A lot of great people are doing great work with biocontrols. So this month I’m featuring an update from an exciting project happening in Eastern NY testing a potential biocontrol solution to wireworms in sweet potatoes. Thank you to Teresa Rusinek (Cornell Cooperative Extension Eastern NY Commercial Horticulture Program) for writing this post! I will definitely be following this project as results from 2018 come in. Check back for future updates!
Professor Elson Shields and Research Specialist Tony Testa of Cornell Dept. of Entomology, have been working with NY native entomopathogenic (insect attacking) nematodes (EPNs) for the past 20 years. Initially, the EPN biocontrol systems were developed to protect alfalfa crops from the destructive snout beetle. This system has been highly successful, over 150 alfalfa fields in NY alone have been inoculated. EPNs have been proven to persist in the soil years after application. They require 2-4 years for full effectiveness determined by the application method.
Cornell Cooperative Extension, Eastern NY Commercial Horticulture Educators Teresa Rusinek and Charles Bornt have been working with Shields and Testa on a multi-year research project at the HV Farm Hub to test the efficacy of NY Native EPNs in the suppression of wireworms which are increasingly damaging to various crops, especially roots crops, grown in the Hudson Valley.
Our project began in May of 2017 at the Farm Hub, where we established research plots in a field where wireworms were found in large numbers. Four control plots had no EPNs applied, four plots were treated with both Steinernema carpocapsae (Sc) and Steinernema feltiae (Sf) nematodes, and the final four plots were treated with Sf and Heterohabditis bacteriophora (Hb) nematodes. Each EPN species occupies a different depth in the soil and has somewhat different modes of action. This research will determine which nematodes species are best adapted to establish in the field as well as which combination of nematodes is most effective at suppressing wireworms.
Results from our harvest evaluation from last year look very promising. 200 sweet potatoes were harvested from each plot on Sept. 26, 2017 and scored for wireworm damage. EPN treated plots overall had 36% less wireworm damage than the untreated control plots. In addition, soil core bioassays taken earlier this spring show that the EPNs, Sf in particular, have well-established and overwintered in the treated plots. We have not yet harvested and evaluated the sweet potatoes from this growing season.
For much of this summer, many people in NY had “water” at the top of their lawn care list. White grubs are another concern for home lawns. But finding a grub in your lawn does not automatically mean that you need to treat. Before you think about doing anything to your lawn to kill grubs, you should know how many grubs you have, and which species they are. If you do need to treat, consider using biocontrol.
Good news! It’s the perfect time of year to scout for white grubs. Starting in mid to late August, and continuing into October, grubs that hatched from eggs laid during the summer will be just beneath the surface of your lawn, feeding on the roots of your grass plants. This is the time to look for grubs. You might also notice some damage to your lawn from white grub feeding during this window.
Take a look at this fact sheet for detailed instructions on sampling your lawn. All you need is a piece of paper, something to write with, and a shovel or trowel. Check 1 foot by 1 foot squares around the lawn. If you have a bulb planter with a diameter of approximately 4.25 inches, or a golf course cup cutter, this works, too. Make notes about where you’ve sampled and how many grubs you found in each spot. Save the grubs from each sampling location separately.
If you didn’t find any grubs, please don’t treat your lawn! You are wasting money, and applying unneeded pesticides (or biocontrol nematodes) is never a good idea. If you did find grubs, it’s important that you determine which species they are. Why? Because the white grubs you are likely to find in NY are the immature (larval) stage of many different insect species. And each species causes different amounts of damage to your lawn. This means that the number of grubs your lawn can tolerate before it’s damaged – and therefore the number of grubs you should tolerate before treating for grubs – depends not only on the overall resilience of your turf, but also on the grub species you have. Check out the following table:
Fortunately, identifying grubs is easy, too! All you need is a penny, a hand lens with at least 15x magnification, and this online Grub ID tool. First, use the green “Learn how to identify grubs” button to find out which part of the grub to look at and how to hold it. Next, follow the instructions to compare each grub you found to the size of a penny.
Finally, inspect its rear end with a hand lens to determine which species you have. Once you’ve identified the species, click on the species name to find specific management information. Now, look at that table again. For the species you found in your yard, do you have more than the listed number per square foot (or per 4.25-inch diameter soil core)? If not, then don’t waste time or money treating your lawn.
