Best Practices for Pesticide Use

Active ingredient: The chemical in a pesticide formulation that is toxic to the targeted pest.

Adjuvant: Chemicals added to a pesticide to enhance the performance of the product. Adjuvants can make the pesticide safer to handle, make the pesticide easier to mix, allow the pesticide to adhere or spread over the plant and/or leaf more efficiently, or have other effects. Note that adjuvants alone can impact bees in laboratory studies

Broad spectrum pesticide: A pesticide that can control a wide range of pests and which may affect a wide range of non-target organisms.

Contact pesticides: Pesticides which must make direct contact with the pest targeted for control.

Hazard: Something that can cause harm. Pesticide hazard is a function of exposure to the pesticide and the pesticide’s toxicity, or ability to impair normal function of the body.

Herbicide: A pesticide used to control plants.

Insecticide: A pesticide used to control insects.

Pest: Any living thing (plant, vertebrate animal, invertebrate animal, or microbe) whose presence or activity is harmful to humans, human endeavors, or the environment.

Pesticide: A chemical used to control, mitigate, or repel pest populations. They are named by the type of pest they target: for example, insecticides affect insects (and often mites), miticides are affect mites, herbicides affect plants, and fungicides affect fungi.

Pesticide exposure: Unwanted contact with pesticides or pesticide residues by people, other organisms, or the environment

Systemic pesticides: pesticides taken up and spread through an organism. For example, a systemic insecticide applied to a plant spreads through its vascular system and kills targeted pests (and sometimes non-pests) that feed on that plant. Similarly, systemic herbicides are taken up through the plant and kill the entire plant, even if they are applied to only a small portion. Insecticide exposure for pollinators occurs through the ingestion of systemic insecticides in plant parts such as nectar, pollen, leaves, and stems. Systemic insecticides can remain in the plant for several weeks to years after application.

Residual pesticides: Pesticides which can be used when a pest is a continual problem. A “residue” remains active long after it is applied, providing long-term control.

Pesticides are important tools for homeowners, growers, land managers, public health officials and beekeepers to control insect pests, disease vectors (such as mosquitos), disease-causing organisms (bacteria, fungi), weeds, and invasive species that threaten the balance of our natural ecosystems.

However, pesticides can be toxic to non-target species. For example, insecticides used to control insect pests can be toxic to insect pollinators as well as non-insect species (including wildlife and humans). Pesticides can have indirect effects on non-target species as well. For example, herbicides used to control weeds in fields may reduce the availability of flowering plants on field edges, robbing pollinators of valuable food sources. The active ingredient in pesticides may not be the only chemical that potentially harms pollinators. Several recent studies have indicated that inert ingredients in the pesticide formulation, such as oils and surfactants, may be toxic to pollinators. Because the inert ingredients are typically unknown to the pesticide applicator, best practice is to apply pesticides only when needed and favor limited application methods such as spot treatments over broadcast treatments.

Moreover, long-term exposure to pesticides can facilitate the selection of pesticide-resistant pest populations, which limits the long-term utility of these pesticides. Pesticide applicators can improve the long-term efficacy of pesticides by engaging in integrated pest management approaches (IPM), which considers a series of pest management tools that extend beyond the implementation of a single chemical application.

The overall hazard that pesticides pose to pollinators is a function of both the pesticide’s toxicity (ability to cause harm) and the pollinator’s exposure to the pesticide. For example, a cockroach gel bait may be highly toxic to pollinators but pose little to no hazard to pollinators because it is applied in cracks and crevices indoors where pollinators cannot access it. Conversely, an agricultural pesticide with moderate to high toxicity to pollinators applied in a way that pollinators are likely to contact or ingest the pesticide has high hazard to pollinators. Thus, it is critical that pesticides be used thoughtfully to reduce off-target impacts and ensure their long-term effectiveness.

Exposure of pollinators to chemicals. Since pollinators actively visit any flowering plants within their foraging range, their exposure rates to pesticides can be substantial. Studies from Penn State found that samples from honey bee colonies contained more than 120 pesticides and metabolites.

