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How many honeybees are there, and how has the number changed across time?

How many honeybees are there, and how has the number changed across time?


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How would you begin to estimate the world population of the European Honeybee (Apis mellifera)? Would recent colony collapse disorder show up as a blip? How about the spread of A. mellifera from Europe to Asia and the New World?

Ideally, I'd love to see a chart with estimates of the kept and feral populations of A. mellifera across time. I realize that this is a tall order; but given that we have available to us:

  • the complete genome,

  • current data from agricultural organizations, and

  • historical and archaeological records,

it seeems that with a combination of genetic and historical methods this shouldn't be impossible. Or is it? There seem to be plenty of articles arguing about A. mellifera's African or European origin, but none that I see that mention actual population sizes.


1 billion hives (at 10,000-50,000 bees/hive this is 10-50 trillion bees)

Managed: 100 million hives

Based on country-level data from FAO, supplemented for a few countries with Apiservices, in 2011 there were about 80 million managed hives. Because FAO lacks any data for some countries, and other countries under-report (for instance US figures don't include hives kept for pollination service and hives kept by small-scale operators) a reasonable round estimate of managed hives in the world is 100 million. (This implies a 128% correction to the FAO numbers). (Aizen and Harder 2009 give context on FAO figures).

Wild/Feral: 900 million hives

Wild/feral hives of Apis mellifera are difficult to count via direct observation. Jaffe et al 2010 use a genetic sampling method, and also report a reasonably strong correlation between the total number of hives (managed and wild) per square kilometer and the mean annual temperature of the area. I used the best fit line from their data to estimate the "hive-carrying-capacity" by country using (the admittedly very general) land area and mean annual temperature. Then I subtracted the number of managed hives from the carrying capacity to estimate wild hives.

Although this formula probably overestimates large, cold countries and underestimates Africa (the formula gives 211 million feral hives in Africa when literature suggests closer to 300 million), in general, it seems to give not unreasonable estimates in comparison to the literature. Globally, this formula gives an estimate of 984 million wild hives. Given that land area included desert and other unsuitable habitat, it seemed reasonable to round down, and I took 900 million as my estimate.

Historical Populations

1961-2011 FAO statistics date to 1961. I plotted their numbers, with the 128% correction for each year. I assumed that during this time the number of wild bees has remained virtually unchanged, at 900 million, because it was defined by mean temperature and land area, which have not changed.*

1650-1961 This period represents the globalization of Apis mellifera. Before 1600, there were no European honey bees beyond their native range (Western Eurasia and Africa). However, once established in new areas (the usually cited first beehive in the USA in 1622), Apis mellifera rapidly spread in both managed and feral populations, in North America (17th c), South America (18th c), Australia (19th c) and East Asia (20th c) (Crane 1999) .

I used carrying capacity of native range countries (just about 35% of the carrying capacity of the globe, or 350 million hives) as a before-1650 estimate, and then assumed a geometric increase of about 2% per decade in available land area (ALA), as Apis mellifera bees and beekeeping made their way around the globe.

To estimate the number of managed bees during this period, I assumed a human:hive ratio of 35:1**, and modelled hives based on historical estimates of human population, multiplied by the ALA for the decade. The 1650 estimate was 5 million managed hives.


*Although diseases, pests, and pesticides have been reported to affect feral populations, I didn't find any solid information on this. For instance, feral populations of Apis mellifera mellifera and A. m ligustica have been widely reported to be in decline in the USA, but at the same time, feral populations of Africanized honeybees (Apis mellifera hybrids) have been rapidly spreading. Even with 90% losses in the USA, Canada, Japan, and Europe (areas affected by varroa) my estimates would only be decreased about 10%. However, it's also possible that land-use change has greatly affected feral bee populations (Moritz et al 2007).

**This wasn't a totally wild guess. I first calculated the human:hive ratio for 1961-2011. This ratio was increasing - there were 71 people / hive in 2011, and 47 in 1961. Initially, I assumed the rate of change in the ratio to be constant, but this led to unrealistically large estimates for historically managed hives. However, the rate was clearly increasing (just, perhaps in a nonlinear way I didn't want to estimate), so I decided instead to compromise on a number less than 47 and greater than 4. I decided on 35, as it produced what seemed like a realistic estimate of 5 million hives in 1650, compared to around 20 million today for Eurasia and North Africa (excluding sub-saharan Africa where wild-harvest remains important and likely was even more so in the past).


  • Aizen MA, Harder LD. 2009. The Global Stock of Domesticated Honey Bees Is Growing Slower Than Agricultural Demand for Pollination. Current Biology 19: 4-4.

  • Crane E. 1999. The World History of Beekeeping and Honey Hunting. Taylor & Francis. (Chapter 12).

  • Jaffé RR, Dietemann VV, Allsopp MHM, Costa CC, Crewe RMR, Dall'olio RR, Rúa PPDL, El-Niweiri MAAM, Fries II, Kezic NN, et al.. 2010. Estimating the density of honeybee colonies across their natural range to fill the gap in pollinator decline censuses. Conservation Biology 24: 583-593.