Most likely, only a few spots in your lawn (if any) warrant grub treatment. This is why you took careful notes about where you found grubs. Late August through September is also a good time to use a curative treatment for grubs in NY. The grubs are small and easier to kill. Some chemicals are effective when used at this time (but not the ones that are taken up by the plant!). A preventative pesticide that is taken up by the plant and kills the next generation of grubs when they start feeding in the late summer and fall should be applied in May or June. Before using any pesticide, find out if it is allowed in NY and find the product label using the New York State Pesticide Administration Database (NYSPAD). If a product isn’t listed in this database, you may not use it in NYS (even if you can buy it online). You must follow all instructions on the label.
But why use a chemical when you could use a biological control? Entomopathogenic nematodes are tiny beneficial worms that don’t harm plants, but kill grubs. See how they do it by watching this short video. Why wouldn’t you want these nematodes working for you? Beneficial nematodes are a curative white grub treatment, so they should be applied between mid to late August and October. But you still only need to apply them to spots where grub numbers exceeded the thresholds in this table. You can purchase nematodes from garden centers or online garden supply stores. Look for the nematode species Heterorhabditis bacteriophora and Steinernema feltiae.
For both species, make sure to follow the instructions on the package for storing and applying them. Nematodes will be harmed by ultraviolet light, so apply them around dawn or dusk, and water them afterwards to wash them into the root zone of the grass (where the grubs are). Any type of sprayer (as long as it doesn’t contain a fine mesh) or even a watering can will work to apply nematodes. If you use a sprayer, keep the pressure below 30 pounds per square inch. When you’re mixing up the nematodes, if non-chlorinated water is available, use that. Chlorinated water is fine for watering them in after you apply them.
Regardless of what treatment you use, scout your lawn again next year to find out how well your IPM strategy worked, and if there are other areas you need to treat (or not).
This post was written by Amara Dunn (NYS IPM) and Kyle Wickings (Department of Entomology, Cornell University).
Are mosquitoes bothering you while you enjoy summer in your backyard? An IPM approach is definitely the way to go. Start by checking your yard to see where water might be standing. It could be in toys, flower pots, tarps, wheel barrows, gutters, bottle caps, or so many other places you may not have noticed. Removing standing water from your yard takes away places where mosquitoes breed. Less mosquito breeding, fewer mosquitoes. Always think prevention first when you’re addressing a mosquito problem. Read more about mosquito IPM on the Think IPM Blog and What’s Bugging You?
If there are still some containers you just can’t empty (for example, a lined garden pond), you can find some biopesticides (remember, some biopesticides are biocontrols, too!) in your local garden center to help you with your mosquito IPM. Just make sure you follow all instructions on the label of any product you buy. Read all about mosquito biocontrol on this new fact sheet.
And, if you want to learn so much more about IPM for both mosquitoes and ticks, you still have a little time to register for the 4th Annual NYS IPM Conference on Integrated Management of Ticks and Mosquitoes. But hurry – the conference is August 7th!
As I mentioned in my January post, I am excited to be working with two NYS IPM colleagues (Dr. Betsy Lamb and Brian Eshenaur) to demonstrate the costs, labor, and effectiveness of different methods for establishing habitat plants for pollinators and other beneficial insects. Remember, habitat for pollinators is also habitat for insects and mites that are natural enemies of pests on your farm or in your garden. Thus, planting for pollinators enables you to practice conservation biocontrol. These demonstration plots are located around a new research planting of Christmas trees at Cornell AgriTech at the New York State Agricultural Experiment Station in Geneva, NY. What we learn from this project can help you choose the best way to establish your own beneficial habitat (on your farm, around your home, near your school, etc.)
We are comparing 6 different methods of establishing habitat for beneficial insects, plus a control (Treatment E). Treatment E plots were sprayed with herbicide last fall and this spring, and will be mowed once this year. A summary of the plan for the other treatments is below.
Because of when spring tillage occurred, plots that were scheduled to be tilled in the spring did not need a second herbicide application. About a week after spring tillage, Treatment C plots were direct seeded. I hand-broadcast a mixture of native wildflower and grass seeds at a rate of half a pound per 1,000 square feet. This worked out to be 26 g of seed for each 5-foot by 23-foot plot. To make it easier to broadcast such a small amount of seed, I first mixed the seed for each plot with about 3 cups of boiled rice hulls. After raking the seed in gently with a garden rake, I stomped the seed into the ground to ensure good contact with the soil. In a larger plot, you might use equipment like a cultipacker or lawn roller to achieve the same result.
