When the Pest Becomes the Pollinator

I think this is an Eastern Black Swallowtail on my zinnia

Because I planted lots of flowers and vegetables this spring, I am especially interested in all the pests that are competing with me for the food and with the pollinators that are insuring that the fruit matures. Getting rid of pests, however, is a delicate balance because some creatures are pests at one time in their development and beautiful pollinators at another, such as butterfly caterpillars. Some are more voracious than others in their caterpillar stage, destroying one's fruit or vegetable crop within days if not exterminated.  For instance, the adult moth (Helicoverpa zea) of the tomato fruitworm is a pollinator, but the caterpillar stage of the moth has been a constant problem this spring and summer. We have used Bacillus thuringiensis to combat the caterpillars, but they return, and by the time I see them (for they start out very small), they've done some damage to the fruit and leaves of an individual tomato plant.

According to Wikipedia, the tomato fruitworm is prolific in the wild,  eats many different kinds of agricultural plants, and is variably susceptible to Bt.  It's called the cotton bollworm when it feeds on cotton and the corn earworm when it feeds on corn, but it eats more crops than these. Because the tomato fruitworm is so voracious and because it eats the summer vegetable we love the most--tomatoes--I have become its sworn enemy this season.

caterpillar of Eastern Black Swallowtail eating my dill this morning

But I'm not consistent when it comes to killing caterpillars that eat my herbs, flowers, and vegetables. This morning, as she was leaving for work, my daughter called my attention to one of my dill plants. "There's a caterpillar on it, Mom!" she said. I know, however, that the larval stage of the Eastern Black Swallowtail can often be found on dill and other plants related to the carrot family. Sure enough, there was the caterpillar of a black swallowtail chomping on my dill. I couldn't bring myself to kill it. The dill is heading now and will soon seed, and while dill is one of my favorite herbs, I also love to see butterflies in the garden. This year, I planted three dill plants, but next year, I'm planting many more in a flower bed that I will devote to butterflies. I plan to remove humanely any butterfly caterpillars from the plants I don't want eaten to the butterfly garden where pollinators can chomp to their heart's content.

closer look at the front of the caterpillar

It is also possible that the Bt that Tom sprayed before the rain of last week might still be viable, especially in the flower heads of the dill, which the caterpillar is now eating. I will be saddened, however, to see another dead caterpillar of the Eastern Black Swallowtail on my dill. I found some earlier after Tom had sprayed the nearby zinnias, trying to get rid of the tomato fruitworms which seem to love zinnia leaves as well as tomato leaves.

Although I have gardened all of my life, for years I didn't pay much attention to pests or pollinators, beyond remarking on the beauty of a butterfly or on the ugly results of the pest. We would sprinkle a little Sevin dust on our plants and go on our way. Sevin is the pesticide that my father used on our tomatoes, too, when I was growing up in Southeast Texas. But Sevin has its issues. Sevin, Bayer's trade name for the active ingredient carbaryl, is very effective, but it's a pretty nasty chemical and will kill honeybees just as quickly as tomato fruitworms.

Sevin is used so often and for so many purposes (to kill bugs in the garden, to kill mite infestations on chickens, etc.) that it's probably safe to say that it is over-used and probably not used carefully. The ecological description on TechPac's "Material Safety Data Sheet" is enough to convince me not to use it:

This product is extremely toxic to aquatic and estuarine invertebrates. For terrestrial uses, do not apply directly to water, or to areas where surface water is present or to intertidal areas below the mean high water mark, except under the forest canopy and use on rice. Discharge from rice fields may kill aquatic and estuarine invertebrates. Do not contaminate water by cleaning of equipment or disposal of wastes. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.

C'mon, does anyone really think that folks who use Sevin are following the advice in that last sentence?

Back to squishing the tomato fruitworms and using biological controls on pests.

Leaving the untilled edges

at the edge of my yard

A few days ago, Tom and I were talking about gardening practices, and he remembered a story that one of our pastors told in a sermon years ago when we were young and still attending the Baptist church. This preacher used a farming story as an analogy for sin. He said that early Norse farmers had a practice of leaving the edges of their fields in weeds; they did not till up to the edges of their fields. Now, Tom didn't know how true this story of Norse farming was, and in several minutes of searching on the Internet, I couldn't find any reference to Norse farmers leaving the edges of their fields untilled. However, that's the story the Baptist preacher told; he probably got it out of a book of illustrations for sermons.

