As mentioned by University of Illinois Extension in several newsletters, radio spots, and other forms of media this past spring, the Illinois Department of Agriculture (IDOA) inspected a number of Illinois greenhouses, nurseries, and farms during the 1999 growing season specifically to assess compliance with the Worker Protection Standards (WPS). IDOA's report is broken down into the major inspection areas shown below. The most common violation (18% of the sites in violation) was attributed to poor information exchange between producers and commercial handlers. The remaining areas of violation (range of 4 to 13% of the sites in violation) are summarized below.
1. Information at a central location. Employees were not always informed about scheduled pesticide applications; the location and description of the areas to be treated; information about the pesticide to be applied; restricted-entry interval; and details about who they should contact in case of an emergency. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 23 to 24.
2. Pesticide safety training. Not all workers and handlers were trained according to the WPS. In a few cases, the training material or content was also inadequate. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 25 to 27.
3. Decontamination sites. The quantity, quality, or accessibility of water for emergency eyeflushing was not always acceptable. In addition, handlers did not always have a clean change of clothes available to them. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 29 to 31.
4. Employer information exchange. Commercial pesticide applicators did not always provide the producer with the information needed to comply with part one (above). Conversely, commercial WPS handlers were frequently not informed about pesticide applications that had already been made and about restrictions on entering those sites. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 33 to 34.
5. Emergency assistance. No violations reported.
6. Notice about applications. Some posting signs were of the wrong size or design. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 41 to 44.
7. Restrictions during/after applications. No violations reported.
8. Early entry work situations. No violations reported.
9. Personal protection equipment for early entry workers. No violations reported.
10. Handler restrictions and monitoring. No violations reported.
11. Specific instructions for WPS handlers. Again, commercial WPS handlers were frequently not informed about pesticide applications that had already been made and restrictions on entering those sites.
12. Equipment safety. No violations reported.
13. Personal protection equipment for handlers. In a few cases, personal protection equipment was not always in clean, operating condition; and gas cartridges (for respirators) were not replaced frequently enough. Covered in EPA's "The Worker Protection Standard–How to Comply," pages 79 to 81.
Overall, the rate of compliance was quite good. However, as pointed out above, several areas still need work. To prepare for future WPS inspections, please consult the EPA's "The Worker Protection Standard–How to Comply" manual (revised July, 1993). Note that Appendix B includes a variety of useful compliance checklists, forms, and fact sheets. For a free copy of this manual, call Tom Walker with the Illinois Department of Agriculture at (217)785-2427. In addition, your local U of I Extension office can provide you with several helpful WPS resources, such as the "WPS Resource Guide," and "The WPS in IL" (http://www.aces.uiuc.edu/~pse/resources/resources.html).
Although the pesticide debate continues to smolder and flare, it is often eclipsed in the popular press by a more "modern" debate–the use of transgenic crops such as Bt corn and RoundUp Ready corn and soybeans. Granted, both debates are important, and we must all monitor and participate in each. In this article, I will point out a few of the newer issues in the pesticide debate and offer an example of how some groups are trying to "cool things down."
By 1998, almost everyone had heard about the 1996 Food Quality Protection Act (FQPA). Passed unanimously by Congress, this comprehensive new food- safety law promised to further protect the health of our children. Who could argue against such a law? Enter the year 2000. After much open debate among experts on both sides of the fence, a number of "high priority" pesticide uses (for example, organophosphate and carbamate insecticides) have been canceled. In fact, some active ingredients have been eliminated voluntarily. Keep in mind that, by law, the US-EPA must reevaluate every pesticide by 2006. There continues to be tremendous pressure on the EPA to avoid using "worst-case scenarios" regarding pesticide use. Crop profiles, created using grower surveys, are one means of providing EPA with actual pesticide-use data.
In addition, there are a number of other recent issues fueling both sides of the pesticide debate: (1) "Prescription-use pesticides" as the next level of use restrictions beyond restricted-use pesticides (a possible alternative to losing a pesticide use due to the FQPA), (2) increasing frequency and concern over pesticide drift, (3) allegations of pesticides' causing frog deformities in Minnesota and several other states, (4) "Consumer Confidence Reports" (annual reports to the public about local water quality), and (5) concern over the use of, and notification about, pesticides in our schools. Most of these issues (and many others) were recently addressed in the Illinois Pesticide Review newsletter.
