Handbook for Mosquito Management on National Wildlife Refuges - June 2018 - U.S. Fish & Wildlife Service

 
Handbook for Mosquito Management on National Wildlife Refuges - June 2018 - U.S. Fish & Wildlife Service
U.S. Fish & Wildlife Service

Handbook for
Mosquito Management on
National Wildlife Refuges

June 2018
Handbook for Mosquito Management on National Wildlife Refuges - June 2018 - U.S. Fish & Wildlife Service
“The mission of the National
Wildlife Refuge System is
to administer a national
network of lands and waters
for the conservation,
management, and where
appropriate, restoration of
the fsh, wildlife, and plant
resources and their habitats
within the United States for the
beneft of present and future
generations of Americans.”
National Wildlife Refuge System Improvement Act of 1997

Photo credit: Don Brubaker, USFWS, 2011

Joy Albertson, Supervisory Wildlife Biologist, San Francisco Bay NWRC, and
Jason Sequeira, Field Supervisor, Marin/ Sonoma Mosquito Control, and
Vector District, CA dipping for mosquito larvae at San Pablo Bay National
Wildlife Refuge.
Handbook for Mosquito Management on National Wildlife Refuges - June 2018 - U.S. Fish & Wildlife Service
U.S. Fish & Wildlife Service

Handbook for Mosquito Management
on National Wildlife Refuges
Introduction ............................................................................................................................................................ 1

Purpose and Scope of the Handbook...................................................................................................................... 2

Principles of Integrated Pest Management.......................................................................................................... 4

Mosquito Management Plan.................................................................................................................................. 5
   Statement of Purpose and Need .............................................................................................................. 6
    Refuge Natural Resources (including maps) .......................................................................................... 6
   Mosquito Ecology and Life History ......................................................................................................... 6
   Climate Change ........................................................................................................................................... 7
   Health Considerations ................................................................................................................................ 7
       Mosquito-Borne Disease ...................................................................................................................... 8
        Mosquito Related Human Health Considerations ........................................................................... 8
       Animal Health Considerations ............................................................................................................ 8
   Mosquito-Vectored Pathogen Surveillance and Mosquito Monitoring ................................................. 8
   Mosquito Management Options .............................................................................................................. 11
        Best Management Practices ............................................................................................................. 11
        Managing Habitats for Mosquito Source Reduction ..................................................................... 11
        Mosquito Control ................................................................................................................................ 12
       Larvicides, Pupacides, Adulticides .................................................................................................. 16
              Modifed Mosquitoes ............................................................................................................. 17
   Thresholds for Action - Risk Management ............................................................................................ 18
              Pesticide Treatment Decisions ............................................................................................ 19
              Human Health Emergencies ................................................................................................ 21
    Natural Resource and Compliance Monitoring and Reporting .......................................................... 21
              Natural Resources Monitoring ........................................................................................ 21
              Mosquito Management Implementation Compliance Monitoring................................... 21
              Reporting ............................................................................................................................... 22
   Adaptive Management .............................................................................................................................. 22
   Education and Outreach ........................................................................................................................... 22
              Local Mosquito Situation and Communication .................................................................... 22
              Prevention ............................................................................................................................... 23
              Natural Mosquito Predators ................................................................................................ 24

Glossary ............................................................................................................................................................... 25

Literature Cited and General References.............................................................................................................. 27

Appendices ......................................................................................................................................................... 30
       Appendix A Authorities and Policies Relevant to Mosquito Management .............................. 30
       Appendix B Summaries of Common Mosquito-Borne Diseases in the United States and
                              Other Mosquito-Related Human Health Considerations..................................... 35
       Appendix C Action Threshold - Example ..................................................................................... 39
       Appendix D Animal Health Considerations ................................................................................ 44

Handbook for Mosquito Management on National Wildlife Refuges                                                                                                                 i
ii   Handbook for Mosquito Management on National Wildlife Refuges
Introduction

The U.S. Fish and Wildlife Service (Service)           Unless mosquitoes interfere with refuge-specifc
considers native mosquitoes a part of the natural      management goals and objectives, or cause a
ecosystem in the National Wildlife Refuge System       public or wildlife health risk, they are allowed to
(Refuge System) habitats in which they occur.          exist unimpeded on a refuge. Mosquito-vectored
The Service allows mosquitoes on refuges to exist      pathogens that cause disease are the primary public
unimpeded unless they pose a specifc human or          health concern associated with mosquitoes on a
wildlife health risk. Sometimes Refuge Managers        refuge. When faced with mosquito management
are called upon to manage mosquitoes on-refuge in      decisions affecting Refuge System lands and waters,
coordination with local public health or mosquito      the Service’s position is to work with public health
control organizations. This handbook applies to        agencies and/or mosquito control organizations
mosquito management activities related to reducing     using the most effective method or combination of
risks to public health from mosquito-borne disease.    methods that pose the lowest risk to fsh, wildlife,
                                                       and their habitats. Often, the Service’s preferred
A Refuge Manager may authorize others to conduct       mosquito management option is to use non-pesticide
mosquito management activities on a refuge to          based tools.
protect public health when local, current mosquito
monitoring data provided by the public health          Under Service policy, integrated pest management
agency or an authorized designated representative      (IPM) is a sustainable approach to managing
indicate that mosquitoes on the refuge are causing,    pests by combining physical, biological, cultural,
or are expected to cause, a public health threat.      and chemical tools in a way that minimizes health,
Mosquito management includes the following             environmental and economic risk. Effective
activities: planning, identifcation and inventory      mosquito management on refuges requires planning
of mosquito species, surveillance and monitoring,      that follows the IPM principles. This handbook for
establishing action thresholds, prevention, control    mosquito management is a stepdown handbook for
(to suppress and/or reduce mosquitoes), restoration,   the Service IPM policy (569 FW 1).
research, and outreach and education activities
used to minimize risks to public health. All Refuge
System mosquito management activities, including
Service planning documents, must be consistent
with all applicable Federal laws, regulations and
policies.