Pollinators (and other beneficial arthropods) can be exposed to pesticides through the following routes:

• Air: Pesticides are sprayed where pollinators are foraging, which can come into direct contact with pollinators as they traverse the landscape. Some of this contact may result from pesticide drift to non-target fields or other adjacent regions where pollinators can be found.

• Floral resources (pollen and nectar): Pesticide residues remain in the nectar or pollen of flowering plants and are collected by pollinators as food for themselves or their developing larvae. Pesticide residues in flowering plants can result from either a direct application or through pesticide-contaminated soil and water runoff from nearby locations. Indeed, recent studies have found that many pesticides in the pollen and nectar collected by foraging bees come from contaminated wildflowers
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• Honeydew: Honeydew is a sweet, sticky substance excreted by true bugs and a few other insects as they feed on plant sap. In some cases, honey bees and other pollinators will collect honeydew as they are foraging.

• Water: Pesticide residues are found in the water sources that pollinators drink or bring back to their nest.

• Soil: Most bee species found in Pennsylvania nest underground and/or spend part or most of their life in contact with soil. Orchard bees, which create their nests in above-ground tubes, use soil to separate their brood cells and thus also are in long-term contact with soil. Pesticide residues infiltrate soils in many ways, such as through agricultural runoff, insecticide-treated seeds, or through direct pesticide applications (soil drenches, foliar applications, etc) which can impair pollinator health and reproduction.

• Wax: Honey bees and bumble bees rear their young and store food in wax, which accumulates pesticide residues from the surrounding landscape or, for managed honey bee colonies, directly through in-hive miticide applications.

• Plant Surfaces: Pollinators come into contact with pesticide-exposed leaves, stems and blossoms as they are collecting pollen and nectar. In addition, many solitary bees collect leaf pieces (or leaf hairs, such as wool carder bees) to build their nests over the course of their adult life.

Consequences of exposure to chemicals on pollinators. The effect of chemicals on pollinators depends on the toxicity of the chemical to the species, the amount of exposure (quantity and duration), and the individual’s physiological state. Toxicity may vary between adults and larvae, for example, and individuals stressed by other factors may be more sensitive. Furthermore, exposure to other chemicals (other pesticides, pesticide adjuvants, and defensive plant metabolites) can increase the sensitivity of an individual to a pesticide.

Herbicide use may have sublethal impacts on pollinators and can reduce the nutritional resources available to pollinators, by

• Reducing the amount of flowering weedy plants available to pollinators. Several studies have found that these weedy flowering plants are key resources for pollinators.

• Drifting into field margins and delaying the onset of flowering and numbers of flowers of non-target plants visited by pollinators in these areas. See this Penn State study.

• Disrupt the gut microbiome of bees.

• Impairs honey bee foraging behavior and bumble bee colony thermoregulation.

• Reduces reproductive success of solitary bees.

Insecticide and fungicide exposure can have a variety of impacts on pollinators, including:

• Immediate death, if exposure levels are sufficiently high.

• Decreased life span, if exposure levels are below lethal doses but impair the pollinators’ ability to forage, locate their nest site, or combat parasites and pathogens.

• Reduced brood production, if exposure reduces egg production or viability, or if the brood is fed nectar or pollen containing pesticides that cause lethal or sublethal effects.

• Reduced overwintering survival.

Death and decline of bees or other pollinators may be caused by several factors, including poor nutrition, parasites and pathogens, or even extreme weather. It is important to investigate any bee kill as soon as possible after it is discovered so that appropriate samples can be collected and tested. More information can be found in the Pennsylvania Pollinator Protection Plan section on Best Practices for Beekeepers. If pesticide exposure is suspected, the incident should be reported immediately to PDA’s Health and Safety Division, 717-772-5231, which may in turn report the incident to the Environmental Protection Agency (beekill@epa.gov). Pesticide exposure to bees may also be reported through the PA Department of Agriculture to to the National Pesticide Information Center (NPIC)’s Ecological Pesticide Incident Reporting portal.

It is strongly recommended that pesticides be used only as part of an “Integrated Pest Management” or IPM approach. More details can be found on the Pennsylvania IPM website. In general, to use an IPM approach, you should

• Take steps to prevent the introduction of pests and diseases (for example, use disease resistant stocks of plants or honey bees).

