Protecting Invertebrates from Pesticides with Garden Futurist Aaron Anderson

Sarah Beck: I’m curious if there are some specific to the Pacific region issues. Certainly, we’ve been watching the story about the western monarchs. I’m curious if you want to talk a little bit about the monarchs or anything else that’s specific to the West.

Aaron Anderson: What I would say is taking a step back when it comes to monarchs, any type of butterfly or moth when you’re thinking about both providing habitat for them and then also protecting them from pesticides, there’s a little bit of a dual consideration because not only are they using the flowers for nectar and food as adults, but they’re also obviously feeding on the foliage.

So that increases their potential exposure to some of these chemicals because if a monarch is sprayed and the caterpillars are out there munching away on the milkweed leaves, then that’s obviously an exposure route that’s of concern, similarly as the adults are nectaring on the flowers.

So I think it’s just one of those things. When you’re thinking about any species of concern that you’re particularly interested in conserving, it’s important to think about the entire life cycle of that organism and all the different places that they might be at risk, whether it’s from pesticides or something else. And also the resources that they need and all of those different life cycles.

Sarah Beck: I actually think we might have skipped something that’s really, in the category of  “5 Minutes to Love Invertebrates,” invertebrates are really weird creatures because they don’t have the same physical existence their entire life, right?

Aaron Anderson: I think that is one of the things that’s so cool about insects is the fact that—invertebrates—you’ll start off with an egg and then potentially a larva or a nymph. It’ll pupate, turn into the adult.

I think it’s something that’s really important to do is, yeah, when you’re interested in learning more about an insect that’s in your yard, do some research. Figure out what it looks like at all of those different life stages and where it might be hanging out, where it might be overwintering. I think overwintering sites are one of the really critical determinations of insect populations in your yard.

So it’s important to keep leaf litter because so many of our native insect species will overwinter as eggs or pupae that are underneath that leaf litter, even adults sometimes. And then sometimes those are the first ones that emerge in the spring because they’re ready to go because they’ve overwintered as an adult. We call it diapause, but it’s essentially insect hibernation.

You think of cavity nesting bees, these are small bees that will nest in something like the center of a plant stem with a pithy center that they can chew their little nest in and lay their eggs there.

So you might have some roses or caneberries, asters, that are in your yard, and you have those dead-looking stems, but actually you’ve got bee larvae inside that are going to pupate and turn into adults and emerge. So there’s all of these cool places in your yards where you have insects hanging out that you might not realize when you first look.

Turning it back around to the pest control issues, because we encourage home gardeners to reduce or hopefully eliminate pesticide use in their yards. When you’re thinking about alternative management, one of the most important things to do is to understand the life cycle of the pest that you’re trying to control, because then you can break that cycle either by interrupting the pest itself, physically or eliminating the conditions and resources that the pest needs to thrive.

So this isn’t just for conserving the insects you want, it also will help you get rid of some of those insects that you don’t want.

Sarah Beck: The power of understanding that life cycle.

I know we’ve talked before about leaving stems and the dead growth, letting that overwinter. I know, Aaron, I think you had told us before, be cautious not to go clean that up too quickly because those bees need a chance to emerge again, right, in the spring?

Aaron Anderson: Right, exactly. Especially when you’re thinking about stems. So if you have a plant stem that was a live plant that just died back, a bee’s not going to be able to use it that year because they would have. So you have to let that stem wait until the next summer when it’s a dry stem that a bee can actually chew its way into, and then you have to leave that all the way until the next year by the time the bees actually emerge and some bees do emerge earlier in the years, but some of them will emerge later in the summer. They’re not all emerging at the same time.

One of our recommendations is that, for those stems, just leave them up until they just start decomposing on their own. Don’t even worry about cutting them back. Because once the plant, if it’s an aster for example, puts up its new foliage, you’re not even going to see those older stems.

But yeah, you have to leave them for a couple winters, if that makes sense.

Sarah Beck: You need to slack off on being too fastidious.

Aaron Anderson: Yeah, exactly.

Sarah Beck: I keep wanting to ask designers to give us some, some tips on this. I think there could be a whole interesting design course on how you, how you camouflage. 

Aaron Anderson: That would be a really cool conversation, honestly, to have somebody with those design skills talk about how they would incorporate habitat.

Sarah Beck: Or find a way to make it add texture somewhere, where it’s adding interesting dimension, where it’s not just going to look like, “Oh, there’s a dead thing next to a green thing.”

Aaron Anderson: Totally. And one of the things we tell people, too, is sometimes people want to have that more conventional manicured garden aesthetic, right? But you can have sections of your yard, maybe,   that are less visible, but you can let be a little bit more wild and provide habitat.

There’s a lot of different ways to do it, which is cool.

Sarah Beck: As I always like to say, brown is a color.