Handbook for Mosquito Management on National Wildlife Refuges                                                 1
Purpose and Scope of this Handbook

    This handbook establishes the Service’s                The Service relies on public health authorities
    interpretation of existing laws, regulations,          and mosquito control organizations to determine
    and policies that allow us to authorize mosquito       the risks and threats to public health related to
    management activities on Refuge System lands           mosquito-borne pathogens and to advise us on
    and waters. The handbook provides consistency in       management actions to minimize these risks. Public
    the decision-making process regarding mosquito         health authorities may work with refuge staff to
    management on national wildlife refuges for            implement integrated pest management principles
    protection of public health. In general, the Service   that include the following:
    does not treat for mosquito-vectored wildlife
    disease. The handbook guides development of                (1) Identifying mosquito species in the area
    Mosquito Management Plans (MMP) in compliance                  and understanding their life history and
    with the National Environmental Policy Act and                 conditions that support their production;
    provides information to make informed management           (2) Monitoring mosquitoes and mosquito-
    decisions and minimize the impacts to natural                  borne pathogen surveillance (as needed)
    resources from mosquito management activities on               to provide relevant information to
    Refuge System lands and waters. Mosquito control               refuge staff;
    activities may include prevention practices, habitat
    management actions, biological controls, chemical          (3) Establishing action thresholds that help
    treatments, and, potentially, modifed mosquitoes.              the Refuge Managers make informed
    Mosquito management planning is most effective                 decisions about actions such as pesticide
    when conducted in partnership with public health               treatments, when needed;
    authorities or their authorized representatives.           (4) Recording decisions and effectiveness
    Such representatives are often mosquito control                of actions implemented; and
    or mosquito abatement districts (referred to               (5) Monitoring for effcacy, compliance,
    throughout the handbook as “mosquito control                   and non-target impacts.
    organizations”).
                                                           Mosquito management planning for a national
    Mosquito management planning includes identifying      wildlife refuge must consider public health while
    acceptable control strategies. An MMP serves as an     protecting natural resources. Pesticides used to
    important tool to communicate with the community       manage mosquitoes have the potential to adversely
    and provides common understanding of acceptable        impact non-target species either directly or
    and permitted mosquito management strategies           indirectly. Some mosquito control pesticides impact
    among the health authority, mosquito control           the immune, reproductive, or nervous system of
    organization, and the refuge staff.                    insects. Some larvicides kill susceptible chironomid
                                                           (midge) larvae, with research suggesting that
    Planning is necessary to ensure that mosquito          population-level impacts may affect the food web at
    management activities on a refuge are compatible       the community-level. Mosquito adulticide products
    with the establishing purposes of the refuge.          are broad-spectrum insecticides that may impact a
    Mosquitoes are a part of the ecosystem; they           wide variety of invertebrates and vertebrates.
    serve as a food resource for other organisms.
    Nevertheless, they are also pathogen vectors.          The degree to which mosquito control pesticides
    Generally, the Service receives no appropriated        may impact non-target organisms or non-target
    funds to conduct mosquito management activities        insect communities is often diffcult to predict
    and implementation of monitoring and treatment on-     because of differences in sensitivity among species,
    refuge is conducted by public health or the mosquito   differences in toxicity of various formulated
    management organizations. Mosquito management          products, and basic knowledge gaps in species-
    activities on refuges are considered a use of a        specifc toxicity. There are few studies that examine
    refuge and require a Special Use Permit (SUP).         the non-target impacts of mosquito control

2                                          Handbook for Mosquito Management on National Wildlife Refuges
pesticides at diverse spatial and temporal scales.   This handbook guides Service review, planning,
The use of mosquito larvicides is considered         and authorization processes for use of lawfully
preferable to mosquito adulticides for several       registered pesticides for mosquito control on-
reasons:                                             refuge. The U.S. Environmental Protection Agency
                                                     (USEPA) assesses human health and non-target
     (1) Larvicides prevent the emergence            resource risks of pesticides during the pesticide
         of adults;                                  registration process. There is increasing attention
     (2) Larvicides can provide up to a month        to mosquito species evolving resistance to mosquito
         (or longer) of control, rather than the     pesticide products currently in use. Uncertainty
         few hours provided by adulticides;          about human health risks of pesticides, non-target
                                                     resources impacts, and resistance is ever changing;
     (3) Most larvicides are far less toxic than     that is why, in part, that the USEPA conducts
         adulticides; and                            pesticide re-registration reviews. These concerns
     (4) Larvicides are generally applied to         support an integrated approach to mosquito
         smaller spatial areas, thus impacting       management.
         fewer non-target resources.
                                                     This handbook is applicable to all units of the
For these reasons and in view of the mission of      Refuge System where the Service has jurisdiction
the Refuge System, when mosquito management          over mosquito management activities, regardless of
actions include pesticide use, they should target    whether the Service or a Service-authorized entity
the mosquito larval stage. Mosquito larvicides /     conducts the mosquito management actions.
pupacides pose less risk than adulticide products
to non-target species and the environment.

Handbook for Mosquito Management on National Wildlife Refuges                                              3
Principles of Integrated
    Pest Management (IPM)
    Integrated Pest Management is a sustainable                 environmental risk. These IPM principles are the
    approach to managing pests by combining                     foundation for mosquito management planning and
    physical, biological, cultural, and chemical tools          implementation.
    in a way that minimizes economic, health, and

                           The Principles of Integrated Pest Management

      • Understand the refuge management
      objectives and establish short- and long-term
      priorities. Refuge objectives would be found in the       • Build partnerships and consensus with
      Comprehensive Conservation Plan (CCP) or in the           stakeholders, such as communities and decision-
      Habitat Management Plan, or both. Decide on your          makers. Example: Public health agency staff
      refuge objectives for mosquito management; use            and technical experts such as mosquito control
      specifc, measurable, achievable, realistic, and time-     organization staff. Partnership building is an on-
      based objectives when choosing tools. Example:            going effort throughout the process.
      Due to past history of mosquito-vectored disease
      in the area, a Refuge Manager may allow a public          • Review available tools and BMPs for mosquito
      health district or a mosquito control organization to     management. Tools and strategies can include: 1)
      treat some mosquito breeding habitat on the refuge        no action, 2) physical (manual and mechanical), 3)
      for larval mosquitoes if the public health district       cultural, 4) biological, and 5) chemicals.
      requests it.                                              • Establish the “action threshold” at which
      • Prevent mosquitoes from becoming a pest at              a management action will be implemented to
      your site. This is the frst line of defense against any   control the pest population. (Action thresholds are
      pest species. See the Best Management Practices           a key Mosquito Management Plan (MMP) element
      (BMPs ) section of the handbook.                          and are discussed in detail later in the handbook.)