• Identify pests and learn their biology well enough to plan management actions

• Monitor levels of pests and diseases to know when it is necessary to use methods to control these populations.

• Determine a treatment threshold, above which the damage caused by pests and diseases is not acceptable (for example, treatment is not always necessary at the first sign of a pest, but rather should be initiated only when pest or disease levels are unacceptable).

• Use multiple non-chemical methods to control pest and disease populations (such as physical removal of pests, weeds, or diseased tissue, as well as encouraging or introducing populations of pathogens or predators that help control pest populations).

• If non-chemical control strategies have not been effective at keeping pests and diseases under the treatment threshold, use chemicals and chemical application methods which are (a) approved for use in controlling the identified pest/disease and (b) have reduced effects on non-target species.

• Evaluate the outcome of your pest management methods to determine if they were effective and whether any non-target harm must be addressed. This step determines if additional action is needed or if different action should be taken if the pest pressure returns.

Relative toxicity of different pesticides is also provided in “Wild Pollinators of Eastern Apple Orchards And How to Conserve Them” (page 17).

The Xerces Society has created a database of research articles related to the impacts of pesticides on pollinators and other invertebrates.

• The label is the law! Read the label and follow instructions before handling and applying a pesticide. For more details on how to read the label, see this resource.

• Check the label (under “Environmental Hazards”) for any pollinator or bee language (i.e. “highly toxic to bees”). Some pesticides (mainly neonicotinoid insecticides) now include an “EPA Pollinator Protection Box” which includes a bee and pollinator hazard icon and explains restrictions that should be addressed when applying the pesticide. It also gives instructions on minimizing drift and limiting pesticide exposure to bees and other pollinators. Many pesticides that are toxic to pollinators and may harm them through normal use do not have an EPA Pollinator Protection Box but discuss pollinator protection in other sections of the label. Always read the entire pesticide label before purchasing, transporting, mixing, applying, cleaning up, and storing a pesticide.

• Use an IPM approach. While IPM is not pesticide-free, it tends to apply fewer pesticides than schedule-based application methods because pesticides are not applied if they are not needed and non-chemical methods often keep pest pressure below pesticide application thresholds.

• Use application methods and approaches that minimize the exposure of pollinators to the pesticide.

  • Target spray or use approaches that reduce drift of pesticides to surrounding areas.

  • Pesticides should ideally be applied when pollinators are not foraging, either at dusk or when the treatment area does not harbor pollinator-attracting blossoms. Some pollinators (e.g., bees) are predominantly active during the day while others (e.g., moths) are predominantly active at dusk or night, so familiarize yourself with the most abundant pollinators in the treatment area and adjust pesticide application times accordingly.

  • Consider how long a pesticide remains active before it degrades or how it may spread through the plant: systemic pesticides may provide long-lasting protection against pests but also may contaminate the nectar and pollen of flowers.

• Know where managed bee colonies are and notify beekeepers when you are applying pesticides nearby.
  • It is strongly recommended that applicators notify beekeepers with registered apiaries in the area prior to pesticide applications. Bees will forage across several miles. Therefore, pesticide applicators should identify and notify beekeepers within two (2) miles of a treatment site at least 48 hours prior to application or as soon as possible. Timely notification will help ensure ample time for the beekeeper and applicator to develop a mutually acceptable strategy to manage pests while mitigating risk to honey bees. This may include covering hives, moving hives, or choosing the time of day to apply. Notifying beekeepers does not exempt applicators from complying with pesticide label restrictions. Many insecticide labels prohibit use if pollinators (bees) are present in the treatment area or the crop is in bloom.
  • The PDA has created an interactive searchable map on the PAPlants website where pesticide applicators can identify and obtain contact information for registered apiaries (locations where honey bee colonies are kept). Businesses or individuals registered in PAPlants can search this site by county, township or spray location to identify nearby hive locations and work with their owners to protect the bees. While checking PAPlants for apiaries, applicators may also check the hypersensitivity registry to notify nearby individuals who are hypersensitive to pesticides of the upcoming application.
    