  • Moritz R, Kraus FB, Kryger P, Crewe RM. 2007. The size of wild honeybee populations (Apis mellifera) and its implications for the conservation of honeybees. Journal of Insect Conservation


Africanized Honey Bees: Where Are They Now, and When Will They Arrive in North Carolina? Africanized Honey Bees

Honey bees have been an integral component of agriculture because they are used to pollinate numerous fruit and vegetable crops. In North Carolina alone, honey bees account for over $150 million per year in added crop yields. The apiculture industry, however, is not without its challenges. Perhaps the greatest challenge has been the introduction and spread of exotic honey bee parasites, which have decimated the wild population and caused a dramatic drop in the number of managed beehives in the state. A second crisis looms with the potential spread of Africanized honey bees (AHB) from states further south, the results of which are difficult to predict. This note attempts to provide a brief history of the AHB in North America, its current distribution, and the likelihood that it will become established in North Carolina.


Nearly 40% decline in honey bee population last winter 'unsustainable,' experts say

Food prices could rise if the number of bees pollinating crops keeps dwindling.

Honey bee populations are continuing to decline sharply, researchers say

Scientists are researching the potential consequences of the rapid decline of the honey bee population in the U.S. and how to mitigate its effects before it causes dire problems for crop management and production.

Honey bees are essential for the pollination of flowers, fruits and vegetables, and support about $20 billion worth of crop production in the U.S. annually, Matthew Mulica, senior project manager at the Keystone Policy Center, a consulting company that works with the Honey Bee Health Coalition, told ABC News.

Worldwide, honey bees and other pollinators help to produce about $170 billion in crops, Scott McArt, assistant professor of pollinator health at Cornell University, told ABC News.

"Honey bees are one of the most important agricultural commodities in the country," Geoff Williams, an assistant professor of entomology at Auburn University who also serves on the board of directors for the Bee Informed Partnership, told ABC News.

Over the past 15 years, bee colonies have been disappearing in what is known as the "colony collapse disorder," according to National Geographic. Some regions have seen losses of up to 90%, the publication reported.

Data shows bee populations dwindling more and more each year

Between Oct. 1, 2018, and April 1, 2019, 37.7% of the managed honey bee population -- colonies kept by commercial beekeepers -- declined, which is 7 percentage points more than the same time frame during the 2017-2018 winter, according to preliminary data from the Bee Informed Partnership, a nonprofit associated with the University of Maryland.

This past winter season represents the highest level of winter losses reported since the survey began in 2006, according to the report.

For the entire year -- April 1, 2018, to April 1, 2019 -- the managed bee population decreased by 40.7%, according to the report. The overall loss rate is around the average of what researchers and beekeepers have seen since 2006, McArt said.

"The main take-home from this is these are unsustainably high losses," McArt said, adding that researchers are not necessarily alarmed at the numbers because they've become "a little bit accustomed to these large loss rates."

The number of hives that survive the winter months is an overall indicator of bee health, according to the U.S. Environmental Protection Agency.

Worker bees tend to live longest during the winter -- up to six months -- and just four weeks in the spring and summer, according to the American Bee Journal.

Managed colonies are shipped around the country to pollinate our food

Much of the produce seen in grocery stores -- watermelon, apples, peppers, cucumbers -- and nuts are pollinated by millions of European honey bees, or Apis mellifera, that travel across the country and are managed by commercial beekeepers, Mulica said.

These U.S. crops are produced with the help of 2.6 million colonies transported by 18-wheelers from place to place during peak flowering, McArt said. Of the $20 billion worth of U.S. crop production supported by pollinators, commercial honey bees are responsible for about half. Wild bees and other pollinators take care of the rest.

In February, about 60% of managed colonies head to California to begin almond production, McArt said.

The bees then travel to Florida to pollinate citrus crops before making their way up through the Southeast for the production of blueberries, cherries and other specialty fruits and vegetables, McArt said.

Apple pollination begins on the Northeast in June, and the last pollination event typically occurs in Maine in late June and early July for lowbush blueberries, McArt said.

The bees then go to a set location for several months, where they gather nectar and produce honey, McArt said.


A Bee’s Dinner Plate

Honey bees are vegetarians. Nectar and pollen collected from flowering plants are the entrees on their dinner plates. Bees harvest the nectar and convert the sugary liquid to honey, the insects’ primary source of carbohydrates. Honey provides the bees with the energy for flight, colony maintenance, and general daily activities.

Pollen, often called “bee bread,” is the bees’ main source of protein. Pollen also provides the bees with fatty acids, minerals, and vitamins. The protein in pollen is necessary for hive growth and young bee development.

Depending on the season, weather, and availability of nectar- and pollen-bearing blossoms, the size of a honey bee colony varies from 10,000 to 100,000 bees. A typical size colony, made up of about 20,000 bees, collects about 125 pounds of pollen per year. 1 Bees carry the pollen in specialized structures on their hind legs called “pollen baskets,” or corbiculae (meaning “little baskets” in Latin). A honey bee can bring back to the colony a pollen load that weighs about 35 percent of its body weight.

In a single day, one worker bee makes 12 or more trips from the hive, visiting several thousand flowers. On these foraging trips, the bee can travel as far as two to five miles from the hive. Although honey bees collect pollen from a variety of flowers, a bee limits itself to one plant species per trip, gathering one kind of pollen.


BugInfo Africanized Bees

Description: The general appearance of "Killer Bees" (= Africanized Bees) is the same as common Honey Bees, but there are some distinctive physical differences between the two. To analyze the differences, a laboratory has to measure and compare some 20 different structures. Another way to check is to analyze the specimen's DNA and enzymes.