      • Identify and monitor the pest species                   • Obtain approval, defne responsibilities, and
      (mosquito), and know the life history, and the            implement preventive and best management
      conditions that support the pest(s). Similarly,           practices (BMPs) and control treatments, in
      know the diseases that are vectored by the                accordance with applicable laws, regulations,
      mosquitoes that occur in your area. The Centers           policies and the refuge MMP.
      for Disease Control and Prevention (CDC),                 • Practice adaptive management. Evaluate
      public health agencies, and mosquito control              results of implemented management strategies
      organizations have relevant information. Access           through authorized monitoring; determine
      information on the CDC website located at https://        if objectives have been achieved, and modify
      www.cdc.gov/niosh/topics/outdoor/mosquito-borne/          strategies, if necessary.
      • Understand the physical (air, water, food,              • Maintain written records. Document decisions
      shelter, temperature, and light) and biological           and report treatments implemented and monitoring
      factors that affect the number and distribution           results.
      of mosquitoes and any natural enemies. Conserve
      natural enemies when implementing any strategy.           • Outreach and education. Inform refuge staff
      Integrated marsh management, for example, can             of the mosquito management issues in and around
      restore high marsh pools to serve as native fsh           the refuge, and prepare informative materials for
      reservoirs in areas that had been previously drained.     outreach to visitors.

4                                              Handbook for Mosquito Management on National Wildlife Refuges
Mosquito Management Plan

If mosquito management activities occur on or          the local public health authorities and mosquito
impact a refuge, then refuge staff should prepare      control organizations. Regardless of refuge-specifc
an MMP. An MMP is a step-down management plan          circumstances, collaborating with experts who
with specifc objectives and strategies that support    work for local public health authorities or mosquito
the objectives identifed in a CCP. An MMP is           control organizations will help refuge staff plan
also identifed as an integrated pest management        for mosquito management. Planning also provides
plan. Mosquito management planning provides            transparency of operations and public inclusion
the Service with the opportunity to assess the         in decision-making. The MMP may include the
impacts of mosquito management activities and          following sections where appropriate, recognizing
helps to ensure the protection of natural resources.   the need for refuge-specifc fexibility in planning.
Mosquito management planning facilitates the
development of the working relationships with

               National Wildlife Refuge Mosquito Management Plan

                           Statement of Purpose and Need
                           Refuge Natural Resources (including maps)
                           Mosquito Ecology, Life History, and Pathogen Transmission
                           Climate Change Infuences
                           Health Considerations - Human and Animal
                           Mosquito-vectored Pathogen Surveillance and Mosquito Monitoring
                           Mosquito Management Options
                                  Best Management Practices
                                   Managing Habitats for Mosquito Source Reduction
                                   Mosquito Control Products
                                           Larvicides, Pupacides, Adulticides
                                           Modifed Mosquitoes
                           Thresholds for Action - Risk Management
                           Pesticide Treatment Decisions
                           Human Health Emergencies
                           Natural Resource and Compliance Monitoring and Reporting
                           Natural Resources Monitoring
                           Mosquito Management Implementation Compliance Monitoring
                           Reporting
                           Adaptive Management
                           Education and Outreach
                                  Local Mosquito Situation and Communication
                                  Prevention
                                  Natural Mosquito Predators

Handbook for Mosquito Management on National Wildlife Refuges                                                 5
I. Statement of Purpose and Need                               •   Structures, components, and functions of
                                                                       the ecosystem(s) of which the refuge is a part;

             State the purpose of the refuge MMP                   •   Rare or declining fsh, wildlife, and plants and
             and clearly articulate the public health                  their habitats and communities; and
      ∑      need for mosquito management on the
             refuge.                                               •   Special management areas (e.g., wild, scenic,
                                                                       and recreational river areas; wilderness
                                                                       areas).
    Relate the need for mosquito management planning
    to refuge goals and objectives, as appropriate. For       III. Mosquito Ecology, Life History,
    example, if the refuge provides habitat for a federally
    listed butterfy, then mosquito management planning             and Pathogen Transmission
    might be crucial to minimize impacts to the species and
    its habitat while conducting mosquito management                   Summarize the inventory of mosquito
    control activities.
                                                                ∑      species on refuge and their potential as
                                                                       pathogen vectors.
    II. Refuge Natural Resources
                                                              This handbook focuses on mosquito management
             Summarize the natural resources and              planning and decision-making as required for the
      ∑      potential impacts from mosquito
             management.
                                                              purposes of protecting public health from diseases
                                                              caused by mosquito-vectored pathogens regardless of
                                                              whether vectored by a native or non-native mosquito
                                                              species. Over 80 million years and the evolution
    A thorough review of the natural resources and the        of 3,500 mosquito species, there are now over 175
    impacts of the mosquito management actions, such          species of native and non-native mosquitoes in the
    as habitat manipulation or effects of pesticides on       contiguous United States. Not all mosquito species
    the natural resources, is necessary. Natural resource     are vectors of disease. Mosquitoes vary in pathogen
    descriptions are often presented in an Environmental      transmission effciency, habitat and host requirements,
    Assessment as part of National Environmental Policy       and, therefore, they may require different control
    Act (NEPA) compliance; however, if natural resources      strategies. Many native mosquito species are prey for
    have been addressed within another NEPA-compliant         other aquatic and terrestrial fauna and because of their
    planning process, such as in a CCP, then you can          role in ecosystems, thorough planning is necessary to
    incorporate that review by reference.                     minimize impacts when mosquito management actions
                                                              are implemented on refuge to protect public health.
    As a publicly vetted document, appropriate CCP
    chapter(s) on natural resources can be copied or          Inventory and identifcation of the mosquito species
    cited into the Natural Resources section of the MMP.      that reproduce on the refuge is fundamental
    Potential content may include, but is not limited to:     information in mosquito management planning. In the
                                                              MMP, include an inventory of the mosquito species
         •   Distribution and abundance of fsh, wildlife,     known or suspected to occur on and near the refuge
             and plant populations, including any             and brief life histories. Species that may vector disease
             threatened or endangered species and             pathogens are particularly important to include. This
             related habitats;                                handbook does not provide life histories because they
                                                              are readily available online. Sources for determining
         •   Wildlife habitat and species’ relationships      species of mosquitoes currently occurring on or near
             that may be impacted by mosquito                 a refuge are usually available on websites of the local
             management;                                      mosquito control organizations, and from the State and
                                                              local public health authorities. If there is no current
         •   Ability of the refuge to meet the habitat        inventory of the mosquitoes species that occur on or
             needs of fsh, wildlife, and plants;              near the refuge, contact the local mosquito control
                                                              organization or public health agency to conduct an
         •   Context of the refuge in relation to the         inventory. This is not a refuge function. A current
             surrounding ecosystem;                           mosquito inventory is necessary because the species
6                                              Handbook for Mosquito Management on National Wildlife Refuges
occurrence may change with climate change or other       decades, the effects of climate change have become
introductions, such as global transport.                 more measurable in coastal wetlands. Signs of
                                                         climate change include increased sea levels, marsh
In the aquatic environment, mosquitoes are most          edge erosion from intense storms, and conversion
effectively managed in the larval and pupal life-        of vegetated salt marshes to open water. Wherever
cycle stages (Figure 1) https://www.cdc.gov/Dengue/      there is increased standing water, mosquitoes are
entomologyEcology/m_lifecycle.html.                      more likely to occur. Managers must continue to
                                                         adapt strategies to the changing landscape and
                                                         consider mosquito production in management and
                                                         also periodically update the mosquito inventory on
                                                         the refuge.