 So, what, according to this pastor, was so bad about leaving the edges of one's fields untilled? Weeds would flourish there, seed, and then disperse throughout the tilled land, infiltrating the harvest. A field with untilled edges is like a person who leaves just a little bit of sin in her life, the pastor said. That little bit of sin will spread its seed and poison the pure actions of a Christian. The Christian should be careful not to follow the practices of pagans; sin must be weeded out of every area of one's life. That Norse farmer would have a better harvest if he pulled out every plant not associated with the fruit of his harvest. 

This story struck us because it emphasizes a worldview that is inimical to any kind of chaos, that prefers an authoritarian control, that categorizes everything as good or evil, black or white, sin or innocence (and innocence is suspect). It's a worldview that preaches "dominion" over the earth, as if humans are the ultimate arbiters in and over Nature.  And it's a worldview with devastating consequences.

When every bit of arable land is pushed to the maximum in farming practices, the natural world suffers. Habitat is destroyed, and the creatures that depend upon that habitat are diminished as their habitat is diminished.  According to a comprehensive survey of American bird life in a report titled "The U.S. State of the Birds,"

[m]ore than 97% of the native grasslands of the U.S. have been lost, mostly because of conversion to agriculture. As a result, grassland bird populations have declined from historic levels far more than any other group of birds.

You see this worldview of authoritarian control over nature in suburban yards, where all the grass is one species, poisoned and pummeled to punish any plant that dares to raise its inflorescence above the height required by neighborhood lawn control. An unholy number of lawn and pest control products enable suburbanites to become little dictators to nature: herbicides and weed killers, fungus and disease control, algae and moss control, animal repellents (deer, rabbit, snake, mole, bird, bat, goose, cat and dog repellents), pest controls of all kinds. According to a 2002 fact sheet of the U.S. Environmental Protection Agency, "Americans use more than a billion pounds of pesticides each year to combat pests on farm crops, in homes, places of business, schools, parks, hospitals, and other public places." (my emphasis)

Everyone knows that our addiction to pest and weed control is hurting us and the planet, and yet we continue to slather the stuff on our lawns and public spaces. It just goes to show how powerful a metaphor can be: the American lawn is a stand-in for the soul--weeds and pests are the dark stain of "sin." Untidy lawns, the untilled edges of a field, are indications of moral failings.

So let's exterminate the metaphors that equate the natural world with sin.

 And leave the edges of the field untilled.


note:
Advice for creating a healthy yard, from Audubon

Where are all the little pollinators?

mountain mint flowering in my backyard

Years ago, my family and I lived in Harris County, Georgia, on approximately 24 acres of land, much of which was mixed pine and hardwoods--hickories, oaks, loblolly pine. We lived there for almost seven years before we decided that we should move back to Texas (which turned out to be not such a great move for my career, but that's another story). On those almost twenty-four acres of land we raised a few chickens (most of which eventually fell prey to the local wildlife) and planted several garden areas. One of our friends, a professor of environmental horticulture with the University of Florida, brought us some mountain mint one year, and we planted it at the edge of our lawn, where it flourished. The plant was rather unassuming, three or four feet high, with inconspicuous flowers, but to our delight, it attracted the most interesting and diverse pollinators. We had never before seen so many different bees and wasps. When we returned to Georgia several years later, we purchased more mountain mint at a local native plant garden and then, a couple of years later, transplanted a plug of that mint at our new home in Louisiana.

The mountain mint is now blooming here where we have planted it at the back of our property near pine trees. However, I have yet to see any pollinators on the mint. I am waiting for those fascinating and diverse bees and wasps to show up. Will they come?

mountain mint flowers

I thought that our vegetable, herb, and flower blooms would be covered with pollinating wasps and bees. In the spring, I left a large patch of white clover in the yard for the bees, expecting to see huge numbers of bees buzzing the oval blooms. Maybe five or six bees seemed to be in the patch at one time. When I go outside in the mornings to check on my vegetables and flowers, I see a few bees and wasps among the tomato vines, in the squash blossoms, and among the hydrangeas, but not the numbers I expect. Where are all the little pollinators?

Have they all gone the way of the honeybee? In 2006, there was a honeybee crisis as bee keepers experienced huge colony losses. Lots of reasons were advanced for what became known as colony collapse disorder: modern transportation (airplanes carrying pathogens and diseases to new territory); drought, which made bees more susceptible to diseases and pathogens; a fungus, nosema ceranae, which is believed to have been introduced into the United States in 2007; pesticides; varroa mites; among others.

