Pest Control Designed by Nature: An Interview with Ron Whitehurst
Ron Whitehurst is a Pest Control advisor for Rincon-Vitova Insectaries, winner of the Global Regenerative Business Award in 2016. Rincon-Vitova has been a pioneer in providing biological solutions to pest management since the 1950’s. Ron is also the author of Reading Weeds as Soil Indicators. Arty Mangan, Bioneers Restorative Food Systems Director, interviewed Ron at the EcoFarm Conference.
ARTY: In a natural environment, what is the relationship between insect predators and prey?
RON: With a natural enemy complex in a natural setting, occasionally you’ll see a large number of some particular insect, but for the most part what you see is a mix of all kinds of different insects and a number of different predators and parasites, as well as a number of pathogens. There’s usually a natural balance. It’s a dynamic balance, though, so occasionally you do see large concentrations of one kind of insect out in the natural environment.
But on farms and such, we encourage people to look at a bunch of one kind of pest as a way of focusing their attention. There should be three or four different predators feeding on it, five or six different parasites, and a number of pathogens keeping it in check. What’s out of balance? How can I gently shift the balance so that this pest is not favored?
ARTY: What are the consequences of spraying pesticides?
RON: There are different consequences with different pesticides. Starting with the softest first, water can be used in a first stage response to an aphid infestation on a plant. The first thing that you’re encouraged to do is pick up the hose and blast the aphids off the plant. During the rapid colonization expansion phase of aphid growth, aphids don’t have wings. The females give birth to live baby aphids, inside of those tiny baby aphids there’s little ovaries, and inside those ovaries there’s more little baby aphids developing. So, they’re literally born pregnant.
The first thing you do is wash them off the plant, which has a very minimal effect on the plant. Another response would be using soapy water. Mix about a 1% soap solution and spray that and it will kill a lot of things on contact because it makes the water wetter and it suffocates the insects.
The next step up would be an oil spray, that has a suffocating effect on a lot of different insects. Then there’s the toxic pesticides, and there’s microbial insecticides. So, it kind of depends on the kind of pesticide, and how much it disrupts the environment. That’s why we, as a first pass, ask people to get off of the toxic synthetic broad spectrum pesticides so they minimize the negative effect on the environment so that the ecology will rebound into a natural equilibrium.
ARTY: Insects can develop resistant to certain pesticides? How does that work?
RON: That’s where biological controls have an advantage. The insects don’t build up a resistance to being eaten. There are some behavioral changes that they can develop so the prey will evade the predator, but for the most part, resistance is not something that we have to concern ourselves with biological control.
Toxic pesticides latch onto a metabolic pathway in the insect. In an insect population, you have lots of diversity of genetics, so when you spray one of those toxic pesticides, it’ll knock out all the insects that are depending heavily on that particular metabolic pathway. Some insects of that group will either be able to put in place another pathway around the pathway that’s not working because of the pesticide, or they’ll develop some kind of mechanism to detoxify the poison.
When my wife was in high school, she worked with a guy looking at the development of resistance in house flies to the common pesticides of that era. She was working with concentrated pesticides on a bench with no ventilation, and she wasn’t able to have babies because of that. Getting off pesticides, for us, is a personal issue.
That was around 1970 or so. Starting from there, we knew we could document a problem with chemical pesticides. We knew that, because of the resistance, pesticide producers would be developing a series of toxins that would have to keep changing and probably become worse and worse. But even before we had the documentation, there were good ecologists who said that chemical pesticides were a stupid idea, and made a case that it is wrong-headed. They understood that we want to be more efficient at killing agricultural pests, but we need to understand the ecology and work with nature.
We think it’s a good idea to work with nature instead of fighting nature and trying to beat her into submission. If you think about it, do we really want to win over nature? If we basically kill off nature, then that means that we have to take on all the roles that nature was providing like thermoregulation of the planet, providing air, water, and nutrients to everything on earth. It wouldn’t be good for our species.
We’re facing the sixth major extinction on the planet, so we feel a very strong imperative to engage as many of our fellow members of our species to do what they can on whatever little patch of paradise that they manage, to learn to work with nature, to not use toxins, to build up the ecology, to build up the whole community of natural enemies – the predators, parasites, pathogens, and antagonists – and grow stuff, sequester carbon into the soil, pull the carbon dioxide out of the air where it’s a pollutant and fix it into the life forms in the soil. That’s what sustains us on the planet.
ARTY: Many years ago, an entomologist from Fresno State told me that synthetic nitrogen, when it’s in a plant, attracts insects and also stimulates their reproductive process.
RON: When you use synthetic nitrogen, it’s taken into the plant and the plant makes what could be thought of as funny proteins, short little peptides. They’re not functional, but they make the sap of the plant sweeter, and so it’s much more attractive to the sucking and chewing insects. There’s this carrot that the chemical fertilizer manufacturers dangle in front of growers: use this chemical nitrogen and your plants will be bigger and lusher and more succulent and more attractive to your customers who want big juicy-looking vegetables. But you’re shooting yourself in the foot because those vegetables then are more attractive to the sucking/chewing insects. Following the chemical paradigm, you are then required to use the chemical pesticides to kill the pest insects that are attracted to these lush, succulent, juicy and very sweet fruits, and kill the beneficial predators of those insects as well.