                                                         Some scientists have reported that higher global
                                                         temperatures will enhance transmission rates of
                                                         mosquito-borne diseases (Shope 1991). Others
                                                         suggest that the geographic range of diseases will
                                                         change (Hales et al. 2002). Gubler et al. (2001)
                                                         reviewed the response of vector-borne pathogens to
                                                         climate changes and suggested that climate changes
                                                         will likely affect transmission patterns - some may
                                                         increase and some may decrease - and that we need
                                                         to understand more about how pathogens persist
It takes a mosquito between 4 to 30 days to develop      and what conditions trigger amplifcation before the
from an egg to an adult, depending on species and        role of the weather and long-term climate trends
water temperature. Mosquito larvae develop through       can be determined. Reiter (2001) argued that
four instars. Skilled observers can determine the        the histories of malaria, yellow fever, and dengue
instar of larvae and infer hatching or adult emergence   suggest that human activities and their impact on
time. Instar information is critical for proper timing   local ecology have generally been more signifcant
of larvicide or pupacide applications for maximum        determinants of disease prevalence than climate.
effectiveness to help avert the need to use mosquito     Since climate change scenarios differ across the
adulticides. Mosquito control organization staff are     country and depend highly on local conditions,
usually skilled in mosquito life stage identifcation;    refuge staff should consult local models as they
we do not expect the refuge staff to conduct this        develop their mosquito management strategies.
identifcation.
                                                         V. Health Considerations
IV. Climate Change Infuences
                                                                 Briefy identify and describe the
        Provide a summary of how climate                    ∑    health considerations that drive the
   ∑    change could infuence mosquito                           MMP on the refuge.
        production and habitats on your refuge.

                                                         Mosquito-vectored pathogens that cause disease
Changing environments, whether naturally                 are the primary public health concern associated
or through actions taken to restore habitats,            with mosquitoes. Health considerations related
may result in increased or decreased mosquito            to mosquitoes vary depending on the species
production. Climate change effects may include           present, abundance, geographic area, and time
increased rainfall that creates ponded water, or         of year. For most refuges and the surrounding
decreased precipitation and drought conditions           communities, public health authorities and their
that reduce mosquito habitats (IPCC 2013). Sea           authorized, designated representatives, such as
level rise may alter a landscape so that areas where     a mosquito control organization, are responsible
mosquitoes have never been an issue eventually           for surveillance of mosquito-vectored disease, and
become a concern. For example, salt marsh                control treatments, where needed.
mosquitoes may come to inhabit areas further
inland than they did historically. Over the past few