More recent studies indicate that pesticides play a bigger role in honeybee decline than companies that manufacture pesticides would want us to know--most specifically, "a new class of pesticides called neonicotinoids." Neonicotinoids were developed in the 1990s

as a relatively less-toxic alternative to pesticides that seriously harmed human health, [and]... soon became the world’s fastest-growing pesticide class and an integral part of industrial agricultural strategy. In the United States alone, neonicotinoid-treated corn now covers a total area slightly smaller than the state of Montana.

Like earlier pesticides, neonicotinoids disrupt insects’ central nervous systems. But unlike earlier pesticides, which affected insects during and immediately after spraying, neonicotinoids spread through the vascular tissues of plants. They’re toxic through entire growing seasons, including flowering times when bees consume their pollen. ["Controversy Deepens Over Pesticides and Bee Collapse," an article by Brandon Keim in Wired, 6 April 2012.]

The chemical and pharmaceutical company Bayer manufactures neonicotinoids,  marketed as imidacloprid, an additive to many products, including flea control products, termite control products, roach bait gel, aerosol sprays for bedbugs, rose and flower food, and on and on and on.

As with the diminished menhaden that I described in my previous post, the primary reason for the disappearance of pollinators is ..... really, our inability or lack of will to connect the dots that demonstrate the interconnectedness of the choices we make to control pests and to grow our food. As Rowan Jacobsen, who has written a book about the honeybee crisis, reminds us:

Honeybee health is inextricably linked to the health of the entire environment, including our own. If we can create systems of domestic food production that take their cues from the cycles of nature, and let honeybees play the roles they evolved to play, then the system will take care of itself. But if we continue to push the system farther and farther out of equilibrium by relying on chemical shortcuts and fossil fuel intervention to fix the inevitable breakdowns, then we will never get off the crisis treadmill. [quoted in The New York Times'  article: "Saving Bees: What We Know Now," 2 September 2009]

Of course, we all want to control the pests that eat our plants and that bite and infect our pets. But at what cost? We use Frontline Plus on our cats to control fleas and mites. I just looked at the description of the product that we keep in a kitchen drawer; Frontline Plus contains fipronil, a pesticide that seems to work similarly to imidacloprid, if I can take Wikipedia's description at face value. Fleas that bite our treated cats die because their central nervous system is affected by the pesticide. Fipronil is also poisonous to bees and other wildlife and has been associated with colony collapse disorder. I'm not putting fipronil on my roses, so I doubt that pollinators are being affected by my cats' flea treatment, but, again, I am reminded of how each of us makes decisions every day that have consequences we least expect. Were I to choose to control the pests on my flowers and herbs with one of these pesticides, I would also be destroying the pollinators that visit those blooms.

Leaf-foot (stink) bugs on my tomato stakes

We have had a terrible recurring infestation of catepillars eating the foliage of our vegetables and flowers. To control them, Tom applied Bacillus thuringiensis (Bt) on the plants. Bt is a bacterium that is considered an environmentally-friendly control for caterpillars. However, it does kill all caterpillars, and that includes the caterpillars of our most beautiful butterflies. I was distressed to discover two dead Swallowtail butterfly caterpillars on the dill that grow near the zinnias that were treated. Also, food crops have now been genetically modified to contain the Bt gene, and the consequences of these modifications might be enormous: the monarch butterfly, for one, has been greatly affected, and some studies suggest other detrimental effects that merit further study.

These are the consequences of the choices we make to control pests, and I am becoming increasingly aware of how my own individual choices are part of those global effects. When I found those dead Swallowtail butterfly caterpillars on my dill, I decided to grow a butterfly garden next year in which I will allow caterpillars to munch to their hearts' content. I've gotten over some of my squeamishness about directly targeting pests and squashing caterpillars with my fingers. I just returned from my garden with fingertips covered with green caterpillar guts. I've even been catching stink bugs with my own hands (ugh) and crushing them with my gardening shoes. And this morning I actually took out the shop vac and hoovered up an entire clump of leaf-foot stink bugs that were hanging out together on the top of some of the tomato stakes. Now that must have been a humorous sight.

Of course, farms that grow huge quantities of vegetables cannot afford to send out scores of folks every day to pinch bugs from their plants, but we have got to find a way to achieve balance in how we control the bugs that compete with us for our food.