I broadcast (again, by hand) buckwheat seeds in the Treatment D plots at a rate of 70 pounds per acre (84 g for each of these small plots), and raked them in on May 31st. If the buckwheat establishes well, it will smother weeds during the summer, and we can mow and transplant into these plots in the fall. We plan to mow this crop of buckwheat when it starts flowering and then reseed it, for a total of two buckwheat plantings this summer.
We transplanted by hand 15 species of wildflowers and 1 grass species into plots assigned to Treatments A and B on June 4th. Because we were able to transplant right after it rained, it wasn’t too difficult to plant into the untilled plots (Treatment A). Some of them still had some stubble from the cover crops and weeds that had been growing in this field last year, and were killed by fall and spring herbicide applications.
The day after we transplanted into Treatment B plots, we mulched the plants to a depth of about 3 inches to (hopefully) control weeds for the rest of the summer while the habitat plants get established. We used chips from shrub willow because they were available, but other types of mulch would work, too.
Finally, we laid clear high tunnel plastic over the plots receiving Treatment F. Ongoing research from the University of Maine suggests that soil solarization can be an effective form of weed control, even in the northeast. So we’re giving it a try! To maximize the efficacy of this technique, we laid the plastic when the soil had been tilled relatively recently, and was still very moist. To keep the plastic firmly in place for the whole summer, we rolled the edges and buried them 4-5 inches deep, then stomped the soil down around all the edges. In the fall, we will hand broadcast a mixture of native wildflower and grass seeds over these plots (same mix as Treatment C).
We’ll give weed seeds in the Treatment G plots a few more weeks to germinate and grow (depending on the rain). Then we’ll kill them with an herbicide, and till these plots again to induce more weed seeds to germinate. Then we will repeat the herbicide application, till again, and so on. This should reduce the weed seed bank in the soil over the course of the summer. After a final tillage in the fall, we will broadcast seed from the same wildflower and grass mix we used for Treatment C. Fall is the recommended time for direct seeding beneficial insect habitat in the northeast. This treatment will also have the advantage of a full season of weed control prior to planting (also recommended). The downside is that it will take longer to establish the beneficial insect habitat.
As we get these plots established, we’re keeping track of the time spent on each treatment and the costs of materials. In the late summer or fall, Dr. Bryan Brown will assess weeds in each treatment, and I will photo document how well our beneficial insect habitat plants have established in each plot. All of these data will help you choose the method that fits your timeline, budget, and equipment/labor availability. Stay tuned for more updates…including an invitation to a field day (not this year), so that you can come see the results of this project for yourself!
Now that the weather is getting warmer and you’re spending more time outside, you might notice ant hills in your lawn. Reaching for a can of something that will kill them should not be your first move! These ants may be cornfield ants (known among scientists as Lasius neoniger). They are yellowish brown to dark brown, and about 1/8 of an inch long (or slightly longer). You are most likely to notice the ant hills they produce at the entrance to their underground nest in a sunny lawn where the grass is short and sparse (since this is their preferred nesting area). While the ant hills could be problematic on parts of a golf course where the grass must be kept very short, they aren’t big enough to be a problem in your backyard (if you’re mowing your grass to the correct height, which should be about 3.5 inches).
In addition to being harmless to humans – they don’t sting or bite – these ants are actually good for your lawn! They eat the eggs of grass pests, including Japanese beetles. One study found that when these ants were present in turf grass, they reduced the numbers of white grubs and other grass pest larvae. Choosing not to apply pesticides to kill these ants will help you practice conservation biocontrol in your own backyard! In other words, by protecting the natural enemies of lawn pests, you will have fewer lawn pests (and less damage) to worry about.
Although these cornfield ants should be a welcome addition to your lawn for the reasons I’ve just described, if the hills they create are bothering you, there are some simple IPM solutions. Water and fertilize your lawn appropriately and use one of the top two height settings on your mower when cutting your grass. These strategies will help you achieve a denser, taller lawn. This type of lawn is less desirable for building new ant nests, and will make remaining ant hills less noticeable. For more information on maintaining healthy lawns, see the Cornell Turfgrass program’s Lawn Care: The Easiest Steps to an Attractive Environmental Asset.