Aaron Anderson: It is, exactly.

Sarah Beck: You have said that a very small percentage of insects in our gardens are actually causing any type of harm. I’m just wondering if you can give us a little perspective on that. Because I think one of the easiest approaches to some of these pest issues is sometimes, are you sure something needs to actually be done?

Aaron Anderson: You hit the nail on the head there. So the statistic that I’ve heard is that, when you’re thinking about pests and insects, only about 2 percent of described insect species are what we would consider pests, and the other 98 percent are directly beneficial to us or they’re otherwise foundational to ecosystems.

So the odds are overwhelmingly, when you’re looking and you see something small crawling in your garden, it’s doing something helpful. When you’re considering, “Oh, do I have to worry about this?”

Just because something is eating your plant doesn’t necessarily mean it’s a pest. Herbivores exist, they’re okay. Most hardy plants will be resistant to a good amount of herbivory. They’re part of that food chain, right? And then beneficial insects like predators and parasitoids will be feeding on those herbivores. You want those in your garden because those will help keep a pest outbreak from actually exploding.

So having this healthy ecosystem, having a little herbivory on your plants is a good thing, especially if you’re hoping to provide habitat because you need to have butterflies and moths, they need to eat plants as caterpillars.

Sarah Beck: When you’re starting with plants that are doing really well, those plants can handle a few munches on some leaves.

Let’s say you are suspicious as a gardener that there is a very real pest situation. Do you recommend taking a closer look when you want to figure out, “Hey, is this a pest?”

Aaron Anderson: Yeah, if something does seem out of balance, because problems do arise even in a really well-planned garden, then—like you were saying—the question is then when and how to intervene. Sometimes intervening with a nonchemical method is needed when something seems out of balance, or the damage is potentially a threat to the survival of the plant.

As home gardeners can tolerate more damage to plants than farmers can, for example, but at a certain point you’re like, okay, this plant looks like it’s really at risk. Or maybe the pest is eliminating the flowers that you wanted to provide for pollinators or something.

The first step is to get a firm identification of what that pest is, because then that’s the only way you can really understand the life cycle and how you might be able to take care of it. Smartphones are a really great gardening tool because you can take photos. So taking notes of whether you see leaf curling or browning or skeletonizing of leaf veins, things like that. Yeah, knowing exactly what you’re dealing with before you make any decisions about management is really important.

Next recommendation would be to contact your local extension service or master gardener hotline which often have a diagnostic lab or can otherwise identify or diagnose those issues.

Sarah Beck: Don’t shoot first.

Aaron Anderson: Yeah, no, you’ve got to understand what’s there. I think you were mentioning this earlier on, Sarah, is that the first foundation is prevention. Making sure you’re planting the right plant in the right place, it has the correct resource for it to survive, appropriate watering, things like that, because stressed plants have a much harder time mustering defenses to insect infestation or to disease. That prevention stage is super important for pest control.

Still at the stepped back level, we really encourage planting a diverse suite of plants, in particular including some native plantings to bolster populations of natural enemies. These are predators and parasitoids that will attack the pest insects.

These diverse plantings have been shown to increase the abundance and diversity of these predators and parasitoids, and that’s really the foundation of good nonchemical pest control, having that diverse suite of natural enemies.

Beyond that, for many diseases and certain larval infestations, just sanitation. So just removing that infested plant material is a really good choice to reduce the level of damage and break that development cycle of that pest or disease. You can cut infested flowers or other plant materials and throw it away. You don’t want to compost it cause you want to take it off site.

Sarah Beck: That is such a great point. In fact, that’s such a simple action, especially if when you’re seeing something, the damage is really concentrated in one spot. It could just be gone.

Some of these insects, you can just come up and be the aggressor yourself as the big, powerful human that you are.

Aaron Anderson: That is a great way to put it. That was actually going to be my next point. For a lot of insect outbreaks, handpicking or squishing them, knocking them off with water, for example, can be a really good first step. It can be a little bit tedious, but I’ve definitely done this in the garden with caterpillars, things like that. You just go out there, look for them, pluck them off.

And it’s deliberate, it’s cautious and it helps save other wildlife from harm. You have aphids, a quick blast of water can knock those off. There’s a lot of simple mechanical ways to deal with those pests.

Sarah Beck: I had a friend whose grandmother used to say, in relation to squishing insects in the garden, “You can wash your hands.”

Aaron Anderson: I love it.

Sarah Beck: You’ll be fine.

Aaron Anderson: That’s a great perspective. I love that.

Sarah Beck: I’m just wondering if you have some suggestions for gardeners who really care about this issue and maybe it’s a concentric circle thing. Are there some things within your neighborhood, within your neighbors, that there’s a role to play? Is there perhaps a community role to play in tracking this issue and supporting?

