About Author: Paige Howorth

Posts by Paige Howorth


It’s (Almost) Black Tuesday for Bees

The damaging effects commercially managed bees experience from pesticides are also suffered by native bees.

The damaging effects commercially managed bees experience from pesticides are also suffered by native bees.

Yes, I mean the catastrophic crash of the stock market in 1929 and the economic Great Depression that followed. As I listened to today’s stock market gains and losses on PBS’s “Marketplace,” I was struck by how closely our society follows this information. We pay attention because it affects our lives directly. The situation with pollinator decline is no less critical yet is barely on the radar of most. Since we have not hit bottom yet, it seems like a problem for another day—and there is no index to tell us how close we are.

Still, the warning bells are ringing. Pollinators like bees, butterflies, beetles, and flies are in crisis worldwide, suffering from pesticide exposure, habitat loss, and disease. Pollinators make fertilization possible for many plants; without them, food as we know it would simply not exist: no fruits, veggies, peanut butter, or chocolate—and that’s just a start.

If this suddenly sounds like the same old story you hear about humans and nature, stay with me a little longer. It’s more than another wildlife-in-crisis story, and I can guarantee that it will affect you personally—and definitely financially—if we keep the current course.

So, in the spirit of “Marketplace,” let’s do the numbers!

Visit the San Diego Zoo’s Pollinator Garden.

30% of the food we eat results from insect pollination.
This includes everything from cucumbers to squash, coffee to basil, strawberries to cantaloupes, cashews, and everything in between. It doesn’t include the insect-pollinated foods like alfalfa and clover that we feed to our livestock (where we get milk, eggs, and meat), so the percentage is likely much higher.

There is a 59% decline in overwintering monarch butterflies in the Central Mexican butterfly preserves since 2012.
75% of the Earth’s flowering plants depend on insect pollination to set seed or produce fruit.
The value of insect-pollinated crops in the US is $27 billion.

US beekeepers experienced a 30% decline of managed honeybee colony winter losses in the 2012-2013 year.
This number is far greater than the acceptable range of losses and only represents winter loss, not total loss. There are only about 2.5 million commercial honeybee colonies in the US. For perspective, it takes 1.6 million colonies to pollinate the annual almond crop alone.

All insects are affected by contact with insecticides. In particular, a newer class of systemic insecticides called neonicotinoids has been shown to severely affect bee health. In agriculture, this type of insecticide is most often applied as a seed coating, and the insect nerve poison is subsequently expressed in every tissue as the plant grows; leaf, stem, pollen, and nectar.

As a result, though the insecticide is targeted at “pest” insects, there can be serious consequences for any insect that visits the plant for nectar or pollen. Some need only be present when the planting occurs, as some of the chemical seed coating is released in a crop “dust” in agricultural plantings. The effects of these pesticide exposures include immediate death by contact, but some are sub-lethal, meaning that the animal does not die right away but experiences disorientation, loss of navigational ability, paralysis, and even memory loss as the result of contact.

Though there are federal regulations governing the concentrations of these poisons in agriculture, there are none for home use. Many products containing this type of insecticide can be found in local home improvement stores for landscaping use. Consumers often do not follow the instructions for application, and the concentrations can be many times higher than federal regulations allow. This means more of the poison will find its way to bees and other insect pollinators through gardens and runoff from irrigation.

It is important to note that the majority of research on pesticide effects in pollinators has been conducted in honeybees, because they are managed commercially and are thus more accessible and measurable. Since their biology is very similar to that of native bees, it is safe to assume that the damaging effects they experience from pesticides (and other sources) are also suffered by native bees.

Habitat loss
As human populations grow, less space remains for native pollinators. Overgrown spaces with wildflowers, weeds, and nesting sites are disappearing, making way for manicured lawns that eliminate key nectar and pollen sources like dandelions and encourage pesticide use. Agricultural practices claim land that was once suitable pollinator habitat with a diversity of nectar and pollen sources and replace it with insecticide and herbicide-laden monocultures.