    
    
    A similar resource to the PAPlants website is FieldWatch, which is a free, non-regulatory communication service provided through Purdue University but supported by the Pennsylvania Department of Agriculture and Penn State University. FieldWatch includes “BeeCheck” which allows beekeepers and specialty crop growers to mark the locations of their bees or specialty crops on an interactive online map so that pesticide applicators can communicate with them to minimize risk of drift affecting their bees or crops.

• Recognize symptoms of pesticide exposure to bees. Honey bee colonies that have been affected by pesticides may have unusually large piles of dead bees at the hive entrance, less activity than would be expected given weather conditions, and bees acting disoriented around the colony.

In addition to the general guidelines outlined above, below we provide specific considerations for pesticide use in different environments. We also provide guidelines for pesticide applicators to minimize potential negative impacts on honey bee colonies.

In urban and suburban areas, homeowners, businesses, landscapers, park managers and public health officials may need to control the spread of pests and diseases, to ensure healthy and attractive landscapes, to optimize yield from fruit and vegetable gardens, and to help control public health pests and disease vectors, such as ticks and mosquitos. In all cases, an IPM approach is critical for ensuring goals are met while minimizing non-target damage.

For more detailed information on pollinator-friendly control of pests and diseases in lawns, ornamental plants, vegetable gardens, and parks see “agricultural areas” and “natural areas” sections in the Pollinator Protection Plan. Additional information on managing golf courses (there are over 660 in Pennsylvania alone) for pollinators can be found in “Optimizing Pest Management Practices to Conserve Pollinators in Turf Landscapes: current practices and future research needs” and in the Audubon Cooperative Sanctuary Program for Golf.

Human Pests and Disease Vectors. Individuals can protect themselves from public health pests and disease vectors by using an IPM approach, which can reduce populations of these pests around homes, schools and businesses and/or greatly reduces the chances of individuals being exposed to these pests. This, in turn, decreases broad spectrum pesticide usage that can negatively impact pollinators. Information on key public health pests can be found on the Penn State Extension website.

Ticks can vector a number of human diseases, including Lyme disease. They are responsible for most of the vector-borne disease transmission in Pennsylvania. However, basic precautions can prevent tick bites and reduce or eliminate the need for large-scale pesticide treatments of properties. Individuals should:

• Avoid wooded or brushy areas (where ticks or more common)

• Wear long sleeves and pants, hats, use appropriate pest repellents (such as those containing DEET, see the EPA repellent website for more information) if spending time in areas where there may be ticks

• Inspect themselves for ticks, especially after spending time in possible tick habitat, and remove any ticks promptly.

• If bitten, individuals should be carefully monitored for signs of disease for at least 30 days and contact a physician if symptoms develop.

• More information can be found through Penn State Extension.

Roadsides cover more than 10 million acres of land in the US. Pennsylvania has more than 40,000 miles of roads, and is one of the top five states in the nation for road miles. More than 100,000 acres of roadside lands are managed in Pennsylvania. The landscapes must be managed to support the needs of drivers, utility companies, and other stakeholders (eg, ensuring visibility and access) but can also provide excellent habitats to support pollinator populations.

Managing weedy and invasive plant species in roadsides and rights of way can be challenging. The Pennsylvania Department of Transportation utilizes biological/cultural, chemical and mechanical/manual methods which collectively form an Integrated Vegetation Management (IVM) program:

• Mechanical (mowing, hand-cutting or hand-pulling), chemical (selective herbicide application), and biological (grazing) methods may be used in tandem.

  • Conservation mowing or delayed mowing avoids removing blooms and pollinator habitat during the growing season.

• Tree removal operations account for over sixty percent of the IVM budget to control the forest invasion of the roadside.

• While accounting for only twenty percent of the IVM expenses, the herbicide application program handles the bulk of the vegetation management controls.
  • When applying herbicides in an IVM approach, selectivity of the herbicide and the application method must be considered.

• When IVM is performed properly, the habitat supports greater diversity and species richness of pollinators than when mechanical approaches are used alone.