Aaron Anderson: It works on all levels. At the individual level, stopping pesticide use at home is something that’s really important and easy that you can do, obviously in your own yard, but then scaling up, like you were saying, at the community level.

Talking to your friends and neighbors, if you have a rapport with them. Tell them why you garden the way you do and your goals, and see if you can get an understanding of where they’re coming from and some of their concerns, maybe why they’re using some of these chemicals if they are. Then you can potentially provide information. I think that meeting people where they’re at thing is really important.

We have the Bee City USA program, is an arm of Xerces. One of the things that you have to pledge when you become a Bee City affiliate is to reduce pesticide use and to have an integrated pest  management (IPM) plan.

If people are interested, I’d 100 percent encourage people to see if they can get a groundswell of support and make their community or campus—because there’s also Bee Campus USA—make their city or campus a Bee City.

I think one practice that ties into the home garden that’s worth talking about is the risk of pesticide exposure from plants purchased at nurseries. At Xerces with partners, we sampled those milkweed plants at nurseries in, I think it was 15 different states. We found that milkweed samples from that study had an average of 12 pesticides present, including plants that were labeled “bee friendly” and “we don’t spray neonics.”

The demand from nursery plants to be aesthetically appealing and pest-free and damage-free is really high. Yeah, so that’s definitely something to be concerned about, both when you’re buying a plant to put into your yard but also in a general sense, like okay, these pesticides are out there.

We’ve produced two fact sheets. One is “Buying Bee-Safe Plants” and the other is “Offering Bee-Safe Plants.”

I think the three basic steps as the consumer you can take are to ask for organic plants, avoid plants treated with those long-lived highly toxic systemic insecticides like neonics, and try to get to know nursery practices to see if they’re using pollinator-friendly production.

A lot of the nurseries might not know the answer because they’re buying them from growers and they might not know all of the particulars, but I think asking those questions will demonstrate consumer demand for bee-safe plants. Hopefully if more and more people are aware of the issue, it can potentially shift what some of the nurseries are offering,

I guess this is where I can dive and talk a little bit about neonics. Neonics are a hot topic insecticide when it comes to bee conservation because they’re highly toxic, and the other issue with them is that they’re systemic, which means the plant uptakes these chemicals and expresses them throughout the plant.

So the leaves, but then also the pollen and the nectar will all be contaminated with the pesticide.

Sarah Beck: So if you’re munching the plant or if you’re pollinating the plant.

Aaron Anderson: Exactly. You’re still going to be exposed to neonics. They’re highly toxic and many of them can be quite persistent, particularly in woody plants. They can stay for, in some cases, years. But for even an herbaceous plant, if you purchased a plant at a nursery that’s contaminated with neonics or has been treated with neonics for that first growing season, there’s likely going to be measurable amounts of neonics.

If you have a plant and you’re not sure whether it’s been contaminated with neonics, you can still plant it, but you can net it with like a fine mesh for that first growing season so that pollinators and other beneficial insects can’t actually access it, that risk of exposure is lessened. You can also try to knock some of the soil off of the roots. Sometimes these pesticides are applied as soil drenches, for the plant’s roots to uptake.

Sarah Beck: That’s shocking. I just had this assumption, you get a nursery plant, you bring it home, it’s got a very minimal amount of soil with it. And my assumption would have been that a short quarantine and these things dissipate. It sounds to me like the neonics are, like you said, persistent, which is very concerning and I think that raises enough of an alarm bell to say when you’re purchasing plants, you need to be asking those questions.

I do appreciate that you mentioned your resources. I want to say that we are going to include along with the transcript we’ll have a whole list of links and resources, fact sheets.

 It’s so fun talking about invertebrates, even though it’s very tragic and sad. And I wish you hadn’t told me about the origin of the name Xerces. I knew that it was a butterfly, but I didn’t realize that it was tragically lost butterfly that was right near my homeland.

Aaron Anderson: I do want to stress, despite the doom and gloom about insect declines and the impacts that pesticides have, the fact that insects are really able to use these small habitat patches, yards, parks, things like that, which is amazing.

Sarah Beck: What does it look like when we design our urban spaces and our towns and landscapes within those to be without the harmful chemicals? That can happen. We can that future, right?

Aaron Anderson: Homeowners, renters, people who are managing our urban spaces, like parks, schools, all of these green spaces and urban areas are reducing or limiting pesticide use and using a lot of these other resources.

There’s a lot of cool organizations doing really neat stuff, trying to promote athletic fields being managed without pesticides. We have golf courses, places like that. The connectivity that would provide for habitat really does scale up to that landscape level and we can provide this connected habitat for invertebrates, but other animals and organisms as well across the landscape and provide connectivity to extant habitat on the outside of cities.

I’m having this mental image of this interconnected, green, wonderful urban space. I think that potential is there. We just have to make the conscious decision to do that.