Genetically modified (GM) crops
Two types of GM crops are routinely used in agriculture. One is an insect-resistant type, where a bacterium that is lethal to certain insects is incorporated into the genome of the plant, and the target insect species are killed upon feeding on the plant.

The second is an herbicide-resistant variety and is definitely of concern for pollinators, especially butterflies and bees. In herbicide-resistant GM crops, the plants are engineered to be resistant to applications of certain herbicides. As a result, the crop can withstand repeated applications of herbicide, which in turn kills all the flowering weeds surrounding the planted area.

This is of particular concern for monarch butterflies, whose larval host plant is milkweed, which thrives in disturbed habitats and has historically been found adjacent to crops. Most people are familiar with the epic migration of the monarch butterfly to the oyamel fir forests of Central Mexico. This year, the count of overwintering monarchs in the protected reserves revealed a catastrophic drop—down an incredible 59 percent from that of 2012 and standing at an all-time historical low since the migration was discovered in the 1970s. Lack of available host plants due to GM-related herbicide application has been identified as a significant contributor to this staggering decline.

There are a great many parasites and pathogens that burden pollinators such as bees, and the ones causing the most damage are introduced species. Native bumblebees suffer from a nonnative fungal disease, while honeybees struggle with introduced ectoparasites such as Varroa mites and fungal infestations from Nosema spores.

A combination of all these and probably other factors has created the phenomenon Colony Collapse Disorder, which is decimating honeybee colonies in the US. The precise cause is unknown, because the bees simply disappear, thus taking the evidence with them. But one thing is clear—life is hard for commercial honeybees these days.

Pollinator gard_1

A native bee house for mason and leafcutter bees in the Pollinator Garden provides holes to make nests.

At the San Diego Zoo, we are committed to helping pollinators recover:

Providing a safe haven
We have a pollinator “way station” at the Pollinator Garden, located at the entrance to Elephant Odyssey. This space is dedicated to helping sustain pollinators by providing a steady supply of pesticide-free nectar and host plants, as well as suitable living spaces for native bees. We have a large section of milkweed available for monarch butterflies to lay eggs on from spring through fall, helping to boost the West Coast population.

Educating our guests
Our Education Department is working with Zoo Corps kids to help raise native milkweed for monarch butterflies in our Pollinator Garden. Staff have also incorporated the garden as a teaching tool for various curricula.

Live and let live
Where possible on Zoo grounds, we allow honeybee swarms to move on in their own time and only actively remove established hives when either human or collection animal health is clearly at risk.
National Pollinator Week awareness
The Entomology Department participates every year in National Pollinator Week, with the help of many departments. During the entire week, the insect keepers are giving daily presentations on bees and other pollinators at the honeybee display in the Insect House at 11:30 a.m. and 2:30 pm.

A steady wave of small choices can help turn the tide. Here are a few ways you can help:

Buy organic
If you don’t currently buy any organic foods or clothing, think about picking even one item the next time you visit the store. For one, you could potentially lower the demand for crops produced using pesticides and reduce the overall application (over one MILLION pounds yearly) of these chemicals in the US. This alone will help pollinators.

Secondly, even if you don’t care about whether or not you eat GM crops, buying crops that are genetically modified supports the practice of widespread herbicide application in agriculture and the decimation of pollinator habitat that results. Organic items cannot intentionally include GM crops; those labeled “No GMO” have been positively determined not to contain them. One item in your basket is a small step in the right direction for pollinators.

Build your own way station
Plant some milkweed! Create a habitat in your yard, garden, or flowerbox that invites pollinators. Some great planting information can be found at www.xerces.org, along with more details on the status of pollinators and insect conservation in general.

Avoid pesticide use at home
If you really, truly must use pesticides, read the manufacturer’s instructions on recommended concentration, and only use it at or below that level.

Let part of your lawn go wild for pollinators
Long, overgrown grasses create a perfect habitat for nesting and overwintering native bees, and flowering weeds are a staple nectar and pollen source for bees and butterflies alike. Keep in mind that most native bees are solitary and do not sting readily. They are good, safe neighbors—especially if you have a garden.

