The Integration Part of IPM
Biocontrol agents, or biocontrols for short, is industry nomenclature for biological pest control agents. Biological in the sense that these agents are living, multicellular organisms capable of acting on their own accord, given they are provided or exist in conditions in which they can do so. Pest Control in the sense that these biocontrols, as predetermined by Ma Nature, consume what we, as humans, consider pests. And as we purchase and employ these organisms to work on our behalf, they are Agents.
Biocontrols can be anything by true definition: If you obliterate a mosquito which lights on your arm and begins to suck your blood, you are a biological pest controller — if you consider the mosquito a pest, that is. This is true of an anteater if the ants it eats are considered pests; it is also true of a chicken if it eats a grasshopper and the grasshopper is considered a pest (which it usually is). In this industry, though, biocontrol agents as they are known, are very specific to certain species of insects, mites and nematodes. To analyze further this industry meaning, there can be two categories which fall under the definition of biocontrols as identified: 1) these would be natural enemies already existing and volunteering on their own at the site needing pest control and; 2) commercially produced biocontrols introduced into a site needing pest control (which, by species, may already exist in limited numbers as natural enemies).
The transportation and introduction of produced biocontrols is regulated by the United States Department of Agriculture (USDA) and the state (in the United States, anyway) in which they will be employed. This is a requirement which affects the producer and distributor of these agents. Both must obtain a USDA permit [PPQ Form 526]. The permit process ensures biocontrol agents not suitable for use in a specific area remain out of said area. The agents do not necessarily have to be indigenous to the area where they are to be used, but they cannot be allowed to become unwanted pests themselves, and these regulations safeguard against this. They cannot, by the rules of nature, become plant pests themselves, but they can displace natural enemies indigenous to the area by eating the native species’ food. Given these circumstances they could be considered pests.
Even though biocontrol agents are commonly and popularly referred to as beneficial insects, the USDA, as was conveyed to me by the chief of the section in charge of permits at the time of my interview several years ago, prefers not to call these agents beneficial insects for two reasons: one they are not, in all circumstances, beneficial by all definitions of the word, i.e., ladybugs are not beneficial to aphids and; not all, as previously stated, are insects.
The word pesticides is a blanket term for something which kills or mitigates pests. Pests can include insects, mites, nematodes, fungi, bacteria, weeds and any other living thing which can harm agricultural or horticultural plants, trees, shrubs, etc. It can even include things which can bring harm to humans and other mammals, birds, fish, and even structures, i.e., termites are household pests. The names of specific pesticides are broken into two parts: the first part denotes the target; the second part, –cide, identifies it as something which takes life, like homicide (to murder a human) or suicide (to kill oneself). Given this information, it now makes sense that some pesticides are called insecticides, miticides or acaricide, nematocides, fungicides, bactericides, herbicides, etc. Very targeted terminology once it’s understood. In this text, though, pesticides will typically refer to insecticides and miticides or acaracides. If another type of –cide is being discussed, I will mention specifically to which one I am referring.
In an IPM program the specific targeting goes a little further than terminology. Especially when it comes to pesticides. First you want to choose a pesticide as specific as possible to the pest in question — the days of the heavy-duty broad-spectrum pesticides and broad coverage are coming to an end. That may not be easy, but you definitely need to choose one which offers the least amount of threat to biocontrols, both introduced and naturally occurring: a soft pesticide. Care must be taken when choosing a soft pesticide as compatibility is a complex issue. One which some pesticide manufacturers may take too lightly-probably for the sake of marketability. Don’t be swayed by the marketers’ claims-of-goodness. As an example, natural pyrethrins are often touted as being environmentally-friendly. Purveyors point out information such as the fact this chemical’s derived from a type of chrysanthemum flower. Sounds almost edible, doesn’t it? After all mums aren’t known killers, right? (Remember, some of the world’s most potent poisons are derived from earth-naturally-occurring.)
To a certain extent this environmental-friendliness is true. Natural pyrethrins do break down quickly-in as little as a week or two-and pose no long-term threats to the environment (none that I know of, anyway). However, this same botanical chemical is very broad-spectrum and very harmful to the vast majority of biocontrol agents, natural and otherwise. In other words, regardless of how “environmentally-friendly” this stuff is, it is not, in most cases, biorational. Moreover, believe it or not, some synthetic chemicals are actually less harmful. There are also other botanical-based products, besides natural pyrethrins, which can also be as unclear in their advertised friendliness.
Rotenone, for example, is another botanical pesticide. And it’s bad news: very toxic. Neem oil, as yet another example, can be pretty harmful; the oil that is. The active ingredient in most neem-based products is azadirachtin (from the East-Indian neem tree, Azadirachta indica), which, in itself, is broad-spectrum to many immature pests, yet seems to be quite compatible with most biocontrol agents. But, again, watch out for the oil. Oils in general smother bugs and may be harmful-even to plants-if applied heavily. However, there are products containing azadirachtin with petroleum oil — which can also be bad news-which are so diluted in their final form, that their biorationality is very much intact. With these products it is the azadirachtin which does the killing and is fairly targeted to what’s on the label, regardless of how broad-spectrum the product seems to be.