A few final (but important) notes. Cornfield ants in your yard are a good thing. Ants in your home are a different story entirely, and NYS IPM has information on how to avoid in-home ant problems. If you are uncertain about what type of ant you have, consult an expert for proper identification. Your local extension office is a great place to start. Or, you can submit a sample to the Cornell Insect Diagnostic Laboratory.
If you were going to tank mix chemical pesticides, you would of course read the label to check for compatibility before mixing products. The same concept applies when using living organisms for pest control. Whether you are using parasitoid wasps, predatory mites, microorganisms, or nematodes, you need to know whether your biocontrols are compatible with each other and any other pest management products you plan to use. For example, a biocontrol fungus might be killed if you tank mix it with (or apply it just before) a chemical fungicide. Insecticides (whether or not they are biological) could be harmful to natural enemy insects and mites. Even some beneficial insects are not compatible with each other because they may eat each other instead of (or in addition to) the pest.
It’s a good idea to keep an updated list of the products and organisms you plan to use for pest management, and their compatibility with each other. For biopesticides (remember the difference between “biopesticide” and “biocontrol”?), start by reading the label (see label excerpt below). You must follow all instructions you find there. Many manufacturers also provide lists, tables, databases, or apps to help you find compatibility information (some links at the end of this post). This is especially useful for insect, mite, and nematode natural enemies, which are not pesticides and do not have pesticide labels. When possible, obtain compatibility information from the manufacturer or supplier you will be using. Different strains of the same microorganism or nematode may have different sensitivities to chemicals.
Remember that NY pesticide labels (including biopesticide labels) can be found through the NYSPAD system.
Below are some links to resources from several manufacturers and suppliers of biocontrol products. No endorsement of specific companies or products mentioned in this post is intended. If you know of a link to additional information that is missing, please let me know so that I can include it!
Beneficial nematodes from BASF – This chart describes compatibility of beneficial nematodes sold by BASF with natural enemies and pesticides. Note that only the genus name of each “biological” active ingredient is listed, and that over time, the names of some predatory mites (and whether they belong to the genus Amblyseius or Neoseiulus) have changed.
Biobest Side Effect Manual – This side effects manual is available either as an interactive website, or as an app. Choose pest management products by active ingredient or name of the commercial product (including the biocontrol microorganisms Beauveria bassiana and several types of Bacillus thuringiensis). The list of “beneficial organisms” to choose from includes bumble bees and nematodes, but not beneficial microorganisms (fungi, bacteria, and viruses). Select active ingredients/commercial products and beneficial organisms from both lists, then use the legend to interpret the compatibility information that is generated.
Koppert Side Effects Information – This information is available either as an interactive website, or as an app. Select beneficial organisms of interest (by either the Koppert product name or the Latin name). Select one or more “Agents” (pest management products) by either the trade name or the active ingredient. Click on Results, and use the Legend to interpret the output.
If you are thinking about trying biological control, of course you want to know if it is effective. The short answer is, “Yes!” But of course it depends on which biocontrol organism you want to use (and how), which pest you want to manage, and where.
First, you should ask yourself a question: What do I hope to achieve? Some great reasons to use biocontrol for pest management include:
Protecting the environment and human health by using more environmentally-friendly pest management strategies
Reducing the number of chemical pesticide applications to a crop
Preventing (or dealing with) pesticide resistance
Meeting a need for a short REI (re-entry interval) or PHI (pre-harvest interval) on the crop
Biocontrols are the most effective (and cost-effective) management strategy (definitely true for some pests and settings!)
Second, in what context are you using biocontrol? Biocontrol is best used within a larger integrated pest management strategy. Are you using good sanitation and cultural practices (e.g., adequate but not excessive nutrition and water) that promote healthy plants? Are you regularly checking your plants so that you will notice pests when they are still infrequent (scouting)?
Biocontrol should also be preventative (before pest pressure becomes high). If you are expecting to use only biological control to solve an already out-of-control pest problem, you will probably be disappointed. Similarly, if environmental conditions are very favorable for a pest, a biocontrol solution will probably be insufficient.