Tell your friends
Most people have no idea that the sustainability of food as we know it is so tightly linked with the health of pollinators. Share what you know!

This week, June 17 through 23, is National Pollinator Week. It is the perfect time to visit the Zoo’s Pollinator Garden and spend some time watching monarch butterflies laying eggs, and bees and hummingbirds finding a nectar or pollen meal in a beautiful flower.

But it is an even better time to act. If we can all make one small change in our habits this week, we could make a big difference for pollinators. To bring it back to our financial analogy, it has been said that if more people knew the current status of pollinator decline, they would be more concerned with that than with the ups and downs of the NASDAQ or S&P 500.

So now you know the stakes—and you are definitely a stakeholder. Will you invest in the solution?

Paige Howorth is an animal care manager at the San Diego Zoo. Read her previous post, The Queen Will Not Be Denied!


The Queen Will Not Be Denied

The queen's head and part of her thorax peek out of the fungus garden at her last "sighting" in 2007. The size difference between the queen and the worker ants is dramatic.

A keeper jokingly told me the other day why, early in his career, he chose to work with large mammals: “I like to actually be able to find and count all the animals in my care.” It made me laugh—who wouldn’t? But at that time I didn’t know that I would soon be counting—at long last—one of the most notorious and elusive animals in the San Diego Zoo’s insect collection and that it would inspire more anxiety than relief!

Tracking animals in the Zoo’s entomology collection affords little of the numerical certainty that helps to manage other animal groups. The reality is that in some of our invertebrate cultures, there are just going to be too many individuals to count, and certainly too many to count each day. This is not to say that we don’t keep track of them—in fact, we adhere to very strict permit conditions issued by the U.S. Department of Agriculture (USDA) in order to display and rear the regulated exotic invertebrates in our collection. When they recommend, as a containment measure, the presence of queen–excluding mesh on our leafcutter ant queen’s accommodations, that’s what we provide. Huh? Allow me to explain…

Paige prepares to moves the young colony and queen into the queen chamber in 2007.

All ant species have a reproductive division of labor, an overlap of at least two generations, and cooperative care of young. For our leafcutter ants (one of the most highly specialized ant species on Earth), it translates to one enormous queen ant, which accomplishes all the egg-laying in the colony, and hundreds of thousands of varied-age sterile worker ants that do everything else. (This is an immense oversimplification, but a treatment of leafcutter ant biology and behavior is another blog entirely!)

Leafcutters are quite famous for the long, green rivers of cut plant material that they produce while traveling back to their nests. They use the cuttings as a substrate to maintain and grow a fungus within their nests that they use for food. In the areas where they occur—particularly Central and South America—they are widely regarded as agricultural pests. So it is no surprise that our regulatory agencies would like to feel secure that though we may not always be able to see the queen ant, we always know where she is. Enter the queen excluder!

The queen ant in the tropical species that we hold, Atta cephalotes, is a big girl. In ant terms, she towers over the other colony members at a size of about one inch in length. But it is the widest, most rigid part of the queen’s body that the excluder must contain—the thorax. Our queen-excluding mesh is ¼-inch x ½-inch, big enough for the largest ants to access her chamber, but sufficient to keep Her Majesty in one spot.

And in one chamber she has remained for the five years she has been with us. We always feel confident that she is doing well based on the colony behavior and health of the fungus gardens (particularly the royal one), and that has to be enough, as we have not actually SEEN her for four years. Buried within the royal chamber, she is busy laying eggs (close to 30,000 per day), and participates in no other daily aspects of colony life. As long as she is producing continual reinforcements for the short-lived adult ants, the work of the colony carries on.

Here’s the containment area in the Insect House, showing the current housing of the two leafcutter ant colonies at the San Diego Zoo. Individual fungus gardens for each colony are maintained within the larger terraria.