Handbook for Mosquito Management on National Wildlife Refuges                                                  7
healthy individuals within hours of a mosquito bite
         Examples of Mosquito-Borne                       and can last for 3 to 10 days. With any break in the
         Diseases in the United States                    skin, there is the potential for secondary (indirect)
                                                          bacterial infection resulting from mosquito bites.
               •   West Nile Virus                        Anaphylactic reactions (life-threatening, whole-body
               •   Dengue Fever                           allergic reaction) to mosquito bites are extremely
                                                          rare. Appendix B provides a non-exhaustive
               •   Chikungunya
                                                          reference list and more information on mosquito-
               •   La Crosse Encephalitis                 associated health considerations.
               •   Eastern Equine Encephalitis
               •   St. Louis Encephalitis                 Animal Health Considerations
               •   Western Equine Encephalitis
                                                          Animal health can be affected by mosquito-borne
               •   Zika Virus
                                                          diseases. This handbook guides development
                                                          of MMPs to reduce the threat to public health
                                                          from mosquito-vectored pathogens. In general,
    Mosquito-Borne Disease                                the Service does not manage mosquitoes for
                                                          mosquito-vectored animal disease. Mosquito
    An MMP must identify which mosquito-borne             management actions, such as managing non-native
    diseases may be vectored by mosquitoes that breed     mosquitoes that threaten endangered species,
    on the refuge, either historically or currently.      would follow another plan, such as an exotic
    This information is helpful to identify source-area   animal or invasive species management plan or an
    control. Brief summaries of diseases and mosquito-    endangered species recovery plan that includes
    related health conditions that are potentially of     a National Environmental Policy Act analysis,
    concern to refuges are provided in Appendix B.        and an Endangered Species Act consultation, if
    Consult the Centers for Disease Control and           appropriate.
    Prevention or your State and local mosquito
    control organization and public health authorities
    for current local information. The Centers for        VI. Mosquito-Vectored Pathogen
    Disease Control and Prevention, National Center
    for Emerging and Zoonotic Infectious Diseases
                                                              Surveillance and Mosquito
    website provides links to useful mosquito-vectored        Monitoring
    pathogen and related diseases information, https://
    www.cdc.gov/ncezid/. The U.S. Geological Survey
    also provides current maps of mosquito-borne                  Describe the pathogen surveillance and
    disease in the U.S. at: https://diseasemaps.usgs.        ∑    mosquito monitoring activities used to
                                                                  direct mosquito management.
    gov/mapviewer/ . If there are no current or
    historical occurrences of mosquito-borne diseases
    in the refuge area, document that fact and the
    source of the information in the MMP.                 Refuge staff, public health authorities, and mosquito
                                                          control organizations must rely on mosquito
    Other Mosquito-Related Human Health Considerations    pathogen surveillance (referred to as “pathogen
                                                          surveillance” throughout the remainder of the
    There are other human health considerations           handbook) and mosquito monitoring to direct
    associated with mosquitoes. Most of the human         mosquito management activities in order to be
    population at any given time will have some           most effective and minimize non-target impacts. In
    reactivity to mosquito bites. Outdoor workers,        general, Refuge Managers may authorize, but do
    young children, immuno-defcient people, and           not implement, disease surveillance and mosquito
    visitors to an area with indigenous mosquitoes to     monitoring. There must be mosquito monitoring or
    which they have not been previously exposed are       pathogen surveillance data to support treatment
    at increased risk for severe reactions to mosquito    decisions. The refuge staff evaluates the mosquito
    bites. Though allergic reactions to mosquito bites    monitoring data results against Action Thresholds
    are common, the clinical diagnosis of “mosquito       to guide mosquito management decisions.
    allergy” is reserved for those with atypical or
    systemic reactions that may occur in otherwise
8                                           Handbook for Mosquito Management on National Wildlife Refuges
The Refuge Manager must:                                  decisions regarding responses to mosquito activity.
                                                          Public health authorities and mosquito control
    •    Identify the public health agency or             organizations conduct mosquito-borne pathogen
         mosquito control organization who will           identifcation and surveillance. Detecting the
         conduct pathogen surveillance and                mosquito-borne pathogens includes testing adult
         mosquito monitoring on or near the refuge        mosquitoes for pathogens or testing reservoir hosts
         and include the contact information and          for pathogens or antibodies.
         their roles in the MMP.
                                                          This is not a refuge function. Request copies of the
    •    Identify the on-refuge restrictions and          surveillance protocols that the local public health
         stipulations in a Special Use Permit (SUP)       authority and/or mosquito control organization use.
         for mosquito monitoring and pathogen             Surveillance of mosquito-borne pathogens may:
         surveillance activities (e.g., access, vehicle
         use, sensitive species and/or habitats, time         •   Confrm the mosquito species vectoring
         of day) to protect sensitive resources while             a pathogen.
         still allowing activities needed to make
         decisions.                                           •   Identify locations where mosquitoes
                                                                  vectoring pathogens breed on-refuge.
    •    Document the communication and
         notifcation procedures between the public            •   Confrm pathogen incidence/prevalence.
         health agency (or their authorized
         representative) and the refuge.                      •   Confrm the seasonality of pathogen
                                                                  prevalence (as appropriate).
    •    Review the monitoring and pathogen
         surveillance protocols (including objectives,        •   Identify and confrm locations where
         methods, frequency, and locations) and                   pathogens (human or wildlife) occur.
         include them in the MMP (and reference
         in the SUP); these protocols are more            Mosquito Monitoring
         appropriate in the MMP than in the Inventory
         and Monitoring Plan for the refuge.              Mosquito monitoring identifes the mosquito species
                                                          present, relative abundance, and distribution.
    •    Archive mosquito monitoring and                  Mosquito monitoring is generally not a refuge
         pathogen surveillance protocols and data         function; public health or mosquito control
         reports in PRIMR and ServCat,                    organizations usually monitor for mosquitoes.
         respectively.                                    Refuge staff should review the protocols used to
                                                          determine that each step is appropriate on the
Mosquito-vectored pathogen surveillance data will         refuge and that the data will be adequate to make
include vector abundance (larval and adult forms)         decisions. Mosquito monitoring protocols should
and may document mosquito-based pathogen                  be standardized protocols that are included in
infection rates on- and off-refuge. Monitoring            the MMP, and referenced in the SUP. Repeated
vector-mosquito abundance and pathogen-related            monitoring should reveal trends in mosquito
data, such as dead bird surveillance and human            production over time. Public health and mosquito
disease cases, can serve as the basis for decision-       control organizations use monitoring data that
making and the thresholds for pesticide treatment.        they collect with standardized methodologies to
Mosquito management is adaptive management,               determine if, when, where, and how to treat; to
where mosquito activity is identifed and quantifed,       assess effectiveness of treatment; and to map
perhaps treated, and re-checked periodically,             mosquito breeding and harboring areas to focus
often every 7 to 14 days, for activity status and, if     treatment strategies. Monitoring protocols are
necessary, treatment effectiveness.                       developed by the State or local public health
                                                          authorities and mosquito control organizations.
Mosquito-borne Pathogen Surveillance
                                                          Objectives for mosquito monitoring are to:
The purpose of mosquito-borne pathogen
surveillance on or near the refuge is to provide              •   Determine if areas on the refuge exceed
the refuge staff information to make informed                     established action thresholds as a basis to

Handbook for Mosquito Management on National Wildlife Refuges                                                    9
determine if treatment is warranted.            species in an area are known, a trained observer can
          •   Establish a baseline of mosquito species        often identify the larvae in the feld; however, this is
              present and relative abundance.                 not always simple or reliable.