Distribution:In 1956, some colonies of African Honey Bees were imported into Brazil, with the idea of cross-breeding them with local populations of Honey Bees to increase honey production. In 1957, twenty-six African queens, along with swarms of European worker bees, escaped from an experimental apiary about l00 miles south of Sao Paulo. These African bee escapees have since formed hybrid populations with European Honey Bees, both feral and from commercial hives. They have gradually spread northward through South America, Central America, and eastern Mexico, progressing some 100 to 200 miles per year. In 1990, Killer Bees reached southern Texas, appeared in Arizona in 1993, and found their way to California in 1995. They are expected to form colonies in parts of the southern United States.

Damage done:Africanized Honey Bees (=Killer Bees) are dangerous because they attack intruders in numbers much greater than European Honey Bees. Since their introduction into Brazil, they have killed some 1,000 humans, with victims receiving ten times as many stings than from the European strain. They react to disturbances ten times faster than European Honey Bees, and will chase a person a quarter of a mile. Other concerns with Africanized Honey Bees are the effects on the honey industry (with an annual value of $140 million dollars) and general pollination of orchards and field crops (with an annual value of 10 billion dollars). Interbred colonies of European and Africanized honey bees may differ in pollination efforts, be more aggressive, excessively abandon the nest, and not survive the winters. Further, beekeepers may not continue their business of honey production if faced with aggressive bees. The packaged bee and queen rearing industries are in the southern United States, which would affect the honey industry across the continent.

Control:Many authorities have been working on the problem of Killer Bees in the United States. Two primary solutions have been considered. The first is termed drone-flooding, which involves maintaining large numbers of common Honey Bees (originally from Europe) in areas where commercially-reared queen bees mate. This process would limit the mating possibilities between Africanized drones and European queens. The second strategy is requeening frequently, where the beekeeper replaces the queen of the colony, thus assuring that the queens are European Honey Bees and that mating has also occurred with European drones.

Selected References:

Gore, Rick. 1976. Those fiery Brazilian bees. National Geographic Magazine, volume 149, number 4, pages 491-501.

Michener, C. C. 1975. The Brazilian bee problem. Annual Review of Entomology, volume 20, pages 399-416.

Rinderer, T. E. 1986: Africanized Bees: The Africanization Process and Potential Range in the United States. Bulletin of the Entomological Society of America, Winter, 1986, pages 222-227.

Taylor, Orley R., Jr. 1977. The past and possible future spread of Africanized honey bees in the Americas. Bee World, vol. 58, 19-30.

Taylor, Orley R., Jr. 1985. African Bees: Potential Impact in the United States. Bulletin of the Entomological Society of America, Vol. 31, No. 4, pages 15-24, 1985.

Prepared by the Department of Systematic Biology, Entomology Section,
National Museum of Natural History, in cooperation with Public Inquiry Services,
Smithsonian Institution


Contents

There are 29 recognized subspecies of Apis mellifera based largely on geographic variations. All subspecies are cross-fertile. Geographic isolation led to numerous local adaptations. These adaptations include brood cycles synchronized with the bloom period of local flora, forming a winter cluster in colder climates, migratory swarming in Africa, enhanced (long-distance) foraging behavior in desert areas, and numerous other inherited traits.

The Africanized honey bees in the Western Hemisphere are descended from hives operated by biologist Warwick E. Kerr, who had interbred honey bees from Europe and southern Africa. Kerr was attempting to breed a strain of bees that would produce more honey in tropical conditions than the European strain of honey bee currently in use throughout North, Central and South America. The hives containing this particular African subspecies were housed at an apiary near Rio Claro, São Paulo, in the southeast of Brazil, and were noted to be especially defensive. These hives had been fitted with special excluder screens (called queen excluders) to prevent the larger queen bees and drones from getting out and mating with the local population of European bees. According to Kerr, in October 1957 a visiting beekeeper, noticing that the queen excluders were interfering with the worker bees' movement, removed them, resulting in the accidental release of 26 Tanganyikan swarms of A. m. scutellata. Following this accidental release, the Africanized honey bee swarms spread out and crossbred with local European honey bee colonies.

The descendants of these colonies have since spread throughout the Americas, moving through the Amazon Basin in the 1970s, crossing into Central America in 1982, and reaching Mexico in 1985. [5] Because their movement through these regions was rapid and largely unassisted by humans, Africanized honey bees have earned the reputation of being a notorious invasive species. [6] The prospect of killer bees arriving in the United States caused a media sensation in the late 1970s, inspired several horror movies, [7] and sparked debate about the wisdom of humans altering entire ecosystems.

The first Africanized honey bees in the U.S. were discovered in 1985 at an oil field in the San Joaquin Valley of California. Bee experts theorized the colony had not traveled overland but instead "arrived hidden in a load of oil-drilling pipe shipped from South America." [8] The first permanent colonies arrived in Texas from Mexico in 1990. [2] In the Tucson region of Arizona, a study of trapped swarms in 1994 found that only 15 percent had been Africanized this number had grown to 90 percent by 1997. [9]

Though Africanized honey bees display certain behavioral traits that make them less than desirable for commercial beekeeping, excessive defensiveness and swarming foremost, they have now become the dominant type of honey bee for beekeeping in Central and South America due to their genetic dominance as well as ability to out-compete their European counterpart, with some beekeepers asserting that they are superior honey producers and pollinators.

