Sunday, May 3, 2015

Pollen shortage a major threat to honeybees



There have been lots of breathless reports about the decline of honeybees, but no consensus on the cause.

A new study suggests it’s not so much pesticides, although they play a role. And not entirely parasitic pests, another favorite bad guy. 

(Image:  A honeybee settles onto a wildflower. Photo credit: U.S. Department of Energy Fermi National Accelerator Laboratory.)

But nutrition. The youngest bees may simply not be getting enough nutritious food to eat, causing impacts for the rest of their lives. Specifically, not enough pollen.

That’s a conclusion of a paper in the journal PLOS ONE, by Hailey Scofield and Heather Mattila, both of the Department of Biological Sciences at Wellesley College.

It's a major discovery, since pollen shortages have not been at the top of anybody's mind with regard to the national loss of bees called colony collapse disorder. It's not even mentioned on the Fish and Wildlife Service web page on the loss of honeybees.

To be clear, parasites, pesticides and diseases are threats—but they’re bigger threats for a weak bee, the authors of the new paper say. 

“A chief concern about the impact of poor nutrition on honey bee colonies is the possibility that it acts synergistically with other environmental stressors to undermine colony function. Notably, undernourished larvae are particularly vulnerable to some of these stressors, including pests, pathogens, and pesticides,” they write.

A hive’s pollen resources can be limited because it’s not flowering season, or because the habitat is poor (just not enough flowering plants around), or because the hive is being so aggressively managed that the bees for one reason or another don’t collect enough pollen—“commercial management practices that put colonies in intense competition for pollen sources that may lack diversity, be poorly nourishing, or flower infrequently.”

Pollen is a bee’s source of protein as well as other nutrients: “The chief source of nutritional stress in colonies is inadequate access to pollen, which provides the essential protein, lipids, vitamins, and minerals that are required for larval development and adult function.”

It is a reason that sugar water, which is sometimes fed to bees in lean times, can be a poor substitute for real food—pollen and nectar.

Pollen shortages can impact a bee for life if they occur during the insect’s larval stage, the paper says.

“Pollen stress during larval development had far-reaching physical and behavioral effects on adult workers. Workers reared in pollen-stressed colonies were lighter and shorter lived than nestmates reared with adequate access to pollen,” the authors write.

The authors don’t say pollen shortages are the only problem for bees, but that the impacts of any other threats are magnified in the presences of nutritional deficiencies.

“We found that pollen stress during larval development had far-reaching negative effects on task performance by adults later in life. Critically, performance deficits extended to foraging and recruitment, which are the most important tasks that honey bees perform as provisioners for their colonies and as pollinators of human-cultivated crops,” they write.

Wild bees as well as managed hives have been severely impacted in the Islands by pests like the varroa mite and the small hive beetle. The health of bees is important, since so many Hawaiian crops are highly dependent on bees for pollination. They include avocado, lychee, longan, rambutan, starfruit, macadamia and guava. 

For more information on Hawaiian bees, check the University of Hawai`i Honeybee Project website

© Jan TenBruggencate 2015

Sunday, April 26, 2015

Volcanic eruption links Hawaiian, Canary Islands.




A volcano eruption in the Canary Islands of the Atlantic has helped prove those islands have a lot in common with the Hawaiian Islands—geologically.

(Image: The Canary Islands from space. Credit: European Space Agency.)

The October 2011 eruption off the Canary island El Hierro trapped ancient rock from the seafloor inside fresh volcanic pumice, and drove it to the surface. 

In some of that rock, scientists found tiny fossils that date to the Cretaceous period. 

The Cretaceous  was 65 to 145 million years ago, when dinosaurs roamed the planet, flowering plants were spreading, ants and butterflies appeared, and humans were still a gleam in Mother Nature’s eye.

The floating rocks from the El Hierro eruption contained “sedimentary xenoliths.” A xenolith is an older rock that gets trapped inside lava.

