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Honey Bee Genome Project Reveals Possible African Origin of All Honey Bees
Thursday, Oct. 26, 2006

Walter S. (Steve) Sheppard, WSU Department of Entomology,
509/335-5180, shepp@wsu.edu
Cherie Winner, WSU News Service, 509/335-4846, cwinner@wsu.edu

PULLMAN, Wash. – An international consortium of researchers announced this week that it has finished sequencing the entire genome -- all the DNA -- of the honey bee. Washington State University entomologist Walter S. (Steve) Sheppard, a member of the sequencing team, also co-authored a study that strongly suggests that honey bees originated in Africa and spread to Europe and Asia during at least two major migratory periods during their history.

The honey bee genome results appear in this week’s issue of the journal Nature, and the report on honey bee origins appears in this week’s issue of Science magazine.

The honey bee, Apis mellifera, is only the fourth species of insect to have its entire genome sequenced. The others are the silkworm, the mosquito that transmits the malaria parasite and the fruit fly on which a large proportion of genetics research depends.

Sheppard said honey bees are one of the most economically important insects in the world. While well-known for honey production, it is their role as pollinators of crop plants that makes them so valuable to agriculture. The genome sequence provides a vast amount of information that will further our understanding of honey bee behavior and the potential impact of “intruder” bees such as the Africanized bees that have moved into parts of Texas and the American southwest over the last decade, he said.

“It’s a huge amount of data, and the statistical basis for how to analyze it is in the developmental stages,” said Sheppard.

Working with colleagues from universities across the U.S., Sheppard helped develop new techniques for tracing honey bee relationships by analyzing SNPs (“snips”), or single-nucleotide polymorphisms, within the DNA of honey bees from different regions. A SNP is a change in one letter of the DNA code that occurs in less than 1 percent of the bees examined. By looking at more than 1000 SNPs in the DNA of each of hundreds of individual bees, the researchers were able to develop a distinctive
DNA profile for bees from each region.

Sheppard said the traditional view of honey bee origins held that they first arose in western Asia, the area comprising current-day Turkey, Afghanistan, Kazakhstan and Kyrgyzistan, and migrated from there to Europe and Africa.

Among the surprising results of the new analysis was that the type of honey bee common to northern and western Europe is more closely related to modern-day African honey bees than to its geographical neighbors in central Europe. Such discoveries led the researchers to conclude that honey bees probably originated in Africa and migrated into Asia and Europe on at least two different occasions.

After hundreds of thousands of years in their new homes, with no interbreeding among the populations in different areas, they evolved into today’s subspecies whose DNA is unique enough that the SNP analysis can tell to which group they belong.

The researchers also examined honey bees captured at various sites in the U.S. They found that the SNP analysis could track the invasion of “Africanized” bees, which have both European and African subspecies in their pedigree.
 

 

All honey bees in the Americas are relative newcomers, Sheppard said. Human settlers first brought western European subspecies in 1622. A Mediterranean subspecies was imported in the mid-1800s, and an African subspecies was brought to Brazil in 1956. Sheppard said the African bees are well-suited to the wet-dry seasonality of Brazil and have one big advantage over European honey bees: they are resistant to a mite that decimates bee colonies and necessitates the use by beekeepers of chemical miticides. It is descendents of the Brazilian-African imports that have recently gained notoriety as fierce defenders of their hives.

“It’s not the stinging behavior that bothers beekeepers,” said Sheppard. “The problem is that in warm places they swarm a lot.” This behavior makes them less suited for the honey production and pollination practices currently being used in the U.S.
He said their swarming behavior, when a large colony breaks into multiple colonies, may be the main reason they have not spread farther north in the U.S. The new, smaller colonies are often too small to survive a cold winter.  
 

Bees Fight Back Against Colony Collapse Disorder: Some Honey Bees Toss Out Varroa Mites

ScienceDaily (Oct. 5, 2009) — Honey bees are now fighting back aggressively against Varroa mites, thanks to Agricultural Research Service (ARS) efforts to develop bees with a genetic trait that allows them to more easily find the mites and toss them out of the broodnest.

 ARS researchers have developed honey bees that more aggressively deal with varroa mites, a parasite that is one of the major problems damaging honey bees today.