Dr. Elaine Ingham, one of our heroes, says that all the nutrients a plant needs are available in all the soils she’s tested. Not necessarily in plant available form, but they are there. What you need to do to grow plants on any soil all over the world is just get the biology right. We don’t need to add chemical fertilizers to the soil, we just need to add nutrients to feed the soil microbiology that will mobilize those nutrients.
ARTY: What effect does monocropping have on pest pressure?
RON: Having a 50 or 100-acre field of just one variety of one plant puts out this huge plume of aroma, that says, “Come, eat me,” to the kinds of insect pests that like to eat that particular crop. For the most part, monocrops are not natural.
Sometimes you’ll see fields of one particular kind of flower or some other plant, but if you look closer, there’s all kinds of other plants mixed into it. The one flower may be dominant, but for the most part, plants are all mixed up in nature. We should take our cues from nature. There’s different shapes of fruit systems, there’s different shapes of the above-ground parts. Physically the plants fit together in different ways.
There are certain plants that have this special relationship with particular bacteria. For example, rhizobium bacteria grow in the nodules of a lot of legume plants and can pull nitrogen out of the air and fix it into soluble forms that the plants can use. Those legume plants can share that with the neighboring plants, or in succession when the legumes die.
Nitrogen is one of the limiting factors for plant growth in a lot of ecosystems. Having a source of nitrogen next to you is a big advantage for plants. That relationship is one of many kinds of relationships where a plant will do better in a community rather than being one kind of plant growing solid in a field.
Plants have different smells. They put off a range of signals and cues to various insects in the environment. Dr. David James at Washington State University looked at the aromas coming off of plants when they’re under attack by aphids, and he found things like phenylethanol and methyl salicylate. Methyl salicylate, the wintergreen aroma in Bengay, signals to the beneficial insects to come and feed on the pest, and the salicylates help turn on or upregulate the immune system in plants.
We’re also learning how mycorrhizae fungi associate with the roots of plants and transfer nutrients from one plant to the other. Plants grow better in a community, just like, for the most part, people do better in a community. There are a few rare individuals who are better off by themselves, but we all do better and thrive in a supportive community.
In most home gardens, people mix up a lot of different things, they generally have a lot of different kinds of plants in the garden. That makes it much easier to manage the nutrition and control pests. Monocrops set up a banquet for pests and ties us to the chemical paradigm of, “see a bug, kill a bug.” We need to get away from that.
Agriculture is often hailed as the start of civilization, but the contrary perspective is that it was our downfall. I subscribe to the view that when we started growing mass quantities of grains and living in dense communities our health went down and there were all kinds of problems as far as social interactions and competition for resources leading to wars, etc. I think we need to get back to horticulture, of growing a diverse mixture of perennial plants with some annual plants in the mix.
ARTY: What role do weeds play in a healthy insect ecology?
RON: In a lot of conventional agricultural situations, the only diversity in the field are the weeds. They can be really important as far as providing alternate food sources for your beneficial insects. Looking at a couple of examples, there’s the lacewing and the syrphid fly. The adult green lacewings are vegetarian. So why would you want them to come to your garden? They eat pollen and nectar and honey dew, things like that. Honey dew is the sugary poop from aphids.
If you have some flowers, lacewing and syrphid flies will be able to use the nectar resource for their energy source, and they’ll be able to fly around in that area and find some of the food that their offspring, their larvae, feed on, like aphids. They’ll lay their eggs next to the colony of aphids. The syrphid fly young are little maggots, and lacewing larvae look like little alligators. The larvae will go and feed on the aphids, and then they’ll pupate and repeat the life cycle. Having that nectar resource in with the crop is really important for hosting the beneficial insects.
Sometimes in row crop agriculture, farmers take all the crop out, but having a row of living plants or sometimes even just dead plant material like perennial bunchgrass will provide really nice places for ladybugs to hide in and stay over winter, or hang out in between crops. Having some diversity in the farm landscape is really important. Sometimes weeds are the only thing that will supply that.
I’ve looked at weeds as indicators of soil conditions. You can look at the weeds growing in a field and quickly point out which weeds indicate intermittent wet like curly dock, or chicory, or cockle burr. You can point out those plants growing in your field and work on lightening up that soil so it can get better drainage or do some mechanical things to improve the drainage, like make swales up higher in the grade so water is retained higher in the landscape.
There are certain weeds that will indicate high levels of salt or other things. You can read the weeds to be able to monitor what’s going on in a dynamic way with the soil condition.
ARTY: What can farmers and gardeners do to promote a healthy biological system?
RON: It all starts with the soil. Fertilize with compost, plant cover crops, and keep the soil covered. Have some above-ground diversity by inter-planting companion plants with your crop. With a lot of the brassicas and a number of other plants, you can throw in 1% of alyssum seed, a low-growing plant that has a nice flower. It grows to about six inches tall, so it doesn’t interfere with plant growth. If you have occasional plants like that throughout your field, then you’ll be able to have a source of nectar for the beneficial insects.
Wherever you can, like along ditch banks or along drive roads, plant a little strip of flowering plants. Some are better than others, dill is a real champion for hosting a lot of beneficials. Get some flowers out there and that will help to draw in the beneficial insects. And avoid using the toxic stuff. We’re available to talk you through some suggestions as far as strategies for controlling a wide range of different insects in a lot of different cropping situations.