          •   Identify mosquito source habitats and           Identifcation keys for regions of North America
              determine the relative contribution of          are available for fourth instar larvae that have been
              refuge sources to the regional vector           collected and are examined under a microscope.
              populations.                                    Some mosquito control organizations raise numbers
                                                              of larvae to adults in rearing chambers to confrm
          •   Detect changes in relative abundance.           that the larvae found in the area (which could
                                                              include a refuge) are the same species as the adults
          •   Determine the seasonality for mosquito          that are causing problems. There may be situations
              monitoring based on mosquito activity and       where treatment will depend on the mosquito
              lifestages.                                     species (as opposed to the genus) present. It is
                                                              preferable that the public health or mosquito control
     The timing and frequency of monitoring is based          organization staff trained in larval (4th instar)
     on such factors as life histories of mosquito            identifcation conduct this identifcation. Specimens
     species present, tidal cycles (if applicable), water     can also be sent to local experts at State universities
     temperature, water levels in wetlands, timing,           or extension offces to confrm identifcation and
     and volume of precipitation events, and available        establish a reference collection.
     resources.
                                                                  2. Adult Mosquito Traps: A variety of adult
     Following are examples of brief, summary                     mosquito traps are available for monitoring
     descriptions of current mosquito monitoring                  purposes: sticky surfaces; fans that draw
     protocols typically used by mosquito control                 mosquitoes into a trap; and some traps that
     organizations (consult local public health district or       use an attractant, such as CO2, that lures
     mosquito control organization websites for other             mosquitoes close enough to be drawn into a
     standardized protocols):                                     trap chamber. Traps are typically set out from
                                                                  sunset to sunrise to sample during periods
         1. Monitoring Larval Mosquitoes: The                     when most species are actively dispersing
         primary technique for larval population                  and feeding. Counts of the species captured
         counts is the dip count (using a standard dip-           each trap night can indicate where adults are
         cup on the end of a pole). Dips are taken in             concentrating and how the adult populations are
         undisturbed pools identifed as representative            changing over time relative to control activities.
         of the breeding areas. The trained feld person           Trap sites at the refuge boundary may identify
         avoids disturbing the water or casting a                 that the species being produced on the refuge
         shadow over the water which will cause larvae            are dispersing to populated areas, although
         to move/dive, thereby lowering counts. For               direction of fight can be diffcult to discern.
         large sites, dipping would likely be conducted           Mosquito control organizations sometimes
         at permanent, identifed (or easily located) dip          use the number, frequency, and location of
         stations; although sampling location is often            complaints from citizens regarding mosquitoes
         random. For small sites, dips may be taken               to help identify locations for mosquito
         at random locations throughout the site. Dips            monitoring, such as setting traps.
         per site will be relative to the area needing
         sampling. Recommendations for treatment of               3. Landing Rate/Bite Counts: Although
         an area may be determined with fewer dips if             many historical datasets include landing rate
         numbers of larvae and pupae per dip exceed               counts, this is not a scientifcally rigorous
         action thresholds established in the refuge              monitoring method and it is not recommended.
         MMP (Walton, W. 2005).                                   For mosquito monitoring on national wildlife
                                                                  refuges, request that mosquito control
     Standards require feld identifcation of larvae at            organizations look for and implement other
     least to the genus level. A trained observer can             methods (see above). Landing rates, or bite
     identify the following genera most of the time:              counts, are equal to the number of mosquitoes
     Aedes, Anopheles, Coquillettidia, Culex, Culiseta,           landing on an observer in a pre-determined
     Psorophora, and Uranetaenia. If the common                   length of time, e.g., in 1 minute intervals. This

10                                              Handbook for Mosquito Management on National Wildlife Refuges
method, when repeated at multiple locations,     Habitat manipulations for mosquito management
     provides a rough, rapid assessment of the        (such as draining or maintaining high water levels)
     likelihood of being bitten in populated areas.   that confict with wildlife management objectives
                                                      are prohibited except when it is necessary to
VII. Mosquito Management                              temporarily suspend, allow, or initiate mosquito
                                                      management activity in a refuge to protect the
     Options                                          health and safety of the public or a fsh or wildlife
                                                      population, as provided in section 8 Emergency
                                                      Power of the National Wildlife Refuge System
         Describe the mosquito management             Improvement Act of 1997.
         options, including BMPs, habitat
  ∑      management, and products that may
         be used on the refuge.                       Managing Habitats for Mosquito
                                                      Source Reduction
                                                      Source reduction is a commonly used term in
Mosquito management options can include grounds-      mosquito management. Whether a refuge has
keeping activities and habitat manipulation to        bogs, swamps, salt marsh, or freshwater marsh
reduce breeding habitat, and, when necessary, may     habitats (collectively referred to as wetlands),
include the use of pesticides. When considering       water circulation is a natural function that impedes
mosquito control measures, the Service authorizes     production of mosquitoes. Since European
those methods that present the lowest risk to         settlement, wetlands have been altered or degraded
our natural resources while still accomplishing       by various practices such as grazing, farming,
the mosquito control goal. Always use BMPs            ditching, and construction of roads and bridges.
preventively when implementing any treatment          Unaltered wetlands are rare, and source reduction
option, including pesticide treatments that may       techniques are not permitted in these unique
be considered. The table below provides BMPs to       wetlands. In some cases, restoration of degraded or
reduce mosquito breeding habitat in and around        previously altered habitat can be an effective and
facilities.                                           economically viable option to accomplish mosquito
                                                      source reduction while also restoring natural
                                                      hydrological function. In contrast, weirs, dams, or
       Best Management Practices                      missing or undersized culverts inhibit natural water
                                                      fow that may promote a low-fow environment for
   Establish and implement a periodic review of       eggs to hatch and adults to emerge before being
       facilities at risk for standing water:         fushed out of the system. Mosquito population
                                                      reduction may occur when a tidal marsh habitat is
 •     Minimize standing water to the                 managed to drain effectively or high marsh ponds
       maximum extent possible                        are created or restored to serve as reservoirs
 •     Remove/eliminate discarded tires, road         for fsh that then control mosquito larvae. Native
       ruts, open tanks, or similar debris/           fsh throughout the country continue to provide
       containers                                     effective mosquito control in natural habitats. In
 •     Clear rain gutters to allow rainwater to       coastal salt marshes, species such as Fundulus
       fow freely                                     heteroclitus, and other cyprinid fsh can exert
 •     Turn over containers that can hold water       control over mosquitoes in the egg, larval, and
       when stored outside                            pupal stages (Rochlin et al. 2012).
 •     Check for trapped water in tarps used
       to cover boats/equipment and arrange           Flowing water is a poor producer of mosquitoes
       covers to drain water                          because egg masses are destroyed and larvae
 •     Pump out boat bilges                           and pupae drown. Restricting the fow of streams
 •     Replace water in birdbaths and livestock       and rivers or channelizing these waterways may
       troughs twice a week                           reduce riffes and rapids, which reduces fow so that
 •     Fix outside water faucets that are             mosquitoes can breed and reproduce effectively.
       dripping.                                      Maintaining or restoring the meander and
 •     Use screens on rain barrels and water          streambed topography will restore hydrology that
       cisterns                                       naturally prevents streams and rivers from being
                                                      sources of mosquitoes. This also diversifes the
Handbook for Mosquito Management on National Wildlife Refuges                                                11
system, providing habitats conducive to mosquito          Establishing and maintaining positive working
     predators both in and out of the water.                   relationships is important when working with
                                                               mosquito control organizations, other State
     Aquatic habitats should be supported by natural           and Federal agencies, and private contractors.
     hydrological processes, where possible. To do so          The refuge staff will work with them from the
     may require researching historic fow conditions,          initial contact and planning phases through
     consulting a hydrologist or restoration ecologist,        implementation, monitoring, and evaluation to adopt
     and coordinating with landowners up- and                  marsh management techniques that enhance fsh
     downstream to re-establish natural fows and               and wildlife benefts for the public while limiting the
     conditions. You may need to clear channels                creation of mosquito breeding habitats.
     of accreted sediment, and remove or enlarge
     structures to increase water fow into and out             Mosquito Control
     of the system. This may require some adaptive
     management before the natural fows return,
     where channels scour properly, and water fows are                  Describe the mosquito control
     regular and consistent through the system. Wetland                 techniques and pesticides that may be
     enhancements may re-create channels to drain or             ∑      used on the refuge. The information
                                                                        below may help you make better
     food a poorly circulating habitat. Engineering a
     tidal marsh restoration should ensure wetlands                     informed decisions.
     have adequate circulation to almost completely
     drain the marsh and allow food-up at regular daily
     tide cycles. Similarly, stream restorations should be
     engineered to keep water moving.                          Mosquito control can be accomplished with prevention
                                                               techniques, habitat management practices, pesticides,
     Marsh alterations, whether for source reduction           and biological controls. Each Regional offce’s
     or marsh enhancement have not been without                Integrated Pest Management (IPM) Coordinator
     unintended consequences. Ditches used to drain            reviews proposed uses of pesticides in coordination
     mosquito breeding habitat on the East Coast also          with the National IPM Coordinator. The public
     drained high marsh pools and salt pannes important        health authority or mosquito control organizations
     for waterfowl and shorebirds (Cottam 1938).               and the Refuge Manager must use data from various
     Projects designed to restore natural hydrology may        sources (e.g. scientifc literature) to identify control
     also fail if, after restoration, they produce excessive   products and ensure new products and technologies
     mosquito populations adjacent to local communities        are reviewed as they become available. The MMP
     where there previously was not a mosquito breeding        should include all potential products that may be
     issue. For this reason, we should continually make        used. In most instances, refuge staffs do not apply
     efforts to develop integrated, ecologically-sound         pesticides for the control of mosquitoes. If the Refuge
     approaches for marsh alteration that not only             Manager authorizes mosquito pesticide application
     restores natural function, but also does not create       through a SUP, the pesticide may be applied by
     mosquito breeding habitats.                               the public health authority or a mosquito control
                                                               organization. The Refuge Manager must understand
     The decision to consider a particular marsh for           the treatment options and consequent risks to
     physical alterations should begin with local, site-       non-target resources, and require the use of IPM
     specifc data and documentation that describes the         principles to minimize pesticide use and impacts.
     need for a management decision. If physical marsh         Refuge staff may work with the Regional IPM
     management is appropriate, the Refuge Manager             Coordinator or Service environmental contaminants
     may invite a technical advisory committee (TAC) of        staff to make an appropriate choice of pesticide-based
     Service staff and external scientists as well as local    control products. Use local mosquito monitoring
     partners, such as mosquito control organizations, to      data provided by the public health authority or the
     help evaluate a suite of potential marsh alterations.     mosquito control organization when considering
     The TAC recommendations may include type, extent,         the pesticide products. Pesticide active ingredients
     intensity of alterations, and physical and biological     described below can be used to develop an MMP
     metrics for post-alteration monitoring. Use BMPs          and to prepare for discussions with public health
     during restoration to avoid heavy equipment ruts,         authorities or mosquito control organizations.
     fll subsidence, or any other action that may result in
     unintended temporary pools of standing water.