Africanized honey bees, as opposed to other Western bee types:

  • Tend to swarm more frequently and go farther than other types of honey bees.
  • Are more likely to migrate as part of a seasonal response to lowered food supply.
  • Are more likely to "abscond"—the entire colony leaves the hive and relocates—in response to stress.
  • Have greater defensiveness when in a resting swarm, compared to other honey bee types.
  • Live more often in ground cavities than the European types.
  • Guard the hive aggressively, with a larger alarm zone around the hive.
  • Have a higher proportion of "guard" bees within the hive.
  • Deploy in greater numbers for defense and pursues perceived threats over much longer distances from the hive.
  • Cannot survive extended periods of forage deprivation, preventing introduction into areas with harsh winters or extremely dry late summers.
  • Live in dramatically higher population densities. [Michener 1975 1] ​ [10] ​ [Michener 1975 2] ​

Africanized honey bees are considered an invasive species in the Americas. As of 2002, the Africanized honey bees had spread from Brazil south to northern Argentina and north to Central America, Trinidad (the West Indies), Mexico, Texas, Arizona, Nevada, New Mexico, Florida, and southern California. Their expansion stopped for a time at eastern Texas, possibly due to the large population of European honey bee hives in the area. However, discoveries of the Africanized honey bees in southern Louisiana show that they have gotten past this barrier, [11] or have come as a swarm aboard a ship.

In June 2005, it was discovered that the bees had entered Texas and had spread into southwest Arkansas. On 11 September 2007, Commissioner Bob Odom of the Louisiana Department of Agriculture and Forestry said that Africanized honey bees had established themselves in the New Orleans area. [12] In February 2009, Africanized honey bees were found in southern Utah. [13] [14] The bees had spread into eight counties in Utah, as far north as Grand and Emery Counties by May 2017. [15]

In October 2010, a 73-year-old man was killed by a swarm of Africanized honey bees while clearing brush on his south Georgia property, as determined by Georgia's Department of Agriculture. In 2012, Tennessee state officials reported that a colony was found for the first time in a beekeeper's colony in Monroe County in the eastern part of the state. [16] In June 2013, 62-year-old Larry Goodwin of Moody, Texas was killed by a swarm of Africanized honey bees. [17]

In May 2014, Colorado State University confirmed that bees from a swarm which had aggressively attacked an orchardist near Palisade, in west-central Colorado, were from an Africanized honey bee hive. The hive was subsequently destroyed. [18]

In tropical climates they effectively out-compete European honey bees and, at their peak rate of expansion, they spread north at almost two kilometers (about one mile) a day. There were discussions about slowing the spread by placing large numbers of docile European-strain hives in strategic locations, particularly at the Isthmus of Panama, but various national and international agricultural departments could not prevent the bees' expansion. Current knowledge of the genetics of these bees suggests that such a strategy, had it been tried, would not have been successful. [19]

As the Africanized honey bee migrates further north, colonies continue to interbreed with European honey bees. In a study conducted in Arizona in 2004 it was observed that swarms of Africanized honey bees could take over weakened European honey bee hives by invading the hive, then killing the European queen and establishing their own queen. [20] There are now relatively stable geographic zones in which either Africanized honey bees dominate, a mix of Africanized and European honey bees is present, or only non-Africanized honey bees are found, as in the southern portions of South America or northern North America.

African honey bees abscond (abandon the hive and any food store to start over in a new location) more readily than European honeybees. This is not necessarily a severe loss in tropical climates where plants bloom all year, but in more temperate climates it can leave the colony with not enough stores to survive the winter. Thus Africanized honey bees are expected to be a hazard mostly in the southern states of the United States, reaching as far north as the Chesapeake Bay in the east. The cold-weather limits of the Africanized honey bee have driven some professional bee breeders from Southern California into the harsher wintering locales of the northern Sierra Nevada and southern Cascade Range. This is a more difficult area to prepare bees for early pollination placement in, such as is required for the production of almonds. The reduced available winter forage in northern California means that bees must be fed for early spring buildup.

The arrival of the Africanized honey bee in Central America is threatening the ancient art of keeping Melipona stingless bees in log gums, although they do not interbreed or directly compete with each other. The honey production from a single hive of Africanized honey bees can be 100 kg annually and far exceeds the much smaller 3–5 kg of the various Melipona stingless bee species. Thus economic pressures are forcing beekeepers to switch from the traditional stingless bees of their ancestors to the new reality of the Africanized honey bee. Whether this will lead to their extinction is unknown, but they are well adapted to exist in the wild, and there are a number of indigenous plants that the Africanized honey bees do not visit, so their fate remains to be seen.

Africanized honey bees have a set of characteristics with respect to foraging behavior. Africanized honey bees begin foraging at young ages and harvest a greater quantity of pollen with respect to their European counterparts (Apis mellifera ligustica). This may be linked to the high reproductive rate of the Africanized honey bee which requires pollen to feed the greater number of larvae. [21] Africanized honey bees are also sensitive to sucrose at lower concentrations. This adaptation causes foragers to harvest resources with low concentrations of sucrose that include water, pollen, and unconcentrated nectar. A study comparing A. m. scutellata and A. m. ligustica published by Fewell and Bertram in 2002 suggests that the differential evolution of this suite of behaviors is due to the different environmental pressures experienced by African and European subspecies. [22]

Proboscis extension responses Edit

Honey bee sensitivity to different concentrations of sucrose is determined by a reflex known as the proboscis extension response or PER. Different species of honey bees that employ different foraging behaviors will vary in the concentration of sucrose that elicits their proboscis extension response. [23]

For example, European honey bees (Apis mellifera ligustica) forage at older ages and harvest less pollen and more concentrated nectar. The differences in resources emphasized during harvesting are a result of the European honey bee's sensitivity to sucrose at higher concentrations. [24]