Compatibility, like I said, is very complex. The pesticides available are biorationally gauged by the effect they have with direct contact after twenty-four hours’ time (less than a twenty-five percent mortality is considered compatible or biorational within this scope). Moreover, consideration to the effects of a product’s inert ingredients, such as oils, must be given, yet there may be similar products which are not considered biorational. This is important because oils and other inert ingredients, whether used for stickiness, spreadability, flowability, emulsification or dispersal of the active ingredient(s), and are often more harmful to the biocontrol agents than the active ingredient(s) themselves. In other words the active ingredient is not the only thing to consider when choosing a product you’re thinking or hoping will be compatible with biocontrols. Please note, though, that horticultural oil can be used in as part of an IPM program due to they way it’s used and its very short residual. It may also be applied directly instead of sprayed.
And compatibility goes even further. Here’s an example of an extended compatibility issue, which is why this subject can be so complex: Ladybugs eat aphids, and if you apply a product which kills all your aphids you will, in effect, be killing all of the ladybug’s food. This can, in itself, be an issue of incompatibility. With biocontrol and IPM one must learn to think around corners.
Another factor of targeting concerns the way pesticides are used. Normally applicators will try to get broad coverage so as to impact yet undiscovered pest concentrations. Moreover, applicators try to thoroughly treat the area they are targeting by ensuring coverage is complete-to the point of dripping off the leaves. The undersides of leaves are sprayed; the stems are sprayed; the growing tips are sprayed; everything in the general area of the pests is sprayed, even the applicator him- or herself. When biocontrols are in use-which often happens naturally in a limited capacity until plants are sprayed-careful consideration should be given to a focused application of pesticides even though the chosen pesticide is as soft as possible. Target only what you absolutely have to hit, try to keep over-spray down by turning off horizontal airflow fans, etc., and use only enough of the chemical required for the micro-task at hand. If the whole greenhouse range doesn’t have pests, there isn’t a need to spray it in its entirety. Spraying, if done as prescribed, will reduce the twenty-five percent mortality acceptable within the parameters of biorationality to a lesser number, and will allow the good bugs a fairer shake. When spraying within the protocols of an IPM program, non-target organisms should not be allowed to be targeted. In the old days we just didn’t think about it or care. That’s all changed now. Think hot-spots; nothing more.
Sometimes you have to take matters into your own hands with physical controls — literally. Handpicking pests is one of the most basic and fundamental forms of physical pest control. Some growers will think handpicking is beneath them. I guess that’s understandable when you have a couple acres of plants under the cover of greenhouses or fifty acres or more of field crops. So understandable, in fact, that a few years ago I conducted an experiment to see just how washed up my thinking was. I measured a plot of nasturtiums to determine its area. It was a fifty square feet (5×10). The nasturtiums had been grown in the area in the past and had a very clear history of infestation by black aphids. In my mind, historically-based, these were known conditions which could be relied upon. I scouted the crop area on a weekly basis upon emergence of seedlings in hope of detecting the first colony of aphids. I found the first aphid colony within a couple of weeks and applied the old thumb and forefinger technique, killing them dead. I continued to scout, and on two more occasions found pioneer aphids and squashed them. Unlike when the control techniques of years’ past was doing nothing-and being that the area’s history was very accurate and predictable-the year of this trial was extremely revealing because the nasturtiums grew fast and large and finished the season without a reoccurrence of black aphids. Upon confirmation of the results I backtracked and analyzed the data I had collected as it pertained to man-hours expenditure: Scouting was included-but perhaps shouldn’t be as I always preach this must be done regularly anyway regardless of your pest control solution-and it took 0.05 man-hours; Pinching was measured at an additional 0.09 man-hours. Granted this was intensive work, maybe a labor of love, but in my eyes it was extremely worthwhile and not beneath me at all. Let me give you the end numbers so you may decide for yourself. All combined, for season-long control of aphids and a picture perfect crop of nasturtiums, including the necessary and continued act of scouting, I spent a total of two man-hours on this crop… For the entire season! Wow. I ascertained my thinking was not in the least bit washed up. Now, why on earth can’t this activity be carried out on a larger scale to the benefit of just about any grower? Ball’s in your court.