12                                            Handbook for Mosquito Management on National Wildlife Refuges
a month of control, rather than the few
Mosquito Control Pesticides                                        hours or days provided by fogging with
                                                                   adulticides
Mosquito control pesticides can be categorized into            •   The commonly used mosquito larvicides
three classes: larvicides, pupacides, and adulticides.             are less toxic than the adulticides and are
There are relatively few products available within                 applied in such a way that there is much
each of these classes, and all differ with regard to               less human exposure
effcacy and effects on non-target organisms. Active            •   Mosquito larvicides generally are applied
ingredients in these pesticide products may include:               to smaller areas than are adulticides
chemicals, naturally occurring bacteria, analogs of
insect molting hormones, and monomolecular oils as        Larvicides. Larvicides are pesticides that
well as inert ingredients. The USEPA registration         affect the four instars of mosquitoes. The most
process for pesticide products considers primarily the    common mosquito larvicides are derived from
toxicity and environmental persistence of the active      natural bacteria or act on insect-specifc pathways
ingredient. In many pesticide products, the active        not shared by other insect species. Spinosad,
ingredient is combined with “inert” ingredients that      s-methoprene, and Bacillus-based Bacillus
alter the environmental behavior of the chemical.         thuringiensis israelensis (Bti) or Lysinibacillus
All inert ingredients in USEPA registered pesticide       sphaericus (Ls), the main active ingredients,
products are pre-approved before being used in a          have unique routes of exposure and modes of
pesticide product formulation (USEPA 2015). These         toxicological action against larval mosquitoes. The
inert ingredients are added to increase activity or       route of exposure and mode of action infuence
modify a physical property such as increase the           their non-target toxicity relative to each other
bulk of the product, lengthen its persistence in the      and to other types of chemical insecticides. They
environment, or otherwise improve its ability to reach    can be applied through a variety of methods
the target species. While these inert ingredients are     including hand application via backpack sprayers,
not intended to have non-target toxicity, in some cases   low-pressure amphibious tracked vehicles, truck-
they do.                                                  mounted equipment, and aerial sprayers. Spinosad
                                                          and s-methoprene work via contact rather than
If mosquito control measures using pesticides are         ingestion. Bacillus-based products have lower
necessary, the Refuge Manager’s next goal is to           risk to non-target organisms in part because they
ensure that the public health authority or mosquito       must be ingested by the insect and are activated
control organization selects products for on-refuge       at a high pH that occurs almost solely in the gut
use that minimize natural resource non-target             of mosquitoes, midges, and black fies. As with all
impacts. Products allowed for use on-refuge should        pesticide use in the Service, we review and approve
correspond with the information known about:              or decline to approve the use of larvicides through
                                                          the Pesticide Use Proposal System.
     •   Mosquito species and targeted life stage
     •   The breeding habitat                             Preferred Active Ingredients
     •   Density of larval populations                    Bacillus thuringiensis israelensis (Bti) is a natural
     •   Temperature                                      soil bacterium that acts as a larval mosquito
     •   Effcacy of the products                          stomach poison. Bti must be ingested by the larval
     •   Potential impacts to non-target resources        form of the insect in order to be effective. Bti
     •   Resistance management                            contains crystalline structures that have protein
     •   Costs                                            endotoxins that are activated in the alkaline
                                                          conditions of an insect’s gut. These toxins attach
Following the long-standing IPM principles, the           to specifc receptor sites on the gut wall and,
Service continually strives to minimize exposure of       when activated, destroy the lining of the gut and
non-target refuge natural resources to pesticides.        eventually kill the insect. The toxicity of Bti to an
Therefore, in general mosquito adulticide products        insect is directly related to the specifcity of the
are not used on refuges. Larvicides are preferred         toxin and the receptor sites. Without the proper
over mosquito adulticides for several reasons:            receptor sites, the Bti will pass through the insect’s
                                                          gut. Bti is most effective on frst, second, third and
     •   Use of mosquito larvicides prevents the          early fourth instar larvae. The earlier instars feed
         appearance of the blood feeding adults           at a faster rate (late fourth instar larvae feed very
     •   Mosquito larvicides can provide up to            little) and require ingestion of fewer crystals to