Evolution Edit

The differences in a variety of behaviors between different species of honey bees are the result of a directional selection that acts upon several foraging behavior traits as a common entity. [24] Selection in natural populations of honey bees show that positive selection of sensitivity to low concentrations of sucrose are linked to foraging at younger ages and collecting resources low in sucrose. Positive selection of sensitivity to high concentrations of sucrose were linked to foraging at older ages and collecting resources higher in sucrose. [24] Additionally of interest, “change in one component of a suite of behaviors appear[s] to direct change in the entire suite.” [24] [25] [a] [b]

When resource density is low in Africanized honey bee habitats, it is necessary for the bees to harvest a greater variety of resources because they cannot afford to be selective. Honey bees that are genetically inclined towards resources high in sucrose like concentrated nectar will not be able to sustain themselves in harsher environments. The noted PER to low sucrose concentration in Africanized honey bees may be a result of selective pressure in times of scarcity when their survival depends on their attraction to low quality resources. [26]

The popular term "killer bee" has only limited scientific meaning today because there is no generally accepted fraction of genetic contribution used to establish a cut-off.

Morphological tests Edit

Although the native East African lowland honey bees (Apis mellifera scutellata) are smaller and build smaller comb cells than the European honey bees, their hybrids are not smaller. Africanized honey bees have slightly shorter wings, which can only be recognized reliably by performing a statistical analysis on micro-measurements of a substantial sample.

One of the problems with this test is that there are other subspecies, such as Apis mellifera iberiensis, which also have shortened wings. This trait is hypothesized to derive from ancient hybrid haplotypes thought to have links to evolutionary lineages from Africa. Some belong to Apis mellifera intermissa, but others have an indeterminate origin the Egyptian honeybee (Apis mellifera lamarckii), present in small numbers in the southeastern U.S., has the same morphology.

DNA tests Edit

Currently testing techniques have moved away from external measurements to DNA analysis, but this means the test can only be done by a sophisticated laboratory. Molecular diagnostics using the mitochondrial DNA (mtDNA) cytochrome b gene can differentiate A. m. scutellata from other A. mellifera lineages, though mtDNA only allows one to detect Africanized colonies that have Africanized queens and not colonies where a European queen has mated with Africanized drones. [27] A test based on single nucleotide polymorphisms was created in 2015 to detect Africanized bees based on the proportion of African and European ancestry. [28]

Western variants Edit

The western honey bee is native to the continents of Europe, Asia, and Africa. As of the early 1600s, it was introduced to North America, with subsequent introductions of other European subspecies 200 years later. [29] Since then, they have spread throughout the Americas. The 29 subspecies can be assigned to one of four major branches based on work by Ruttner and subsequently confirmed by analysis of mitochondrial DNA. African subspecies are assigned to branch A, northwestern European subspecies to branch M, southwestern European subspecies to branch C, and Mideast subspecies to branch O. The subspecies are grouped and listed. There are still regions with localized variations that may become identified subspecies in the near future, such as A. m. pomonella from the Tian Shan Mountains, which would be included in the Mideast subspecies branch.

The western honey bee is the third insect whose genome has been mapped, and is unusual in having very few transposons. According to the scientists who analyzed its genetic code, the western honey bee originated in Africa and spread to Eurasia in two ancient migrations. [30] They have also discovered that the number of genes in the honey bee related to smell outnumber those for taste. [31] The genome sequence revealed several groups of genes, particularly the genes related to circadian rhythms, were closer to vertebrates than other insects. Genes related to enzymes that control other genes were also vertebrate-like. [32]

African variants Edit

There are two lineages of the East African lowland subspecies (Apis mellifera scutellata) in the Americas: actual matrilineal descendants of the original escaped queens and a much smaller number that are Africanized through hybridization. The matrilineal descendants carry African mtDNA, but partially European nuclear DNA, while the honey bees that are Africanized through hybridization carry European mtDNA, and partially African nuclear DNA. The matrilineal descendants are in the vast majority. This is supported by DNA analyses performed on the bees as they spread northwards those that were at the "vanguard" were over 90% African mtDNA, indicating an unbroken matriline, [33] but after several years in residence in an area interbreeding with the local European strains, as in Brazil, the overall representation of African mtDNA drops to some degree. However, these latter hybrid lines (with European mtDNA) do not appear to propagate themselves well or persist. [34] Population genetics analysis of Africanized honey bees in the United States, using a maternally inherited genetic marker, found 12 distinct mitotypes, and the amount of genetic variation observed supports the idea that there have been multiple introductions of AHB into the United States. [35]

A newer publication shows the genetic admixture of the Africanized honey bees in Brazil. The small number of honey bees with African ancestry that were introduced to Brazil in 1956, which dispersed and hybridized with existing managed populations of European origin and quickly spread across much of the Americas, is an example of a massive biological invasion as earlier told in this article. Here, they analysed whole‐genome sequences of 32 Africanized honey bees sampled from throughout Brazil to study the effect of this process on genome diversity. By comparison with ancestral populations from Europe and Africa, they infer that these samples had 84% African ancestry, with the remainder from western European populations. However, this proportion varied across the genome and they identified signals of positive selection in regions with high European ancestry proportions. These observations are largely driven by one large gene‐rich 1.4 Mbp segment on chromosome 11 where European haplotypes are present at a significantly elevated frequency and likely confer an adaptive advantage in the Africanized honey bee population. [36]