Are there any hints that the pesticide debate is "cooling?" Yes! In several states, producer and environmental groups are coming together to find common ground. Often, this cooperation consists of good, open discussion and the selection of pest-management strategies and pesticides that offer reduced environmental impact without sacrificing crop protection. How do they measure and document reduced environmental impact? Of course, the simple way is to show that you are using pesticides that pose fewer potential problems, based on information provided on the pesticide label. However, some groups are using new and sophisticated computer software to do this. What is the benefit to the grower? Besides the potential health and environmental benefits, the new software offers a number of production benefits, such as factoring in pest threshold levels, pesticide cost, effectiveness against the pest, croptolerance ratings, persistence (carryover) ratings, and resistance risk ratings.
Does such cooperation sound like a hassle or opportunity to you? Would you view it as losing control or taking control? One thing is certain, both sides of the pesticide debate must engage in honest, factual discussion, in pursuit of creative, win-win solutions. The alternative? Dig in your heels and continue in a risk/benefit debate that will only get hotter.
Insecticidal nematodes are effective in controlling insects. Nematodes are very tiny, unsegmented roundworms that are best known to landscapers, farmers, and other agriculturists by the diseases that they cause. Ten thousand nematode species are known to science, but the number of species that exist has been estimated at 500,000. With that many species, there are some that feed on plants, others that feed on animals, but probably most species are scavengers, feeding on dead plant and animal material. Most nematode species (including the scavenger nematodes and those that attack harmful nematodes, harmful insects, and weeds) would be considered beneficial to humans.
Insecticidal nematodes, also called entomopathogenic nematodes, do not attack plants, but attack only insects and their relatives. The infective juvenile stage of the nematode usually enters an insect through a natural opening, such as the mouth, anus, or spiracle. (Spiracles are openings used by the insect for breathing.) Some nematodes, such as Heterorhabditis spp., can make their own hole through the insect's body wall. Once inside the insect, the nematode penetrates the gut lining or air tube, releasing bacteria into the haemocoel, the cavity inside the insect that contains the blood.
The bacteria that are released attack and feed on the blood and other body tissues of the insect, causing its death within 2 days. The nematode feeds on the broken-down tissues of the insect, as well as the bacteria. This allows the nematode to grow, develop, mate, and produce additional infective juveniles within the dead insect. Usually three generations of nematodes are produced within the dead insect before the insect's body wall breaks down. At that point comes the release of infective juveniles, with bacteria in their intestines, that can attack new hosts.
The bacterial species that occur within insecticidal nematodes are not found anywhere else, and insecticidal nematodes that do not contain these bacteria are ineffective in killing insects. In this mutualistic arrangement, the nematode transports the bacteria into a suitable host, and the bacteria provide food for the nematode by breaking down the tissues of the host insect.
These bacteria produce antibiotics that inhibit the development of fungi and other bacteria. Thus, insects killed by these nematodes do not rot and disappear as quickly as those killed by natural causes or insecticides. The presence of dead larvae in treated areas makes it likely that they were killed by the nematodes rather than by some other means.
Insecticidal nematodes are rather fragile animals, with most stages protected within the cadaver of the attacked insect. The infective juvenile stage is the most resistant stage, but it is still very susceptible to drying and to the ultraviolet rays in sunlight. For this reason, insecticidal nematodes are most effective in the soil and tunnels of boring insects, where they are protected from dry air and sunlight. Insecticidal nematodes use one of two methods to locate their hosts–ambushing or cruising.
Ambusher nematode species sit and wait for a suitable host by nictating. That is, they stand on their tails, waiting to attack a host as it comes by. Because infective juveniles are only a couple of millimeters long, a host that is even a few millimeters away will not be attacked. In addition, these nematodes are most effective in soil near the surface, where spaces between the soil particles are sufficient to allow this nictating behavior. Thus, ambushers are most effective against very active insects near the soil surface–such as cutworms, armyworms, sod webworms, and other soil-living caterpillars and mole crickets. Steinernema carpocapsae and S. scapterisci are examples of ambusher insecticidal nematodes.
S. carpocapsae is sold under the trade names Biosafe, Savior, Millenium, and BioVector 25. It is labeled for cranberry girdler, black vine weevil, strawberry root weevil, strawberry girdler, mint root borer, and mint flea beetle. S. scapterisci has been shown to be effective against mole crickets. It is not available commercially.
Cruiser nematodes actively search out their hosts. Although they can nictate, the infective juveniles also tunnel through the soil looking for their hosts. These cruisers are attracted to carbon dioxide and other chemicals that are exuded by potential hosts. Due to their searching behavior, cruisers are more effective than ambushers against less active insects and those that live deeper in the soil–such as white grubs, black vine weevil larvae, and fungus gnat larvae. Heterorhabditis bacteriophora and Steinernema glaseri are examples of cruiser nematodes. Some species of insecticidal nematodes are intermediate in activity between ambushers and cruisers, including Steinernema feltiae and S. riobravis.
