in honey bee colonies—this is must reading for any serious beekeeper! It’s a free download, and I’ve included the URL in the references. To summarize their comprehensive paper, protein from pollen, and sugars from nectar, are in dynamic states of movement in the colony based upon the availability of the raw materials from foraging, and the nutrient requirements of the queen, larvae, nurses, foragers, and drones. There are complex feedback and behavioral mechanisms to ensure that food reserves are shared and distributed optimally in both good times and bad.
Incoming nectar is quickly distributed within the hive among all age groups of bees, and to the larvae. But it’s the dynamics of protein transfer within the colony that are really important to understand! Especially the degree to which nurse bees are continuously feeding the foragers. In experiments, up to 25% of radioactively tagged amino acids fed to nurse bees were transferred to foragers overnight! Nurse bees not only feed brood, but also are continuously feeding protein to the foragers.
Fat Bees – Part 1 (C)
Pollen foraging by those foragers is stimulated not only by brood pheremones, but also by the inventory of pollen stores, and the amount of jelly in the shared food fed by nurse bees to the foragers. The quality of the jelly is dependent upon the vitellogenin levels of those nurses. Even just a few days of rain results in an almost total loss of pollen stores, forcing the nurse bees to dig into their vitellogenin reserves. When protein levels drop, nurse bees neglect young larvae, and preferentially feed those close to being capped. When protein levels drop lower, nurses cannibalize eggs and middle aged larvae. The protein in this cannibalized brood is recycled back into jelly. Nurses will also perform early capping of larvae—resulting in low body weight bees emerging later.
When a colony goes into protein deficit, the nurses cut back on the amount of jelly fed to larvae. Note how little jelly these larvae have been given. Pollen-starved nurses may also consume newly-laid eggs, and eventually larvae.
What’s happening is that the honeybee has figured out ways to keep most of the precious protein stores within the hive, and since vitellogenin is necessary for immune function (Amdam 2005a), the colony delegates the risky task of foraging to the oldest bees, who have depleted their vitellogenin levels. Indeed, if older bees are forced to revert to nurse behavior, and build up their protein reserves, their immune level also increases again! Vandam points out that “A functional immune system is apparently costly in social insects,” so don’t waste it on the foragers. “When bees switch from the hive bee to the forager stage, their cellular defence machinery is down-regulated by a dramatic reduction in the number of functioning haemocytes (immunocytes)” (Amdam, et al. 2004a).
Fat bees and wintering
So the European honeybee, in adapting for the long winters of temperate climates, has figured out ways to store energy in the form of honey for the winter, and protein in the form of vitellogenin. This allowed the species to maintain a large social population year round, despite the vagaries of nectar and pollen flows. Amdam (2003) states: “the vitellogenin-to-jelly invention…made possible the establishment of a very simple and flexible ambient condition-driven mechanism for transforming a nurse bee into a bee with large enough protein and lipid stores to survive several months on honey only.” When broodrearing is curtailed in fall, the emerging workers tank up on pollen, and since they have no brood to feed, they store all that good food in their bodies, thus preparing themselves for a long life through the winter. These well-nourished, long-lived bees have been called “fat” bees (Sommerville 2005; Mussen 2007). Fat bees are chock-full of vitellogenin. Understanding the concept of fat bees is key to colony health, successful wintering, spring buildup, and honey production.
Indeed, one of the big differences between African and European bees is the degree of fatness. Back to Amdam again (2005b): “Our data indicate that European workers have a higher set-point concentration for vitellogenin compared to their African origin. Considered together with available life history information and physiological data, the results lend support to the view that “winter bees”, a longlived honey bee worker caste that survives winter in temperate regions, evolved through an increase in the worker bees’ capacity for vitellogenin accumulation.” Thus the African bees’ strategy of absconding and searching for new food resources, rather than hunkering down and waiting it out.
Foraging and swarming
Think that’s all there is to vitellogenin? Dr. Amdam got together with California’s Dr. Rob Page (Nelson, et al. 2007), who had previously developed a pollen-collecting line of bees. Page had found that bees genetically biased to collect pollen were characterized by high levels of vitellogenin. Together the researchers discovered that the vitellogenin titer developed by a worker bee in its first four days after emergence, affected its subsequent age to begin foraging, and whether it preferentially foraged for nectar or pollen! If young workers are short on food their first days of life, they tend to begin foraging precociously, and preferentially for nectar. If they are moderately fed, they forage at normal age, again preferentially for nectar. However, if they are abundantly fed immediately after emergence, their vitellogenin titer is high, and they begin foraging later in life, preferentially collect pollen, and have a longer lifespan. This scenario certainly makes sense—a starving colony would want skip raising brood, and send out foragers to gather as much nectar as they could. A fat colony would want to rear brood and build protein reserves in order to swarm.
The high proportion of returning pollen foragers indicate that this colony is probably rearing brood.
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