The chief difference between the European subspecies of honey bees kept by beekeepers and the African ones is attributable to both selective breeding and natural selection. By selecting only the most gentle, non-defensive subspecies, beekeepers have, over centuries, eliminated the more defensive ones and created a number of subspecies suitable for apiculture. The most common subspecies used in Europe and the United States today is the Italian honey bee (Apis mellifera ligustica), which has been used for over 1,000 years in some parts of the world and in the Americas since the arrival of the European colonists. [ citation needed ]

In Central and southern Africa there was formerly no tradition of beekeeping, and the hive was destroyed in order to harvest the honey, pollen and larvae. The bees adapted to the climate of Sub-Saharan Africa, including prolonged droughts. Having to defend themselves against aggressive insects such as ants and wasps, as well as voracious animals like the honey badger, African honey bees evolved as a subspecies group of highly defensive bees unsuitable by a number of metrics for domestic use. [ citation needed ]

As Africanized honey bees migrate into regions, hives with an old or absent queen can become hybridized by crossbreeding. The aggressive Africanized drones out-compete European drones for a newly developed queen of such a hive, ultimately resulting in hybridization of the existing colony. Requeening, a term for swapping out the old queen with a new, already fertilized one, can reduce hybridization in apiaries. As a prophylactic measure, the majority of beekeepers in North America tend to requeen their hives annually, maintaining strong colonies and avoiding hybridization.

Defensiveness Edit

Africanized honey bees exhibit far greater defensiveness than European honey bees and are more likely to deal with a perceived threat by attacking in large swarms. [37] These hybrids have been known to pursue a perceived threat for a distance of well over 500 meters (1,640 ft). [ citation needed ]

The venom of an Africanized honey bee is the same as that of a European honey bee, but since the former tends to sting in far greater numbers, deaths from them are naturally more numerous than from European honey bees. [38] While allergies to the European honey bee may cause death, complications from Africanized honey bee stings are usually not caused from allergies to their venom. Humans stung many times by the Africanized honey bees can exhibit serious side effects such as inflammation of the skin, dizziness, headaches, weakness, edema, nausea, diarrhea, and vomiting. Some cases even progress to affecting different body systems by causing increased heart rates, respiratory distress, and even renal failure. [39] [40] Africanized honey bee sting cases can become very serious, but they remain relatively rare and are often limited to accidental discovery in highly populated areas.

Fear factor Edit

The Africanized honey bee is widely feared by the public, [41] a reaction that has been amplified by sensationalist movies (such as The Swarm) and some of the media reports. Stings from Africanized honey bees kill on average one or two people per year. [42]

As the Africanized honey bee spreads through Florida, a densely populated state, officials worry that public fear may force misguided efforts to combat them.

News reports of mass stinging attacks will promote concern and in some cases panic and anxiety, and cause citizens to demand responsible agencies and organizations to take action to help ensure their safety. We anticipate increased pressure from the public to ban beekeeping in urban and suburban areas. This action would be counter-productive. Beekeepers maintaining managed colonies of domestic European bees are our best defense against an area becoming saturated with AHB. These managed bees are filling an ecological niche that would soon be occupied by less desirable colonies if it were vacant.

Misconceptions Edit

"Killer bee" is a term frequently used in media such as movies that portray aggressive behavior or actively seeking to attack humans. "Africanized honey bee" is considered a more descriptive term in part because their behavior is increased defensiveness compared to European honey bees that can exhibit similar defensive behaviors when disturbed. [ clarification needed ] [44]

The sting of the Africanized honey bee is no more potent than any other variety of honey bee, and although they are similar in appearance to European honey bees, they tend to be slightly smaller and darker in color. Although Africanized honey bees do not actively search for humans to attack, they are more dangerous because they are more easily provoked, quicker to attack in greater numbers, and then pursue the perceived threat farther, sometimes for up to a kilometer (approx. 5 ⁄ 8 mile) or more. [ citation needed ]

While studies have shown that Africanized honey bees can infiltrate European honey bee colonies and then kill and replace their queen (thus usurping the hive), this is less common than other methods. Wild and managed colonies will sometimes be seen to fight over honey stores during the dearth (periods when plants are not flowering), but this behavior should not be confused with the aforementioned activity. The most common way that a European honey bee hive will become Africanized is through crossbreeding during a new queen's mating flight. Studies have consistently shown that Africanized drones are more numerous, stronger and faster than their European cousins and are therefore able to out-compete them during these mating flights. The results of mating between Africanized drones and European queens is almost always Africanized offspring. [45]

In areas of suitable temperate climate, the survival traits of Africanized honey bee colonies help them outperform European honey bee colonies. They also return later and basically work under conditions that often keep European honey bees hive-bound. This is the reason why they have gained a well-deserved reputation as superior honey producers, and those beekeepers who have learned to adapt their management techniques now seem to prefer them to their European counterparts. Studies show that in areas of Florida that contain Africanized honey bees, the honey production is higher than in areas in which they do not live. [46] It is also becoming apparent that Africanized honey bees have another advantage over European honey bees in that they seem to show a higher resistance to several health issues, including parasites such as Varroa destructor, some fungal diseases like chalkbrood and even the mysterious colony collapse disorder which is currently plaguing beekeepers. So despite all its negative factors, it is possible that the Africanized honey bee might actually end up being a boon to apiculture.