Inside some of that older rock, the scientists found tiny fossils that they were able to date, and researchers led by Kirsten Zaczekconcluded that by dating the rock, they were able to conclude that the Canaries were formed through the same process by which the Hawaiian Islands were formed.

 “The sedimentary xenoliths were contained in ‘floating stones’ of up to soccer ball size that consisted of dominantly light-coloured pumiceous glass coated with basanite, which we have termed ‘xeno-pumice,’” the scientists wrote.

Their discovery led to the overturning of the dominant theory about the formation of the Canary islands and shed information that clarified ancient geologic mysteries.

“The origin and life cycle of ocean islands have been debated since the early days of geology,” they wrote.

A popular account in phys.org is here


Zaczek and her colleagues were able to show that the Canary Islands were successively older going from east to west. It suggested that, like Hawai`i, that the Canaries were formed from a volcanic plume that erupts through the earth’s mantle as the region's tectonic plate moves over the plume.

“The erupted El Hierro sedimentary relicts provide crucial support for an east-west age progression for the onset of volcanism in the Canary archipelago by demonstrating unequivocally that the youngest pre-island sediment is located beneath El Hierro. 

“The fossil evidence from El Hierro therefore concludes the current debate on the origin of the Canary Islands and reinstates a mantle-plume as the most plausible cause of volcanism in the Canary Islands,” the paper’s authors conclude.

They found in the pumice-encased sediment rock a lot of coccolithophores.
These are open ocean single-celled algae that deposit calcium, and which becomes fossils after settle to the sea floor. Different species of coccolithophores have gone extinct at known times, making them good markers for dating geological sediment.

The Hawaiian Islands are also older as you move west from the newest, Hawai`i Island.

© Jan TenBruggencate 2015

Tuesday, April 21, 2015

“Naturally transgenic” sweet potato upends conventional wisdom



New research confirms that things are a lot wilder outside the genetic modification laboratory than in it.

We’ve known for a long time that genetic modification between distant species occurs in nature. It’s a process called horizontal gene transfer.

(Image: Naturally genetically modified sweet potato in a Hawaiian garden.)

Shucks, we’ve got virus DNA in our own genome. And RaisingIslands reported earlier about animals containing genes from plants. 

By comparison, this latest bit of information isn’t so strange: Bacterial DNA being found inside sweet potatoes. 

The new paper’s authors, led by Tina Kyndt of the Department of Molecular Biotechnology at Belgium’s Ghent University, call it “an example of a naturally transgenic food crop.”

What is notable, perhaps, is that the other examples revealed to date aren’t food crops, but sweet potatoes clearly are. What is also notable is that if you’re claiming that that there’s something inherently unnatural about moving genes between distantly related species, you don’t know nature.

In the case of the sweet potatoes, researchers found evidence of the genetic material of two different kinds of bacteria inside the sweet potato genome. Both are bacteria that are known to insert themselves into other species.

Agrobacterium rhizogenes and Agrobacterium tumefaciens are plant pathogenic bacteria capable of transferring DNA fragments ... bearing functional genes into the host plant genome,” the authors write.

That is, the genes not only get into the sweet potato, but they do things there. They remain functional. The authors suggest—but admit they can’t be sure yet—that something about the introduced genetic material is what made early humans select it for agriculture.

“It is … conceivable that one or more of the transferred genes contributed to the expression of a trait that was subsequently selected for during domestication,” they wrote. Kyndt and her co-authors assume that since none of the closely-related wild relatives of the sweet potato have the bacterial genes in them.

Sweet potatoes, Ipomoea batatas, are originally from South and Central America, but have been carried by early people around the world. The authors compared hundreds of samples of domesticated sweet potatoes from South and Central America, Oceania, Asia and Africa with wild varieties in South and Central America.

“The acquisition of new genes that confer a selective advantage is an important factor in genome evolution,” they wrote.

The  techniques used by the bacteria to insert their own genes into plants have been used by plant geneticists to do essentially the same thing, Kyndt and her co-authors say.