Each year, university researchers, extension staff, and private companies conduct efficacy trials to quantify how well pest management strategies work. Knowing how a biocontrol product/organism performed in these trials can help you decide if you want to try it on your farm or in your yard. It helps to know a little about how these trials are structured. Efficacy trials typically include some combination of the following types of control treatments:
non-treated control – plants are exposed to pests (either naturally, or deliberately by the researcher), but no pest management strategy is used; disease/damage severity should be highest in this treatment
chemical control – plants are exposed to pests, and a chemical pesticide is applied to manage the pest; sometimes an “industry standard” (what is typically used to manage that pest in that crop and setting) is designated by the author of the study; if no industry standard is designated, comparisons can still be made to the chemical treatment that worked best; disease/damage severity should be very low in this treatment
non-inoculated control – no pest pressure (i.e., plants were not deliberately exposed to the pest); sometimes disease or damage still occurs because of natural pest pressure, or because disease or insects spread from other treatments in the trial; disease/damage severity should be lowest in this treatment
Efficacy trials also include statistical analysis. In a nutshell, this analysis tells you whether two values are really different (often described as “statistically different”), or not. If two numbers are not statistically different from each other, it means that only by chance is one larger or smaller than the other. If you did the same experiment again, you might see the opposite relationship. One common way of expressing these differences is by using letters. If two treatments are assigned the same letter, then they are not statistically different. So in the example below, “Bio1” is statistically different from “Bio3” but neither is different from “Bio2”.
When interpreting an efficacy trial, you should compare a biocontrol of interest to the control treatments. Of course, it would be great to see biocontrol products that are just as effective as the chemical control (like “Bio1”), and sometimes they are. Sometimes, a biocontrol may be less effective than the chemical control, but more effective than the non-treated control (like “Bio3”). Sometimes there’s so much variability (represented by the lines extending above and below the blue bars on the chart), that a biocontrol product is not statistically different from either the non-treated control, or the chemical control (like “Bio2”). This makes it difficult to draw conclusions about how well the product worked.
But, it’s not always quite that simple. For example, in these efficacy trials, researchers deliberately expose plants to pests, and often they manipulate the environment to favor pest populations (for example, over-watering plants to promote a soil-borne disease like damping off). While there can be value in assessing product efficacy in a “worst case scenario”, this may be much higher pest pressure than you are likely to encounter on your farm or in your yard. When looking at efficacy trials, you should consider:
How much disease/damage was observed on plants that were not protected in any way (non-treated/control)? If it’s too low, it’s hard to be confident that the biocontrols being tested were effective, since even unprotected plants were pretty healthy.
How much did the most successful treatment (chemical control) reduce disease/damage? If even the “best” pest management strategy in the trial was not very effective, then pest pressure may have been too high, and it’s not surprising that the biocontrol was ineffective. If you practice good IPM, you likely won’t experience such high pest pressure.
How was the biocontrol applied (alone, or as part of a spray program with other products)? Applying single products in an efficacy trial can simplify interpretation, but may not mimic how you plan to use a biocontrol product. If a biocontrol was applied in combination with other products, you should compare the “biocontrol + other products” to the “other products alone” to see what the biocontrol added to pest management.
What was your goal, again? For example, if you are hoping to replace one or two chemical applications in a larger spray program with a biocontrol, then a moderately effective biocontrol product (like “Bio3”) may meet this goal.
Because the efficacy of a biocontrol can depend a lot on the environment in which it is used (temperature, humidity, soil conditions, etc.), it’s also a good idea to initially try a new biocontrol in a small area of your farm or yard, and keep notes on what you did and how well it worked for you. You can modify your plan to find what works best for you. The manufacturer or distributor should be able to provide you with important details on how (and for how long) the biocontrol should be stored, and exactly how and when to apply it. And (as always!) if you are using a biocontrol that is also a pesticide (see previous post), make sure that you read, understand, and follow the label.
The following resources summarize efficacy results for biocontrol of plant diseases. As I find efficacy summaries of insect and mite pest biocontrol, I will add them. Or, feel free to suggest efficacy resources you know of in the comments!
There are a lot of different “biological” products on the market. Frankly, the terms used to describe them can be a little confusing. So let’s take a closer look at a few terms and exactly what they mean.