Approximately 75% of major agricultural crops require or benefit from pollinators to set seed and produce fruit, and all crops can benefit from the arthropods that prey on or parasitize pest species, thereby reducing the negative impacts of these pest populations. Thus, there can be tremendous economic advantages to conserving and expanding populations of beneficial arthropods (managed and wild pollinators, predatory and parasitoid species) in agricultural landscapes. Unfortunately, many beneficial arthropods are also sensitive to the chemicals that are used in these agricultural landscapes. However, use of insecticides, fungicides, and herbicides is critical in many agricultural systems to control pests.

Here, we provide an overview of best practices for pesticide use in agricultural systems, to help growers maximize the yield and economic benefits they receive from beneficial arthropods, and minimize the cost of pesticide applications. However, agricultural crop production is obviously a highly specialized process, requiring integration of information on crop-specific requirements, soil, weather and climatic conditions, and current and future pest and disease pressures. Thus, these recommendations are quite general, and growers are encouraged to contact Penn State extension specialists for more detailed information, see for example, information on tree fruit production or in greenhouses.

Additional information can be found from the Pennsylvania Vegetable Growers Association, the State Horticultural Association of Pennsylvania the Pennsylvania Association for Sustainable Agriculture, and Food Alliance.

Integrated Pest and Pollinator Management (IPPM). Using an “Integrated Pest and Pollinator Management” approach helps growers both manage pests and promote populations of pollinators and other beneficial arthropods to maximize their yields and economic benefits (see review from Penn State researchers, ref and ref). Integrated Pest Management is a well-established approach which uses multiple methods (biological, cultural, physical and chemical) to control pest populations below economic thresholds. IPPM integrates pollinators into this established framework. IPPM recommendations will be specific for certain crops, regions, and agricultural practices. However, there are several basic principles that can be consistently applied to balance the use of pesticides and pollination services (also see online resources from the Xerces Society for more information, "Guidance to Protect Habitat from Pesticide Contamination" and "Preventing Or Mitigating Potential Negative Impacts Of Pesticides On Pollinators Using Integrated Pest Management And Other Conservation Practices").

• Pesticides should only be used when pest and disease levels exceed a pre-determined economic threshold, and after other options (biological, physical, and cultural control) have been deployed. While no one uses pesticides unless there is a perceived need, there are certainly differences in perception of need. For example, some believe that pesticides should be used prophylactically as an ‘insurance’ against pest build-up. Because this practice can increase overall pesticide use, the likelihood of off-target effects, and the likelihood of pests populations becoming resistant to the pesticides, growers are encouraged to refrain from pesticide use unless a pest or disease threat is clearly imminent.

The use of pesticides in natural areas such as forests is sometimes needed to protect ecosystem biodiversity, forest resources, watersheds, stream buffers, and threatened habitats from significant damage by various forest pests and competing native vegetation. The principal targeted pests for treatment in Pennsylvania are non-native invasive species such as the spongy moth, hemlock woolly adelgid, elongate hemlock scale, emerald ash borer, and invasive plants. In addition, competing vegetation in some locations requires control so that forest regeneration can proceed according to established silvicultural practices. In all cases, an Integrated Pest Management (IPM) and Integrated Vegetation Management (IVM) approach must be used along with site-specific environmental reviews, to protect pollinators and other beneficial organisms from unnecessary harm.

Furthermore, Pennsylvania State Forests are independently certified according to the Forest Stewardship Council (FSC) standards, and the Pennsylvania Department of Conservation and Natural Resources(DCNR) Bureau of Forestry follows the best management practices guidelines provided by the FSC. The FSC provides extensive guidelines on pesticide use and alternative pest control strategies that are required for certification.

To illustrate Best Management Practices (BMP) for pesticide use in natural habitats, programs utilized by the PA DCNR are briefly described below, with an emphasis on pollinator protection and mitigation practices for non-target species. The approaches discussed here can be used by private landowners for their forested areas. Use of biological control and other management strategies are highlighted to describe the IPM and IVM approaches to pest management.