A couple of other forms of physical control are worthy of a mention here. They can affect your program so positively you’ll likely wonder why you waited so long to try them. The first is vacuuming. This technique is used to provide instant eradication of whitefly adults. It works like this: Have you ever experienced a really terrible whitefly explosion — one where the pests are so abundant they’re like clouds in a greenhouse? You know what I mean, right? Disturb the plants ever so slightly and the whitefly adults go airborne. You can almost hear their wings beating. This is where the fun begins. Take a vacuum cleaner or Shop-Vac into the greenhouse or structure, disturb the plants, then suck up whitefly adults by the hundreds, thousands, maybe even millions. Instant eradication; instant gratification! This technique won’t solve your problem, but it sure helps. For every whitefly which ends up in your vacuum cleaner bag, there are several eggs which won’t be deposited on your plants, and several larvae which will never be pupae, and several pupae which won’t emerge as adults to repeat the cycle. Sounds crazy doesn’t it? I’ve sure heard that before-until someone tries it and enthusiastically tells me how well it worked.
The second is web-wiping. This works pretty well to reduce two-spotted mite numbers. It works like this: Certain spider mites, like the two-spotted mite, produce a fine webbing-which is especially abundant indoors. This webbing usually begins its life on the undersides of infested leaves. It is run from one side of the leaf, over the midrib, to the other side. This forms a tent of sorts. Inside this tent resides female mites, their eggs and offspring. The web tent affords protection from all sorts of hazards-like some sprays, predators, etc. Now here’s where the grower intervenes. With a soapy sponge, wipe the webbing away on leaves where it is practical to do so. Between leaves rinse the sponge in more soapy water to reduce the likelihood of transferring the problem to other plants. When you’re through, you’ve successfully taken a huge bite out of the overall mite population. Now all you should have to do is to mist the plants, not so much to remove any soapy residues but to actually increase the microclimate humidity surrounding the leaves. This slows the reestablishment of the pests- they like hot, dry conditions-and it creates a better atmosphere for most predatory mites (which should be introduced shortly after you’ve wiped out the webs). Again, I’ve gotten strange looks [or puzzled grunts over the phone] upon this suggestion-especially from commercial types-until it’s tried. Then they say “thanks.”
Physical controls does go way beyond handpicking, vacuuming and wiping webs. There are other forms which are more widely accepted. For instance let’s look at trapping. The scout’s tool for one thing, a.k.a. the sticky trap, catches pests. This is known. Now if you replicate the utilization of one trap a hundred fold, won’t the number of pests which are trapped be increased a hundred fold, too? I think that would be the case. (Warning: yellow sticky traps are dangerously non-selective and may trap many biocontrol agents.) There are many other types of traps. Not designed for scouting, but used exclusively to capture pests in order to reduce overall numbers. I can’t recommend all traps as being beneficial to pest control. Some, like I wrote about yellow sticky traps, are non-selective and can do more harm than good. Others tend to attract mating pairs to a crop location which can have negative consequences. The common Japanese beetle trap is one such trap. I heartily recommend against using this type of trap as it can lure many pests of both sexes but do not capture them all, as this can exacerbate the problem.
There are many other kinds of physical controls, though, which are worth their weight in gold. A pest barrier adhesive is one such type. This goop is applied in a band around the trunk of a host tree. As caterpillars, some ants and other pests try to cross this barrier they become hopelessly mired. This type of trap or barrier should be employed at a specific time of year depending on the life cycle of the target pest. An additional consideration regarding this type of control is that it is so effective, and so many pests are captured, a regular spot-check must be made to ensure the goop is not bridged by the dead pests trapped in it. If it is bridged, the remaining pests can navigate past the trap by walking on the bodies of their dead brethren. The goop must remain clean or be reapplied as deemed necessary. Other physical barriers can include diatomaceous earth and others, but I’ll wait before I get into the thick of it. Many of the finer points will be spelled out later on this website.
There are characteristics concerning individual plants which may make some more susceptible to pests than others. These characteristics can include proximity — to vents, fans, sources of pests, etc. The attraction may also include the pests themselves, i.e., one pest leads to two pests which then leads to more. To clarify, pests send out allelochemic substances or chemical signals which to their fellow kind spell f-o-o-d, like a neon sign which says Eat at Joe’s. Or it’s like a group of people gawking at the scene of an automobile accident. To most people, curiosity make our necks a bit rubbery. Bugs are drawn to bugs as people are drawn to people. Another characteristic which may single out a specific plant amongst a crop of like plants is health. Like the lions to the antelope on the Serengeti, many pests will target the young, weak plant unable to defend itself. The plant which strays from the herd because it can’t keep pace. We see this plant as one with stunted growth or poor color. Perhaps it has a root malady or pest already. Regardless of the cause, the health, or lack thereof, is typically detected by pests long before we become aware of the condition. One reason for this is thought to be resonance. It is theorized that every living thing on earth emits a sort of energy-a vibration, if you will. All the healthy plants in the greenhouse or field resonate or vibrate on the same frequency. To the pests they see nothing which looks small enough to single out and take down. (Rarely will the lion enter the herd in an effort to take them all down.) They aren’t ambitious or stupid enough to think they have the ability to wipe out the entire crop (or herd as in the case of the lions). Pests do, however, have an uncanny ability to detect the weak plant-the one vibrating or resonating at a different frequency. The one standing out like a sore thumb. If your plants are healthy, the crop [herd] looks like one big indestructible entity moving in unison like a herd of antelope or school of bait fish. Is plant health important to pest control? I think it is. And, yes, Virginia, plants do have an immune system. So what’s the difference between an aphid and a lion? The number of fangs. And what’s the difference between a crop of plants and a herd of antelope? The plants can’t run like hell.