Early in November, we noticed that the ants were reducing the amount of fungus in the queen chamber, little by little. Knowing that as the queen goes, so goes the colony (for leafcutter ants are not capable of producing a “backup” queen if their foundress dies), this was an unsettling turn of events. Each day we would check the garden and try to triangulate the height and shape of the fungal peaks (“Do you think it looks smaller today? I think it looks smaller.”), until we could no longer deny that something was changing. And that change seemed likely to include the relocation of the queen, since the ants had already started the demolition of her quarters.

The ants, of course, are quite oblivious to our needs, wants, and regulations. If they encounter an obstacle in nature, they do what it takes to surmount it. So here we were, faced with the unconquerable result of a decision rule (the obvious desire to move her), a very large queen, and a port of exit too small to safely accomplish the task (the excluder mesh). This made me very nervous, because I knew they would try to get the queen where they wanted her to be, but the outcome of that effort might be MOST unsatisfactory to ALL parties involved.

When I came in on Sunday, senior keeper Barb told me that the ants had been trying to move the queen out through the mesh, royal head first. Panic! There are anecdotal reports of other captive colonies, faced with this very circumstance, giving it a try and ending up with the head of the queen on the outside of the chamber and the rest of her body inside—effectively excluded, but with a huge price. Barb covered the entrance with a piece of plastic, and I headed for the toolbox in a hurry.

The young colony's fungus garden was only the size of a softball when it arrived at the San Diego Zoo.

As long as the excluder keeps the queen in a controlled area (one that could be examined if need be), we are well within the limits of our permit. Since the back area of our display colony houses several fungus chambers, including the queen’s, we decided to give her access to all of the other chambers in the off-exhibit area and move the excluder to the port that leads into the exhibit. In this way, the ants would have some freedom to choose where to house the queen, and all we would lose is the ability to know exactly in which of the 11 chambers she resides. Though that specific knowledge is a huge benefit for long-term management of the colony, I decided that we could live without it—after all; there is no long-term management for a colony with a headless queen.

In fits and starts, scraping angry, biting ants off of each hand as I went, I snipped away the steel excluder mesh at the chamber entrance, placed a fitting with a new excluder on the exit tubing, and removed the plastic barrier that Barb had placed earlier that morning. Within an hour or so, I got a call from lead keeper Kelli: “They are taking her out!” I ran back to the containment room, and we all watched a few supermajors (also known as soldiers) emerge with an entourage of medium-size workers carrying the queen! They made a direct line for a chamber on the bottom row, and after a few gut-wrenching (for us) tries to get her in there sideways, they figured it out, and she was in. And then she was GONE! During the transport, she remained still, but once she hit the ground in the chamber, she made her way quickly to the interior.

Seeing the queen of a leafcutter ant colony is a really unique, fascinating, and rare experience. It is a glimpse of a hidden world, and for insect lovers, akin to seeing a celebrity—only way better! But in managed care, it can be nerve-racking, because it could mean that the colony is rejecting something about their current living arrangement. So it appeared here, and we are happy to have been able to read the signs and facilitate the transition.

A few days later, there is harmony again, with all chambers receiving new leaf material and business resuming as usual. Leafcutter queens can live at least a decade, laying more than ten million eggs per year. Assuming there was no disease or failing in fertility that precipitated this event (or any that follow it), I hope she stays with us for the rest of her long life. And please understand that I say this in the most respectful way: I would gladly count lions, eagles, or stick insects all day long, but I hope I NEVER see Her Royal Majesty again!

Paige Howorth is an animal care manager at the San Diego Zoo. Read her previous post, Off with his Leeeeg!


Off with His Leeeeg!

A bird-eating spider like Mino

Mino is a spider—a really, really big one! In fact, he is a goliath bird-eating spider, one of the largest tarantula species in the world. With a leg span of around 9 to 11 inches (23 to 28 centimeters) measured toe to toe across the body, an abdomen covered with urticating or barbed, itchy hairs, and an attitude, he is a perfect example of “look but don’t touch.”

So what happens when you have to get up close and personal with this guy? You do it very, very carefully!