Queen management Edit

In areas where Africanized honey bees are well established, bought and pre-fertilized (i.e. mated) European queens can be used to maintain a hive's European genetics and behavior. However, this practice can be expensive, since these queens must be bought and shipped from breeder apiaries in areas completely free of Africanized honey bees, such as the northern U.S. states or Hawaii. As such, this is generally not practical for most commercial beekeepers outside the U.S., and it is one of the main reasons why Central and South American beekeepers have had to learn to manage and work with the existing Africanized honey bee. [ citation needed ] Any effort to crossbreed virgin European queens with Africanized drones will result in the offspring exhibiting Africanized traits only 26 swarms escaped in 1957, and nearly 60 years later there does not appear to be a noticeable lessening of the typical Africanized characteristics.

Gentleness Edit

Not all Africanized honey bee hives display the typical hyper-defensive behavior, which may provide bee breeders a point to begin breeding a gentler stock [47] (gAHBs). [48] [49] Work has been done in Brazil towards this end, but in order to maintain these traits, it is necessary to develop a queen breeding and mating facility in order to requeen colonies and to prevent reintroduction of unwanted genes or characteristics through unintended crossbreeding with feral colonies. In Puerto Rico, some bee colonies are already beginning to show more gentle behavior. This is believed to be because the more gentle bees contain genetic material that is more similar to the European honey bee, although they also contain Africanized honey bee material. [49] This degree of aggressiveness is surprisingly almost unrelated to individual genetics - instead being almost entirely determined by the entire hive's proportion of aggression genetics. [50] [48] Also while bee incidents are much less common than they were during the first wave of Africanized honey bee colonization, this can be largely attributed to modified and improved bee management techniques. Prominent among these are locating bee-yards much further from human habitation, creating barriers to keep livestock at enough of a distance to prevent interaction, and education of the general public to teach them how to properly react when feral colonies are encountered and what resources to contact. The Africanized honey bee is considered the honey bee of choice for beekeeping in Brazil. [51] [52]

AHBs are a threat to outdoor pets, especially mammals. The most detailed information available pertains to dogs. [53] [54]

Less is known about livestock as victims than is known about dogs as victims. [54] There is a widespread consensus that cattle are suffering occasional AHB attacks in Brazil, but there is little documentation about this. [54] It appears that cows sustain hundreds of stings if they are attacked, but can survive with injury. [54]


Biology 112, Homework Collection P3

What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential?

2. many voltage-gated Na+ channels open

3. Na+ ions rush into the cell

5. At location g, the axon membrane is at resting potential.

2. At location f , the axon membrane reaches threshold and the voltage-gated Na+ channels open.

7. At location e, the membrane potential changes sign (from a negative value to a positive value) and the voltage-gated Na+ channels are open.

4. At location d, the voltage-gated Na+ channels are inactivating and the voltage-gated K+ channels are opening.

1. At location c , the membrane potential changes sign (from a positive value to a negative value) and the voltage-gated K+ channels are open.

6. At location b, the voltage-gated K+ channels are closing.

Suppose, however, that an action potential is artificially triggered at the point indicated by the red arrow. In what sequence would the action potential pass through points (a), (b), and (c)?

The first step in the diagnostic process is to develop a list of "candidate" conditions that might explain the patient's symptoms. Your attending physician mentions a few possible causes of muscle weakness and paralysis:

- myasthenia gravis
- botulism
- hypokalemia
- hyperkalemia

She orders some initial blood work and turns the patient over to you. From talking to the patient, you get the following information about his general health and family medical history.

*He has no significant medical history and is not taking any medication.
*There is no family history of heart disease, stroke, diabetes or cancer.
*He does not smoke.
*He drinks moderately but denies use of illegal substances.
*His diet is exclusively fresh vegetables and organically raised meats.
*He does not eat pre-packaged foods.
*He works out four times a week at his local gym.
*He does not report having been sick recently.
*He has had repeated episodes of muscle weakness and paralysis over the last three months.

- Hyperkalemia is a condition in which the level of potassium (K+) in the blood rises above normal.

- Myasthenia gravis is an autoimmune disorder. Antibodies block acetylcholine receptors, preventing the opening of ion channels to depolarize the muscle cell. Patients first exhibit eyelid and eye muscle weakness or paralysis.

*Physical Examination
*Breathing, swallowing, and speech are normal.
*He has no weakness in his facial muscles, no drooping eyelids, and no vision impairments.
*Patient does not report any headaches, dizziness, or confusion.
*He has no cough or shortness of breath lungs sound clear on examination.
*His skin appears normal and intact with no open wounds.

The patient's bloodwork indicates that the potassium level in the blood is lower than normal, suggesting that the patient is hypokalemic, not hyperkalemic.

2.As a result of K+flowing down its concentration gradient, the nerve cell becomes ____hyperpolarised______.(inside of cell will lose K+ and become more negative than usual, note that resting membrane potential is -70mV.).

3. Therefore, the patients resting membrane potential has a more ____negative___ value than normal.

4. This makes it ___harder____ for the nerve cell to reach the threshold for an action potential.(threshold is -55mV).

5. As a result, the nerve cell release ____less___ neurotransmitter into the synaptic cleft,

*The kidneys are important for regulating the levels of potassium released in urine. A patient with malfunctioning kidneys may be releasing too much potassium in urine, causing the level of potassium in the blood to drop.
*Abnormal ion channels can allow large amounts of potassium to be shifted from the blood into cells under certain conditions, causing the level of potassium in the blood to drop.

A quick way to tell the difference between these two diagnoses is to calculate the transtubular potassium gradient (TTKG). The TTKG is a measurement of the amount of K+ kept in the collecting ducts of the kidneys. If the patient's kidneys are working properly, low blood potassium should trigger the kidney to severely reduce the amount of K+ being released into urine in order to attempt to raise blood K+ levels. However, if the hypokalemia is caused by malfunctioning kidneys, K+ levels in the urine will be high.