H. bacteriophora is commonly called the Hb nematode in trade literature and is sold under the trade names Cruiser, Heteromask, and Gardens Alive Hb Nematodes. This nematode has a shorter shelf life than most others. It is labeled for white grubs, billbugs, cutworms, sod webworms, cranberry girdler, armyworm, black vine weevil, strawberry root weevil, pine weevils, fungus gnats, and flea larvae. The bacteria in this nematode is luminescent, which causes killed insects to glow slightly in the dark. Killed insects turn brick red instead of the medium brown color typical of insects killed by other nematode species.
H. magidis is a cruiser nematode sold as Nemasys II. This very large nematode is labeled for the control of black vine weevil. Its large size makes it too big to fit through the body openings of many other insects.
Steinernema feltiae is both a cruiser and an ambusher, sold under the trade names Nemasys, Entonem, X-Gnat, and Magnet. It is labeled for the control of sciarid flies and fungus gnats. Unlike most insecticidal nematodes, it is infective against insects in soil temperatures below 50°F.
Steinernema riobravis is both a cruiser and an ambusher. It is sold as BioVector 355 and Devour. It is labeled for the control of sugarcane rootstalk borer, citrus root weevil, and blue-green weevil. In the laboratory, S. riobravis has been shown also to be effective against mole crickets. It is active in drier soils than other insecticidal nematodes, but it needs high soil temperatures. It is most effective at temperatures above 95°F. Although this trait greatly limits its usefulness in Illinois, this nematode may prove very useful in the southern United States.
Insecticidal nematodes may be applied with most chemical-application equipment. Application is typically made through sprayers and irrigation systems. Some drip-irrigation systems have such a slow flow that the infective juveniles can settle out in the lines. However, increasing the flow during nematode application can overcome this problem. Infective juveniles are small enough to pass through most sprayer-nozzle orifices but are large enough to catch on pump and nozzle screens. For this reason, it is recommended that these screens be removed before application. Nematodes can survive tank agitation. In fact, without tank agitation, they may die from lack of oxygen in the spray tank.
Formulations of insecticidal nematodes include water suspension, gel, water-dispersible granule, and vermiculite. Storage time for the water-suspension formulation may be limited to only a few days under refrigeration due to the oxygen needs of the infective juveniles. The gel formulation is usually soaked in water to remove the infective juvenile-containing gel from the screen matrix. The gel, vermiculite, and breakdown products of the water-dispersible granules can easily clog screens within the application system. However, their storage times are longer, usually from one to several months, particularly if refrigerated.
Application of insecticidal nematodes is normally recommended for late in the day, after 3 p.m., when the sun is low enough to reduce evaporation and intense sunlight. For turf applications, the turf should be wetted both before and immediately after application to reduce the chances of the nematodes' drying out and dying. Similarly, sufficient irrigation, usually at least one-half inch, is necessary to move the nematodes into the soil, where they are protected from both drying and ultraviolet light.
Transgenic research is being conducted with insecticidal nematodes to make them less susceptible to severe environmental conditions. This trait will make them easier to work with in many practical applications. So far, this research has produced nematodes with increased resistance to high temperatures. Research is also being conducted to determine whether the bacteria can be effective without the nematodes and whether there are substances within the bacteria that can be used alone, without the use of either the bacteria or the nematodes. So far, it appears that both are necessary for control to be achieved.
Being living organisms, insecticidal nematodes are exempt from many of the USEPA's pesticide regulations. Tests have shown them to be harmless to mammals. This characteristic allows them to be brought to market much more quickly than chemical insecticides. However, it also allows the avoidance of much of the consumer protection provided by pesticide registration. When using a new insecticidal nematode or one under an unfamiliar label, try it out on a small area to be sure that you will be satisfied with the results before applying it to a large area.
Control of pests with insecticidal nematodes can be quite high, but 60 to 70% control is more common in turf applications. This level of control is usually enough to reduce pest numbers below damaging levels. Although insecticidal nematodes are living organisms and reproduce in attacked insects, they should be used as conventional insecticides are used–apply them when control is needed. Do not expect the nematodes to survive in the soil from year to year in numbers sufficient to provide a high level of control.
Insecticidal nematodes are expensive, perhaps costing ten times more per unit area than conventional insecticides. These costs should decline with increased production in the future. Insecticidal nematodes also demand extra care in storage, length of storage, timing of application, field conditions, and application to avoid clogged equipment. By contrast, there are situations in which conditions or clientele may demand nonchemical control. In these cases, the benefits may be worth the extra cost and trouble.