“This naturally occurring mechanism has been adapted by plant biotechnologists to develop genetically modified crops that today are grown on more than 10% of the world’s arable land, although their use can result in considerable controversy.”

© Jan TenBruggencate 2015

Monday, April 20, 2015

Delisting Hawai`i's humpbacks--when are there enough of them?



The federal government has proposed delisting the Hawaiian humpback whale from endangered status, and the move has much of the marine environmental community in an uproar of opposition.

But this has been a long time coming. 

(Image: Humpbacks in Hawaiian waters. Credit: Lou Herman/NOAA.)

NOAA started reviewing the listing status of humpbacks in 2009. In 2013, the Hawaii Fishermen's Alliance for Conservation and Tradition called for delisting, and last year, the State of Alaska called for delisting of the central North Pacific whale population.
 
“After reviewing the petitions, the literature cited in the petitions, and other literature and information available in our files, we found that both petitioned actions may be warranted,” the agency said.

NOAA’s National Marine Fisheries Service announced: “We … have completed a comprehensive status review of the humpback whale (Megaptera novaeangliae) under the Endangered Species … and announce a proposal to revise the listing status of the species.”

NOAA will publish in tomorrow’s (4/21/15) Congressional Register its proposal to consider 14 populations for humpbacks and to delist 10 of them, including the population that comes to Hawai`i. (Two populations would remain endangered and two would be recategorized threatened.)

The four populations still in trouble are the Arabian Sea and Cape Verde Islands/Northwest Africa populations, as well as the Western North Pacific and Central America populations. 

But the agency concluded that: “the West Indies, Hawaii, Mexico, Brazil, Gabon/Southwest Africa, Southeast Africa/Madagascar, West Australia, East Australia, Oceania, and Southeastern Pacific DPSs are not in danger of extinction throughout all or a significant portion of their ranges or likely to become so in the foreseeable future.” (DPS is the acronym for distinct population segment.)

The reasons for proposed delisting: Humpack whales have recovered strongly since whaling for them was largely stopped half a century ago, and since they were granted Endangered Species Act protection. 

NOAA found that the Hawaiian population, which winters in the Islands and summers in cooler waters near Alaska, is genetically distinct from other Pacific populations and seldom moves between populations.

Their population has jumped many times its pre-protection level. The population is estimated at 12,000 individual whales, and is believed increasing at 5.5 to 6 percent each year. They are so common today that boaters sometimes have difficulty avoiding running into them in Hawai`i. 

“Reports of vessel collisions in Hawaii have increased since 2003 … Numerous collisions have also been reported from Alaska and British Columbia,” the NOAA report says.

The facts seem clear, but any time the government proposes delisting species, there’s an uproar. The Mainland U.S. has seen angry debates over the proposed delisting of the wolf. And Hawai’i residents are currently debating suggestions that the green sea turtle be delisted.

The Pacific Whale Foundation lists three reasons for its opposition to delisting:


“Lack of sufficient pre-exploitation population estimates for North Pacific populations of humpback whale; Poor understanding of the relationship between humpback whale stocks within the North Pacific; An inadequate evaluation of threats to humpback whales in the North Pacific, including entanglement in fishing gear, underwater noise pollution, ocean acidification, habitat loss and destruction, ship strikes, loss of prey, ecosystem changes and climate change.”

The Center for Biological Diversity also cited climate change and ocean acidification for its opposition. 

Of course, every creature in the sea is at risk from climate change and ocean acidification, and many species are impacted by marine debris and other human activities in the oceans. A reasonable question seems to be, given large and increasing populations, what justification would keep an animal on the endangered species list.

A Honolulu public hearing on the issue will be held, and electronic comments on the proposed delisting will be received for 90 days. NOAA’s webpage on the whales is here.

It is notable that the report assumes the continuation of the protection for whales in Hawai`i under the Hawaiian Islands Humpback Whale National Marine Sanctuary, either in that form, or as an ecosystem-based sanctuary, as proposed under a new draft management plan

The sanctuary is accepting comments through June 19 on that plan.

© Jan TenBruggencate 2015