Mino’s keeper, Chris, noticed recently that his right rear leg had developed a necrotic area near the “knee.” Mino is an old guy (for a male tarantula), and we expect him to go on for another few months at best, so we opted to wait and see if he could get the leg portion off or if it would dry up and fall off on its own. Since Mino’s leg was not leaking hemolymph (spider blood), we felt safe to watch it for a while. Chris became concerned about a week later, when the leg “rot” seemed to have traveled to the segment closest to his body, so we decided it was time to intervene.

The typical response to a leg injury for a tarantula is to remove the leg, or portion of it, at the closest joint, and then stem the flow of hemolymph with superglue or other quick-drying adhesive (no, I am not kidding!). I decided on Saturday morning that we should proceed with the surgery as soon as possible, and Isabel and I got him prepped while we waited for our veterinary technicians, Marianne and Jill.

Tarantula, and really any invertebrate, medicine has been historically limited; however, there have been many advances in recent years within the veterinary community, and of course our vet staff has been riding the wave. I was prepared to provide anesthesia in the form of carbon dioxide (CO2) gas for Mino, both to reduce the stress of the procedure and ensure the safety of those of us sticking our hands in his tank! Thanks to Kim, the nursery keeper that day, we had a lab tray ready with long-handled cotton swabs and a big syringe with a curved tip for irrigation. Isabel and I were suited up with safety glasses for the hairs that aerosolize when kicked off, leather gloves, and a CO2 tank and plastic cover for administering the anesthesia.

A word about anesthesia and invertebrates: within the invertebrate collection, we regularly use CO2 to ensure the safety of the keepers and animals. When I moved the leafcutter ant queen and workers over to their new home on exhibit, I used CO2 to “chill them out” during the move and avoided being ravaged by the huge soldier ants. When Ester services the assassin bug exhibit, she uses CO2 to do a thorough cleaning, rather than have to dodge the piercing mouthparts of 300 venomous bugs! Using CO2 seemed like the logical step for Mino’s surgery, though we had never before needed to use it on a tarantula.

When Marianne and Jill got there, I went over what I thought would be the best plan: gas, forceps, irrigation, swabs, glue, new enclosure. Any questions? Marianne then told me that she had attended a veterinary lecture dealing specifically with tarantula leg removal (wow, what are the odds?!), and that the use of CO2 would interfere with the animal’s natural mechanism to cast the leg. She also said that when the spider wakes up from the anesthesia, it can be very aggressive as a result. Armed with this information, and since I already consider Mino to be a fairly aggressive spider, we decided to go cold turkey.

I coaxed Mino out of his burrow. His leg looked close to coming off, but still needed some help. I put a clear, square plastic container over his body to protect Marianne as she grabbed the end of the leg with forceps and applied pressure. Mino bared his fangs and protested, but, to my surprise, eventually began rotating in a circle (as Isabel chased him with the flashlight), almost like he knew what was going on and wanted to help. That is me being incredibly anthropomorphic, but in reality his behavioral responses are probably lined up for something like this if it happened in the wild! After a few minutes, the leg released, cleanly separating from the joint near the base. We moved him to a new enclosure with a more sterile substrate, and since no hemolymph was leaking at all, we didn’t even have to apply the glue. Success—and high fives all around!

The ailing leg, along with tools of the trade

Mino is still in recovery but doing well. Chris and I have since been using a natural umbilical cord-care powder on the stump, and it looks dry and clean. Since he is not getting too defensive when we reach in to apply the powder, he is still getting his attitude back—but we have every reason to believe he will recover and live out the rest of his days in seven-legged peace.

This was a great example of how progressive our vet staff is and how we all have new things to learn, every day. And also how to give TLC to an animal that can be hard to get close to, in more ways than one! Look for more adventures from Mino’s “brothers” in future blog posts—we are working on breeding this species, and since we have one receptive female and several males, it is going to be an interesting summer.

Paige Howorth is an animal care manager at the San Diego Zoo.