Spongy Moth. Spongy moth, formerly known as gypsy moth (Lymantria dispar), an exotic species introduced to the United States in 1868, causes tremendous damage to forest trees. A spongy moth suppression program in Pennsylvania began in 1972 to minimize spongy moth defoliation and prevent tree decline and mortality in targeted areas. The program is request-based, whereby the landowner or managing agency requests areas to be treated. The DCNR Bureau of Forestry has very specific criteria, operations manuals, participation guidelines, environmental review process, and pre- and post-treatment evaluations.

The program currently uses three insecticides to treat forest areas: Bacillus thuringiensis subspecies kurstaki (BTK) (Foray 76B - based on a naturally occurring bacteria that can affect only certain species of lepidopteran larvae), tebufenozide (Mimic 2LV - an insect growth regulator which also affects only lepidopteran larvae), and Gypchek (the spongy moth virus). Gypcheck is specific for gypsy moth, but since it is in limited supply it is only used when there are other lepidopteran species of concern present. Biocontrol programs are also in place, which take advantage of disease organisms, parasitoids and predators.

Hemlock Woolly Adelgid and Elongate Hemlock Scale. The Pennsylvania Hemlock Conservation plan was developed to provide a sustainable conservation strategy for eastern hemlock. While the primary focus is currently on DCNR-managed hemlocks in State Forests and State Parks (Cook Forest State Park is an example of a high value hemlock site), the IPM approach is applicable to private forest lands. See the DCNR Bureau of Forestry Hemlock Conservation Plan for full details.

Neonicotinoids are used to protect eastern hemlocks from hemlock woolly adelgid (HWA) and the elongate hemlock scale (EHS) in high value focus areas. The use of systemic insecticides is needed to keep hemlocks alive long enough so that predatory beetle populations can become well enough established to control these pests. Hemlock trees only have to be treated once every 5 to 7 years to prevent HWA infestations from building up.

If neonicotinoid treatment is required, precautions are taken to minimize potential non-target impacts. These include:

• Avoiding flowering plants (e.g., mountain laurel) and flowering trees (e.g., basswood) if they are next to a treatment tree.

• Preferentially injecting the soil surrounding the tree, but only if sufficient organic matter is present around the base of the tree. Neonicotinoid insecticides, if bound to organic matter, only move about 18 inches in the soil. Thus it is critical that sufficient organic matter be present around a hemlock tree before the soil injection method is used.

• If a hemlock is next to a stream, or does not have sufficient organic matter, or if the water table is too high, direct stem injection can be used to limit the exposure.

Emerald Ash Borer. The Pennsylvania DCNR Bureau of Forestry has developed a comprehensive strategy to control Emerald Ash Borer populations and conserve ash trees in Pennsylvania forests as part of a national strategy to control EAB.

The strategy includes the use of the systemic insecticide ememectin benzoate (Tree-age), identifying “lingering ash” or surviving trees for breeding resistant populations, and releasing EAB parasitoids. Ememectin benzoate has the advantage of preventing attack by EAB, protecting the tree for 3 to 5 years, and becoming concentrated in the sapwood of the tree. Ash is wind pollinated, so the impact of the insecticide to pollinators is minimal. Ememectin benzoate is a restricted use pesticide, so only certified licensed applicators can use this insecticide to inject ash trees. More information on the use of insecticides to protect ash trees from EAB can be found here.

Invasive Plants.

The PA DCNR Bureau of Forestry is committed to managing invasive plant species across all state forest lands and has developed a comprehensive program. The goals of the Bureau of Forestry’s invasive plant management program are to 1) control and eradicate novel and high threat invasive plant species populations, and 2) limit the spread of additional invasive species that threaten forest and wetland ecosystems or forest management activities.

However, managing invasive plant species in natural landscapes can be challenging, time-consuming, and expensive, and typically requires an individualized approach for each plant species. It is often not possible to simply remove all individuals of an invasive plant population, and there are often multiple invasive species. Thus, to prioritize invasive species management, it is necessary to determine a “treatment threshold” (as in all IPM and IVM approaches), which requires a full evaluation of the potential threat to the ecosystem, the density and scale of the infestation, how recently the species was introduced, whether the location has been targeted for management, and the available resources that can be used for managing a particular species.