(Credit: Photo by Stephen Ausmus)

The parasitic Varroa mite attacks the honey bee, Apis mellifera L., by feeding on its hemolymph, which is the combination of  blood and fluid inside a bee. Colonies can be weakened or killed, depending on the severity of the infestation. Most colonies eventually die from varroa infestation if left untreated.  

Varroa-sensitive hygiene (VSH) is a genetic trait of the honey bee that allows it to remove mite-infested pupae from the capped brood—developing bees that are sealed inside cells of the comb with a protective layer of wax. The mites are sometimes difficult for the bees to locate, since they attack the bee brood while these developing bees are inside the capped cells.

ARS scientists at the agency’s Honey Bee Breeding, Genetics and Physiology Research Unit in Baton Rouge, La., have developed honey bees with high expression of the VSH trait. Honey bees are naturally hygienic, and they often remove diseased brood from their nests. VSH is a specific form of nest cleaning focused on removing varroa-infested pupae. The VSH honey bees are quite aggressive in their pursuit of the mites. The bees gang up, chew and cut through the cap, lift out the infected brood and their mites, and discard them from the broodnest.

This hygiene kills the frail mite offspring, which greatly reduces the lifetime reproductive output of the mother mite. The mother mite may survive the ordeal and try to reproduce in brood again, only to undergo similar treatment by the bees.

To test the varroa resistance of VSH bees, the Baton Rouge team conducted field trials using 40 colonies with varying levels of VSH. Mite population growth was significantly lower in VSH and hybrid colonies than in bee colonies without VSH. Hybrid colonies had half the VSH genes normally found in pure VSH bees, but they still retained significant varroa resistance. Simpler ways for bee breeders to measure VSH behavior in colonies were also developed in this study.

This research was published in the Journal of Apicultural Research and Bee World.


 

Elephants Have Word for 'Bee-Ware'

ScienceDaily (Apr. 28, 2010) — For the first time elephants have been found to produce an alarm call associated with the threat of bees, and have been shown to retreat when a recording of the call is played even when there are no bees around. 

Elephants run from bee sounds making 'bee rumble'. (Credit: OU/Lucy King)

A team of scientists from Oxford University, Save the Elephants, and Disney's Animal Kingdom, made the discovery as part of an ongoing study of elephants in Kenya. They report their results in the journal PLoS One.

'In our experiments we played the sound of angry bees to elephant families and studied their reaction,' said Lucy King of Oxford University's Department of Zoology and charity Save the Elephants, who led the research. 'Importantly we discovered elephants not only flee from the buzzing sound but make a unique 'rumbling' call as well as shaking their heads.'

The team then looked to isolate the specific acoustic qualities associated with this rumbling call and played the sounds back to the elephants to confirm that the recorded call triggered the elephants' decision to flee even when there was no buzzing and no sign of any bees.

'We tested this hypothesis using both an original recording of the call, a recording identical to this but with the frequency shifted so it resembled a typical response to white noise, and another elephant rumble as a control,' said King. 'The results were dramatic: six out of ten elephant families fled from the loud speaker when we played the 'bee rumble' compared to just two when we played a control rumble and one with the frequency-shifted call. Moreover, we also found that the elephants moved away much further when they heard the 'bee' alarm call than the other rumbles.'

The researchers believe such calls may be an emotional response to a threat, a way to coordinate group movements and warn nearby elephants -- or even a way of teaching inexperienced and vulnerable young elephants to beware. Further work is needed to confirm whether the rumble call is used for other kinds of threats, not just bees.

'The calls also give tantalising clues that elephants may produce different sounds in the same way that humans produce different vowels, by altering the position of their tongues and lips,' said Dr Joseph Soltis of Disney's Animal Kingdom. 'It's even possible that, rather like with human language, this enables them to give superficially similar-sounding calls very different meanings.'

Earlier Oxford University research found that elephants avoid bee hives in the wild and will also flee from the recorded sound of angry bees. In 2009 a pilot study led by King showed that a fence made out of beehives wired together significantly reduced crop raids by elephants. The team hopes that the new findings could help develop new ways to defuse potential conflicts between humans and elephants.

Despite their thick hides adult elephants can be stung around their eyes or up their trunks, whilst calves could potentially be killed by a swarm of stinging bees as they have yet to develop this thick protective skin.

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