First, what is a pesticide? According to the Cornell Pesticide Management Education Program, “a pesticide is any substance or mixture of substances used to kill pests or to prevent or reduce the damage pests cause”. Pesticides include repellents, but exclude traps (if they are only mechanical or physical). The important point is that pesticides are defined by their purpose, not by their ingredients. Pesticides may be chemicals, plant extracts, or microorganisms, but their purpose is to prevent pest damage. Pesticides are regulated by the Environmental Protection Agency (EPA), and must always be used according to their labels.
“Biopesticide” is a term defined by the EPA as “certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals.” All biopesticides are pesticides, and must be handled and applied as such. They fall into one of three groups:
Microbial – active ingredient is a living microorganism (fungi, bacteria, viruses, protozoa) or a product made by a microorganism
Biochemical – natural compounds including both plant extracts and naturally-occurring chemicals
Plant-incorporated protectants – the products that result from inserting new genes into plants (i.e., the result of genetic engineering)
Biopesticides control pests or prevent pest damage in four ways:
Consuming or parasitizing the pest, directly – An example of this is a beneficial fungus that eats a pest fungus, or a beneficial fungus that infects and kills a pest insect.
Poisoning the pest – Some microorganisms produce antibiotics that are toxic to pests. There are numerous bacteria that do this.
Crowd out the pest – Pest microorganisms (pathogens) can’t colonize and invade a plant if the surface of the plant (leaves, roots, etc.) are already covered with beneficial microorganisms. There just isn’t space.
Stimulating plant defenses – Although very different from human immune systems, plants do practice self-defense. Beneficial microorganisms can cause plants to “turn on” their defenses before they encounter a pest. The plant is then less likely to be damaged by the pest.
Sometimes a single biopesticide functions in more than one of the above ways. But, again, the purpose of using a biopesticide is to control a pest. Biostimulants have a different primary purpose: enhancing plant health (which can lead to the plant being less susceptible to attack by a pest). The European Biostimulants Industry Council has defined a biostimulant as “containing substance(s) and/or microorganisms [e.g., bacteria and fungi] whose function when applied to plants or the rhizosphere [soil surrounding plant roots] is to stimulate natural processes to enhance/benefit nutrient uptake, nutrient efficiency, tolerance to abiotic [non-biological] stress, and crop quality.” This definition is also supported by the Biological Products Industry Alliance. No regulatory definition of biostimulant currently exists in the United States. Biostimulants are registered either as fertilizers or as biopesticides, depending on the claims (pest control vs. plant health enhancement) made by the registrant.
Biostimulants can include a wide variety of ingredients, which can be placed in the following four categories:
Microorganisms (e.g., fungi and bacteria)
Extracts from plants or seaweed
Organic (i.e., carbon-containing) molecules including various components of soil organic matter
Inorganic (i.e., not carbon-containing) elements or molecules
Biostimulants can enhance plant health in multiple ways. In some cases, scientists don’t yet know how a biostimulant enhances plant health, just that it does. Like biopesticides, a biostimulant may have more than one of the following modes of action:
Improve soil quality by impacting soil characteristics like water holding capacity, structure, or aeration
Improve plant access to nutrients already present in the soil
Stimulate plant defenses or otherwise increase the plant’s tolerance to stress (from biological or non-biological sources)
Improve root growth of the plant (so that the plant can take up nutrients better)
Improve the quality of something produced from or by the plant (e.g., improved flavor or nutrition of fruit)
And where does biocontrol fit in? In several places on this blog, I have noted that definitions of biocontrol vary. I think most scientists who study biocontrol would agree that a living microorganism that is applied to the soil or to a plant and that consumes or parasitizes a pest (a type of biopesticide) is a biocontrol agent. But there are lots of gray areas. What if the biopesticide contains only products of the microorganism which are antagonistic to the pest, and no living organisms? If a microbial biostimulant enables a plant to more efficiently take up nutrients, making the plant more tolerant of stress (whether from an abiotic source like drought, or a biotic source like a pathogen that causes disease) is that still biocontrol?
These are debates I’d rather not spend a lot of time on (at least on this blog). Suffice it to say that at least some biopesticides and at least some biostimulants are also considered types of biocontrol. There are a lot of biological products available to you. Exactly how each is classified (biostimulant versus biopesticide) makes a difference in how the product can be legally used. Know what you are using and why. And always, always, always read and follow the label!