Trap- and banker-crops
Another way the antelope can keep from being eaten by lions is to hang out with pork chops. Okay, a silly analogy. But, nevertheless, it holds water in pest control. Let’s simply change the elements. Another way plants can avoid being attacked by pests is to hang out with crops those pests prefer. I’ve been curious about trap-crops for many years. I think a great deal of pest control merit goes to trap-crop logic. In order to prove it to myself, though, and because few growers were actually practicing this at the time, I set up a trial a number of years ago. This was the situation: My wife and I always grew bush beans in our garden. And every year those beans were attacked by Japanese beetles and Mexican bean beetles. We always harvested too many beans for our own immediate use but felt we could do better if not for these two pests. We did, after all, blanche and freeze our excess for off-season meals, so adding to our harvest wouldn’t be wasteful. One year we had some seeds left over from the previous season. I felt this was a perfect opportunity to test not only stress induced attraction (as discussed in brief under Plant Health), but trap-cropping as well. Our bean plot was approximately twelve feet from a short rock wall. On the other side of the rock wall was scrub growth for thirty feet, then woods. My plan was to plant those old beans in the ill-maintained scrub area just beyond the wall while the new beans were planted in the garden proper. The results, I feel, were very revealing. The stressed bean plants in the scrub area were absolutely inundated with both beetle species. Meanwhile, the beans in the garden were the cleanliest we’d ever seen. Nothing fancy here. No data to tabulate. Just an assumption being made by way of simple observation. The beetles were obviously more attracted by the stressed beans in the scrub than they were to the lush beans in the garden (which may partially have been due to the proximity of the test beans to the woods). We enjoyed a better-than-ever harvest due to the lack of pest pressure. Now here’s the kicker: we also got a small harvest from the bean plants in the scrub. No fuss. No muss. Not a waste of time. However, can conclusions really be drawn from such an unscientific experiment? Well, yeah, I think so. I’ve told other growers this story about our beans and they have, in keeping an open mind, tried similar tactics. The reports have been primarily positive.
Another great trap-crop, which I’ve written about before because it’s almost like setting up your own insectary, is eggplant. Eggplant is a whitefly magnet. Place an eggplant in the midst of your cash crop, say tomatoes, and wait until you see your first whitefly or two to appear. More than likely they will show up on the eggplant before the tomatoes. When this happens, inundate the eggplant with whitefly parasitoids — Encarsia formosa or Eretmocerus eremicus (to choose the appropriate parasitoid, know which whitefly species you’re dealing with-but this will covered in greater detail later). The parasitoids will often take off like wildfire using the eggplant as a breeding ground, reproducing with wild abandon. From this insectary sort of plant they stand a fair chance of establishing for the season. From this centralized plant they can protect the entire crop.
With trap-crops we are trying to lure pests-and biocontrols — to a given area so the war can take place there instead of in the cash crop. With banker-crops though, the plants used are intermingled with the cash crop. The reason for this is explained in what a banker-crop is and how it is supposed to work. Here’s an example: Tomato plants can be a difficult host plant for predatory mites to survive in-even though the pest mites seem to do well. (This probably has to due with the acclimation of the mites to the plant.) Bean plants, though, tend to be a very favorable host plant to predatory mites-as well as to the pest mites. Plant bean plants among the tomato plants. (In fact you may even trellis pole bean plants on the tomato plants.) The reason is simple. The predatory mites like Phytoseiulus persimilis don’t do well, as said, on the tomatoes, but do do well on the beans, and now they have a place, right there in the crop being protected, to prosper. Not rocket science, but not too obvious either.
On this web site I’m not going to define all the possible crop mixes of trap- and banker-crops. I’ll leave that to you, the grower. You know plants and I’m fully confident you can put two and two together and come up with your own solutions. I’m not trying to provide all the answers on this website, I’m just trying to point you in the right direction. Food for thought is all; I’m not serving up a seven course meal.
This was discussed in some detail on the The Transition II page. But here’s some tidbits: read up, brush up, talk to those in the know (including your supplier of choice) and get out there and do it. There’s no teacher like experience, but in order to get some, you’ll have to start. Remember, learning by doing is a lesson well remembered.