Handbook for Mosquito Management on National Wildlife Refuges                                                      13
induce mortality. Bti has been shown to have toxic       the mosquito larvae will continue to feed and may
     activity against mosquitoes, black fies, and certain     reach pupal stage, but the S-methoprene interferes
     species of midge; no direct effects of Bti toxicity      with the maturation of the pupa and they will not
     have been found for aquatic invertebrates and this       emerge as adults. The mosquito third and fourth
     profle is preferred for use on a refuge. Bti has         larval instars are the most susceptible stages of
     limited acute and no chronic toxicity to mammals,        development when exposed to S-methoprene.
     birds, fsh, or vascular plants (USEPA 1998). Bti-        Mammals, birds, fsh, reptiles, and amphibians do
     based products with labels indicating effcacy for        not have this juvenile hormone nor do they share
     1-2 weeks are preferred for use on refuges, however      this biochemical pathway, which is what makes
     a number of product labels indicate effcacy for up       S-methoprene a relatively targeted insecticide.
     to 40 days, and the activity of Briquet formulations     S-methoprene is essentially non-toxic to mammals,
     can last for months.                                     has some limited toxicity to birds, amphibians, fsh,
                                                              and certain non-target freshwater invertebrates,
     Lysinibacillus sphaericus (Ls) is a registered           and some marine crustaceans, that share
     larvicide, and few feld studies have examined            similar biochemical pathways to those on which
     its non-target effects. Data available indicate a        S-methoprene acts in target organisms. Hormones
     high degree of specifcity of Ls for mosquitoes,          act on biological systems at exceedingly low levels,
     with no demonstrated toxicity to midge larvae at         thus, a very low concentration of S-methoprene
     mosquito control application rates (Mulla 1984; Ali      is required in the environment to control target
     1986; Lacey 1990; and Rodcharoen 1991). Some Ls          organisms. This fact, combined with its low toxicity
     product labels indicate effects lasting for as long as   to birds and mammals makes S-methoprene a useful
     four weeks.                                              mosquito larvicide alternative that can be used in
                                                              an integrated approach. Products are available
     Less Preferred Active Ingredients                        in several formulations: liquid, granular, pellet,
     Spinosad is derived from two fermentation                and briquette. There are several extended-release
     products of a soil actinomycete bacteria                 formulations that remain effective for up to 150
     (Saccharopolyspora spinosa), the spinosyns A             days. Due to the fact that S-methoprene can act
     and D. Spinosad is a contact neurotoxin that             on invertebrates that share the juvenile hormone
     disrupts the nicotinic acetylcholine receptors in        and biochemical mode of action as well as the active
     insects. This mode of action is similar to that of       ingredients persistence, it is less preferred for use
     the neonicotinoid insecticides, and similar to the       on refuges (Pinkney et al. 2000).
     organophosphates which act on a different receptor
     in the same biochemical system. Due to the mode          Not Recommended for Use on Refuges
     of action on a pathway that is conserved across          Organophosphate mosquito larvicides (e.g.,
     taxa, spinosad acts on a broad array of insects.         temephos) inhibit the enzyme acetylcholinesterase
     Products designed to increase the environmental          by binding it irreversibly and cause cumulative
     persistence of spinosad have been found to enable        effects in animals repeatedly exposed to these
     target (mosquito) and non-target toxic effects           chemicals. This biochemical pathway is essential
     that can persist for several weeks (Duchet et al.        to nerve function in insects, humans, and other
     2015; Lawler and Dritz 2013). Due to spinosad’s          animals, and the effects of exposure are cumulative,
     mode of action that impacts a diversity of aquatic       therefore, safer alternatives are preferred.
     invertebrates and its persistence, this active           The USEPA banned most residential uses of
     ingredient is less preferred for use on-refuge than      organophosphates in 2001, but they are still used in
     the Bacillus-based products.                             agriculture and for control of larval mosquitoes.

     S-methoprene is a synthetic mimic of the naturally       Surface Oils and Films. Surface oils and flms are
     produced insect juvenile hormone (JH); it is             applied to aquatic mosquito breeding sites to kill
     commonly referred to as an insect growth regulator.      mosquito larvae and pupae. The products create a
     Mosquitoes produce JH in the larval stages,              barrier to the air-water interface and suffocate the
     with the highest levels occurring in the early           insects, which generally require periodic contact
     developmental stages. As an insect reaches the           with the water surface to obtain oxygen. Surface
     fnal stages of larval development, the JH level is       oils can prevent female mosquitoes from landing
     low. This low level of JH triggers the development       to lay eggs. Due to the broad-spectrum action of
     of adult characteristics. When S-methoprene is           surface oils and flms, they are not appropriate
     applied directly to larval mosquito breeding habitat,    and are rarely authorized for use on refuges. The

14                                             Handbook for Mosquito Management on National Wildlife Refuges
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