At this time of year, glossy catalogs start arriving in my mailbox full of pictures of all the beautiful fruits, vegetables, and flowers that I could grow after the snow melts. What these pictures don’t usually show are the arthropod (insect, mite, and related species) pests that can’t wait to eat what I plant. There are many IPM strategies you can use to fight back against these pests, and you can learn more here.
One of these strategies (and seldom is a single strategy sufficient) is to think about what else is growing near the vegetables, fruits, and flowers you want to protect. There aren’t just pest arthropods in your garden. These pests have natural enemies, too. If you provide good habitat for the natural enemies (including food and shelter), you will attract more natural enemies, and they are likely to consume more pests, protecting your plants. This is one way to practice conservation biocontrol – protecting and supporting the biocontrol organisms (natural enemies) that are already present.
So, what makes good habitat for natural enemies? In general, plants that bloom throughout the growing season (early spring to late fall) provide pollen and nectar to the natural enemies that use these as alternate food sources (in addition to pests). These plants also provide good shelter, both for natural enemies and the arthropods (including some pests) they feed on. As these natural enemies reproduce in the habitat you have created for them, they will also venture beyond this habitat and into your fruit, vegetable, and other flower plants, where they will eat more pests.
What is good habitat for natural enemies is also (in general) good habitat for pollinators. You have probably already heard how important pollinator protection is. Those glossy catalogs (or wherever else you buy your seeds or plants) likely sell species and varieties labeled as being “good for pollinators”. Just make sure you include plenty of variety. Because most plants (especially perennials) bloom for a limited time, you will need multiple species to ensure season-long blooms. Also, the variation in height and structure of the plants will provide diverse habitat for all of the different natural enemies you want to attract.
And what about protecting a larger area of plants (like a 5-acre field of pumpkins on a farm)? Will creating habitat for natural enemies help with pest control? The answer is complicated. It probably depends on a lot of things. How big the field is, how much habitat there is and where it’s located, which pests are a problem, and other pest management strategies (especially use of chemical pesticides) will have an impact. Research has shown that in some scenarios, yes, providing habitat for natural enemies can reduce some pest populations in some crops (one example).
Later this spring, I and two of my NYS IPM colleagues (Dr. Betsy Lamb and Brian Eshenaur) will set up a field experiment that will answer this question (over the next several years) in a Christmas tree planting. We will also compare different strategies for creating this habitat (seeds versus plants, and different weed control methods). Stay tuned for updates!
Biocontrol can be an important part of an integrated pest management strategy (learn more about “IPM in a Nutshell”). For example, biocontrol organisms that support plant health can make them less susceptible to the pests that damage them (prevention). If something needs to be applied to reduce pest populations (or keep them low), biocontrol products tend to be less harmful to other critters or people than chemical pesticides (choosing a pest management strategy with low environmental impact).
In the images at the top of this blog, you can see some examples of biocontrol. From left to right…
Syrphid flies are often seen foraging for pollen and nectar on flowers, but immature syrphid flies (larvae; not pictured) also eat pest insects. (Photo credit: Ken Wise)
Some bacteria produce compounds that slow the growth of pest fungi, or even kill them. (Photo credit: Carly Summers)
Many different species of parasitic wasps use their stingers to lay eggs inside pest insects (which is what happened to this aphid). The egg hatches, and the developing wasp eats the pest from the inside out, eventually leaving through the exit hole seen in this picture. (Photo credit: Ken Wise)
Some stink bugs are pests, while other stink bugs (like this one) are predators of pests. (Photo credit: Ken Wise)
Adult ladybugs are more easily-recognized than immature ladybugs (larvae), like the one that is eating aphids in this picture. (Photo credit: Ken Wise)
In the background is a picture taken under the microscope of nematodes (tiny worms). Some nematode species seek out and enter soil-dwelling pest insects, carrying bacteria that will kill the insect. (Photo credit: Maxwell Helmberger)
Posts on this blog will explain how biocontrol is already contributing to IPM in New York, and how its use in pest management could be improved. The information is posted by Amara Dunn, Biocontrol Specialist with the New York State Integrated Pest Management Program. If you have questions about biocontrol, you can contact Amara by email (email@example.com), call her office (315-787-2206), or leave a comment on this blog.