For a list of plants that are not native to the state, grow aggressively, and spread and displace native vegetation, see the DCNR Invasive Plants List. Fact sheets with information on how to identify and control invasive plants are available at the DCNR Invasive Plants Website. Specific information on locations of invasive species and control efforts can be found at iMapInvasives.

When a population of invasive plant species has been identified for management, they can be physically removed or treated with herbicides. The Forest Stewardship Council provides guidance on selecting pesticides with decreased risk to wildlife.

Competing Vegetation Treatment Program on State Forest Lands. The DCNR Bureau of Forestry Silviculture Section coordinates vegetation treatments each year on State Forest Lands where the end goal is to regenerate a forested area by replacing undesirable native and exotic invasive vegetation with a desirable mix of trees, shrubs, and small herbaceous plants. Regenerated forests provide sustained ecological, economic, and social values. For more details, see the Pennsylvania Bureau of Forestry Planting and Seeding Guidelines.

The following plant species are often targeted for control:

• Common invasive woody species such as striped maple, American beech root sprouts, sweet birch, pin cherry, red maple, witch hazel, mountain laurel, and a host of exotic invasive species such as tree-of-heaven, paulownia, Japanese angelica, Japanese honeysuckle, multiflora rose, Japanese barberry, etc.

• Common herbaceous species such as Hayscented and New York fern, Japanese stiltgrass, mile-a-minute vine, Japanese knotweed, etc.

Honey bee colonies in Pennsylvania are hosts to many parasites and pathogens that can weaken colonies and lead to colony losses. Management of these is described in detail in the “Best Practices for Beekeepers” chapter and is summarized briefly below.

The most important parasite is the Varroa mite (Varroa destructor), and uncontrolled Varroa mite populations are strongly associated with overwintering colony losses in the United States and Europe . It is strongly recommended that beekeepers monitor and manage Varroa populations using an Integrated Pest Management (IPM) approach (see Penn State Extension article on Varroa management, as shown in figure below).

Honey bees are also parasitized by Vairimorpha (Nosema) microsporidia (Vairimorpha apis and Vairimorpha ceranae) which are intestinal parasites that weaken colonies and have been linked to large-scale colony losses in Europe. Wax moths (Galleria mellonella) are commonly found in very weak or abandoned colonies and can damage brood, honey stores, and wax comb. In some parts of Pennsylvania, small hive beetles (SHB) (Aethina tuminda) are found in honey bee colonies; SHB can contaminate honey stores and, at high population levels, lead to colony losses. Honey bees in the United States also host more than 20 different types of viruses, many of which can infect other pollinator species as well. Several of these (Deformed Wing Virus and Israeli Acute Paralysis Virus) have been correlated with honey bee colony losses. Finally, brood diseases such as American Foulbrood (Paenibacillus larvae), European Foulbrood (Melissococcus plutonius), and Chalkbrood (Ascosphaera apis), can kill brood. While Chalkbrood and European Foulbrood are typically “stress” diseases and strong colonies can recover from these, American Foulbrood is the most virulent and contagious and requires immediate notification of the Pennsylvania Apiary Inspection Program and treatment.

Details about these and other parasites and pathogens can be found in the “Field Guide to Honey Bees and their Maladies”, produced by Penn State Extension. This guide provides details about how to recognize and monitor levels of these pests and diseases and approaches to prevent infestation. Additionally, the USDA offers a free diagnostic screening service to help beekeepers monitor for mites, Vairimorpha (Nosema) and brood diseases:.

To manage pests and diseases in a honey bee colony, an IPM approach is critical. Many of the chemicals used to control these pests and pathogens can negatively impact bees and humans. Overuse of these can lead to resistance of the parasite or pathogen to the chemical. For example, many populations of Varroa are now resistant to fluvalinate (a pyrethroid), coumaphos (an organophosphate), and amitraz (an amidine) which are commonly used for Varroa control.

If a chemical treatment is warranted, it is important for beekeepers to read and follow all pesticide label directions, as required by law. It is also important to understand the risks involved in using products not registered by EPA or FDA for use on or around managed bees.

More useful information can be found on best management practices to reduce pesticide exposure to managed bee colonies in this Pollinator Protection Plan, Best Practices for Beekeepers.