TTKO=([K+]urine × Plasma osmolarity) ÷ ([K+] Plasma × urine osmolarity)

Since your patient is Japanese, you decide to order a thyroid function test (TFT) panel that measures thyroid hormone levels (T3, T4) and thyroid stimulating hormone level (TSH). (The figure here shows how hormones in the hypothalamus-pituitary-thyroid system are regulated.) In addition, you order a test for autoantibodies that will indicate whether or not there is an autoimmune disorder such as Graves disease contributing to the patient's condition.

Use your patient's results to determine if he has TPP, and if so, the cause of the hyperthyroidism. There are several possible causes of hyperthyroidism:

*Graves disease is an autoimmune disorder in which thyroid autoantibodies are produced that bind to and activate the TSH receptor, causing an increase in the release of T3 and T4 from the thyroid.
*A thyroid tumor causes an increase in T3- and T4-producing cells in the thyroid.
*A pituitary tumor causes an increase in TSH-secreting cells in the anterior pituitary.

Scientists classify behaviors as either innate or learned, depending on whether the behavior has been influenced by previous experiences. They also attempt to determine both the proximate causes and ultimate causes of the behaviors they study.

- Egyptian vultures use rocks to break open ostrich eggs, which they then eat.
- A vulture may search as far as 50 m away from an ostrich egg for an appropriate rock (which is generally egg-shaped) to use to break the egg. The vulture then throws the rock at the egg until the egg cracks.
- This same rock-throwing behavior also occurs in young captive-hatched birds that have not been exposed to rock-throwing adults. However, these naive vultures had to learn that the ostrich eggs were a source of food.

Some scientists theorize that this behavior developed from the tactic of throwing smaller eggs to break them open. Ostrich eggs, however, are too big to pick up and throw, so perhaps the rock-throwing technique evolved in the vultures. This could explain why vultures choose rocks that are egg-shaped, rather than ones that are jagged or irregular.
Based on the scientists' observations and your knowledge of animal behavior, which of the following statements are true?

- Questioning whether the rock-throwing behavior arose from egg-throwing relates to ultimate causation.


Understanding an Abstract Concept

Zero is nothing but a number. It is one of the most important discoveries for humans. Zero has a very simple definition but still, a kid under the age of 6 struggles to comprehend the idea of zero because it is a very abstract and tricky. When we ask them to count, they start from one, not zero. If they have one toy, they say “I have one toy.” If they don’t have any toy, they don’t say “I have zero toys.” Zero is not even a number for them. However, a honeybee literally knows what is zero.

To understand that zero is less than one is a challenging thing because even a toddler is told zero represents something, such as the absence of a cookie, a toddler still doesn’t get that zero represents a quantity. For instance, in an experiment with four-year-old kids, researchers asked the kids to pick cards with the fewest dots, and when they compared a blank card and a card with one dot, less than half of the kids got the answer right. The same scientists from the University of RMIT were able to teach honeybees that zero is a quantity less than one.They presented bees with cards showing different numbers of dots. The bees were rewarded with sugar water when they selected the card with the smallest amount. After the bees were trained to always choose the lower number, the researchers upped the challenge and added blank cards to the test. Surprisingly, although the bees had never seen blank cards, they had chosen the blank card. This proved that bees can understand zero as a quantity on the number line because they chose the blank card when comparing it to a larger number like five or six than when they compared it to just one.

This is really big news for humans because if it only takes a bee-sized brain to get complex abstract concepts, maybe there are far more efficient ways to design AI. We could make better, more efficient computers one day.


European honey bee (Apis mellifera)

European honey bees have been present in Australia for about 190 years, but their distribution and abundance has increased dramatically over the last 80 years. The actual number of feral colonies is unknown but they are patchily distributed being least abundant, if not absent, from alpine areas and inland areas away from water. European honey bees visit the flowers of at least 200 Australian plant genera and interact with a wide diversity of native flower-visiting animals.

Feral European honey bees can outcompete native fauna for floral resources, disrupt natural pollination processes and displace endemic wildlife from tree hollows. However, there is insufficient research about interactions between European honey bees and Australian biota to fully describe their impacts.

Managed hives of European honey bees form the basis of an industry that provides significant crop pollination services around Australia. Pollination services and the production of honey and associated bee products were estimated by the House of Representatives Inquiry into the Future Development of the Australian Honey Bee Industry as between $4 and $6 billion in 2008.


More than 700 North American Bee Species Are Headed Toward Extinction

P opulation levels of more than 700 North American bee species are declining as habitat loss and pesticide use continue at a breakneck pace, according to a new report.

The report from the Center for Biological Diversity relies on an evaluation of more than 1,400 bee species with sufficient data for the assessment. More than half of those species are on the decline and nearly a quarter is at risk of extinction, according to the report.

&ldquoWe&rsquore on the verge of losing hundreds of native bee species in the United States if we don&rsquot act to save them,&rdquo said study author Kelsey Kopec, a pollinator researcher, in a statement. “If we don&rsquot act to save these remarkable creatures, our world will be a less colorful and more lonesome place.&rdquo

The study joins a growing body of research sounding the alarm on the threats facing bees. A 2015 report from a United Nations group found that populations are declining for 37% of bee species, with 9% of butterfly and bee populations facing extinction.

The insects play an important economic role as pollinators helping sustain agricultural production. In the United States, that value reaches billions of dollars annually, according to a 2015 White House report.


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