Continue reading “Breeding a better bee: Three social immunity traits, one massive experiment”
The harpoon shoots out from its egg-shaped case like a microscopic military-grade weapon. It hits its target – a honey bee midgut cell – dead on, piercing the cell membrane and latching on. But the harpoon was not built to kill (at least not right away). Instead, still attached to its case via a tubular tether, it begins injecting infectious material into the host cell, seizing the cell’s resources to do its bidding in as little as two seconds. The poor cell has no choice but to comply, facilitating the mass production of more tiny, egg-shaped spores until it ruptures, releasing new spores into the gut to begin the cycle anew. And so, the nosema infection takes hold.
Nosema spores might look nondescript, but their modus operandi is anything but. The microscopic spore particles drift in the honey bee’s midgut lumen, waiting to come across the unsuspecting epithelial cells lining the gut wall. Nosema disease, or nosemosis, is now the most globally prevalent honey bee disease, and in some regions (mainly in the Mediterranean), it can be devastating.1 Although once thought to only affect adult bees, it can actually proliferate in larvae, too.2 The only approved treatment against nosemosis is the antibiotic fumagillin, but now, it’s no longer for sale.
On April 12, 2018, Medivet Pharmaceuticals Ltd. – a company based out of High River, Alberta – announced that they were closing their doors. And shutting down Medivet means shutting down production of the world’s supply of fumagillin, in the form of their quick-dissolving product, Fumagilin-B. “The production and sale of Fumagilin-B has been the bread and butter of Medivet Pharmaceuticals for many years,” Ursula Da Rugna, president of Medivet, wrote in a public letter announcing their closure. “Once all our inventories have been sold we will dismantle our facilities; it is expected we will be closed by June 2018.”
Medivet’s ghostly website still warns of a scam, where an unknown, ineffective substance was being sold cheaply under the label of Fumagilin-B. But this fraud, which was confined mainly to Middle-Eastern countries, is not what forced them to close.
Medivet relied on another company, CEVA Sante Animale in Libourne, France, to supply the active ingredient in Fumagilin-B: fumagilline DCH (which stands for dicyclohexylamine). But for reasons that aren’t clear, CEVA Sante Animale’s outsourced manufacturer is no longer allowed to produce it, and it’s unlikely that another company will step in soon to fill their shoes. “I don’t know of another company that can do it,” Ursula says. “Without fumagilline DCH, no more Fumagilin-B can be produced.”
Now, as we tip-toe into fall – when most beekeepers would begin treating for nosema – many are wondering where to turn. After their announcement last spring, Medivet’s Fumagillin-B inventory quickly sold out to their distributors and customers. No doubt some beekeepers have a stockpile of the antibiotic at home, but even that won’t last forever. “There are no other chemical medications approved for treatment of nosema anywhere in the world,” Ursula says. “There are some labs around that are trying to test other compounds to treat nosema, but I don’t know of any that are close to registration and approval for sale.”
This sounds like a disaster, but could it actually be good for the industry in the long term? It’s certainly not a practical solution, but if there is no longer an effective treatment for the disease, there will be stronger selective pressure for innately resistant colonies over time. Understandably, most beekeepers in heavily affected regions probably wouldn’t be willing to risk these losses to natural selection. But fumagillin treatment may not be as beneficial as we think, at least, with the way it is currently administered in practice. Some evidence suggests it may actually be exacerbating infections, rather than annihilating them.
Read the full article in the September 2018 issue of American Bee Journal.
“Give the drone’s thorax a pinch,” Jeff Pettis instructed as I took the drone he handed me. “Then squeeze the abdomen between your thumb and forefinger, rolling from the front of the abdomen to the tip.” I flipped the drone upside down and started to pinch the thorax as coached, feeling a crispy crunch as it buckled and killed the bee. I stifled a shudder – I always hate the sensation of crushing an exoskeleton, whether it belongs to a bee or another insect. The drone’s abdomen still pulsed with reflexive breaths, which quickly stopped as I squeezed it from front to back.
Jeff was showing me how to harvest fresh semen from drones. That day, we were just practicing, but semen collected in this way can then be used for instrumental insemination or tested for sperm viability. And sperm viability is a critical determinant of queen quality, and ultimately, colony longevity—dud sperm directly translate into fewer workers, less genetic diversity, and potentially smaller colonies. New research suggests that sperm viability is compromised by common challenges like temperature stress and pesticide exposure, even more than previously thought.
As I squeezed the abdomen, it felt like it was going to explode between my fingers. But sure enough, instead of bursting, the endophallus shot out from the hind end, pausing with two bright orange horns (cornuae) poking out as if someone was blowing into an inside-out rubber glove. It looked truly alien. “That’s a partial eversion,” Jeff confirmed. “Now keep squeezing.”
The rest of the phallus exploded from the abdomen with a pop. Sitting on top of the bulbous end were a few microlitres of creamy café au lait colored semen, poised for collection.
A drone’s purpose in life is to grow big enough and strong enough to compete with other drones for access to a virgin queen during her nuptial flight. If successful, they mate in mid-air, he deposits that drop of semen inside of her (explosive pop included), his phallus rips from his body, and he falls to his death. For every queen, about fifteen to twenty drones mate with her and reach this morbid fate. But while the drones themselves may die, their sperm will live inside the queen for years, fathering millions of offspring over the course of the queen’s life.
How is it possible for sperm to stay alive in the queen for so long, when in other animals, they live only minutes or days? Human sperm, for example, only stays alive outside a male’s body for about twenty minutes (or several days, in the female’s fallopian tube). Queen ants, which are also social insects, put even honey bees to shame; most ant queens store live sperm for upwards of ten years.
In a social insect’s kingdom, the dogma is not only long live the queen, but also long live the queen’s sperm. Researchers have been searching for the mechanism of these remarkable feats of sperm storage since the 1960s, when Eugenia Alumot, from Rehovot, Israel, began investigating the sugars and enzymes that could be providing honey bee sperm with energy inside the queen’s spermatheca (the specialized organ that stores the sperm).
Now, we know that after a burst of energy used to out-swim other sperm and gain access to the spermatheca, the sperm fall into a fairly quiescent life. Specific metabolic pathways are dialed back, so once inside the spermatheca, the sperm metabolize nutrients differently. This probably enables them to minimize damage – and cell death – caused by molecules called “reactive oxygen species,” which are by-products of some types of energy-generating metabolism. But these carefully tuned metabolic shifts can easily be thrown off-balance.
Continue reading the full article in the August 2018 issue of American Bee Journal.
Love it or hate it, in this INK article I argue that genetic engineering is not inherently evil. Whether it’s good or bad is dictated by the context, motive, and intent – not the technology.
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